Ocorrência e aspectos fisiológicos de bactérias associadas a carnes vermelhas, frango e peixes disponíveis varejo em Juiz de Fora, MG: susceptibilidade a drogas, tolerância a metais e expressão de bombas de efluxo

Abstract

Multidrug-resistant (MDR) Enterobacterales are a public health issue and their spread from animal source foods to humans is of great concern all over the world. Hence, the aim of this study was to analyze the physiological aspects, drug susceptibility profile, tolerance to toxic metals and expression of efflux mechanisms in Enterobacterales strains isolated from different types of meat. Chicken, beef, pork and fish samples were acquired in retail establishments in the city of Juiz de Fora – MG and analyzed regarding their mesophilic aerobic bacteria total viable counts, Gram-negative rods selective counts and Grampositive cocci selective counts. Selective isolation of the Enterobacterales order members was carried out, and their susceptibility to antimicrobials, tolerance to toxic metals and expression of efflux mechanisms were evaluated. The study revealed that fish presented significantly less Gram-positive cocci compared to other types of meat, possibly due to the fact that it goes through less handling by retail employees. Out of 436 Enterobacterales isolated, 271 (62.9%) were resistant to at least one of the antimicrobials tested, 32.3% of which was resistant to one and 8.1% to two. MDR Enterobacterales comprised 22.7% of obtained isolates, 7.9% of which was resistant to three of the tested drugs, 11.4% to four, 2.3% to five and 0.9% to six. Chicken was the meat with the most isolates considered MDR, and fish was the one with the least. It was not possible to distinguish among the different types of meat based on the antimicrobial resistance profile presented by the isolated bacteria, suggesting that resistance in the present study is widespread and more parameters are needed so as to separately classify the meats. Analysis of inhibition zone sizes resulting from the isolates’ response to the presence of antimicrobial drugs showed that the bacteria derived from chicken have a inhibition zone size mean for ceftazidime and ceftriaxone significantly smaller compared to other meats, indicating higher selective pressure in their environment. All MDR Enterobacterales showed higher tolerance to mercury and cadmium, probably due to the fact that the tolerance genes to these metals are frequently found in association with drug resistance genes. Efflux activity was observed in MDR, non-susceptible and susceptible microorganisms, suggesting that apart from antimicrobials, their target substrates could comprise biocides and toxic ions. It is concluded that chicken is the meat with higher associated risk to its consumption from the point of view of bacterial resistance to antimicrobials.