Coliform and Escherichia coli Contamination on External and Internal Surfaces of Beef Carcasses with and without Tissue Adhesion Excision.

ABSTRACT: Following removal of hides and viscera during beef processing, carcasses are inspected for tissue adhesions that can affect meat quality or harbor bacteria. Carcasses with pleural or abdominal adhesions may be diverted from the production line for manual excision and then returned to the line. No published data indicate whether adhesion excision is associated with bacterial contamination. Therefore, our objective was to determine the presence and concentration of generic Escherichia coli and non-E. coli coliforms from the internal and external surfaces of carcasses that were, or were not, diverted for adhesion excision. During 9 processing days over a 4-month period in a large commercial beef processing facility, 1,738 carcass sponge samples from 2,730 cm2 areas on both the internal and the external surfaces of carcasses with and without tissue adhesions were collected. Coliforms and E. coli were cultured and enumerated using Petrifilm procedures, and data were analyzed with mixed models. Coliforms were present at higher concentrations than E. coli, and prevalence and mean log concentrations of both coliforms and E. coli were significantly higher for samples from the external than from the internal surfaces of carcasses. However, differences in prevalence and concentration of coliforms between external and internal surfaces varied significantly based on whether carcasses had adhesions excised. The difference was greatest for coliforms present on the external (2.06 log CFU/100 cm2) versus the internal (0.93 log CFU/100 cm2) carcass surfaces without adhesions, whereas the difference in concentrations from the external (1.80 log CFU/100 cm2) and the internal (1.31 log CFU/100 cm2) surfaces of carcasses with adhesions was not as large. These results indicate that surveillance of carcass bacteria may be affected by whether the external versus the internal surfaces are sampled and whether carcasses are diverted for excision of adhesions.

Multidisciplinary response to the Escherichia coli 0104 outbreak in Europe.

The 2011 outbreak of Escherichia coli (E. coli) O104 in northern Germany resulted in over 4,100 illnesses, 900 cases of hemolytic uremic syndrome, and 50 deaths. The U.S. Army's Public Health Command Region-Europe established a multidisciplinary advisory team to prevent E. coli O104 exposure in the Department of Defense (DoD) population. This decentralized, interagency team engaged European public health authorities and coordinated control measures including risk communication. Following German public health investigations, the DoD advisory team compiled information from available official reports, assessed risk, and published guidance to halt the local procurement and supply of suspect foods for all DoD installations in Europe. Advisory team members processed outbreak information, adjusted advisories, and coordinated response efforts. The advisory team quickly identified authoritative information sources, coordinated case definitions, and streamlined potential case reporting. Timely and accurate risk assessment, management, and communication were vital in protecting the DoD population during this outbreak. There were no cases in DoD-related personnel.

Modeling preharvest and harvest interventions for Escherichia coli O157 contamination of beef cattle carcasses.

Field studies evaluating the effects of multiple concurrent preharvest interventions for Escherichia coli O157 are logistically and economically challenging; however, modeling techniques may provide useful information on these effects while also identifying crucial information gaps that can guide future research. We constructed a risk assessment model with data obtained from a systematic search of scientific literature. Parameter distributions were incorporated into a stochastic Monte Carlo modeling framework to examine the impacts of different combinations of preharvest and harvest interventions for E. coli O157 on the risk of beef carcass contamination. We estimated the risk of E. coli O157 carcass contamination conditional on preharvest fecal prevalence estimates, inclusion of feed additive(s) in the diet, vaccination for E. coli O157, transport and lairage effects, hide intervention(s), and carcass intervention(s). Prevalence parameters for E. coli O157 were assumed to encompass potential effects of concentration; therefore, concentration effects were not specifically evaluated in this study. Sensitivity analyses revealed that fecal prevalence, fecal-to-hide transfer, hide-to-carcass transfer, and carcass intervention efficacy significantly affected the risk of carcass contamination (correlation coefficients of 0.37, 0.56, 0.58, and -0.29, respectively). The results indicated that combinations of preharvest interventions may be particularly important for supplementing harvest interventions during periods of higher variability in fecal shedding prevalence (i.e., summer). Further assessments of the relationships among fecal prevalence and concentration, hide contamination, and subsequent carcass contamination are needed to further define risks and intervention impacts for E. coli O157 contamination of beef.

Prevalence and persistence of Salmonella in cohorts of feedlot cattle.

Our objectives were to determine factors associated with fecal prevalence of Salmonella at feedlot entry and within 24 h of harvest (preharvest), and to assess potential persistence of Salmonella strains within cattle populations. This repeated cross-sectional study followed 5559 beef cattle within 30 feedlot cohorts. Samples (n = 30) of fresh feces were collected from the pen floor of each cohort at feedlot entry and preharvest. Samples were subjected to a selective Salmonella isolation protocol and serotypes were determined for Salmonella isolates. Genetic similarity of a subset of isolates was determined using pulsed-field gel electrophoresis (PFGE). Cattle health and performance data were recorded electronically by feedlot personnel. Cohort-level generalized linear mixed models were used to assess bivariable associations. Fecal prevalence of Salmonella within a cohort at feedlot entry (mean = 64.7%) was not associated with preharvest prevalence (mean = 72.6%). Prevalence at feedlot entry was negatively associated with mean entry weight (p = 0.02). Preharvest prevalence was positively associated with the number of days in the feedlot (p = 0.02), cumulative morbidity (p = 0.01), and cumulative mortality (p = 0.03). We recovered Salmonella isolates with identical PFGE profiles both at feedlot entry and preharvest from 14 cohorts of cattle. Fecal prevalence of Salmonella immediately before harvest may be higher in subsets of the feedlot population, but does not appear to be affected by prevalence at feedlot entry. However, PFGE subtypes of Salmonella appear to persist within and among feedlot cohorts throughout the feeding period.

Evaluation of the effects of a commercially available Salmonella Newport siderophore receptor and porin protein vaccine on fecal shedding of Salmonella bacteria and health and performance of feedlot cattle.

OBJECTIVE: To evaluate effects of a Salmonella Newport siderophore receptor and porin protein (SRP) vaccine on cattle health and performance and on prevalence of fecal shedding of Salmonella bacteria in feedlot cattle. ANIMALS: 1,591 beef cattle. PROCEDURES: Cattle were randomly allocated within a replicate (n = 10 replicates [20 total pens]), administered 2 mL of a Salmonella Newport SRP vaccine (n = 795 cattle) or a placebo (796), and revaccinated approximately 21 days after the first administration. Health and performance data were recorded by trained feedlot personnel who were blinded to treatment. Fresh fecal samples (n = 25) were collected from pen floors on days 0, 60, and 120 and within 24 hours of cattle harvest and were subjected to selective Salmonella culture and serotyping by laboratory personnel who were blinded to treatment. Pen-level mixed models were used to analyze data. RESULTS: Significant differences in fecal prevalence of Salmonella bacteria or health and performance variables were not detected between vaccinated and control cattle. Salmonella bacteria were recovered from all 10 replicates, and cumulative prevalence estimates ranged from 1.5% to 22%. Overall prevalence of fecal shedding of Salmonella bacteria was 10.2% and 10.9% in vaccinated and control cattle, respectively. Overall morbidity risk was 34.8% for both vaccinated and control cattle. Overall mortality risks were 1.9% and 1.1% for vaccinated and control cattle, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: In this setting, administration of the Salmonella Newport SRP vaccine in feedlot cattle had no effect on fecal prevalence of Salmonella bacteria or cattle health and performance.

Genetic relatedness of Escherichia coli O157 isolates from cattle feces and preintervention beef carcasses.

Our objective was to define and compare pulsed-field gel electrophoresis (PFGE) profiles of Escherichia coli O157 isolated from cattle feces and carcass samples to evaluate relationships between beef carcass contamination and fecal shedding of E. coli O157 at harvest. We used PFGE separation of Xba1-digested DNA to characterize E. coli O157 isolates (n = 174) from preevisceration carcasses (n = 39) and feces (n = 135) that were recovered from 37 E. coli O157-positive truckloads sampled at a commercial abattoir. Semiquantitative fecal culture techniques differentiated high-shedding, low-shedding, and negative cattle. Among all isolates, there were 17 PFGE types (95% homology) and 37 subtypes (100% homology). Specific subtypes were detected on multiple occasions and from different sample types within loads, among loads, and among days. Seventeen subtypes were recovered from carcasses; most were also recovered from feces of high-shedding cattle (13) and low-shedding cattle (14). Within truckload, the percentages of carcass isolates that were identical to high-shedder or low-shedder fecal isolates, as determined by PFGE, were 69.2% and 46.0%, respectively, whereas among different truckloads within the same study day, the percentages of carcass isolates that were the same subtype as high-shedder or low-shedder fecal isolates were 35.3% and 58.8%, respectively. Our results suggest that cattle feces from both low- and high-shedders pose a potential risk for E. coli O157 contamination of carcasses. Truckload may be an important factor in the potential transmission of E. coli O157, but isolates from carcasses also may be similar to those from feces of cattle on different truckloads and harvest days.

Prevalence of Escherichia coli O157 in cattle feeds in Midwestern feedlots.

Comparisons of enrichment methods (with or without antibiotics and with or without a preenrichment step) using gram-negative (GN) broth or tryptic soy broth (TSB) were conducted with feeds inoculated with Escherichia coli O157:H7. TSB was more sensitive than GN broth, and TSB with a preenrichment step followed by TSB with antibiotics was more sensitive than plain TSB enrichment, in detecting E. coli O157 in inoculated feeds. Feed samples were collected from feed bunks from 54 feedlots to determine the prevalence of E. coli O157 in cattle feeds. TSB preenrichment followed by TSB with antibiotics and the standard GN broth enrichment were used for each feed sample. All samples underwent immunomagnetic separation and were plated onto sorbitol MacConkey agar with cefixime and potassium tellurite. Identification of E. coli O157 was based on indole production, positive latex agglutination for O157 antigen, API 20E test strip results, PCR for the eaeA gene, and the presence of at least one Shiga toxin. E. coli O157 was detected in 52 of 504 feed samples (10.3%) by using GN broth enrichment and in 46 of 504 feed samples (9.1%) by using TSB followed by TSB supplemented with cefixime and vancomycin. E. coli O157 was detected in 75 of 504 feed bunk samples (14.9%) by one or both methods. There was no correlation between E. coli O157 prevalence and generic coliform counts in feeds. The prevalence of E. coli O157 in cattle feed warrants further studies to increase our knowledge of the on-farm ecology of E. coli O157 in order to develop strategies to prevent food-borne disease in humans.