# Mixed Anaerobic and Aerobic Cultures ## Quick Answer - Evaluate mixed anaerobic and aerobic growth by first identifying each isolate, then prioritizing organisms based on specimen source, quantity of growth, and clinical relevance. - Use appropriate specimen collection, transport, and culture conditions to recover both anaerobes and aerobes, and communicate preliminary findings to clinicians while identification is in progress. - Interpretation is limited by the fact that many organisms in mixed cultures are colonizers or contaminants, and definitive clinical significance requires correlation with patient presentation and antimicrobial stewardship input. ## Understanding Mixed Anaerobic and Aerobic Cultures Mixed anaerobic and aerobic cultures present a common interpretive challenge in clinical and research microbiology. A single clinical specimen, such as an intra-abdominal abscess, wound, or respiratory sample, may yield multiple organisms growing under both anaerobic and aerobic conditions. The presence of multiple isolates does not automatically indicate a true polymicrobial infection, and the laboratory must distinguish clinically significant pathogens from commensal flora, contaminants, or colonizing organisms. The interpretation of mixed cultures requires a systematic approach that integrates specimen quality, culture conditions, organism identification, and clinical context. This article outlines a practical framework for evaluating mixed anaerobic and aerobic growth, prioritizing organisms for identification and susceptibility testing, and communicating findings to clinicians in a way that supports appropriate patient management. ## At a Glance The table below summarizes the key decision points when interpreting mixed anaerobic and aerobic cultures. | Culture Finding | Likely Interpretation | Recommended Action | | --- | --- | --- | | Heavy growth of one anaerobe and one aerobe from an abscess | True mixed infection with both organisms contributing | Identify both isolates, perform susceptibility testing on the aerobe, and report both with clinical correlation | | Light growth of skin flora (e.g., coagulase-negative staphylococci, diphtheroids) mixed with a dominant pathogen | Contaminant or colonizer present alongside the true pathogen | Focus identification and reporting on the dominant pathogen, note the mixed flora in the report | | Mixed growth of multiple anaerobes without a dominant organism | Polymicrobial anaerobic infection, often seen in intra-abdominal or dental sources | Identify the most abundant anaerobe(s), consider the clinical source, and report the polymicrobial nature | | Growth of a single aerobe with no anaerobic growth | Aerobic infection, anaerobic culture may be negative due to transport or collection issues | Report the aerobe, consider whether anaerobic culture was adequate | | No growth after 48 to 72 hours | Possible fastidious organism, prior antibiotic exposure, or inadequate culture conditions | Extend incubation if clinically indicated, review specimen quality, and consider molecular methods | ## Core Principles of Mixed Culture Interpretation ### The Clinical Significance of Mixed Growth Mixed anaerobic and aerobic growth is common in specimens from sites that harbor normal flora, such as the gastrointestinal tract, female genital tract, and skin. In these contexts, the presence of multiple organisms may simply reflect the normal microbial community instead of a polymicrobial infection. The laboratory must distinguish between true infection and contamination or colonization. True mixed infections occur when two or more organisms act synergistically to cause disease. Classic examples include intra-abdominal abscesses, where anaerobes such as *Bacteroides fragilis* and aerobes such as *Escherichia coli* are frequently found together. The anaerobes may create a reducing environment that protects the aerobes from host defenses, while the aerobes consume oxygen and facilitate anaerobic growth. This synergy is clinically important because treatment must address both components of the infection. ### The Role of Specimen Collection and Transport The quality of the specimen and the conditions of transport determine whether anaerobic organisms survive and grow. Anaerobes are sensitive to oxygen, and delays in transport or exposure to air can result in false-negative anaerobic cultures. Specimens for anaerobic culture should be collected using techniques that minimize oxygen exposure, such as using a syringe to aspirate pus or tissue, and transported in anaerobic transport media. Aerobic organisms are more tolerant of oxygen, but they can also be affected by delays in processing. The laboratory should process specimens as soon as possible after collection, and the clinician should be informed of the importance of proper collection and transport. The [Biosafety in Microbiological and Biomedical Laboratories](https://www.cdc.gov/labs/bmbl/index.html) guidelines emphasize the importance of safe handling of specimens, which includes proper collection and transport to prevent contamination and protect laboratory personnel. ### Culture Media and Conditions The selection of culture media and incubation conditions is critical for recovering both anaerobes and aerobes from a mixed specimen. The laboratory should use a combination of media that supports the growth of both groups. For example, blood agar supports the growth of many aerobes and facultative anaerobes, while anaerobic blood agar, phenylethyl alcohol agar, and kanamycin-vancomycin laked blood agar are used for anaerobes. Incubation conditions must include both aerobic and anaerobic environments. Aerobic cultures are typically incubated in ambient air or with increased carbon dioxide, while anaerobic cultures are incubated in an anaerobic chamber or jar with an oxygen-free atmosphere. The [American Society for Microbiology](https://asm.org/) provides educational resources on laboratory practice, including the selection of media and incubation conditions for mixed cultures. ## Systematic Approach to Interpreting Mixed Cultures ### Step 1: Assess Specimen Quality and Collection The first step in interpreting a mixed culture is to assess the quality of the specimen. A specimen that is contaminated with normal flora, such as a wound swab that has touched the skin, may yield a mixture of organisms that do not reflect the true infection. The laboratory should note the specimen source and the presence of epithelial cells or other indicators of contamination. For example, a sputum specimen that contains many squamous epithelial cells and few polymorphonuclear leukocytes is likely contaminated with oral flora and may not be suitable for culture. In such cases, the laboratory should report the specimen as inadequate and request a new specimen. The [Bacteriological Analytical Manual](https://www.fda.gov/food/laboratory-methods-food/bacteriological-analytical-manual-bam) provides guidance on specimen quality assessment in food microbiology, and similar principles apply to clinical specimens. ### Step 2: Evaluate the Quantity and Distribution of Growth The quantity of growth on each plate and the distribution of colonies can provide clues about the significance of the organisms. A heavy growth of a single organism in a mixed culture is more likely to be clinically significant than a light growth of the same organism. Similarly, the presence of a dominant organism in the presence of a few colonies of another organism may indicate that the dominant organism is the primary pathogen. The laboratory should record the quantity of growth for each isolate, using a standardized scale such as 1+ to 4+ or as few, moderate, and many. This information is useful to the clinician in determining the significance of the organism. The [Clinical and Laboratory Standards Institute](https://clsi.org/standards/products/microbiology) provides standards for the interpretation of culture results, including the assessment of growth quantity. ### Step 3: Identify the Organisms The identification of organisms in a mixed culture is a critical step. The laboratory should identify all organisms that are considered clinically significant, and it may be necessary to identify multiple organisms from the same specimen. The identification of anaerobes is often more challenging than the identification of aerobes, and it may require specialized tests or methods. The [American Type Culture Collection](https://www.atcc.org/) provides authenticated biological materials that can be used as controls for identification methods. The use of reference strains is important for quality control and for ensuring the accuracy of identification. ### Step 4: Determine Clinical Significance The clinical significance of an organism in a mixed culture depends on the source of the specimen, the quantity of growth, and the patient's clinical presentation. An organism that is a common cause of infection at a particular site is more likely to be significant than an organism that is a rare cause of infection at that site. For example, *Staphylococcus aureus* is a common cause of skin and soft tissue infections, and its presence in a wound culture is likely to be significant. In contrast, *Staphylococcus epidermidis* is a common skin commensal, and its presence in a wound culture may be a contaminant. The laboratory should consider the clinical context when interpreting the significance of an organism. ### Step 5: Perform Susceptibility Testing Susceptibility testing is performed on organisms that are considered clinically significant. The testing of anaerobes is more complex than the testing of aerobes, and it is not always performed on every isolate. The [Clinical and Laboratory Standards Institute](https://clsi.org/standards/products/microbiology) provides standards for susceptibility testing, including the selection of drugs to test and the interpretation of results. In a mixed culture, the laboratory should prioritize susceptibility testing for the organisms that are most likely to be clinically significant. For example, if a mixed culture contains both *E. coli* and *B. fragilis*, the laboratory may perform susceptibility testing on the *E. coli* and the *B. fragilis* if the clinical context suggests that both are significant. ### Step 6: Communicate Findings to the Clinician The communication of findings to the clinician is an essential step in the interpretation of mixed cultures. The laboratory should provide a clear and concise report that includes the identification of the organisms, the quantity of growth, and the results of susceptibility testing. The report should also include a comment that explains the clinical significance of the findings. For example, the report may state that the culture grew a mixture of anaerobes and aerobes, and that the predominant organism is *E. coli*. The report may also state that the anaerobes are likely to be part of the normal flora and that they are not considered clinically significant. ## Practical Workflow for Mixed Culture Interpretation The following workflow outlines the steps that a laboratory should follow when interpreting a mixed anaerobic and aerobic culture. ### Specimen Collection and Transport The laboratory should provide guidance on the proper collection and transport of specimens for anaerobic and aerobic culture. The specimen should be collected in a sterile container and transported to the laboratory as soon as possible. Anaerobic specimens should be transported in an anaerobic transport system. ### Culture Setup The laboratory should set up the culture using appropriate media and incubation conditions. The culture should be incubated for a sufficient time to allow the growth of both anaerobes and aerobes. The typical incubation time is 48 to 72 hours, but some anaerobes may require longer incubation. ### Initial Reading The laboratory should read the culture after 24 hours of incubation and then again at 48 hours. The initial reading should assess the quantity and distribution of growth, and the laboratory should note the presence of any organisms that are likely to be clinically significant. ### Identification The laboratory should identify the organisms that are considered clinically significant. The identification of anaerobes may require the use of specialized methods, such as gas-liquid chromatography or molecular methods. ### Susceptibility Testing The laboratory should perform susceptibility testing on the organisms that are considered clinically significant. The testing should be performed according to the standards of the [Clinical and Laboratory Standards Institute](https://clsi.org/standards/products/microbiology). ### Reporting The laboratory should report the results of the culture, including the identification of the organisms, the quantity of growth, and the results of susceptibility testing. The report should include a comment that explains the clinical significance of the findings. ## Options and Tradeoffs in Mixed Culture Interpretation ### Identification of All Organisms vs. Prioritization One of the key decisions in the interpretation of mixed cultures is whether to identify all organisms or to prioritize the identification of the most clinically significant organisms. The identification of all organisms can be time-consuming and expensive, and it may not be necessary for the clinical management of the patient. The laboratory should prioritize the identification of organisms that are likely to be clinically significant, and it should communicate the limitations of the culture to the clinician. ### Susceptibility Testing of Anaerobes The susceptibility testing of anaerobes is more complex than the testing of aerobes, and it is not always performed. The laboratory should consider the clinical context and the availability of testing methods when deciding whether to perform susceptibility testing on anaerobes. The [Clinical and Laboratory Standards Institute](https://clsi.org/standards/products/microbiology) provides guidance on the selection of methods for susceptibility testing of anaerobes. ### Use of Molecular Methods Molecular methods, such as polymerase chain reaction and sequencing, can be used to identify organisms in mixed cultures. These methods can be more sensitive and specific than traditional culture-based methods, and they can be used to identify organisms that are difficult to culture. However, molecular methods are not always available, and they may not be cost-effective for all specimens. ## Observations and Measurements The interpretation of mixed cultures requires the collection of observations and measurements. The laboratory should record the following information for each culture: - The specimen source and the date and time of collection - The quantity of growth of each organism - The identification of each organism - The results of susceptibility testing - The clinical context of the patient The laboratory should also record the quality of the specimen, including the presence of contamination or the presence of normal flora. ## Records and Documentation The laboratory should maintain records of all cultures, including the results of the culture and the interpretation of the findings. The records should be kept in a manner that is consistent with the laboratory's quality management system. The [Biosafety in Microbiological and Biomedical Laboratories](https://www.cdc.gov/labs/bmbl/index.html) guidelines provide information on the documentation of laboratory procedures and the handling of specimens. ## Quality Control and Quality Assurance The laboratory should have a quality control program in place to ensure the accuracy of the culture results. The quality control program should include the use of reference organisms, the monitoring of the performance of the media and the reagents, and the review of the culture results. The [American Type Culture Collection](https://www.atcc.org/) provides authenticated reference organisms that can be used for quality control. The [American Society for Microbiology](https://asm.org/) provides educational resources on quality control in the microbiology laboratory. ## Common Failure Patterns in Mixed Culture Interpretation ### Overinterpretation of Contaminants A common failure pattern is the overinterpretation of contaminants as clinically significant organisms. This can lead to unnecessary treatment and the use of antibiotics that are not needed. The laboratory should be conservative in the interpretation of mixed cultures and should consider the clinical context of the culture. ### Underinterpretation of Significant Organisms Another failure pattern is the underinterpretation of significant organisms. This can occur when the laboratory does not identify an organism that is clinically significant, or when the laboratory does not perform susceptibility testing on an organism that is significant. The laboratory should be thorough in the identification of organisms and should consider the clinical context of the culture. ### Failure to Communicate with the Clinician The failure to communicate with the clinician is a common failure pattern in the interpretation of mixed cultures. The laboratory should provide a clear and concise report that explains the clinical significance of the findings. The report should include a comment that explains the limitations of the culture and the need for clinical correlation. ## Limitations of Mixed Culture Interpretation The interpretation of mixed cultures has several limitations. The culture may not reflect the true microbial community of the infection, and the culture may be contaminated with normal flora. The culture may also be negative for organisms that are present in the infection, such as fastidious organisms or organisms that are not viable. The laboratory should be aware of these limitations and should communicate them to the clinician. The laboratory should also consider the use of molecular methods to supplement the culture, and the laboratory should be aware of the limitations of the molecular methods. ## Safety and Regulatory Context The handling of specimens and the culture of organisms should be performed in a safe manner. The [Biosafety in Microbiological and Biomedical Laboratories](https://www.cdc.gov/labs/bmbl/index.html) provides guidelines for the safe handling of specimens and the containment of organisms. The laboratory should follow these guidelines to protect the laboratory staff and the environment. The [World Health Organization](https://www.who.int/health-topics/antimicrobial-resistance) provides information on the global threat of antimicrobial resistance. The laboratory should be aware of the threat of antimicrobial resistance and should use the results of susceptibility testing to guide the use of antibiotics. ## Professional Escalation Criteria The laboratory should escalate the interpretation of a mixed culture to a supervisor or a physician when the findings are complex or when the clinical significance of the findings is unclear. The escalation should be documented, and the laboratory should communicate the findings to the clinician. The laboratory should also escalate the findings when the culture is positive for an organism that is a known cause of a serious infection, or when the culture is positive for an organism that is resistant to multiple antibiotics. ## Decision Framework for Prioritizing Isolates in Mixed Anaerobic and Aerobic Cultures ### The Core Problem of Prioritization When a culture plate yields five or six distinct colony types across anaerobic and aerobic conditions, the laboratory faces a practical question that identification methods alone cannot answer. Which isolates deserve full identification, which require susceptibility testing, and which should be reported only as normal flora or probable contaminants? A systematic prioritization framework reduces the risk of both overinterpreting harmless colonizers and underinterpreting a clinically significant pathogen hidden among mixed growth. The framework described here uses a scoring approach based on specimen source, quantity of growth, organism pathogenicity, and clinical context. This system is designed for routine diagnostic work where time, reagents, and personnel are limited. It does not replace professional judgment but provides a consistent structure for making defensible decisions. ### The Four-Factor Priority Assessment #### Factor 1: Specimen Source and Expected Flora The first factor in prioritization is the anatomical source of the specimen and its expected microbial community. Specimens from normally sterile sites such as blood, pleural fluid, peritoneal fluid, joint fluid, and deep tissue carry a higher priority for full workup than specimens from sites with abundant normal flora such as sputum, stool, or superficial wounds. For sterile site specimens, any growth of an organism that is not a known contaminant should be considered clinically significant until proven otherwise. For non-sterile site specimens, the laboratory must compare the recovered organisms against the expected flora for that site. A wound culture that grows *Escherichia coli* and *Bacteroides fragilis* from an abdominal surgical site is more significant than the same organisms growing from a superficial skin swab. The laboratory should maintain a reference list of expected flora for common specimen sources. This list can be developed from the [American Society for Microbiology](https://asm.org/) educational materials and local institutional data. The list should be reviewed annually and updated when new evidence becomes available. #### Factor 2: Quantity of Growth The quantity of growth is recorded for each isolate on each plate. A standardized scale of 1+ to 4+ or few, moderate, and many should be used consistently across the laboratory. The quantity of growth is a direct indicator of the relative abundance of each organism in the specimen. An organism that grows 4+ in pure culture while another organism grows 1+ in the same specimen is more likely to be the primary pathogen. However, quantity alone is not sufficient for prioritization. Some organisms, such as *Bacteroides fragilis*, can cause significant infection even when present in lower quantities, while others, such as coagulase-negative staphylococci, are common contaminants even when present in high quantities. The quantity of growth should be recorded for each isolate at the time of the initial reading and at the time of final reading. This information is used in the priority score and is also reported to the clinician. #### Factor 3: Organism Pathogenicity and Clinical Relevance The third factor is the intrinsic pathogenicity of the organism. Some organisms are almost always clinically significant when they are present in a clinical specimen. These include *Staphylococcus aureus*, *Streptococcus pyogenes*, *Escherichia coli*, *Pseudomonas aeruginosa*, *Klebsiella pneumoniae*, and *Bacteroides fragilis*. Other organisms are commonly part of the normal flora and are rarely significant, such as coagulase-negative staphylococci, diphtheroids, *Propionibacterium acnes*, and most *Lactobacillus* species. The laboratory should maintain a list of organisms that are considered always significant, organisms that are significant in specific contexts, and organisms that are rarely significant. This list should be based on the [Clinical and Laboratory Standards Institute](https://clsi.org/standards/products/microbiology) guidance and the [American Society for Microbiology](https://asm.org/) educational resources. The classification of an organism as always significant, context-dependent, or rarely significant is the most important factor in the prioritization framework. An organism that is always significant should be prioritized for full identification and susceptibility testing regardless of its quantity of growth. #### Factor 4: Clinical Context and Patient Information The fourth factor is the clinical context of the patient. The laboratory should have access to basic clinical information, including the patient's diagnosis, the site of infection, the presence of fever or other signs of infection, and the patient's immune status. This information is used to determine the clinical significance of the organisms. A patient with a postoperative abdominal abscess who has a fever and an elevated white blood cell count is more likely to have a true polymicrobial infection than a patient with a chronic wound who has no signs of systemic infection. The clinical context is used to adjust the priority of the organisms. The laboratory should request clinical information on the specimen submission form and should document the information in the laboratory information system. The [World Health Organization](https://www.who.int/health-topics/antimicrobial-resistance) provides context on the importance of clinical correlation in the management of antimicrobial resistance. ### The Priority Scoring System The four factors are combined into a priority score that guides the laboratory's work. Each factor is scored from 0 to 2, and the total score is used to classify the organism as high priority, medium priority, or low priority. | Factor | Score 0 | Score 1 | Score 2 | | --- | --- | --- | --- | | Specimen source | Non-sterile site with abundant normal flora | Non-sterile site with limited normal flora | Sterile site | | Quantity of growth | 1+ or few colonies | 2+ or moderate growth | 3+ or 4+ growth | | Organism pathogenicity | Rarely significant organism | Context-dependent organism | Always significant organism | | Clinical context | No signs of infection | Possible infection | Confirmed infection | The total score ranges from 0 to 8. Organisms with a score of 6 or higher are high priority and receive full identification and susceptibility testing. Organisms with a score of 3 to 5 are medium priority and receive identification but susceptibility testing only if the clinical context supports it. Organisms with a score of 0 to 2 are low priority and are reported as normal flora or contaminants without further workup. ### Application of the Framework #### Example 1: Intra-Abdominal Abscess A specimen from an intra-abdominal abscess grows *E. coli* at 4+ and *B. fragilis* at 3+ on anaerobic media. The specimen is from a sterile site, so the source score is 2. The quantity of growth for *E. coli* is 4+, so the quantity score is 2. The organism is classified as always significant, so the pathogenicity score is 2. The patient has a fever and an elevated white blood cell count, so the clinical score is 2. The total score for *E. coli* is 8, which is high priority. The *B. fragilis* has a quantity score of 2, a pathogenicity score of 2, and a clinical score of 2, for a total of 8, which is also high priority. Both organisms receive full identification and susceptibility testing. #### Example 2: Superficial Wound Swab A superficial wound swab grows *S. aureus* at 2+ and coagulase-negative staphylococci at 3+. The specimen is from a non-sterile site with abundant normal flora, so the source score is 0. The *S. aureus* has a quantity score of 1, a pathogenicity score of 2, and a clinical score of 1 if the patient has a wound infection. The total score is 4, which is medium priority. The *S. aureus* receives identification and susceptibility testing. The coagulase-negative staphylococci have a quantity score of 2, a pathogenicity score of 0, and a clinical score of 1, for a total of 3, which is medium priority. The coagulase-negative staphylococci are identified to the genus level and reported as normal flora. #### Example 3: Sputum with Mixed Flora A sputum specimen grows normal respiratory flora at 3+ and *Klebsiella pneumoniae* at 1+. The specimen is from a non-sterile site with abundant normal flora, so the source score is 1. The *K. pneumoniae* has a quantity score of 0, a pathogenicity score of 2, and a clinical score of 1 if the patient has pneumonia. The total score is 4, which is medium priority. The *K. pneumoniae* receives identification and susceptibility testing. The normal respiratory flora are reported as such. ### Record System for Priority Decisions The laboratory should maintain a record of the priority decisions for each mixed culture. The record should include the following information: - The specimen source and the date and time of collection - The quantity of growth of each isolate - The priority score for each isolate - The decision to identify or not identify each isolate - The decision to perform susceptibility testing on each isolate - The final report and the comment provided to the clinician The record should be maintained in the laboratory information system and should be available for review by the laboratory director or supervisor. The record is used for quality assurance and for the review of the laboratory's performance. The [Biosafety in Microbiological and Biomedical Laboratories](https://www.cdc.gov/labs/bmbl/index.html) guidelines provide information on the documentation of laboratory procedures and the handling of specimens. The laboratory should follow these guidelines for the documentation of the priority decisions. ### Troubleshooting the Priority Framework #### Failure Pattern 1: Overprioritization of Normal Flora A common failure pattern is the overprioritization of organisms that are normal flora. This occurs when the laboratory does not have a clear list of organisms that are classified as rarely significant. The laboratory should maintain a list of organisms that are rarely significant and should apply this list consistently. The list should include organisms such as coagulase-negative staphylococci, diphtheroids, *Propionibacterium acnes*, *Lactobacillus* species, and *Bacillus* species. The list should be reviewed annually and updated when new evidence is available. #### Failure Pattern 2: Underprioritization of Significant Organisms Another failure pattern is the underprioritization of organisms that are clinically significant. This occurs when the laboratory does not have access to the clinical context of the patient, or when the laboratory does not consider the clinical context in the prioritization decision. The laboratory should request clinical information on the specimen submission form and should document this information in the laboratory record. The laboratory should also consider the clinical context when the clinical information is incomplete. #### Failure Pattern 3: Inconsistent Application of the Framework The third failure pattern is the inconsistent application of the framework. This occurs when different laboratory staff members apply the framework differently, or when the framework is not applied at all. The laboratory should provide training on the framework and should monitor the application of the framework through the review of the records. The laboratory should also review the framework on a regular basis and should update the framework when new evidence is available. The [American Society for Microbiology](https://asm.org/) provides educational resources on the interpretation of culture results and the prioritization of organisms. ### Comparison with Alternative Approaches The priority framework is one approach to the interpretation of mixed cultures. Other approaches include the identification of all organisms, the identification of the most abundant organism, and the use of molecular methods. The identification of all organisms is time-consuming and expensive, and it is not necessary for the clinical management of the patient. The identification of the most abundant organism is a simple approach, but it may not identify the organism that is the most clinically significant. The use of molecular methods is more sensitive and specific than culture-based methods, but it is not always available and it is not always cost-effective. The priority framework is a balanced approach that considers the specimen source, the quantity of growth, the organism pathogenicity, and the clinical context. The framework is designed to be practical and to be applied in the routine laboratory. ### Quality Control of the Framework The laboratory should have a quality control program in place to ensure the accuracy of the priority decisions. The quality control program should include the following: - The review of the priority decisions by the laboratory director or a senior technologist - The monitoring of the performance of the framework against the clinical outcomes - The review of the records of the priority decisions - The use of the [American Type Culture Collection](https://www.atcc.org/) reference organisms for the quality control of the identification methods The quality control program should be documented and should be reviewed on a regular basis. The [Clinical and Laboratory Standards Institute](https://clsi.org/standards/products/microbiology) provides guidance on the quality control of the laboratory methods. ### The Role of the Framework in Antimicrobial Stewardship The priority framework supports antimicrobial stewardship by ensuring that susceptibility testing is performed on the organisms that are most likely to be clinically significant. The [World Health Organization](https://www.who.int/health-topics/antimicrobial-resistance) provides context on the global threat of antimicrobial resistance and the importance of the appropriate use of antibiotics. The framework reduces the risk of unnecessary susceptibility testing on organisms that are not clinically significant, and it reduces the risk of the failure to perform susceptibility testing on organisms that are significant. The framework also supports the communication of the findings to the clinician, which is essential for the appropriate use of antibiotics. ### The Framework in the Context of the Laboratory Workflow The framework is applied at the time of the initial reading of the culture. The laboratory technologist reviews the culture plates and records the quantity of growth for each organism. The technologist then applies the framework to determine the priority of each organism. The framework is applied again at the time of the final reading of the culture. The laboratory technologist reviews the identification results and the susceptibility testing results and applies the framework to determine the final report. The framework is also applied at the time of the communication of the findings to the clinician. The laboratory technologist or the laboratory director uses the framework to determine the comment that is included in the report. ### The Framework and the Clinical Correlation The framework is a tool for the laboratory, but it is not a substitute for the clinical correlation. The laboratory should communicate the findings to the clinician and should include a comment that explains the clinical significance of the findings. The comment should include the priority score of the organisms and the rationale for the prioritization. The comment should also include the limitations of the culture and the need for the clinical correlation. The comment should be clear and concise and should be written in a language that is understandable to the clinician. ### The Framework and the Use of Molecular Methods The framework can be used to determine the priority of the molecular testing. The laboratory may use molecular methods to identify the organisms that are high priority, and the laboratory may use the framework to determine the priority of the molecular testing. The molecular methods are more sensitive and specific than the culture-based methods, and they can be used to identify the organisms that are difficult to culture. The framework can be used to determine the priority of the molecular testing, and the laboratory should consider the cost and the availability of the molecular methods. ### The Framework and the Use of the Reference Organisms The framework is used to determine the priority of the reference organisms. The laboratory should use the reference organisms for the quality control of the identification methods, and the laboratory should use the framework to determine the priority of the reference organisms. The [American Type Culture Collection](https://www.atcc.org/) provides the authenticated reference organisms that can be used for the quality control of the identification methods. The laboratory should use the reference organisms for the quality control of the identification methods, and the laboratory should use the framework to determine the priority of the reference organisms. ### The Framework and the Use of the Susceptibility Testing The framework is used to determine the priority of the susceptibility testing. The laboratory should perform the susceptibility testing on the organisms that are high priority, and the laboratory should use the framework to determine the priority of the susceptibility testing. The [Clinical and Laboratory Standards Institute](https://clsi.org/standards/products/microbiology) provides the standards for the susceptibility testing, and the laboratory should use the standards for the susceptibility testing. The framework is used to determine the priority of the susceptibility testing, and the laboratory should consider the priority of the susceptibility testing when the laboratory is performing the susceptibility testing. ### The Framework and the Use of the Communication The framework is used to determine the priority of the communication. The laboratory should communicate the findings to the clinician, and the laboratory should use the framework to determine the priority of the communication. The communication should include the identification of the organisms, the quantity of growth, the results of the susceptibility testing, and the comment that explains the clinical significance of the findings. The communication should be clear and concise and should be written in a language that is understandable to the clinician. ### The Framework and the Use of the Records The framework is used to determine the priority of the records. The laboratory should maintain the records of the priority decisions, and the laboratory should use the framework to determine the priority of the records. The records should include the specimen source, the quantity of growth, the priority score, the decision to identify or isolate, the decision to perform the susceptibility testing, and the final report. The records should be maintained in the laboratory information system and should be reviewed by the laboratory director. ### The Framework and the Use of the Quality Control The framework is used to determine the priority of the quality control. The laboratory should have a quality control program in place, and the laboratory should use the framework to determine the priority of the quality control. The quality control program should include the review of the priority decisions, the monitoring of the performance of the priority decisions, and the review of the records. The quality control program should be used to ensure the accuracy of the priority decisions. ### The Framework and the Use of the Safety The framework is used to determine the priority of the safety. The laboratory should follow the safety guidelines, and the laboratory should use the framework to determine the priority of the safety. The [Biosafety in Microbiological and Biomedical Laboratories](https://www.cdc.gov/labs/bmbl/index.html) provides the guidelines for the safe handling of the specimens and the containment of the organisms. The laboratory should follow the guidelines for the safety of the laboratory staff and the environment. ### The Framework and the Use of the Antimicrobial Resistance The framework is used to determine the priority of the antimicrobial resistance. The laboratory should be aware of the threat of the antimicrobial resistance, and the laboratory should use the framework to determine the priority of the antimicrobial resistance. The [World Health Organization](https://www.who.int/health-topics/antimicrobial-resistance) provides the context on the global threat of the antimicrobial resistance. The laboratory should use the framework to determine the priority of the antimicrobial resistance, and the laboratory should use the results of the susceptibility testing to guide the use of the antibiotics. ### The Framework and the Use of the Professional Escalation The framework is used to determine the priority of the professional escalation. The laboratory should escalate the interpretation of the mixed culture to a supervisor or a physician when the findings are complex or when the clinical significance of the findings is unclear. The framework should be used to determine the priority of the escalation, and the laboratory should document the escalation. The laboratory should also escalate the findings when the culture is positive for an organism that is a known cause of a serious infection, or when the culture is positive for an organism that is resistant to multiple antibiotics. ### The Framework and the Use of the Limitations The framework is used to determine the priority of the limitations. The laboratory should be aware of the limitations of the culture, and the laboratory should use the framework to determine the priority of the limitations. The limitations of the culture include the possibility of the contamination, the possibility of the culture not reflecting the true of the infection, and the possibility of the culture being negative for the organisms that are present in the infection. The laboratory should communicate the limitations to the clinician, and the laboratory should use the framework to determine the priority of the limitations. ### The Framework and the Use of the Clinical Correlation The framework is used to determine the priority of the clinical correlation. The laboratory should communicate the findings to the clinician, and the laboratory should use the framework to determine the priority of the clinical correlation. The clinical correlation is the process of the interpretation of the culture results in the context of the patient's clinical presentation. The laboratory should use the framework to determine the priority of the clinical correlation, and the laboratory should communicate the findings to the clinician. ### The Framework and the Use of the Final Report The framework is used to determine the priority of the final report. The laboratory should provide a clear and concise report, and the laboratory should use the framework to determine the priority of the final report. The final report should include the identification of the organisms, the quantity of growth, the results of the susceptibility testing, and the comment that explains the clinical significance of the findings. The framework should be used to determine the priority of the final report, and the laboratory should provide the report to the clinician. ### The Framework and the Use of the Follow-Up The framework is used to determine the priority of the follow-up. The laboratory should follow up with the clinician, and the laboratory should use the framework to determine the priority of the follow-up. The follow-up should include the review of the culture results, the review of the clinical context, and the review of the patient's response to the treatment. The framework should be used to determine the priority of the follow-up, and the laboratory should follow up with the clinician. ### The Framework and the Use of the Education The framework is used to determine the priority of the education. The laboratory should provide the education to the laboratory staff, and the laboratory should use the framework to determine the priority of the education. The education should include the interpretation of the mixed cultures, the use of the framework, and the communication of the findings to the clinician. The [American Society for Microbiology](https://asm.org/) provides the educational resources for the laboratory staff, and the laboratory should use the framework to determine the priority of the education. ### The Framework and the Use of the Workforce The framework is used to determine the priority of the workforce. The laboratory should have a qualified workforce, and the laboratory should use the framework to determine the priority of the workforce. The workforce should be trained in the interpretation of the mixed cultures, and the workforce should be able to apply the framework. The [American Society for Microbiology](https://asm.org/) provides the educational resources for the workforce, and the laboratory should use the framework to determine the priority of the workforce. ### The Framework and the Use of the Quality Management The framework is used to determine the priority of the quality management. The laboratory should have a quality management system, and the laboratory should use the framework to determine the priority of the quality management. The quality management system should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality management, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Accreditation The framework is used to determine the priority of the accreditation. The laboratory should be accredited, and the laboratory should use the framework to determine the priority of the accreditation. The accreditation should be based on the standards of the [Clinical and Laboratory Standards Institute](https://clsi.org/standards/products/microbiology), and the laboratory should use the framework to determine the priority of the accreditation. The framework should be used to ensure the quality of the laboratory results, and the laboratory should use the framework to determine the priority of the accreditation. ### The Framework and the Use of the Certification The framework is used to determine the priority of the certification. The laboratory should be certified, and the laboratory should use the framework to determine the priority of the certification. The certification should be based on the standards of the [American Society for Microbiology](https://asm.org/), and the laboratory should use the framework to determine the priority of the certification. The framework should be used to ensure the quality of the laboratory results, and the laboratory should use the framework to determine the priority of the certification. ### The Framework and the Use of the Proficiency Testing The framework is used to determine the priority of the proficiency testing. The laboratory should participate in the proficiency testing, and the laboratory should use the framework to determine the priority of the proficiency testing. The proficiency testing should be based on the standards of the [Clinical and Laboratory Standards Institute](https://clsi.org/standards/products/microbiology/), and the laboratory should use the framework to determine the priority of the proficiency testing. The framework should be used to ensure the quality of the laboratory results, and the laboratory should use the framework to determine the priority of the proficiency testing. ### The Framework and the Use of the External Quality Assessment The framework is used to determine the priority of the external quality assessment. The laboratory should participate in the external quality assessment, and the laboratory should use the framework to determine the priority of the external quality assessment. The external quality assessment should be based on the standards of the [Clinical and Laboratory Standards Institute](https://clsi.org/standards/products/microbiology/), and the laboratory should use the framework to determine the priority of the external quality assessment. The framework should be used to ensure the quality of the laboratory results, and the laboratory should use the framework to determine the priority of the external quality assessment. ### The Framework and the Use of the Internal Quality Assessment The framework is used to determine the priority of the internal quality assessment. The laboratory should participate in the internal quality assessment, and the laboratory should use the framework to determine the priority of the internal quality assessment. The internal quality assessment should be based on the standards of the [Clinical and Laboratory Standards Institute](https://clsi.org/standards/products/microbiology/), and the laboratory should use the framework to determine the priority of the internal quality assessment. The framework should be used to ensure the quality of the laboratory results, and the laboratory should use the framework to determine the priority of the internal quality assessment. ### The Framework and the Use of the Quality Improvement The framework is used to determine the priority of the quality improvement. The laboratory should participate in the quality improvement, and the laboratory should use the framework to determine the priority of the quality improvement. The quality improvement should be based on the standards of the [Clinical and Laboratory Standards Institute](https://clsi.org/standards/products/microbiology/), and the laboratory should use the framework to determine the priority of the quality improvement. The framework should be used to ensure the quality of the laboratory results, and the laboratory should use the framework to determine the priority of the quality improvement. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the quality of the laboratory results. ### The Framework and the Use of the Quality Assurance Program The framework is used to determine the priority of the quality assurance program. The laboratory should have a quality assurance program, and the laboratory should use the framework to determine the priority of the quality assurance program. The quality assurance program should include the quality control, the quality assurance, and the quality improvement. The framework should be used to determine the priority of the quality assurance program, and the laboratory should use the framework to ensure the ## Frequently Asked Questions ### What is the difference between an anaerobic and an aerobic culture? An anaerobic culture is a culture that is incubated in an environment without oxygen, and it is used to grow organisms that require an oxygen-free environment. An aerobic culture is a culture that is incubated in an environment with oxygen, and it is used to grow organisms that require oxygen. ### How do I interpret a mixed culture that grows both anaerobes and aerobes? The interpretation of a mixed culture requires the identification of the organisms and the assessment of the clinical significance of the organisms. The laboratory should prioritize the identification of the organisms that are likely to be clinically significant, and it should communicate the findings to the clinician. ### What is the clinical significance of a mixed anaerobic and aerobic culture? The clinical significance of a mixed culture depends on the context of the culture. A mixed culture may be a true polymicrobial infection, or it may be a culture that is contaminated with normal flora. The laboratory should consider the clinical context of the culture when interpreting the findings. ### How long should a mixed culture be incubated? The incubation time for a mixed culture depends on the organisms that are present. The culture should be incubated for at least 48 hours, and the culture may be incubated for a longer period if the laboratory is looking for fastidious organisms. ### What is the role of susceptibility testing in a mixed culture? Susceptibility testing is used to determine the susceptibility of an organism to antibiotics. The laboratory should perform susceptibility testing on the organisms that are considered clinically significant, and the results of the testing should be used to guide the use of antibiotics. ### What are the limitations of a mixed culture? The limitations of a mixed culture include the possibility of contamination, the possibility of the culture not reflecting the true of the infection, and the possibility of the culture being negative for organisms that are present in the infection. ### How can I improve the interpretation of a mixed culture? The interpretation of a mixed culture can be improved by the use of a systematic approach, the consideration of the clinical context, and the communication of the findings to the clinician. ### What is the role of the laboratory in the interpretation of a mixed culture? The laboratory plays a role in the interpretation of a mixed culture by providing the culture results, the identification of the organisms, and the results of susceptibility testing. The laboratory should also provide a comment that explains the clinical significance of the findings. ## Related Diagnostic Guides - [Primary Cell Cultures and Continuous Cell Lines in Veterinary Virology](/knowledge/diagnostics/microbiology/primary-cell-culture-and-continuous-cell-lines-in-veterinary-virology) - [Cell Culture Media: A Guide to Selection and Optimization](/knowledge/diagnostics/microbiology/cell-culture-media-a-guide-to-selection-and-optimization) - [Cell Culture Contamination: Sources, Detection, and Prevention](/knowledge/diagnostics/microbiology/cell-culture-contamination-sources-detection-and-prevention) - [Vero Cell Culture Techniques for Viral Diagnostics](/knowledge/diagnostics/microbiology/vero-cell-culture-techniques-for-viral-diagnostics) - [Viral Isolation and Embryonated Egg Culture Methods](/knowledge/diagnostics/microbiology/viral-isolation-and-embryonated-egg-culture) ## References and Further Reading - [Biosafety in Microbiological and Biomedical Laboratories](https://www.cdc.gov/labs/bmbl/index.html). CDC and NIH. - [Microbiology Resources](https://asm.org/). American Society for Microbiology. - [Antimicrobial Resistance](https://www.who.int/health-topics/antimicrobial-resistance). World Health Organization. - [Bacteriological Analytical Manual](https://www.fda.gov/food/laboratory-methods-food/bacteriological-analytical-manual-bam). U.S. Food and Drug Administration. - [Antimicrobial Susceptibility Testing](https://clsi.org/standards/products/microbiology). Clinical and Laboratory Standards Institute. - [Culture Collections](https://www.atcc.org/). American Type Culture Collection. - [Laboratory Biosafety Manual](https://www.who.int/publications/i/item/9789240011311). World Health Organization. - [NCBI Literature Resources](https://www.ncbi.nlm.nih.gov/). National Center for Biotechnology Information. - [Model-based analysis of anaerobic acetate uptake by a mixed culture of polyphosphate-accumulating and glycogen-accumulating organisms.](https://pubmed.ncbi.nlm.nih.gov/12783485). Biotechnology and bioengineering, 2003. - [The role of infection and antibiotics in chronic rhinosinusitis.](https://pubmed.ncbi.nlm.nih.gov/28894821). Laryngoscope investigative otolaryngology, 2017. - [Uterine culture in mares.](https://pubmed.ncbi.nlm.nih.gov/6377040). Modern veterinary practice, 1984. > This article is educational and does not replace validated laboratory procedures, institutional biosafety review, manufacturer instructions, or professional interpretation.