Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/9/2003
Publication Date: 11/9/2003
Citation: FRANA, T.S., CARLSON, S.A., GRIFFITH, R.W. INVESTIGATION OF MCC24-PRODUCING ESCHERICHIA COLI ON SALMONELLA ENTERICA SEROTYPE TYPHIMURIUM SHEDDING AND MAR ACTIVATION IN PIGS. CONFERENCE OF RESEARCH WORKERS IN ANIMAL DISEASES. 2003. ABSTRACT P. 27P.
Technical Abstract: Objective - To investigate in swine the effect of daily, oral inoculations of an Escherichia coli producing microcin 24 (Mcc24) on Salmonella enterica serotype Typhimurium (ST) shedding and to look for evidence of Mcc24-mediated MAR (Multiple Antibiotic Resistance) activation in vivo. Procedure - Two groups of crossbred, 17-day-old, weaned pigs (12 pigs/group) were orally dosed on a daily basis with either a Mcc24-producing E. coli or a non-Mcc24-producing E. coli and challenged with ST Chi4232 (ST4232). A third group of six pigs received Mcc24-producing E. coli were and challenged with a marA deleted strain of ST4232 (ST4232DeltamarA). In addition, two groups of three pigs each were challenged with either the ST4232 or ST4232DeltamarA but did not receive E. coli. After ST challenge each pig was monitored for ST by fecal culture and any ST isolates screened for resistance to ciprofloxacin. Fecal and tissue samples were collected until 20 days post ST challenge. Results - No difference in ST shedding pattern was found between groups receiving Mcc24-producing or non-Mcc24-producing E. coli. No evidence of mar activation in challenge strains of ST was seen in any group. Conclusions and Clinical Relevance - Under the conditions of this experiment Mcc24-producing E. coli did not exert an effect on ST shedding or mar activation in pigs. If Mcc24 is to be considered as part of a competitive exclusion intervention to reduce ST the conditions need to be carefully considered. Bacterial host, method of delivery, and ST ecology are important factors.