Abstract
Contamination of retail chicken meat by Extended Spectrum Beta-Lactamase (ESBL) producing bacteria likely contributes to the increasing incidence of infections with these bacteria in humans. This study aimed to compare the prevalence and load of ESBL positive isolates between organic and conventional retail chicken meat samples, and to compare the distribution of ESBL genes, strain genotypes and co-resistance. In 2010, 98 raw chicken breasts (n=60 conventional; n=38 organic) were collected from 12 local stores in the Netherlands. Prevalence of ESBL producing micro-organisms was 100% on conventional and 84% on organic samples (p<0.001). Median loads of ESBL producing micro-organisms were 80 (range <20-1360) in conventional, and <20 (range 0-260) CFU/25 g in organic samples (p=0.001). The distribution of ESBL genes in conventional samples and organic samples was 42% versus 56%, respectively (N.S.), for CTX-M-1, 20% versus 42% (N.S.) for TEM-52, and 23% versus 3% (p<0.001) for SHV-12. CTX-M-2 (7%), SHV-2 (5%) and TEM-20 (3%) were exclusively found in conventional samples. Co-resistance rates of ESBL positive isolates were not different between conventional and organic samples (cotrimoxazole 56%, ciprofloxacin 14%, and tobramycin 2%), except for tetracycline, 73% and 46%, respectively, p<0.001). Six of 14 conventional meat samples harbored 4 MLST types also reported in humans and 5 of 10 organic samples harbored 3 MLST types also reported in humans (2 ST10, 2 ST23, ST354). In conclusion, the majority of organic chicken meat samples were also contaminated with ESBL producing E. coli, and the ESBL genes and strain types were largely the same as in conventional meat samples.
Generated Summary
This study, published in the *International Journal of Food Microbiology*, investigated the prevalence and characteristics of Extended Spectrum Beta-Lactamase (ESBL)-producing bacteria in organic and conventional retail chicken meat. The research aimed to compare the presence and load of ESBL positive isolates in both types of chicken meat and to analyze the distribution of ESBL genes, strain genotypes, and co-resistance patterns. Raw chicken breasts were collected from local stores in the Netherlands. The methodology involved microbiological analysis to quantify ESBL-producing microorganisms and genetic analysis to identify ESBL genes and strain types. The study’s scope included assessing differences in ESBL contamination between organic and conventional chicken meat, which is pertinent to the increasing incidence of infections with these bacteria in humans. The study also analyzed antibiotic resistance patterns among the isolates, providing insights into the potential public health implications of ESBL contamination in the food supply.
Key Findings & Statistics
- Prevalence of ESBL-producing microorganisms: 100% in conventional samples and 84% in organic samples (p<0.001).
- Median loads of ESBL-producing microorganisms: 80 (range <20-1360) CFU/25 g in conventional samples and <20 (range 0-260) CFU/25 g in organic samples (p=0.001).
- Distribution of ESBL genes:
- CTX-M-1: 42% in conventional vs. 56% in organic (N.S.).
- TEM-52: 20% in conventional vs. 42% in organic (N.S.).
- SHV-12: 23% in conventional vs. 3% in organic (p<0.001).
- Specific ESBL genes exclusively found in conventional samples: CTX-M-2 (7%), SHV-2 (5%), and TEM-20 (3%).
- Co-resistance rates:
- Co-trimoxazole: 56% in both conventional and organic samples.
- Ciprofloxacin: 14% in both conventional and organic samples.
- Tobramycin: 2% in both conventional and organic samples.
- Tetracycline: 73% in conventional vs. 46% in organic (p<0.001).
- MLST types reported:
- Six of 14 conventional meat samples harbored 4 MLST types also reported in humans.
- Five of 10 organic samples harbored 3 MLST types also reported in humans (2 ST10, 2 ST23, ST354).
Other Important Findings
- The study found a significant difference in the prevalence of ESBL-producing microorganisms between conventional and organic chicken meat samples, with a higher prevalence in conventional samples.
- Median loads of ESBL-producing microorganisms were significantly higher in conventional samples compared to organic samples.
- The distribution of ESBL genes showed some variation between conventional and organic samples, with certain genes being more prevalent in one type of sample over the other.
- Co-resistance rates to certain antibiotics were similar between conventional and organic samples, while tetracycline resistance differed significantly.
- The study identified that some MLST types found in the chicken meat samples were also reported in human infections, indicating a potential transmission of ESBL-producing bacteria from chicken meat to humans.
Limitations Noted in the Document
- The study’s sample size, particularly for organic samples, may limit the generalizability of its findings to the broader population of chicken meat.
- The study was conducted in a specific geographical location (the Netherlands), which may limit the applicability of the results to other regions with different agricultural practices and antibiotic usage patterns.
- The study focused on raw chicken breasts, and the findings may not be representative of other chicken products or cooking methods.
- The study’s cross-sectional design limits the ability to establish causal relationships between chicken meat consumption and human infections.
- The study did not investigate the specific sources of contamination in the chicken meat, such as farm practices or processing methods.
Conclusion
The research underscores the pervasive presence of ESBL-producing bacteria in both conventional and organic retail chicken meat, with higher contamination levels observed in conventional samples. The statistical analysis demonstrated a significant disparity in the prevalence and load of ESBL-producing microorganisms between conventional and organic chicken meat samples. The presence of ESBL genes and specific strain types in both types of meat, some of which were also found in human infections, suggests a potential pathway for the transmission of antibiotic-resistant bacteria from chicken to humans. The findings suggest the need for stringent measures within the poultry industry to curb the spread of ESBL-producing bacteria, including reducing antibiotic usage in animal agriculture and improving hygiene practices at processing facilities. Furthermore, public health interventions may be required to mitigate the risk of human infections associated with contaminated chicken meat. The study’s findings highlight the importance of monitoring antibiotic resistance in the food supply and implementing strategies to ensure food safety.