Resistoma de bactérias Gram- negativas de importância médica isoladas de produtos cárneos de produção livre de antibióticos e produção convencional

Abstract

Epidemiological studies have shown that the propagation and spread of bacteria resistant to antibiotics in clinical use, is not a problem restricted to hospitals, but also extends to the environment and food. Brazil is one of the largest food producers and exporters, both plant and animal origin and to maintain its high productivity of meat, it has adopted the use of antimicrobial extensively in the production chain of meat. The objective of the work is to obtain and analyze genomic data of Gram-negative bacteria resistant to antibiotics of medical importance, isolated from meat products of antibioticfree and conventional production systems. Analyzed commercial samples of chicken (n = 12), beef (n = 10) and pork (n = 10) of different marks, collected from August 2019 to February 2020. Samples were screened on agar MacConkey supplemented with ceftriaxone and colistin, in order to select phenotypes of production of ESBL (extendedspectrum β-lactamases), pAmpC and MCR (mobile colistin resistance). The isolates were identified by the MALDI-TOF technique and were subjected to the antimicrobial susceptibility test by the disk-diffusion technique. Of the total samples analyzed, 46.9% were positive for Escherichia coli (n = 15) MDR, and these nine were sequenced on the Illumina platform. Sequence analysis revealed the presence of genes blaCMY-2, blaCTX-M-8 e blaCTX-M-55, which provide resistance to penicillins and cephalosporins of broad spectrum, used in the treatment of human and veterinary infections; in addition to other genes and mutations that confer resistance to tetracyclines (tetA, tetB), sulfonamides (sul1, sul2), fosfomycin (fosA3), quinolones [gyrA (S83L,D87N,D87G), parC (S80I)], aminoglycosides [aadA1, aadA2, aph(3'')-Ib] e macrolídeos [mdf(A)]. Tolerance genes for heavy metals (including arsenic, tellurium and mercury), disinfectants (quaternary ammonia) and pesticides (glyphosate) were also predicted. In addition, virulence genes that code for toxins, adherence, siderophores and secretion system have been identified. The strains belonged to the international clones of type ST38, ST2179, ST443, ST57, ST117. Our results report the presence of pathogens of critical priority in "antibiotic-free" meats, warning about the possibility that foods of animal origin may be sources that contribute to the silent spread of these pathogens, and / or their resistance genes.