Submitted to: American Society for Microbiology General Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2014
Publication Date: 5/17/2014
Citation: Schmidt, J.W., Harhay, D.M., Shackelford, S.D., Wheeler, T.L., Arthur, T.M. 2014. Antibiotic resistant Escherichia coli and Salmonella enterica in the beef production and processing chain. [abstract] American Society for Microbiology 114th General Meeting. No. 1033.
Technical Abstract: Background: Concerns have been raised that extended-spectrum cephalosporin-resistant Escherichia coli (CefR EC), trimethoprim-sulfamethoxazole-resistant E. coli (TxsR EC), extended-spectrum cephalosporin-resistant Salmonella enterica (CefR SE), and nalidixic acid-resistant S. enterica (NalR SE) in cattle production environments may persist through beef processing, potentially contaminating final products, and possibility impacting human health. Materials: Sterile sponges were used to sample 184 animals from three lots at four points in the beef chain: feedlot hides (FH), processing plant hides (PH), pre-evisceration carcasses (PC), and final carcasses (FC). The presence of CefR EC and TxsR EC in each sample was determined by enrichment in MacConkey broth followed by plating on CHROMagar E. coli (CEC) + cefotaxime and CEC + trimethoprim-sulfamethoxazole, respectively. The presence of S. enterica, CefR SE, and NalR SE in each sample was determined by enrichment in RVS broth followed by plating on XLD, XLD + cefotaxime, and XLD + nalidixic acid, respectively. CefR EC, TxsR EC, S. enterica, CefR SE, and NalR SE were enumerated from each sample by direct plating on the same media used to determine their respective prevalences. Results: CefR EC prevalences were 89.1% on FH, 100% on PH, 2.7% on PC, and 0.5% on FC. CefR EC levels were 0.2 log CFU/100 cm2 on FH and 1.6 log CFU/100 cm2 on PH, but were below enumerable levels on PC and FC. TxsR EC prevalences were 100%, 100%, 32.6%, and 0.5% on FH, PH, PC, and FC, respectively. TxsR EC levels were 1.1 log CFU/100 cm2 on FH and 3.0 log CFU/100 cm2 on PH, but were below enumerable levels on PC and FC. S. enterica prevalences on FH, PH, PC, and FC were 26.1%, 99.5%, 2.2%, and 0%, respectively. S. enterica was present at a level of 1.5 log CFU/100 cm2 on PH, but was below enumerable levels on FH, PC, and FC. CefR SE was below enumerable levels at all points and prevalent on 10.9% of FH, 7.6% of PH, 0% of PC, and 0% of FC. NalR SE was detected from only one PH sample. Conclusions: Almost all cattle begin processing with CefR EC, TxsR EC, and S. enterica on hides. Currently employed processing interventions are effective since CefR EC, TxsR EC, CefR SE, and NalR SE were detected on < 1% of final carcasses.