Submitted to: Antimicrobial Agents and Chemotherapy
Publication Type: Abstract only
Publication Acceptance Date: 9/11/2011
Publication Date: 9/13/2009
Citation: Thitaram, S.N., Frank, J.F., Dargatz, D.A., Siragusa, G.R., Bailey, J.S., Lyon, S.A., Cray, P.J. 2009. Isolation of Clostridium difficile from healthy food animals. Antimicrobial Agents and Chemotherapy. September 12-15, 2009. San Francisco, CA. Interpretive Summary:
Technical Abstract: Background: Clostridium difficile-associated disease is increasingly reported and studies indicate that food animals may be sources of human infections. Methods: The presence of C. difficile in 345 swine fecal, 1,325 dairy cattle fecal, and 371 dairy environmental samples were examined. Two isolation techniques, single and double alcohol shock, were compared. The resulting 188 isolates (94 swine, 40 dairy cattle, and 54 environmental) and 33 human C. difficile isolates were tested for their susceptibility to 9 antimicrobials by Etest. Repetitive extragenic palindromic-polymerase chain reaction (rep-PCR) was used for isolate genotyping. Results: Fifty-five swine fecal samples, 32 dairy cattle fecal samples and 32 environmental samples were positive for C. difficile by either single or double alcohol shock method. Double alcohol shock was significantly better than single alcohol shock for the recovery of C. difficile in swine and environmental samples. All isolates were susceptible to amoxicillin-clavulanic acid, metronidazole, and vancomycin; 2 were susceptible to rifampicin. All isolates were resistant to levofloxacin. One hundred nineteen distinct patterns were identified by rep-PCR. Overall, 20 (9%) isolates from animal origin were indistinguishable from one human isolate by rep-PCR. Conclusions: While C. difficile was more prevalent in swine than in dairy cattle and environment, each is a potential reservoir of C. difficile. Resistance to metronidazole and vancomycin has yet to develop in swine and dairy cattle. Additional research is warranted to determine if this presents an impact on human health.