Caracterização por métodos fenotípicos e moleculares dos mecanismos de resistência aos antimicrobianos em cepas de Aeromonas spp. isoladas de origens diversas

Abstract

Aeromonas, microorganisms widely distributed in the environment, are responsible for various infectious diseases in animals and both immunocompetent and immunocompromised individuals. This genus is currently considered an emerging pathogen in nosocomial infections. 46 samples of Aeromonas spp obtained from fish, human, cheese, vegetables and water were studied. Strains were phenotypically characterized as A. caviae (n = 30), A. hydrophila (n = 14) and A. veronii bv. sobria (n = 2). Assessment of susceptibility to antimicrobial agents was performed by disk diffusion test. The strains were fully susceptible to ciprofloxacin, gentamicin, amikacin, cefepime and aztreonam. The highest percentage of resistance was observed for ampicillin / sulbactam (71.7%), followed by cefoxitin (32.6%), amoxicillin / clavulanic acid (30.4%), cefotaxime (21.7%), ceftazidime (19.6%) and tetracycline (19.6%). The strains with the screening criteria determined by the CLSI (2015), were subjected to phenotypic testing for production of ESΒLs and determining minimum inhibitory concentration (MIC) of ceftazidime and cefotaxime antimicrobials. Phenotypic ESΒL production was confirmed for a strain of A. caviae isolated from clinical specimen. Some MIC results were discrepant relative to the disc-diffusion test. Resistance genes, blaTEM, blaSHV, blaOXA-1LIKE, bla CTX-M, bla VEB, bla PER e bla GES, qnrA, qnrB, qnrS qepA, tetA, tetB, tetG, catA, cmlA, floR, sul1, sul2, intl1 and class 1 integron were searched by polymerase chain reaction (PCR). Genes bla CTX-M-2, blaGES, tetB, catA, sul1, intl and class 1 integron were amplified in Aeromonas spp. Samples that showed genotypic characteristics of resistance were subjected to typing based on replicons of the major plasmid incompatibility groups enterobacteria. Analysis was positive for incFIA, incFIB and IncB /O groups, which were distributed between two strains of A. caviae (positive tetB) isolated from clinical specimens.