Abstract
This one-year study describes isolation of 6 carbapenem-resistant Acinetobacter baumannii strains from 920 urine samples from urinary tract infection patients attending an Indian hospital. A search for bla(CTX-M), bla(TEM), armA, rmtA, rmtB and integrons was performed. Four strains were identified as extended-spectrum-beta-lactamase (ESBL)-producers. Two bla(CTX-M-15) and 2bla(TEM-150) and 3 Class 1 integrons were amplified. Ceftazidime and cefotaxime resistance markers were found to be located on the plasmid DNA of the clonally related bla(CTX-M-15)-positive strains and were transmissible through conjugation. Ramachandran Z-score for modeled-CTX-M was found to be -1.277. The study suggests that in regions having known prevalence of bacteria simultaneously resistant to carbapenems and advanced generation cephalosporins, the drugs of choice for empiric treatment could be amikacin and ampicillin/sulbactam. Furthermore, we recommend extensive use of bioinformatics tools to understand structures of CTX-M-variants as these are emerging at a fast pace and it is painstaking to crystallize each variant. Key words: Acinetobacter baumannii, carbapenem resistance, CTX-M, extended spectrum beta-lactamases, modeling.