Carcass chilling is considered a critical step for inhibiting bacterial growth during poultry processing. The objective of this study was to compare microbiological loads and the incidence of Salmonella spp. and Campylobacter spp. on broiler carcasses subjected to immersion chilling and air chilling. Additionally, the antibiotic resistance patterns of pathogen isolates were determined. The results of this study indicated that the incidence of Salmonella spp. and Campylobacter spp. tends to be significantly lower in air-chilled broilers, suggesting that cross-contamination may be more prevalent for immersion-chilled broilers. No significant differences were detected between chilling treatments for total aerobic populations or for generic E. coli or coliform counts. Psychrotrophic populations were significantly larger (P < 0.05) in immersion-chilled broilers than in their air-chilled counterparts. Campylobacter isolates from immersion-chilled broilers had a higher incidence of resistance to nalidixic acid (NAL) and related fluoroquinolones than isolates from air-chilled broilers did. Additionally, Campylobacter isolates from air-chilled broilers had a higher frequency of resistance to tetracycline than isolates from immersion-chilled broilers did. With regard to Salmonella, isolates from immersion-chilled broilers had a higher incidence of resistance to NAL than isolates from air-chilled samples did. No Salmonella isolates from immersion- or air-chilled broilers were resistant to the fluoroquinolones tested. The chilling method used during processing may influence the microbial profile of postchilled broilers.

To determine patterns of cross-contamination and antibiotic susceptibility of microorganisms commonly associated with cattle, 60 cattle shipped to a commercial abattoir (20 in each of three separate trial periods) were followed through processing. Samples for bacterial isolation were collected from the feces and hides immediately before shipping, from the hides at the abattoir after exsanguination, and from the carcasses before evisceration and in the cooler. Samples were cultured for Salmonella and non-type-specific Escherichia coli. Salmonella was identified in 33.9% (n = 20) of the fecal samples and on 37.3% (n = 22) of the hides before shipment. At the abattoir, the proportion of hides from which Salmonella was isolated increased (P < 0.001) to 84.2% (48 hides). Nonspecific E. coli and Salmonella were recovered from 40.4 and 8.3% of preevisceration carcass samples, respectively. No Salmonella or nonspecific E. coli were recovered from hotbox carcass samples. Isolates were tested for antimicrobial drug susceptibility. For nonspecific E. coli, 80.3% (n = 270) of the isolates were resistant to at least one antimicrobial drug. For Salmonella, 97% (n = 101) of the isolates were resistant to at least one antimicrobial drug; however, only 4.0% were resistant to two or more. The most common resistance was to sulfamethoxazole. These results indicate that the presence of microorganisms resistant to antimicrobial drugs is common in cattle and beef. Further studies are needed to identify the sources and causes of this drug resistance.

The microbiological profile of an air-chilling poultry process was investigated from the farm through the processing plant. Within a 1-year period, nine broiler flocks from four different farm sources were studied. Numbers of total aerobes, coliforms, psychrotrophic organisms, E. coli Biotype I (generic E. coli), Salmonella spp., and Campylobacter spp. were determined for multiple sampling sites on the farm as well as in the processing plant. Farm samples were collected the day before the chickens were slaughtered at the plant. The same flock was sampled at the plant on the day of slaughter. Sites located before evisceration (BE), after evisceration (AE), and after chilling (AC) were sampled. Results indicated a positive correlation between contamination of ceca with Salmonella on the farm and the presence Salmonella in carcass samples from the plant for all three types of sampling sites. The in-plant trend for total aerobes, coliforms, and generic E. coli revealed a significant decrease from counts obtained before evisceration to those obtained for the (AC) final product when flock variations were taken into account. The average coliform counts were 3.91, 3.27, and 2.59 log10 CFU/ml of rinse for BE, AE, and AC samples, respectively. Generic E. coli counts were 3.74, 3.08, and 2.20 log10 CFU/ml of rinse for BE, AE, and AC samples, respectively. No reductions in numbers of Campylobacter or Salmonella were observed during processing, which suggests that practical intervention strategies for lowering pathogen levels are critical on a multilevel basis at the farm and in the plant.

To investigate evidence of cross-contamination and to determine patterns of antimicrobial drug susceptibility of Enterococcus isolates in a commercial cattle processing system, samples were collected from 60 cattle shipped to a commercial abattoir. Enterococcus isolates were recovered from fecal and hide samples collected immediately before shipment from a feedlot to the abattoir, from postexsanguination hide samples at the abattoir, and from carcass samples collected after hide removal (preevisceration) and in the cooler. Of the fecal samples, 53.9% were culture positive for Enterococcus. Of hide samples collected at the feedlot, 77.8% were positive for Enterococcus, significantly lower (P < 0.01) than the proportion of hides that were culture positive at the abattoir (96.1%). For preevisceration carcass samples, Enterococcus was recovered from 58.3% of carcasses. Only 8.3% of the carcasses sampled in the cooler yielded Enterococcus. Resistance among Enterococcus isolates was common regardless of the type or location of sample from which the isolate was recovered. All 279 Enterococcus isolates were resistant to at least one antimicrobial drug, and 179 (64.2%) of these isolates were resistant to at least six drugs. The most common resistance was to chloramphenicol (100% of isolates) followed by flavomycin (90.3%), lincomycin (87.8%), tylosin (78.5%), erythromycin (76.3%), tetracycline (58.9%), quinupristin-dalfopristin (47.7%), bacitracin (17.9), streptomycin (9.0%), ciprofloxacin (1.4%), linezolid (0.7%), and salinomycin (0.4%). Enterococcus isolates also were characterized using pulsed-field gel electrophoresis to evaluate molecular similarities. Similar or indistinguishable electrophoresis patterns were found among isolates recovered at the feedlot and in the plant, providing evidence that feedlot-origin bacterial isolates are being transferred from cattle to carcasses within the processing environment through cross-contamination.