Resistencia a antibióticos en E. coli y S. aureus aislados de fuentes animales y ambientales

Abstract

El uso amplio de antibióticos para tratamiento, prevención de enfermedades en animales y humanos, y en producción animal para promoción de crecimiento, está relacionado con la emergencia y diseminación de bacterias antibiótico-resistentes y genes de resistencia. Sumado a esto los residuos de antibióticos y bacterias resistentes eliminados por excretas (orina y materia fecal), el manejo de desechos en granjas y el uso de materia fecal como abono o compost, puede favorecer la diseminación de genes de resistencia y la selección de bacterias multi-resistentes a antibióticos en el ambiente. Esto se ha reconocido como un problema de Salud Pública y uno de los vacíos en vigilancia y contención de éste, se da por falta de información sobre la resistencia a antibióticos en bacterias de origen alimentario, y su impacto potencial en salud animal, humana y ambiental (WHO, 2014). Este proyecto analizó una granja de porcícola, su sistema de producción, uso de antibióticos, caracterizó fenotípica y molecularmente bacterias (bacterias indicadoras: Escherichia coli, Enterococcus faecalis, Enterococcus faecium y patógenos: Staphylococcus aureus, Salmonella spp) recuperadas de materia fecal e hisopado nasal de cerdos y trabajadores, muestras ambientales (residuos de piso de corral, hisopo de arrastre de corral y concentrado), y evaluó las relaciones entre los antibióticos utilizados durante todo el proceso de producción y la resistencia identificada en las bacterias recuperadas de las diferentes fuentes de estudio. Las bacterias recuperadas en las muestras fueron 96% de E. coli , 14% de E. faecium, 30% de E. faecalis y 2% S. aureus. Se documentó uso de un rango amplio de antibióticos para profilaxis, principalmente quinolonas y betalactámicos. Se identificaron resistencia a antibióticos así como también genes de resistencia a estos grupos de antibióticos indicando relación entre uso y resistencia expresada. Se documentaron además genes de importancia clínica previamente reportados en aislamientos causantes de infecciones en humanos; los tipos de plásmidos identificados hacen parte de los principales grupos de incompatibilidad mostrados como los portadores más frecuentes de genes de resistencia a -lactámicos y quinolonas. Se identificó policlonalidad en las cepas analizadas, lo que sugiere que la transferencia de resistencia entre éstas puede estar asociada con transferencia de elementos genéticos. La información de este proyecto fue utilizada como línea de base para la caracterización de otros sistemas de producción animal, con el fin de obtener información con sustento epidemiológico para proponer nuevas estrategias de investigación y vigilancia de uso de antimicrobianos y resistencia a éstos que permitan minimizar y contener esta problemática. Abstract The widespread use of antibiotics for treatment, prevention of disease in animals and humans, and in animal production for growth promotion is related to the emergence and spread of antibiotic-resistant bacteria and genes that confer resistance. Added to this, the residues of antibiotics and resistant bacteria eliminated by excreta (urine and stool), waste management on farms and the use of fecal matter as fertilizer or compost, may favor the spread of resistance genes and selection of bacteria multi-antibiotic resistant in the environment. This has been recognized as a public health problem. One of the gaps in the surveillance and containment of it, is the lack of information on antibiotic resistance in foodborne bacteria and their potential impact on animal, human and environmental health (WHO, 2014). This project analyzed a pig farm, its production system, use of antibiotics, characterized phenotypically and molecularly bacteria (the indicator bacteria: Escherichia coli, Enterococcus faecalis, Enterococcus faecium and the pathogens: Staphylococcus aureus, Salmonella spp) recovered from feces and nasal swabs from pigs, workers, as well as environmental samples (residues floor poultry, swab drag and poultry concentrate), and evaluated the relationship between antibiotics used throughout the production process and resistance identified in bacteria recovered from different sources. The bacteria recovered in samples were 96% of E. coli, E. faecium in 14%, E. faecalis in 30% and S. aureus in 2%. The use of a wide range of antibiotics for prophylaxis, principally quinolones and β-lactams was documented. Isolates showing antibiotic resistance were recovered from the collected samples. Resistance genes were also identified to the antibiotic groups used, indicating a relation between use and expressed resistance. Important genes previously reported in isolates from human infections were also identified; the types of identified plasmids are part of the main groups of incompatibility reported as the most frequent resistance genes for β-lactams and quinolones. Polyclonality identified in strains tested, suggests that the transfer resistance between them may be associated with transfer of genetic elements. Information from this project was used as a baseline for the characterization of other animal production systems, in order to obtain information with epidemiological support to propose new strategies for research and monitoring of antimicrobial use and resistance to minimize and contain this problem.

Abstract: The widespread use of antibiotics for treatment, prevention of disease in animals and humans, and in animal production for growth promotion is related to the emergence and spread of antibiotic-resistant bacteria and genes that confer resistance. Added to this, the residues of antibiotics and resistant bacteria eliminated by excreta (urine and stool), waste management on farms and the use of fecal matter as fertilizer or compost, may favor the spread of resistance genes and selection of bacteria multi-antibiotic resistant in the environment. This has been recognized as a public health problem. One of the gaps in the surveillance and containment of it, is the lack of information on antibiotic resistance in foodborne bacteria and their potential impact on animal, human and environmental health (WHO, 2014). This project analyzed a pig farm, its production system, use of antibiotics, characterized phenotypically and molecularly bacteria (the indicator bacteria: Escherichia coli, Enterococcus faecalis, Enterococcus faecium and the pathogens: Staphylococcus aureus, Salmonella spp) recovered from feces and nasal swabs from pigs, workers, as well as environmental samples (residues floor poultry, swab drag and poultry concentrate), and evaluated the relationship between antibiotics used throughout the production process and resistance identified in bacteria recovered from different sources. The bacteria recovered in samples were 96% of E. coli, E. faecium in 14%, E. faecalis in 30% and S. aureus in 2%. The use of a wide range of antibiotics for prophylaxis, principally quinolones and β-lactams was documented. Isolates showing antibiotic resistance were recovered from the collected samples. Resistance genes were also identified to the antibiotic groups used, indicating a relation between use and expressed resistance. Important genes previously reported in isolates from human infections were also identified; the types of identified plasmids are part of the main groups of incompatibility reported as the most frequent resistance genes for β-lactams and quinolones. Polyclonality identified in strains tested, suggests that the transfer resistance between them may be associated with transfer of genetic elements. Information from this project was used as a baseline for the characterization of other animal production systems, in order to obtain information with epidemiological support to propose new strategies for research and monitoring of antimicrobial use and resistance to minimize and contain this problem.