A National Antimicrobial Resistance Monitoring System Survey of Antimicrobial-Resistant Foodborne Bacteria Isolated from Retail Veal in the United States

Abstract

Abstract: Little is known about the prevalence of antimicrobial-resistant (AMR) bacteria in veal meat in the United States. We estimated the prevalence of bacterial contamination and AMR in various veal meats collected during the 2018 U.S. National Antimicrobial Resistance Monitoring System (NARMS) survey of retail outlets in nine states and compared the prevalence with the frequency of AMR bacteria from other cattle sources sampled for NARMS. In addition, we identified genes associated with resistance to medically important antimicrobials and gleaned other genetic details about the resistant organisms. The prevalence of Campylobacter, Salmonella, Escherichia coli, and Enterococcus in veal meats collected from grocery stores in nine states was 0% (0 of 358), 0.6% (2 of 358), 21.1% (49 of 232), and 53.5% (121 of 226), respectively, with ground veal posing the highest risk for contamination. Both Salmonella isolates were resistant to at least one antimicrobial agent as were 65.3% (32 of 49) of E. coli and 73.6% (89 of 121) of Enterococcus isolates. Individual drug and multiple drug resistance levels were significantly higher (P < 0.05) in E. coli and Enterococcus from retail veal than in dairy cattle ceca and retail ground beef samples from 2018 NARMS data. Whole genome sequencing was conducted on select E. coli and Salmonella from veal. Cephalosporin resistance (blaCMY and blaCTX-M), macrolide resistance (mph), and plasmid-mediated quinolone resistance (qnr) genes and gyrA mutations were found. We also identified heavy metal resistance genes ter, ars, mer, fieF, and gol and disinfectant resistance genes qac and emrE. An stx1a-containing E. coli was also found. Sequence types were highly varied among the nine E. coli isolates that were sequenced. Several plasmid types were identified in E. coli and Salmonella, with the majority (9 of 11) of isolates containing IncF. This study illustrates that veal meat is a carrier of AMR bacteria.

Keywords: Enterococcus; Escherichia coli; Salmonella; Antimicrobial resistance; National Antimicrobial Resistance Monitoring System; Retail veal.

Figure 1:

Comparison of antimicrobial resistance in E.coli isolates from retail veal, retail ground beef, and dairy cattle ceca *For these antimicrobials, there are significant differences between percentage of isolates resistant in retail veal and retail ground beef as well as between retail veal and dairy cattle ceca. ǂFirst line therapies for the treatment of complicated salmonellosis include ciprofloxacin, azithromycin, and ceftriaxone. Note: percent resistance to ciprofloxacin includes isolates with decreased susceptibility (MIC >= 0.12).

Figure 2:

Comparison of antimicrobial resistance in Enterococcus spp. isolates from retail veal, retail ground beef, and dairy cattle ceca *For these antimicrobials, there were significant differences between percentage of isolates resistant in retail veal and retail ground beef as well as between retail veal and dairy cattle ceca. § CLSI Quinupristin-Dalfopristin breakpoints are only available for non-E. faecalis species. For this drug the following denominators were used: Dairy Cattle Ceca (N= 363), Retail Ground Beef (N= 178), Retail Veal (N= 28). ǂFirst line therapies for the treatment of Enterococcus include vancomycin and tigecycline (vancomycin-susceptible infections) and daptomycin and linezolid (vancomycin-resistant infections).