Efecto de la aplicación de gallinaza de compostaje tradicional y comercial sobre las densidades de bacterias resistentes y genes de resistencia a antibióticos en cultivo de rábano (Raphanus sativus) y lechuga (Lactuca sativa)

Abstract

Poultry manure is traditionally used as a good source of nutrients and organic matter in agricultural soils, especially in organic-farming systems. However, these materials can cause adverse effects on general soil conditions, since they contain high densities of potentially pathogenic enteric bacteria; such as antibiotic resistant bacteria (ARBs) and their corresponding antibiotic resistance genes (ARGs). The use of these materials may represent a probable route of dissemination of pathogenic microorganisms and their determinants through the food chain. This thesis is part of the project "EVALUACIÓN DE LA DISEMINACIÓN AMBIENTAL DE GENES DE RESISTENCIA A ANTIBIÓTICOS POR MEDIO DEL ESTIÉRCOL DE GALLINA" (HCU 1752-CU-P-2019). The aim of this thesis is the evaluation of the effect of the addition of traditional and commercial composting on the densities of ARBs and ARGs in vegetables (lettuce and radish). The virulence and resistance mechanisms of the detected E. coli isolates were evaluated. The results suggest that traditional composting chicken manure influences to a greater extent the spread of ARBs and ARGs in relation to commercial chicken manure. The E. coli isolates presented an antibiotic multiresistance profile. The transconjugation experiments suggest the mechanisms of antibiotic resistance of these bacteria were found encoded in chromosomes and not in plasmids. On the other hand, the qPCR technique was used to detect ARGs, which showed very high levels of detection for sul1 and blaTEM and low levels of detection to qnrS, tetW, ermB and 16S rDNA. The dissemination of ARBs and ARGs from traditional and commercial poultry manure to food is plausible, representing this a potential route of dissemination of antibiotic resistance determinants through the food chain.