Submitted to: Journal of Food Protection
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/22/2011
Publication Date: 1/7/2011
Citation: Thitaram, S.N., Frank, J.F., Lyon, S.A., Siragusa, G.R., Bailey, J.S., Lombard, J.E., Haley, C.A., Wagner, B.A., Dargatz, D.A., Cray, P.J. 2011. Clostridium difficile from healthy food animals: Optimized isolation and prevalence. Journal of Food Protection. 74(1):130-133. Interpretive Summary: Clostridium difficile is recognized as a hospital-acquired pathogen associated with antimicrobial drug-associated diarrhea and pseudomembranous colitis in humans. Recent studies have demonstrated the occurrence of C. difficile in clinically ill food animals which may act as a source of infection to humans. The presence of C. difficile in 345 swine fecal, 1,325 dairy cattle fecal, and 2,965 beef cattle fecal samples were examined. Two isolation techniques, single and double alcohol shock, were compared. A total of 55, 32, and 188 fecal samples from swine, dairy cattle and beef cattle respectively were positive for C. difficile by either single or double alcohol shock. Double alcohol shock was significantly better than single alcohol shock for the recovery of C. difficile in swine feces. However, single alcohol shock was significantly better than double alcohol shock for the recovery of C. difficile in beef cattle feces. There was no significant difference for the recovery of C. difficile between any combination of isolation methods for dairy cattle feces. This study demonstrates that C. difficile can be found in fecal samples from food animals that are not clinically ill and provides critical information that isolation methods may not have universal application across animal species.
Technical Abstract: Two isolation methods were compared for isolation of Clostridium difficile from food animal feces. The single alcohol shock method (SS) used selective enrichment in cycloserine-cefoxitin fructose broth supplemented with 0.1% sodium taurocholate (TCCFB) followed by alcohol shock and isolation on tryptic soy agar supplemented with 5% sheep blood (BA) and cycloserine-cefoxitin fructose agar (CCFA). The double alcohol shock method (DS) used alcohol shock prior to and after selective enrichment in TCCFB followed by isolation on BA and CCFA. A total of 55 (15.9%; n = 345) swine fecal samples, 32 (2.4%; n = 1,325) dairy cattle fecal samples, and 188 (6.3%; n = 2,965) beef cattle fecal samples were positive for C. difficile by either method. However, the DS was significantly better than SS for the recovery of C. difficile in swine feces while the SS was significantly better than the DS for the recovery of C. difficile in beef cattle feces. There was no significant difference between methods for the recovery of C. difficile from dairy cattle feces. This study demonstrates that C. difficile can be cultured from feces of food animals and provides critical information that isolation methods may not have universal application across animal species.