Occurrence and Genetic Characteristics of Third-Generation Cephalosporin-Resistant Escherichia coli in Swiss Retail Meat

Abstract

Prevalence and genetic relatedness were determined for third-generation cephalosporin-resistant Escherichia coli (3GC-R-Ec) detected in Swiss beef, veal, pork, and poultry retail meat. Samples from meat-packing plants (MPPs) processing 70% of the slaughtered animals in Switzerland were purchased at different intervals between April and June 2013 and analyzed. Sixty-nine 3GC-R-Ec isolates were obtained and characterized by microarray, PCR/DNA sequencing, Multi Locus Sequence Typing (MLST), and plasmid replicon typing. Plasmids of selected strains were transformed by electroporation into E. coli TOP10 cells and analyzed by plasmid MLST. The prevalence of 3GC-R-Ec was 73.3% in chicken and 2% in beef meat. No 3GC-R-Ec were found in pork and veal. Overall, the bla(CTX-M-1) (79.4%), bla(CMY-2) (17.6%), bla(CMY-4) (1.5%), and bla(SHV-12) (1.5%) β-lactamase genes were detected, as well as other genes conferring resistance to chloramphenicol (cmlA1-like), sulfonamides (sul), tetracycline (tet), and trimethoprim (dfrA). The 3GC-R-Ec from chicken meat often harbored virulence genes associated with avian pathogens. Plasmid incompatibility (Inc) groups IncI1, IncFIB, IncFII, and IncB/O were the most frequent. A high rate of clonality (e.g., ST1304, ST38, and ST93) among isolates from the same MPPs suggests that strains persist at the plant and spread to meat at the carcass-processing stage. Additionally, the presence of the blaCTX-M-1 gene on an IncI1 plasmid sequence type 3 (IncI1/pST3) in genetically diverse strains indicates interstrain spread of an epidemic plasmid. The bla(CMY-2) and bla(CMY-4) genes were located on IncB/O plasmids. This study represents the first comprehensive assessment of 3GC-R-Ec in meat in Switzerland. It demonstrates the need for monitoring contaminants and for the adaptation of the Hazard Analysis and Critical Control Point concept to avoid the spread of multidrug-resistant bacteria through the food chain.

Characteristics of ESBL-producing Enterobacteriaceae and Methicillinresistant Staphylococcus aureus (MRSA) isolated from Swiss and imported raw poultry meat collected at retail level

“…The most relevant bla ESBL genes harbored by Enterobacteriaceae are plasmid-encoded bla CTX-M-blaSHV-and blaTEM -variants (Bush and Jacoby, 2010). It is well recognized that food animals and meat (particularly chicken meat) are a source of ESBL-producing bacteria (Leverstein-van Hall et al, 2011;Seifert et al, 2013;Abgottspon et al, 2014;Vogt et al, 2014) and the Federal Food Safety and Veterinary Office (FSVO) national monitoring system tracks antibiotic resistance in livestock and retail meats in Switzerland (Müntener and Overesch, 2015). Furthermore, the very recent emergence of Enterobacteriaceae harboring the plasmid-mediated colistin resistance gene mcr-1 in food animals and retail meat including chicken (Liu et al, 2015;Webb et al, 2015), is highly alarming, since colistin is a last-line antimicrobial drug for treating infections caused by multidrug resistant Gram-negative bacteria.…”

Bacteriophages Isolated from Chicken Meat and the Horizontal Transfer of Antimicrobial Resistance Genes

“…Food of animal origin represents an important and direct link between animals and humans. Despite approved recommendations regarding the prudent use of antimicrobial substances in production animals, the rate of resistance to certain classes of antibiotics (e.g., extended-spectrum cephalosporins) used in human medicine continues to rise (2,3). Escherichia coli, an important indicator bacterium for antimicrobial resistance, can frequently be found on food surfaces and has been reported to be resistant to many different classes of antimicrobial agents.…”

Quinolone resistance mechanisms among extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolated from farm animals in Switzerland

“…Four cattle isolates showed an additional mutation in parE (aa substitution: Ser458→Ala). Vogt and colleagues (Vogt et al, 2014) isolated recently ciprofloxacin resistant ESBL-producing genes (Poirel et al, 2012a). So far, the modified acetyltransferase was frequently detected in E. coli isolates harboring bla CTX-M-15 from companion animal (Gibson et al, 2010;Shaheen et al, 2013), and in human E. coli isolates (Poirel et al, 2012b;Strahilevitz et al, 2009).…”