Co-Harboring of Beta-Lactamases and mcr-1 Genes in Escherichia coli and Klebsiella pneumoniae from Healthy Carriers and Backyard Animals in Rural Communities in Ecuador

Resumen

Few studies have addressed drug resistance of Enterobacterales in rural communities in developing countries. This study aimed to determine the coexistence of extended-spectrum β-lactamase (ESBL) and carbapenemase genes in <i>Escherichia coli</i> and <i>Klebsiella pneumoniae</i> strains carrying the <i>mcr-1</i> gene in rural communities in Ecuador from healthy humans and their backyard animals. Sixty-two strains, thirty <i>E. coli</i> and thirty-two <i>K. pneumoniae</i> strains carrying the <i>mcr-1</i> gene were selected from a previous study. PCR were performed for the presence of ESBLs and carbapenemase genes. The strains were further characterized, and the genetic relationship was studied with multi-locus sequencing typing (MLST) of seven housekeeping genes. Fifty-nine of the sixty-two <i>mcr-1</i> isolates (95%) harbored at least on β-lactam resistance gene. The most prevalent ESBL genes were the <i>bla</i>_TEM genes (present in in 80% of the <i>E. coli</i> strains) and the <i>bla</i>_SHV gene (present in 84% of the <i>K. pneumoniae</i> strains). MSLT analysis revealed 28 different sequence types (ST); 15 for <i>E. coli</i> and 12 for <i>K. pneumoniae</i>, with most ST never described in humans and animals. The coexistence of <i>mcr-1</i> and β-lactams resistant genes in <i>E. coli</i> and <i>K. pneumoniae</i> strains is alarming and threatens the efficacy of last-resort antibiotics. Our findings highlight backyard animals as a reservoir of <i>mcr-1/</i>β-lactams resistant genes.