Bacterial Pathogens in Chicken Meat: Risk Assessment and Public Health Impact

Introduction

Chicken meat is a major global protein source and a frequent vehicle for foodborne bacterial pathogens [1, 2]. Contamination occurs along the entire farm-to-fork continuum, from primary production through processing, retail, and consumer handling. The primary zoonotic bacterial hazards in chicken meat include thermotolerant Campylobacter spp., non-typhoidal Salmonella enterica, Shiga toxin-producing and extraintestinal pathogenic Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Clostridium perfringens, and Yersinia enterocolitica [3, 2, 67]. Quantitative microbial risk assessment (QMRA) provides a systematic framework to estimate population-level risks and evaluate intervention strategies [4, 5, 12]. This article reviews the prevalence, concentration, antimicrobial resistance (AMR) profiles, and risk assessment models for key bacterial pathogens in chicken meat, with an emphasis on veterinary and food safety implications.

Prevalence and Contamination Levels

Salmonella spp.

Salmonella is a leading cause of bacterial foodborne illness worldwide, and chicken meat is a primary reservoir [2, 18]. Prevalence estimates vary widely by region and production system. In a Japanese national surveillance system, Salmonella was detected in 18% of retail chicken samples [1]. In Cambodia, prevalence in traditional-market chicken meat reached 42.6% with mean concentrations of 10.6 MPN/g [18, 23]. In Burkina Faso and Ethiopia, baseline QMRA models estimated mean annual salmonellosis incidences of 2,713 and 4,745 cases per 100,000 persons, respectively [5]. In China, a genomic survey of 134 Salmonella isolates from food animals found 85.82% multidrug-resistant (MDR), with sequence type ST469 predominant [24]. The Salmonella serovars most frequently isolated from chicken include Enteritidis, Typhimurium, Infantis, and Kentucky [24, 39, 70]. Extensively drug-resistant (XDR) Salmonella Kentucky co-harboring cfr, mcr-1, and a tet(A) variant was reported from retail chicken meat in Shanghai, conferring resistance to last-resort antibiotics such as tigecycline and colistin [39]. In Ghana, Salmonella prevalence in eggs (a product closely linked to chicken meat) was 5.5%, with isolates carrying multiple virulence genes [70]. In India, a meta-analysis reported pooled Salmonella prevalence of 18% in retail chicken [2].

Campylobacter spp.

Campylobacter jejuni and C. coli are the most frequently reported bacterial causes of human gastroenteritis in many countries, and poultry is the principal source [4, 11, 30]. In Peru, Campylobacter was detected in 76% of chicken meat samples by qPCR, with mean loads of 4.9 log10 genome copies/g [4]. In Switzerland, chilled chicken meat showed 62% Campylobacter recovery, with higher prevalence in organic (72%) and free-range (77%) products [11]. In Central China, 17.2% of retail chicken samples were positive, with counts ranging from 3.6 to 360 MPN/g [58]. In Tanzania, all 45 broiler meat samples were positive for Campylobacter, averaging 5.30 log10 CFU/g [36]. In Brazil, 359 C. jejuni strains from chilled carcasses displayed high multi-virulence; 97.77% carried the hcp gene linked to severe human infection [64]. In New Zealand, whole chicken carcasses yielded significantly higher Campylobacter counts than drumsticks, indicating product type influences exposure [66]. In France, a quantitative approach to assess compliance with a performance objective for C. jejuni in poultry meat used a stochastic model to evaluate processing efficacy [92].

Escherichia coli

E. coli is a ubiquitous indicator of fecal contamination and a pathogen of concern when carrying virulence or resistance genes [6, 13, 29]. In Tunisia, 82% of chicken carcasses were contaminated with E. coli, and 76.5% of isolates produced extended-spectrum β-lactamases (ESBLs), with blaCTX-M, blaTEM, and blaSHV detected [6]. In Brazil, ESBL-producing E. coli from antibiotic-free chicken meat belonged to sequence types ST117, ST443, ST1559, and ST3258, with isolates carrying heavy metal and disinfectant resistance genes [13]. In Hong Kong wet markets, ESBL-E. coli prevalence was 88.8% and colistin-resistant (CSR)-E. coli 6.7%, with mcr-1 detected in all CSR isolates [29]. In Norway, 141 ESC-resistant E. coli from retail chicken harbored blaCMY-2, with highly variable uropathogenic potential [62]. In Spain, poultry meat was a source of MDR Enterobacteriaceae including uropathogenic E. coli lineages such as ST131-H22 [37]. In Kenya, E. coli prevalence in raw chicken reached 61.6%, with 87.3% MDR and 16.0% extensively drug-resistant [20].

Staphylococcus aureus

S. aureus is a common contaminant in retail chicken, with pooled prevalence of 56% in a meta-analysis from India [2]. In Bangladesh, S. aureus from chicken meat showed 100% resistance to amoxicillin and erythromycin [7]. In Nepal, 68% of raw meat samples harbored S. aureus, with 100% resistance to amoxicillin and high resistance to tetracycline [47]. MRSA has been detected in retail chicken; in Kathmandu, all S. aureus isolates from raw chicken were resistant to ampicillin and cefoxitin, indicating MRSA [16]. In Germany, methicillin-resistant S. aureus from broiler and turkey farms carried diverse resistance and virulence markers, persisting from farm to fork [105].

Other Pathogens

Listeria monocytogenes showed pooled prevalence of 13% in Indian retail chicken [2]. Clostridium perfringens was found in 35% of samples [2]. Shigella spp. has been isolated from chicken meat; in Pakistan, 30% of samples were positive, with high resistance to cefotriaxone (86%) and ciprofloxacin (73%) [55]. Yersinia enterocolitica biotype 1A has been recovered from pork and poultry meat, with genomic heterogeneity indicating multiple sources [74]. Arcobacter spp., considered an emerging foodborne zoonotic agent, has been documented in poultry [119]. Clostridioides difficile was detected in fresh poultry meat in Germany, with phylogenetic relationships suggesting contamination at cutting plants [91].

Antimicrobial Resistance Profiles

AMR among chicken meat bacterial isolates is a critical public health concern [49]. A systematic review of AMR in meat from Asia found high pooled prevalence of resistance in E. coli to β-lactams and tetracyclines, with blaTEM, tetA, mcr-1, and sul1 as prevalent resistance genes [49]. In Nepal, E. coli from chicken meat exhibited 100% resistance to amoxicillin, 93% to tetracycline, and 25% to nalidixic acid [47]. In Bangladesh, E. coli and Salmonella from chicken meat and eggs displayed MDR patterns with high resistance to amoxicillin and erythromycin [7]. In Indonesia, E. coli from traditional-market chicken showed highest resistance to streptomycin (66.7%) and erythromycin (66.7%) [33]. In Ethiopia, Campylobacter and E. coli from cattle meat (parallel pathogen) showed 100% resistance to vancomycin, and moderate resistance to amoxicillin [3]. In India, ESBL-producing E. coli from chicken exhibited MDR patterns including resistance to ceftazidime, cefotaxime, and aztreonam [8]. In Kenya, E. coli from chicken meat was highly resistant to ampicillin (95.3%), amoxicillin-clavulanate (78.7%), and tetracycline (72.0%) [20]. In South Korea, ESBL-producing E. coli from imported meat was characterized by multiple beta-lactamase genes [99].

Campylobacter isolates show particularly high resistance to fluoroquinolones and tetracyclines. In Central China, all Campylobacter isolates were resistant to norfloxacin and ciprofloxacin [58]. In Cameroon, Campylobacter from chicken exhibited increased resistance to ciprofloxacin, tetracycline, and erythromycin [60]. In the Netherlands, reducing antimicrobial use in livestock alone was insufficient to reduce AMR among human Campylobacter infections, suggesting complex transmission dynamics [76].

Salmonella isolates from chicken meat frequently display MDR. In China, 85.82% of Salmonella from food animals were MDR, with resistance to third-generation cephalosporins and fluoroquinolones [24]. XDR Salmonella Kentucky co-harboring cfr, mcr-1, and tet(A) variant was reported from Shanghai chicken meat [39]. In Mexico, genomic diversity of Salmonella from raw chicken at retail revealed multiple serovars and resistance determinants [79].

The following table summarizes prevalence and resistance patterns for major pathogens in retail chicken meat across selected studies.

Quantitative Microbial Risk Assessment (QMRA)

QMRA is a structured, data-driven methodology used to estimate the probability and severity of adverse health outcomes from exposure to foodborne pathogens [4, 5, 12, 30]. The process typically includes hazard identification, exposure assessment, hazard characterization (dose-response), and risk characterization. Many QMRA models for chicken meat have focused on Campylobacter and Salmonella because of their high disease burden [30].

Campylobacter QMRA

A QMRA for Campylobacter in Peruvian traditional markets used empirical contamination levels and consumer handling data to estimate that the entire modeled population develops campylobacteriosis at least once annually [4]. In Burkina Faso and Ethiopia, stochastic QMRA models for Salmonella and Campylobacter along the chicken supply chain estimated mean annual campylobacteriosis incidences of 6,482 and 12,145 per 100,000 persons, respectively [5]. Combining interventions (improved hand washing, designated utensils, improved cooking) reduced risk by 75% to 94% [5].

In Australia, a QMRA model for cross-contamination during salad preparation predicted an average probability of illness per serving of 7.0 x 10^-4, and showed that a 30% reduction in retail prevalence yields a proportional risk reduction [12]. In France, a quantitative approach assessed compliance with a performance objective for C. jejuni in poultry meat using a modular process risk model [92]. In the US, an exposure assessment model estimated Campylobacter concentration in broiler processing plants, incorporating variability across processing stages [73].

Salmonella QMRA

A QMRA for Salmonella in Cambodian chicken salad consumers estimated an annual risk of salmonellosis of 11.1% per person, with cross-contamination during salad preparation as the most influential factor [18, 23]. In China, a risk assessment model for chicken meals prepared in households predicted that retail contamination was the node with highest contribution to infection risk (33.5%) [41]. In Canada, a farm-to-fork QMRA was developed for third-generation cephalosporin-resistant Salmonella Heidelberg in broilers, incorporating antimicrobial use and processing effects [94]. In Senegal, a risk assessment of campylobacteriosis and salmonellosis linked to chicken meals in Dakar estimated high annual risks, particularly under poor kitchen hygiene [112].

E. coli QMRA

An exposure assessment for uropathogenic E. coli (UPEC) in ready-to-eat chicken in Taiwan estimated a 4.0% probability of high UPEC exposure (>8 log CFU/serving) from wet markets, and showed that reducing retail duration to 2 hours and maintaining storage at 18°C reduced risk by 98-99% [40]. A QMRA model for cross-contamination in the kitchen (KCC) estimated that the dominant route is cutting board-to-salad, and that proper hand washing and utensil replacement can reduce the fraction ingested from 3.2 x 10^-3 to 3.6 x 10^-6 [27].

The following Mermaid diagram illustrates a generic QMRA workflow for bacterial pathogens in chicken meat, integrating data from farm-to-fork.

flowchart TD
    A["Primary Production: broiler flock infection"] --> B[Transport & Slaughter]
    B --> C[Processing & Carcass chilling]
    C --> D["Retail: storage, display"]
    D --> E["Consumer handling: storage, preparation"]
    E --> F["Cross-contamination: cutting board, hands, utensils"]
    F --> G["Ready-to-eat food (salad, RTE chicken")]
    G --> H[Ingestion & dose-response model]
    H --> I["Risk characterization: probability of illness per serving"]
    I --> J["Intervention scenarios: prevalence reduction, hygiene improvements, cold chain"]
    J --> A

Consumer Handling and Cross-Contamination

Consumer behavior is a critical determinant of risk [30, 56, 115]. In South Africa, a survey found that 55% of consumers do not handle raw chicken correctly during purchasing and 44% during thawing, and 36% do not wash hands after handling raw chicken [56]. In the US, a QMRA model for cross-contamination during salad preparation showed that the cutting board-salad route is dominant [27]. In Puerto Rico, bacterial contamination of hands increased the risk of cross-contamination among low-income meal preparers [115]. In Mozambique, rinse water reuse during slaughtering at open-air markets led to accumulation of Campylobacter and E. coli, with 100% detection after the first carcass rinse [35]. In Burkina Faso, washing chicken carcasses with water proved unreliable for reducing bacterial contamination under unhygienic market conditions [21].

Vaccination of meat chickens against Campylobacter and Salmonella has been reviewed systematically, with meta-analysis showing variable efficacy depending on vaccine type and administration route [83]. Probiotics and organic acids have also been explored as anti-Campylobacter interventions in poultry [93, 106].

Public Health Impact and Zoonotic Risk

The public health impact of bacterial pathogens in chicken meat is substantial. Campylobacter infection is associated with Guillain-Barré syndrome, and virulence genes cstIII, neuABC, wlaN, and cdtABC linked to this condition have been identified in chicken meat isolates [11, 64]. In Peru, the high Campylobacter load in chicken meat correlates with the alarming number of Guillain-Barré syndrome cases [4]. Uropathogenic E. coli (UPEC) lineages, including ST131, have been recovered from poultry meat, raising concerns about extraintestinal infections [37, 40]. In Norway, ESC-resistant E. coli from chicken meat exhibited low uropathogenic potential, but variability among isolates suggests risk cannot be dismissed [62]. In Brazil, ESBL-producing E. coli from chicken meat belonged to sequence types previously identified in poultry and polluted environments, supporting intercontinental dissemination under a One Health framework [13].

MDR and XDR Salmonella strains in chicken meat pose treatment challenges. The co-occurrence of cfr and mcr-1 in Salmonella Kentucky from Shanghai chicken meat leaves virtually no treatment options for potential infections [39]. In China, a large plasmid carrying blaNDM-1 was identified in Salmonella Indiana from chicken, highlighting the spread of carbapenemase genes [100]. In Germany, Salmonella Infantis clones disseminated widely in poultry, carrying multiple resistance genes [113].

A systematic review of avian pathogenic E. coli (APEC) provided meta-analytic evidence of shared serogroups and virulence factors between APEC and human extraintestinal pathogenic E. coli (ExPEC), supporting the zoonotic potential [78]. In Bangladesh, multidrug-resistant E. coli, Salmonella, and S. aureus in chicken meat, eggs, and feces indicated a high risk of resistance gene transmission [7]. In Nepal, raw chicken meat harbored MDR bacteria including MRSA, posing risks to consumers [16, 25].

Source attribution meta-analysis using statistical modelling identified poultry as the primary source of sporadic Campylobacter and Salmonella infections in many countries [87]. In Japan, one-fourth of total food poisoning cases are caused by Campylobacter, primarily due to consumption of raw or undercooked chicken meat (torisashi) [65].

Intervention Strategies

Intervention strategies to reduce bacterial contamination and AMR in chicken meat span the entire production chain. At the farm level, vaccination, probiotics, and biosecurity measures can reduce colonization [83, 106]. Pre-scald brushing in slaughterhouses can reduce carcass bacterial loads [104]. Chilling is a critical control point; Campylobacter growth is inhibited by reducing carcass temperature, and commercial chilling practices resulted in lower bacterial counts compared to backyard slaughter [32]. Organic acid treatments, such as lactic acid and peroxyacetic acid, have shown synergistic effects against Campylobacter [93].

At the consumer level, education on safe handling practices, designated kitchen utensils, adequate cooking, and hand washing are effective [5, 27, 56]. Freezing chicken meat prior to retail significantly reduces Campylobacter levels and has been recommended as a cost-effective intervention in Switzerland [11]. In Japan, recommendations include establishing a national Campylobacter reduction strategy and mandatory HACCP for small food businesses [65].

Papain, a proteolytic enzyme, has been evaluated as a meat-preservation agent; it significantly lowered total viable and coliform counts during storage of chilled chicken meat [9]. Essential oils, particularly cinnamon and clove oils, show antimicrobial activity against Staphylococcus strains isolated from poultry meat [59]. Bacteriophages, such as the lytic siphophage vB_StyS-LmqsSP1, have been shown to reduce Salmonella on chicken skin [88].

Detection methods for Salmonella in chicken meat have advanced from traditional culture to real-time PCR and whole-genome sequencing (WGS) [14, 68, 110, 116]. Phage-coated magnetoelastic sensors enable real-time detection of Salmonella on chicken surfaces [14]. Long-read 16S metabarcoding allows characterization of the microbiome and detection of Salmonella contamination in poultry meat [68]. Viability PCR methods combining propidium monoazide with qPCR have been developed to distinguish live Campylobacter cells in chicken skin [85, 86].

Conclusion

Bacterial pathogens in chicken meat represent a major food safety and public health challenge globally. Prevalence of Salmonella, Campylobacter, E. coli, and S. aureus remains high across diverse regions, and the rapid emergence of MDR and XDR strains compounds the risk. QMRA provides a powerful tool to quantify risks and prioritize interventions along the farm-to-fork chain. Effective control requires a One Health approach integrating veterinary surveillance, improved farm biosecurity, optimized slaughter hygiene, consumer education, and prudent antimicrobial use. Continued genomic surveillance of isolates from chicken meat is essential to monitor the spread of resistance and virulence determinants and to inform evidence-based policy.

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Disclaimer: This article is for educational and informational purposes only. It is not intended to substitute for professional veterinary advice, diagnosis, treatment, or regulatory guidance. Always consult a licensed veterinarian or qualified specialist regarding animal health, disease diagnosis, and therapeutic decisions.