Genomic surveillance of antimicrobial resistance shows cattle and poultry are a moderate source of multi-drug resistant non-typhoidal Salmonella in Mexico

PLoS One. 2021 May 5;16(5):e0243681. doi: 10.1371/journal.pone.0243681. eCollection 2021.

Abstract

Multi-drug resistant (MDR) non-typhoidal Salmonella (NTS) is a public health concern globally. This study reports the phenotypic and genotypic antimicrobial resistance (AMR) profiles of NTS isolates from bovine lymph nodes (n = 48) and ground beef (n = 29). Furthermore, we compared genotypic AMR data of our isolates with those of publicly available NTS genomes from Mexico (n = 2400). The probability of finding MDR isolates was higher in ground beef than in lymph nodes:χ2 = 12.0, P = 0.0005. The most common resistant phenotypes involved tetracycline (40.3%), carbenicillin (26.0%), amoxicillin-clavulanic acid (20.8%), chloramphenicol (19.5%) and trimethoprim-sulfamethoxazole (16.9%), while more than 55% of the isolates showed decreased susceptibility to ciprofloxacin and 26% were MDR. Conversely, resistance to cephalosporins and carbapenems was infrequent (0-9%). MDR phenotypes were strongly associated with NTS serovar (χ2 = 24.5, P<0.0001), with Typhimurium accounting for 40% of MDR strains. Most of these (9/10), carried Salmonella genomic island 1, which harbors a class-1 integron with multiple AMR genes (aadA2, blaCARB-2, floR, sul1, tetG) that confer a penta-resistant phenotype. MDR phenotypes were also associated with mutations in the ramR gene (χ2 = 17.7, P<0.0001). Among public NTS isolates from Mexico, those from cattle and poultry had the highest proportion of MDR genotypes. Our results suggest that attaining significant improvements in AMR meat safety requires the identification and removal (or treatment) of product harboring MDR NTS, instead of screening for Salmonella spp. or for isolates showing resistance to individual antibiotics. In that sense, massive integration of whole genome sequencing (WGS) technologies in AMR surveillance provides the shortest path to accomplish these goals.

MeSH terms

  • Animals
  • Anti-Bacterial Agents* / pharmacology
  • Cattle
  • Drug Resistance, Multiple, Bacterial* / genetics
  • Genomics / methods
  • Genotype
  • Mexico
  • Microbial Sensitivity Tests
  • Poultry / microbiology
  • Salmonella Infections, Animal / epidemiology
  • Salmonella Infections, Animal / microbiology
  • Salmonella* / drug effects
  • Salmonella* / genetics
  • Salmonella* / isolation & purification

Substances

  • Anti-Bacterial Agents

Grants and funding

This research was funded by the National Autonomous University of Mexico (www.unam.mx), grant number PAPIIT IN212817, awarded to MSRL and OSR. Whole genome sequencing of isolates was conducted free of charge by the Mexican Department of Agriculture (Secretaría de Agricultura y Desarrollo Rural, Centro Nacional de Referencia de Plaguicidas y Contaminantes, Dirección General de Inocuidad Agroalimentaria, Acuícola y Pesquera, Servicio Nacional de Sanidad, Inocuidad y Calidad Agroalimentaria) (https://www.gob.mx/senasica/acciones-y-programas/centro-nacional-de-referencia-de-plaguicidas-ycontaminantes- cnrpyc). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. There was no additional external funding received for this study.