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United States Department of Agriculture

Agricultural Research Service

Title: PREVALENCE AND ANTIMICROBIAL RESISTANCE OF ENTEROCOCCI ISOLATED FROM GROCERY ITEMS

Authors
item Jackson, Charlene
item Cray, Paula
item Barrett, John

Submitted to: National Antimicrobial Resistance Monitoring System Scientific Meeting
Publication Type: Abstract Only
Publication Acceptance Date: November 1, 2003
Publication Date: November 19, 2003
Citation: Jackson, C.R., Cray, P.J., Barrett, J.B. 2003. Prevalence and antimicrobial resistance of enterococci isolated from grocery items. National Antimicrobial Resistance Monitoring System Scientific Meeting. November 19-22, 2002. Hilton Head, SC.

Technical Abstract: The use of antimicrobials in the food supply and the potential for transfer of antimicrobial resistant bacteria into the human population is cause for concern. Because commensal bacteria such as enterococci have natural gene transfer mechanisms and can harbor multiple resistances, it is important to characterize the strains that are isolated from food. From 2000-2001, 19 different types of food items (vegetables, fruits, and meats) were obtained from 6 popular grocery store chains in the North Georgia USA area and cultured for the presence of enterococci. Enterococcus isolates were speciated and then analyzed for antimicrobial susceptibility to a panel of 16 or 17 antimicrobials for 2000 and 2001, respectively. Fifty-five percent (186/337) of the samples were positive for enterococci. Interestingly, enterococci were most often recovered from potatoes (50/186 positive samples) than from any other item. For fruits, enterococci were cultured most often from tomatoes (4.3%) and apples (2.7%). Among the meat items tested, enterococci were isolated from 20/23 chicken, 18/22 beef, 18/21 turkey, and 14/21 pork samples. The predominant species identified was Enterococcus faecalis (n=76) followed by Enterococcus casseliflavus (n=62) and Enterococcus faecium (n=14). While high numbers of isolates were resistant to bacitracin (167/186), lincomycin (173/186), and flavomycin (100/186), very few isolates were resistant to ciprofloxacin (n=6), gentamicin (n=8), penicillin (n=2), linezolid (n=2) or nitrofurantoin (n=1). Additionally, although 47% of enterococci were resistant to the human medical use drug Synercid, intrinsic resistance of E. faecalis accounted for the majority of resistance (34%) observed for this antimicrobial. Most important, none of the isolates were resistant to vancomycin. These data suggest that foods commonly purchased and consumed from grocery stores are a source of enterococci. However, overall resistance to antimicrobials is relatively low. Further surveillance is warranted.

Last Modified: 9/1/2014
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