[Identification and antibiotic susceptibility of Aeromonas spp. in a University Hospital in the city of Buenos Aires].

Abstract

Aeromonas spp. are opportunistic pathogens that cause both intra- and extraintestinal infections. The objective of this work was the phenotypic and genotypic characterization of a collection of Aeromonas strains, in addition to determining their sensitivity to different antimicrobials. Thirty seven isolates were analyzed. 54% were of intra-abdominal origin, 22% from skin and soft tissues, 19% from the bloodstream, among other less frequent sites. By amplification and sequencing of the gyrB gene, which was considered the reference method, the following were identified: 37,8% as species of the Aeromonas hydrophila complex, 32,4% as species of the Aeromonas veronii complex, and 29,7% as species of the complex Aeromonas caviae. Identification by traditional biochemical tests presented a better correlation with molecular identification than mass spectrometry (MALDI TOF MS). Regarding antibiotic sensitivity, cefotaxime, ceftazidime, cefepime, piperacillin-tazobactam, trimethoprim-sulfamethoxazole, ciprofloxacin, amikacin, gentamicin and nitrofurantoin showed activity on more than 80.0% of the isolates tested. The sensitivity and specificity of the phenotypic methods to determine the presence of carbapenemases in relation to the detection of the cphAgene, the reference method, was 60,9% and 100%, respectively, for the colorimetric assay (Blue Carba), and of 91,3% and 50,0% respectively, for the modified Hodge test. The overall resistance to colistin was 32,4%. The automated method showed a very higher error (VME) of 16,2%, while the rapid colorimetric screening method (CRTc) showed an excellent correlation (VME 0%) with the reference method, broth microdilution.