Mutations in the quinolone resistance determining region in isogenic mutant Acinetobacter baumannii strains

Abstract

The aim of the study is to explore the change or mutation of DNA gyrase (gyrA) and topoisomerase IV (parC) in Quinolone Resistance Determining Region (QRDR) inAcinetobacter baumannii isogenic mutant strains which were insensitivity or resistant to fluoroquinolones (FQs). A total of 11 strains were studied, one is isolated from clinical sample as a wide-type parent strain and the others isogenic mutant strains which were selected by ciprofloxacin in vitro environment. Three of the isogenic mutant strains have amino acid mutation in GyrA and ParC of QRDR, two of the three have the mutation Ser-97 to Thr and Asp-150 to His in GyrA, another one which is highly resistant to ciproi¬‚oxacin (MICs of ciproi¬‚oxacin, 64 μg/ml) has the mutations Ser-97 to Thr in GyrA and Ala-85 to Pro in ParC. Key words: Acinetobacter baumannii, quinolone resistance determining region, mutation, isogenic strain.