# Quality Control in Culture Media Preparation and Performance Testing ## Quick Answer - Implement a documented quality control program that includes physical inspection, sterility testing, and growth promotion testing with authenticated reference strains for each new batch of prepared media. - Establish acceptance criteria before testing begins and record all results in a permanent log that links each batch to its preparation date, sterilization cycle, and expiration date. - Quality control testing verifies performance but cannot correct errors in preparation, so media must be prepared by trained personnel following written procedures and standard laboratory safety practices. ## Scope and Purpose of Culture Media Quality Control Culture media quality control is the systematic process of verifying that each batch of media prepared in the laboratory performs as intended for its specific diagnostic or research application. The purpose is to confirm that the medium supports the growth of target organisms, inhibits the growth of unwanted organisms, and remains free of contaminating microorganisms. This process applies to commercially prepared media, dehydrated media, and media prepared in-house from individual components. Laboratory professionals who prepare culture media must understand that quality control is not a single test but a coordinated system of checks that begins before the media is prepared and continues through storage and use. The system includes verification of raw materials, monitoring of preparation conditions, testing of the finished product, and documentation of all results. Each step in this system contributes to the reliability of the final culture result. The need for rigorous quality control is directly tied to the consequences of media failure. A contaminated batch of media can produce false-positive results that lead to unnecessary treatment or investigation. A batch that fails to support growth can produce false-negative results that delay diagnosis or allow a pathogen to go undetected. Both outcomes have clinical and public health implications that extend beyond the individual laboratory. The framework for culture media quality control is built on standards and guidelines from professional organizations. The Clinical and Laboratory Standards Institute publishes standards for antimicrobial susceptibility testing and related microbiology procedures that laboratories can reference when establishing their quality control programs. The [CLSI microbiology standards](https://clsi.org/standards/products/microbiology) provide the basis for many laboratory accreditation requirements. The [FDA Bacteriological Analytical Manual](https://www.fda.gov/food/laboratory-methods-food/bacteriological-analytical-manual-bam) describes official methods for food microbiology that include specific quality control requirements for culture media used in those methods. Laboratory professionals should also be aware of the broader context of microbiology practice. The [American Society for Microbiology](https://asm.org/) provides professional education and laboratory practice resources that support the development of competent microbiologists. The [CDC Biosafety in Microbiological and Biomedical Laboratories](https://www.cdc.gov/labs/bmbl/index.html) provides the biosafety framework that governs how laboratories handle the microorganisms used in quality control testing. --- ## At a Glance | Quality Control Component | What It Verifies | Typical Frequency | Key Records | |---------------------------|------------------|-------------------|-------------| | Sterility testing | Absence of contaminating microorganisms in the prepared media | Each batch after preparation | Sterility test results, incubation conditions, observation dates | | Growth testing | Ability of the media to support growth of target organisms | Each batch before release for use | Reference strain used, inoculum size, growth result, incubation conditions | | Performance testing | Selective and differential properties of the media | Each batch before release | Expected reactions, observed reactions, comparison to expected results | | Physical inspection | Appearance, color, volume, and integrity of the media | At preparation and before each use | Preparation date, expiration date, visual inspection results | | Documentation review | Completeness and accuracy of all records | At batch release and during audits | Batch records, preparation logs, corrective action reports | --- ## Core Principles of Culture Media Quality Control ### The Quality Control Cycle Culture media quality control operates on a cycle that begins with the decision to prepare media and ends with the release of the media for use. Each stage of the cycle has specific checks that must be completed and documented. The cycle includes the following stages: 1. Selection of the appropriate media for the intended application 2. Verification of the raw materials including dehydrated media and supplements 3. Preparation according to the manufacturer instructions or validated in-house procedure 4. Sterilization using the validated method 5. Cooling and dispensing into the final containers 6. Physical inspection of the prepared media 7. Sterility testing of the batch 8. Growth testing with reference strains 9. Release of the batch for use 10. Monitoring of the media during its shelf life Each stage depends on the previous stage. A batch of media that is prepared from expired dehydrated media cannot be made acceptable by growth testing. A batch that is contaminated during the cooling process will fail sterility testing regardless of how well the sterilization step was performed. The quality control program must therefore address every stage of the process. ### Verification of Raw Materials The quality of the final media depends on the quality of the starting materials. Dehydrated culture media must be stored according to the manufacturer's instructions, typically in a cool, dry place with the container tightly sealed. The container must be inspected before use for signs of moisture, clumping, or discoloration. The expiration date on the container must be checked and the media must not be used after the expiration date. The laboratory must also verify that the correct dehydrated media is being used for the intended application. Many dehydrated media have similar names and similar appearances. The laboratory must have a system for verifying the product name, catalog number, and lot number before the media is prepared. This verification is recorded in the preparation log. Supplements such as blood, antibiotics, and growth factors must be verified in the same manner. The supplements must be within their expiration dates and must be stored according to the manufacturer instructions. The volume of supplement added to the media must be measured and recorded. ### Preparation and Sterilization The preparation of culture media must follow a written procedure that specifies the amount of dehydrated media, the volume of water, the mixing method, the heating method, and the sterilization conditions. The procedure must be based on the manufacturer's instructions or on a validated in-house procedure. The person preparing the media must be trained in the procedure and must have access to the written procedure during preparation. The sterilization step is critical to the quality of the media. Most culture media are sterilized by autoclaving at a specified temperature and pressure for a specified time. The autoclave must be validated to ensure that it reaches the required temperature and holds it for the required time. The sterilization cycle must be recorded for each batch of media. Some media components are heat-sensitive and must be added after sterilization. These components include certain antibiotics, blood, and other supplements. The procedure must specify when these components are added and the temperature of the media at the time of addition. The media must be cooled to the specified temperature before the heat-sensitive components are added. ### Physical Inspection The prepared media must be inspected before it is released for use. The inspection includes the following checks: - The media has the expected color and appearance - The media has the expected consistency - The media is free of cracks, bubbles, and other defects - The media is free of visible contamination - The volume of media in each container is consistent - The containers are properly labeled The physical inspection is performed by the person who prepared the media and is recorded in the preparation log. Any batch that fails the physical inspection is discarded and the failure is recorded. --- ## Sterility Testing ### Purpose of Sterility Testing Sterility testing is performed to verify that the prepared media does not contain contaminating microorganisms. The test is performed on each batch of media after preparation and before the media is released for use. The purpose of the test is to detect contamination that may have occurred during preparation, cooling, or dispensing. Sterility testing is not a test of the sterilization process. The sterilization process is validated separately. Sterility testing is a test of the final product to verify that the product is free of viable microorganisms. ### Sterility Testing Procedure The sterility testing procedure depends on the type of media being tested. For media in tubes, a representative sample of tubes from the batch is selected and incubated under the conditions specified in the procedure. For media in plates, a representative sample of plates is selected and incubated. The incubation conditions must be appropriate for the detection of the types of contamination that are most likely to occur. The incubation temperature and time must be specified in the written procedure. The incubation period must be long enough to allow slow-growing contaminants to become visible. The sterility test results must be recorded in the sterility testing log. The log must include the date of the test, the batch number, the number of units tested, the incubation conditions, and the results. The log must be reviewed by the laboratory supervisor or the designated quality control person. ### Interpretation of Sterility Testing Results A batch of media passes sterility testing when no growth is observed in any of the tested units. A batch of media fails sterility testing when growth is observed in any of the tested units. The entire batch must be discarded when the sterility test fails. The failure of a sterility test must be investigated. The investigation must determine the source of the contamination and the corrective action that will be taken. The investigation must be documented in the quality control records. --- ## Growth Testing with Reference Strains ### Purpose of Growth Testing Growth testing is performed to verify that the media supports the growth of the target organisms and produces the expected reactions. The purpose of the test is to verify that the media performs as intended for its specific application. Growth testing is performed with reference strains of known characteristics. The reference strains are obtained from a recognized culture collection such as the [American Type Culture Collection](https://www.atcc.org/). The reference strains must be authenticated and maintained according to the culture collection instructions. ### Selection of Reference Strains The reference strains used for growth testing must be appropriate for the media being tested. The strains must be known to grow on the media and to produce the expected reactions. The strains must be selected from the list of strains specified in the laboratory procedure or in the manufacturer's quality control documentation. The reference strains must be maintained in a way that preserves their characteristics. The strains must be stored according to the culture collection instructions and must be subcultured at the specified intervals. The passage number of the strains must be recorded. ### Growth Testing Procedure The growth testing procedure depends on the type of media and the intended application. The procedure must specify the following: - The reference strains to be used - The inoculum preparation method - The inoculum concentration - The inoculation method - The incubation conditions - The expected results - The method for recording the results The inoculum must be prepared from a fresh culture of the reference strain. The inoculum concentration must be adjusted to the specified concentration. The inoculum must be used within the specified time after preparation. The inoculated media must be incubated under the specified conditions. The incubation time must be long enough to allow the expected growth to occur. The results must be observed and recorded at the specified time. ### Interpretation of Growth Testing Results The growth testing results are interpreted by comparing the observed results with the expected results. The media passes the growth testing when the observed results match the expected results. The media fails the growth testing when the observed results do not match the expected results. The expected results include the amount of growth, the appearance of the growth, and the reactions of the media. For example, a selective media for a specific organism is expected to support the growth of that organism and to inhibit the growth of other organisms. The growth testing must verify both the growth of the target organism and the inhibition of the non-target organisms. A batch of media that fails growth testing must be rejected. The batch must not be released for use. The failure must be investigated and the investigation must be documented. --- ## Performance Testing of Selective and Differential Media ### Selective Media Testing Selective media are designed to support the growth of target organisms and to inhibit the growth of non-target organisms. The performance testing of selective media must verify both properties. The growth testing of selective media uses two types of reference strains: the target strains that should grow and the non-target strains that should be inhibited. The target strains must show the expected growth on the media. The non-target strains must show no growth or significantly reduced growth on the media. The testing procedure must specify the inoculum concentration for the non-target strains. The inoculum concentration must be high enough to demonstrate the selective properties of the media. The results must be recorded for both the target and non-target strains. ### Differential Media Testing Differential media are designed to allow the differentiation of organisms based on their biochemical reactions. The performance testing of differential media must verify that the media produces the expected reactions for the reference strains. The testing of differential media uses reference strains that produce known reactions on the media. The strains are selected to produce both positive and negative reactions. The testing must verify that the positive strains produce the expected positive reaction and that the negative strains produce the expected negative reaction. The results of the differential testing must be recorded with the specific reactions observed. The reactions must be described in the laboratory records. ### Combined Selective and Differential Media Many media types are both selective and differential. The performance testing of these media must verify both properties. The testing uses target strains, non-target strains, and strains that produce positive and negative reactions. The testing procedure must be designed to verify all of the properties of the media. The results must be recorded for each strain and each property. The batch of media is released only when all of the properties are verified. --- ## Documentation and Records ### The Purpose of Documentation Documentation is the record of the quality control activities performed in the laboratory. The documentation serves several purposes: - It provides evidence that the quality control activities were performed - It provides a record of the results of the quality control activities - It provides a basis for the investigation of failures - It provides the information needed for the review of the quality control program - It provides the evidence needed for the accreditation of the laboratory The documentation must be complete, accurate, and legible. The documentation must be recorded at the time the activity is performed. The documentation must be reviewed by the appropriate person. ### The Preparation Log The preparation log records the details of each batch of media prepared in the laboratory. The log must include the following information: - The date of preparation - The name of the person who prepared the media - The type of media - The lot number of the dehydrated media - The expiration date of the dehydrated media - The volume of media prepared - The sterilization conditions - The supplements added - The physical inspection results - The batch number The preparation log must be completed at the time of preparation. The log must be reviewed by the supervisor or the quality control person. ### The Sterility Testing Log The sterility testing log records the results of the sterility testing. The log must include the following information: - The date of the testing - The batch number - The number of units tested - The incubation conditions - The results of the testing - The signature of the person who performed the testing ### The Growth Testing Log The growth testing log records the results of the growth testing. The log must include the following information: - The date of the testing - The batch number - The reference strains used - The inoculum concentrations - The incubation conditions - The results of the testing - The signature of the person who performed the testing ### The Batch Release Record The batch release record is the final record that documents the release of the batch for use. The record must include the following information: - The batch number - The date of the release - The results of the sterility testing - The results of the growth testing - The signature of the person who released the batch The batch release record is the record that the batch has passed all of the quality control tests and is suitable for use. --- ## Common Failure Patterns and Troubleshooting ### Contamination of the Media Contamination of the media is the most common failure pattern in culture media quality control. The contamination can occur at any stage of the preparation process. The contamination can be caused by the following factors: - Contaminated dehydrated media - Contaminated water - Contaminated equipment - Contaminated supplements - Improper sterilization - Contamination during the cooling process - Contamination during the dispensing process The investigation of contamination must determine the source of the contamination. The investigation must include a review of the preparation process, the equipment, and the materials. The corrective action must be implemented and the process must be repeated. ### Failure to Support Growth The failure of the media to support growth is a serious failure that can lead to false-negative results. The failure can be caused by the following factors: - Incorrect preparation of the media - Incorrect sterilization conditions - Incorrect pH of the media - Incorrect concentration of the media - Incorrect storage of the media - Expired media The investigation of the failure to support growth must determine the cause of the failure. The investigation must include a review of the preparation process, the sterilization process, and the storage conditions. ### Incorrect Selective Properties The failure of the selective media to inhibit non-target organisms is a failure of the selective properties of the media. The failure can be caused by the following factors: - Incorrect concentration of the selective agents - Incorrect preparation of the media - Incorrect sterilization of the media - Incorrect storage of the media The investigation of the failure must determine the cause of the failure. The investigation must include a review of the preparation process and the selective agents. ### Incorrect Differential Reactions The failure of the differential media to produce the expected reactions is a failure of the differential properties of the media. The failure can be caused by the following factors: - Incorrect preparation of the media - Incorrect concentration of the indicators - Incorrect incubation conditions - Incorrect storage of the media The investigation of the failure must determine the cause of the failure. The investigation must include a review of the preparation process and the indicators. --- ## Biosafety and Containment ### Biosafety Principles The quality control of culture media involves the handling of microorganisms. The laboratory must follow the biosafety principles described in the [Biosafety in Microbiological and Biomedical Laboratories](https://www.cdc.gov/labs/bmbl/index.html). The biosafety principles include the following: - The risk assessment of the microorganisms being handled - The selection of the appropriate biosafety level - The use of the appropriate containment equipment - The use of the appropriate personal protective equipment - The decontamination of the waste materials The laboratory must conduct a risk assessment of the microorganisms used in the quality control testing. The risk assessment must consider the pathogenicity of the microorganisms, the route of transmission, and the concentration of the microorganisms. ### Containment of the Quality Control Strains The reference strains used in the quality control testing must be contained according to the biosafety level of the laboratory. The strains must be handled in the appropriate containment equipment. The strains must be decontaminated after use. The laboratory must have a written procedure for the handling of the reference strains. The procedure must include the storage, the subculture, the use, and the decontamination of the strains. ### Decontamination of the Media The media used in the quality control testing must be decontaminated after use. The decontamination must be performed according to the laboratory procedure. The decontamination must be performed in a way that prevents the release of the microorganisms into the environment. The decontamination of the media must be performed in the autoclave or by the appropriate method. The decontamination must be verified by the appropriate method. --- ## The Role of Culture Collections ### The Use of Authenticated Strains The reference strains used in the quality control testing must be authenticated strains. The authenticated strains are obtained from a recognized culture collection such as the [American Type Culture Collection](https://www.atcc.org/). The authenticated strains have been verified to have the characteristics that are expected. The use of authenticated strains is important because the quality control testing depends on the characteristics of the strains. If the strains are not authenticated, the results of the quality control testing may not be valid. ### The Maintenance of the Reference Strains The reference strains must be maintained in a way that preserves their characteristics. The strains must be stored according to the culture collection instructions. The strains must be subcultured at the specified intervals. The passage number of the strains must be recorded. The passage number is the number of times the strain has been subcultured. The passage number must be kept within the limits specified by the culture collection. ### The Verification of the Reference Strains The reference strains must be verified before use. The verification must confirm that the strains have the expected characteristics. The verification must be performed according to the laboratory procedure. The verification of the reference strains must be recorded in the laboratory records. The verification must be performed at the specified intervals. --- ## Documentation and Accreditation ### The Role of Documentation in Accreditation The documentation of the quality control activities is the basis for the accreditation of the laboratory. The accreditation is the recognition that the laboratory meets the standards for the quality of the testing. The accreditation is performed by the accreditation body. The accreditation body reviews the documentation of the laboratory to verify that the laboratory meets the standards. The documentation must be complete, accurate, and legible. The documentation must be available for the review by the accreditation body. ### The Quality Control Program The quality control program is the system of activities that the laboratory performs to ensure the quality of the culture media. The program must be documented in the quality control manual. The quality control manual must describe the following: - The quality control policies of the laboratory - The quality control procedures of the laboratory - The quality control records of the laboratory - The quality control responsibilities of the laboratory The quality control manual must be reviewed and updated at the specified intervals. ### The Audit of the Quality Control Program The quality control program must be audited at the specified intervals. The audit must be performed by the appropriate person. The audit must review the quality control activities and the quality control records. The audit must identify the areas where the quality control program is not being followed. The audit must identify the areas where the quality control program is not effective. The audit must make the recommendations for the improvement of the quality control program. --- ## The Role of the Laboratory Professional ### The Competence of the Laboratory Professional The quality of the culture media depends on the competence of the laboratory professional. The laboratory professional must have the knowledge and the skills to perform the quality control activities. The laboratory professional must be trained in the quality control procedures. The training must be documented. The training must be updated at the specified intervals. The [American Society for Microbiology](https://asm.org/) provides professional education and laboratory practice resources that support the development of the laboratory professional. The laboratory professional should use these resources to maintain the competence. ### The Responsibilities of the Laboratory Professional The laboratory professional has the responsibility to perform the quality control activities according to the procedures. The laboratory professional has the responsibility to record the results of the quality control activities. The laboratory professional has the responsibility to report the failures of the quality control activities. The laboratory professional has the responsibility to follow the biosafety principles. The laboratory professional has the responsibility to use the appropriate personal protective equipment. --- ## The Global Context of Antimicrobial Resistance ### The Role of the Laboratory in Antimicrobial Resistance The laboratory has a role in the global context of antimicrobial resistance. The [WHO Antimicrobial Resistance](https://www.who.int/health-topics/antimicrobial-resistance) describes the global problem of antimicrobial resistance. The laboratory contributes to the surveillance of antimicrobial resistance through the testing of the susceptibility of the microorganisms. The quality of the culture media is essential for the accuracy of the antimicrobial susceptibility testing. The quality of the media affects the results of the susceptibility testing. The laboratory must ensure the quality of the media used for the susceptibility testing. ### The Quality of the Susceptibility Testing The quality of the susceptibility testing depends on the quality of the media. The media used for the susceptibility testing must be prepared and tested according to the standards. The [Clinical and Laboratory Standards Institute](https://clsi.org/standards/products/microbiology) provides the standards for the susceptibility testing. The laboratory must follow the standards for the susceptibility testing. The laboratory must use the media that meets the standards. The laboratory must perform the quality control of the media used for the susceptibility testing. --- ## The Implementation of the Quality Control Program ### The Steps for the Implementation The implementation of the quality control program requires the following steps: 1. The assessment of the current quality control activities 2. The identification of the gaps in the quality control activities 3. The development of the quality control procedures 4. The training of the laboratory professionals 5. The implementation of the quality control procedures 6. The monitoring of the quality control activities 7. The review of the quality control program The implementation of the quality control program must be documented. The implementation must be reviewed at the specified intervals. ### The Assessment of the Current Activities The assessment of the current quality control activities must identify the activities that are being performed and the activities that are not being performed. The assessment must identify the gaps in the quality control activities. The assessment must be performed by the appropriate person. The assessment must be documented. ### The Development of the Procedures The development of the quality control procedures must be based on the standards and the guidelines. The procedures must be written in a clear and concise manner. The procedures must be reviewed and approved by the appropriate person. The procedures must be available to the laboratory professionals. The procedures must be followed by the laboratory professionals. --- ## The Records and the Measurements ### The Records of the Quality Control The records of the quality control are the evidence of the quality control activities. The records must be complete, accurate, and legible. The records must be stored in a secure location. The records must be retained for the specified period. The retention period must be specified in the quality control manual. ### The Measurements of the Quality Control The measurements of the quality control are the results of the quality control activities. The measurements must be recorded in the quality control records. The measurements must be reviewed at the specified intervals. The measurements must be used to identify the trends in the quality control activities. The measurements must be used to identify the issues in the quality control activities. --- ## The Limitations of the Quality Control ### The Limitations of the Testing The quality control testing has limitations. The testing cannot detect all of the problems with the media. The testing can only detect the problems that are tested. The sterility testing can only detect the contamination that is present in the tested units. The sterility testing cannot detect the contamination that is present in the untested units. The growth testing can only detect the problems that are tested. The growth testing cannot detect the problems that are not tested. ### The Limitations of the Reference Strains The reference strains have limitations. The reference strains are not the same as the clinical strains. The reference strains may not have the same characteristics as the clinical strains. The reference strains may not be representative of the strains that are encountered in the clinical laboratory. The reference strains may not be representative of the strains that are encountered in the food laboratory. ### The Limitations of the Documentation The documentation has limitations. The documentation can only record the activities that are performed. The documentation cannot record the activities that are not performed. The documentation can only record the results that are observed. The documentation cannot record the results that are not observed. --- ## The Professional Escalation Criteria ### The Escalation of the Quality Control Issues The laboratory professional must escalate the quality control issues to the appropriate person. The escalation must be performed when the issue cannot be resolved by the laboratory professional. The escalation must be performed when the following issues are identified: - The failure of the quality control testing - The failure of the media to perform as expected - The failure of the equipment - The failure of the materials The escalation must be documented. The escalation must be performed in a timely manner. ### The Escalation of the Biosafety Issues The laboratory professional must escalate the biosafety issues to the appropriate person. The escalation must be performed when the biosafety issue cannot be resolved by the laboratory professional. The escalation must be performed when the following issues are identified: - The exposure to the microorganisms - The contamination of the laboratory - The failure of the containment equipment The escalation must be documented. The escalation must be performed in a timely manner. --- ## Frequently Asked Questions ### What is the difference between sterility testing and growth testing? Sterility testing verifies that the prepared media is free of contaminating microorganisms. Growth testing verifies that the media supports the growth of the target organisms and produces the expected reactions. Both tests are required for the release of a batch of media. ### How many units of media should be tested for sterility? The number of units tested for sterility is specified in the laboratory procedure. The number is based on the batch size and the risk of contamination. The number must be sufficient to provide confidence that the batch is free of contamination. ### What reference strains should be used for growth testing? The reference strains used for growth testing are selected based on the media type and the intended application. The strains must be appropriate for the media and must be obtained from a recognized culture collection such as the [American Type Culture Collection](https://www.atcc.org/). ### How long should the quality control records be retained? The retention period for the quality control records is specified in the laboratory policy. The retention period is typically based on the accreditation requirements and the regulatory requirements. The records must be retained for the specified period. ### What should be done when a batch of media fails the quality control testing? The batch of media must be rejected when it fails the quality control testing. The failure must be investigated to determine the cause. The corrective action must be taken to prevent the recurrence of the failure. ### How should the reference strains be maintained? The reference strains must be maintained according to the culture collection instructions. The strains must be stored under the specified conditions and subcultured at the specified intervals. The passage number of the strains must be recorded. ### What is the role of the laboratory in the antimicrobial resistance? The laboratory contributes to the surveillance of antimicrobial resistance through the testing of the susceptibility of the microorganisms. The quality of the media used for the susceptibility testing is essential for the accuracy of the results. The [WHO Antimicrobial Resistance](https://www.who.int/health-topics/antimicrobial-resistance) provides the global context for this work. ### What are the biosafety requirements for the quality control testing? The biosafety requirements for the quality control testing are based on the risk assessment of the microorganisms being handled. The requirements include the appropriate biosafety level, the containment equipment, and the personal protective equipment. The [Biosafety in Microbiological and Biomedical Laboratories](https://www.cdc.gov/labs/bmbl/index.html) provides the biosafety principles. --- ## Using the Evidence | Source | Best use in this topic | Important limitation | |---|---|---| | [Biosafety in Microbiological and Biomedical Laboratories](https://www.cdc.gov/labs/bmbl/index.html) | official guidance | Check the linked page for current local requirements | | [Microbiology Resources](https://asm.org/) | official guidance | Check the linked page for current local requirements | | [Antimicrobial Resistance](https://www.who.int/health-topics/antimicrobial-resistance) | official guidance | Check the linked page for current local requirements | ## Related Diagnostic Guides - [Microbiology Quality Control: Essential Practices for Reliable Culture Results](/knowledge/diagnostics/microbiology/microbiology-quality-control-essential-practices-for-reliable-culture-results) - [Cell Culture Media: A Guide to Selection and Optimization](/knowledge/diagnostics/microbiology/cell-culture-media-a-guide-to-selection-and-optimization) - [Microbiology in Water Testing: Methods and Significance](/knowledge/diagnostics/microbiology/microbiology-in-water-testing-methods-and-significance) - [Motility Testing in Microbiology: Semisolid Agar Method](/knowledge/diagnostics/microbiology/motility-testing-in-microbiology-semisolid-agar-method) ## 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. - [Quality control of culture media in a microbiology laboratory.](https://pubmed.ncbi.nlm.nih.gov/16100420). Indian journal of medical microbiology, 2005. - [Aseptic technique for cell culture.](https://pubmed.ncbi.nlm.nih.gov/18228291). Current protocols in cell biology, 2001. - [[Environmental microbiological control].](https://pubmed.ncbi.nlm.nih.gov/27474243). Enfermedades infecciosas y microbiologia clinica, 2016. > This article is educational and does not replace validated laboratory procedures, institutional biosafety review, manufacturer instructions, or professional interpretation.