High Frequency of Extended-Spectrum Beta-Lactamase-Producing Nosocomial Strains Isolated from a Teaching Hospital in Brazil.

The aim of this study was to investigate the frequency, antimicrobial sensitivity profile, and genetic characteristics of nosocomial strains of extended-spectrum β-lactamase (ESBL)-producing isolated from inpatients at a teaching hospital in Brazil. The bacterial identification, phenotypic detection of ESBL, and antimicrobial susceptibility profile were performed by the VITEK 2 automated system. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) mass spectrometry was used to confirm the identity of the species and genotyping of ESBL-producing was performed by pulsed-field gel electrophoresis (PFGE). Thirty-six ESBL-producing nosocomial strains isolated from November 2013 to August 2014 were analyzed. High resistance rates were observed for ceftriaxone, ceftazidime, cefepime, gentamicin, and ciprofloxacin. However, all isolates were susceptible to amikacin and meropenem. All strains harbored and genes. Molecular typing by PFGE showed a diversity of genotypes distributed among 25 clusters, but two isolates collected in different wards had the same genotypic profile and carried the same genes, so they were considered clones. The data showed that there was a high frequency of ESBL-producing multidrug-resistant among patients in the studied hospital. Furthermore, the detection of genes in all isolates suggests that these enzymes are the major ESBL responsible for the beta-lactam resistance phenotypes among the analyzed strains.