Prevalence and antimicrobial resistance of Campylobacter from antibiotic-free broilers during organic and conventional processing.

Campylobacter is one of the leading cause of foodborne illness in the US and worldwide, especially linked to poultry and poultry products. In recent years, the increasing popularity of organic chicken products and chickens raised without antibiotics (RWA) has resulted in more companies adopting organic and antibiotic-free production and processing methods; however, it is not evident what effect these practices have on pathogens such as Campylobacter. The purpose of this study was to determine the effects of RWA and organic methods on the prevalence and antimicrobial resistance (AMR) of Campylobacter. Samples were collected from a processing facility that used organic and conventional methods to process RWA broilers. Samples included fecal grab samples from incoming birds, carcass rinses at important steps throughout processing, and environmental samples including equipment swabs, water samples, and air samples. Samples were analyzed for prevalence of Campylobacter by enrichment, and populations of presumptive Campylobacter were quantified. Isolates collected in this study were analyzed for AMR according to the National Antimicrobial Resistance Monitoring System (NARMS) protocol. Results showed that organic birds had a lower prevalence (P < 0.05) of Campylobacter and lower populations of presumptive Campylobacter during early processing steps, but no differences (P > 0.05) between organic and conventional birds were seen post-chill, with the exception of a lower prevalence in post-water-chill organic birds. These observations show that organic methods can be associated with lower initial Campylobacter levels than conventional methods, although appropriate processing interventions result in similar Campylobacter populations post-chill, regardless of processing method. Prevalence of AMR Campylobacter in chickens at slaughter suggest that raising birds without the use of antimicrobials may not be effective in reducing the incidence of AMR Campylobacter in chicken.

Thermal Inactivation of Shiga Toxin-Producing Escherichia coli in Ground Beef with Varying Fat Content.

Decimal reduction time ( D-value) was calculated for six non-O157 Shiga toxin-producing Escherichia coli (STEC) in a laboratory medium and ground beef. For the laboratory medium, an overnight culture of each strain of STEC was divided into 10-mL sample bags and heated in a water bath for a specific time on the basis of the temperatures. Survival curves were generated by plotting the surviving bacterial population against time, and a linear-log primary model was used to estimate the D-values from survival curves. The z-values (the temperature raised to reduce the D-value by one-tenth) were calculated by plotting the log D-values against temperature. Similarly, for ground beef, six fat contents, 5, 10, 15, 20, 25, and 30% of ground beef were formulated for this study. Inoculated meat was divided into 5-g pouches and submerged in a water bath set at specific temperatures (55, 60, 65, 68, and 71.1°C). The average D-value for these strains in a laboratory medium was 17.96 min at 55°C, which reduced significantly ( P < 0.05) to 1.58 min at 60°C, and then further reduced ( P < 0.05) to 0.46 min at 65°C. In ground beef, a negative correlation ( P < 0.05) between fat content of ground beef and D-values was observed at 55°C. However, at temperatures greater than 60°C, there was no impact ( P > 0.05) of fat content of ground beef on the thermal resistance of non-O157 STECs. Irrespective of the fat content of ground beef, the D-values ranged from 15.93 to 11.69, 1.15 to 1.12, and 0.14 to 0.09 min and 0.05 at 55, 60, 65, and 68°C, respectively. The data generated from this study can be helpful for the meat industry to develop predictive models for thermal inactivation of non-O157 STECs in ground beef with varying fat content.