Resistance to cephalosporins and quinolones by Escherichia coli isolated from irrigation water from eastern Lima, Perú

Abstract

Objetives. Bacterial resistance to antibiotics is a public health problem, however, few studies are performed in natural water ecosystems in middle-low-income countries. The objective of this study was to evaluate the presence and sensitivity to antimicrobials of Escherichia coli strains isolated from 24 irrigation water samples from the Rimac River in eastern Lima. Materials and methods. E.coli were identified by PCR. Antibiotic susceptibility was determined by disk diffusion method. The extended-spectrum beta-lactamase (ESBL), quinolones and virulence involved genes were determined by PCR. Results. All samples exceeded the permissible limits established in the Environmental Quality Standards for vegetable irrigation. Of the 94 strains, 72.3% showed resistance to at least one antibiotic, 24.5% were multidrug-resistant (MDR), and 2.1% were extremely drug resistant. The highest percentages of resistance were observed against nalidixic acid (50%), trimethoprim-sulfamethoxazole (35.5%) and ciprofloxacin (20.4%). Among the isolates, 3.2% presented ESBL phenotype related to blaCTX-M-15 gene. The transferable mechanisms of resistance to quinolones, qnrB were more frequent (20.4%), and 2.04% had the qnrS. It was determined that 5.3% were diarrheagenic E. coli and of these, 60% were enterotoxigenic E. coli, 20% were enteropathogenic E. coli and 20% were enteroaggregative E. coli. Conclusions. Our results show the existence diarrheagenic pathotypes in water used to irrigate fresh produce and highlights the presence of ESBL-producers and MDR E. coli, demonstrating the role that irrigation water plays in disseminating resistance genes in Peru.

Objetivos. Evaluar la presencia y sensibilidad a los antimicrobianos de cepas de Escherichia coli aisladas de 24 muestras de agua de riego del rio Rímac de Lima Este, Perú. Materiales y métodos. Las cepas de E. coli fueron identificadas por PCR. La susceptibilidad a los antibióticos se procesaron por el método de difusión en disco. Los genes implicados en betalactamasas de espectro extendido (BLEE), quinolonas y virulencia se determinaron por PCR. Resultados. Todas las muestras superaron los limites permisibles establecidos en las Normas de Calidad Ambiental para el riego de hortalizas. De los 94 aislados, el 72,3% mostro resistencia al menos a un antibiótico, el 24,5% eran multirresistentes (MDR) y el 2,1% extremadamente resistentes. Los mayores porcentajes de resistencia se observaron para ampicilina-sulbactam (57,1%), el ácido nalidixico (50%), trimetoprim-sulfametoxazol (35,5%) y ciprofloxacino (20,4%). Entre los aislados, el 3,2% presentaba fenotipo BLEE relacionado con el gen bla CTX-M-15. Los mecanismos transferibles de resistencia a las quinolonas, qnrB fueron más frecuentes (20,4%), y el 2,04% tenian el qnrS. Se calcularon que el 5,3% eran E. coli diarreagenicas y de estas, el 60% eran E. coli enterotoxigenicas, el 20% E. coli enteropatogenas y el 20% E. coli enteroagregantes. Conclusiones. Los resultados muestran la existencia de patotipos diarreogenicos en el agua utilizada para el riego de productos frescos y destaca la presencia de E. coli productores de BLEE y MDR, demostrando el papel que juega el agua de riego en la diseminación de genes de resistencia en el Perú.