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P2-152 Presence of Disinfectant Resistance Genes in Escherichia coli Isolated from NARMS Retail Meats

Tuesday, July 30, 2013
Exhibit Hall (Charlotte Convention Center)
Likou Zou, Sichuan Agricultural University, Dujiangyan, China
Shaohua Zhao, U.S. Food and Drug Administration, Laurel, MD
Patrick McDermott, U.S. Food and Drug Administration, Laurel, MD
Fei Wang, University of Maryland-College Park, College Park, MD
Qianru Yang, Louisiana State University, Baton Rouge, LA
Guojie Cao, University of Maryland-College Park, College Park, MD
Jianghong Meng, University of Maryland-College Park, College Park, MD
Introduction: Retail meats are commonly contaminated with Escherichia coli and probably also an important reservoir of antimicrobial-resistant E. coli. The frequent use and misuse of quaternary ammonium compounds (QACs) in food processing industries may have imposed a selective pressure and contributed to the emergence of resistant microbes. However, little information is available regarding the QAC resistance genes in E. coliisolates from retail meats.

Purpose: The objective of this study was to determine the prevalence of QAC resistance genes, the correlation of their presence and resistance to QAC and other antimicrobials in E. coliisolated from retail meats in the U.S.

Methods: Five hundred seventy E. coli isolated from National Antimicrobial Resistance Monitoring System (NARMS) retail meat program in 2006 were included in this study. The presence of 10 QAC resistance genes (qacE, qacEΔ1, qacF, qacG, emrE, sugE(c), sugE(p), mdfA and ydgE/F) were determined by PCR. Minimum inhibitory concentrations of QACs were examined using agar dilution method.

Results: Chromosomally encoded emrE, sugE(c), mdfA and ydgE/F were widely distributed in E. coli, with a prevalence ranging from 77.2% (n = 440) to 100% (n = 570). However, qacE was not detected in any of the isolates. The prevalence of the other genes ranged from 22.3% (qacEΔ1, n = 127) to 0.4% (qacG, n = 2). sugE(p) was detected in 6.8% (n = 39) of the isolates. A significant correlation was found between the presence of sugE(p), qacEΔ1 and antibiotic-resistance isolates (P < 0.01). Also qacEΔ1 was significantly more common (P < 0.05) in E. coli isolated from poultry meats than from beef and pork.  MICs showed that all isolates showed reduced susceptibility to QACs compared with the control strain.

Significance: E. coli could serve an important reservoir for the dissemination of QAC resistance. The use of QACs in food processing environments may have played a role in the emergence of QAC-resistant bacteria.

Back to: Poster Session 2 - Pathogens, Antimicrobials
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