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Title: Application of a plasmid classification system to determine prevalence of replicon families among multidrug resistant enterococci

Author
item Jackson, Charlene
item Barrett, John
item Hiott, Lari
item Woodley, Tiffanie
item CHO, SOHYUN - University Of Georgia
item Frye, Jonathan

Submitted to: American Society for Microbiology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/29/2016
Publication Date: 6/19/2016
Citation: Jackson, C.R., Barrett, J.B., Hiott, L.M., Woodley, T.A., Cho, S., Frye, J.G. 2016. Application of a plasmid classification system to determine prevalence of replicon families among multidrug resistant enterococci. American Society for Microbiology Conference. June 16-20, 2016. Boston, Massachusetts.

Interpretive Summary:

Technical Abstract: The presence and transfer of plasmids from commensal bacteria to more pathogenic bacteria may contribute to dissemination of antimicrobial resistance. However, prevalence of plasmids from commensal bacteria in food animals such as the enterococci remains largely unknown. In this study, the prevalence of plasmid families from multidrug resistant (MDR; resistance to three or more antimicrobials) enterococci from poultry carcasses was determined. Plasmid positive MDR enterococci were also tested for the ability to transfer plasmids and resistance to other enterococci. Enterococcus faecalis (n=98) and Enterococcus faecium (n=702) used in this study were isolated from poultry carcass rinsates between 2004 and 2011. Isolates were identified to species and analyzed for antimicrobial susceptibility as part of the animal arm of the National Antimicrobial Resistance Monitoring System (NARMS)—Enteric Bacteria at the US Department of Agriculture—Agricultural Research Service (USDA-ARS), Athens, GA. MDR enterococci were tested for the presence of 19 plasmid replicon (rep) families using multiplex PCR. Transfer of plasmids and antimicrobial resistance was determined by filter mating. Approximately 48% of E. faecalis (47/98) and 17% of E. faecium (116/702) were positive for at least one rep-family. Fourteen rep-families were detected indicating the presence of 14 different plasmids among the isolates. The most common MDR pattern among the isolates was GenKanLinTet and LinNitTet. The rep-family 9 (rep9) was predominant among both E. faecalis and E. faecium for all years tested. Host range for E. faecalis and E. faecium was different as 13 rep-families were found among E. faecalis and 12 among E. faecium. The rep7 and rep17 family were unique to E. faecalis, while the rep5 family was unique to E. faecium. The most number of rep-families detected was in 2005 (n=10) and the least in 2009 (n=1). No transfer of tetracycline or erythromycin resistance was detected among selected isolates. Results from this study show that E. faecalis and E. faecium from poultry carcasses contain numerous and diverse rep-families. Additional conjugation studies are ongoing to determine if the plasmids can transfer into other enterococci.