Genetic characterisation of drug resistance and clonal dynamics of Acinetobacter baumannii in a hospital setting in Mexico.

The aim of this study was to determine the clinical characteristics, molecular epidemiology and biofilm production of Acinetobacter baumannii clinical isolates obtained from a tertiary-care hospital in Mexico. Clinical isolates of A. baumannii (n=152) isolated from 2007 to 2012 were included. Clonal diversity was analysed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Antimicrobial susceptibility was determined using the broth microdilution method. IMP, VIM, NDM and OXA-type genes were screened by PCR. Biofilm production was analysed using the crystal violet method. Mortality attributable to A. baumannii infection was 14.5%. Fifty-four clones were detected, of which five predominated. MLST results showed three new sequence types and two reported sequence types. More than 86% of the isolates were resistant to ciprofloxacin, ceftazidime and cefotaxime. Furthermore, 50.7% and 35.5% of the isolates were resistant to imipenem and meropenem, respectively. Of the isolates evaluated, 28.3% and 25.7% were positive for the blaOXA-58 and blaOXA-72 genes, respectively. Biofilm production was associated with resistance to imipenem (P=0.002).