Identification of mutation in gyrA gene obtained from quinolone-resistant clinical isolates of Acinetobacter baumannii

Acinetobacter spp. is one of the most important ethiology of nosocomial infections worldwide. The presence of multiple antibiotic-resistant strains have limited effective treatments for Acinetobacter spp. The purposes of this study were to screen gyrA gene mutation in quinolone resistance clinical isolates of A. baumannii and their antimicrobial susceptibility pattern in Isfahan.

In this cross-sectional study, 70 isolates of Acinetobacter were collected from patients hospitalized in the ICU of Isfahan Alzahra Hospital. Biochemical tests were used for detection of isolates. Antimicrobial susceptibility tests were performed on all isolates using the Kirby-Bauer Disk diffusion method and employment of eight antibiotics. Minimum inhibitory concentrations (MIC) of ciprofloxacin and levofeloxacin resistant isolates were determined using the E-test method according to the CLSI guideline. Furthermore, a PCR-RFLP test was performed to investigate gyrA gene mutation in ciprofloxacin/ levofloxacin resistance isolates.

The most antibiotic resistance was related to ciprofloxacin (100%) and gentamicin (100%) while the lowest antibiotic resistance were observed in case of application of imipenem (8.92%) and meropenem (90%). Based on MIC test the ratio of resistance to ciprofloxacin and levofeloxacin antibiotics were 100% and 65.7%, respectively. Also, overall 66.7% of these isolates showed multidrug resistant and 93% of the isolates carry a mutation at position 83 in gyrA gene.

The present study revealed that A. baumannii isolates carry a mutation in gyrA gene. This mutation causes increases in the microbial resistance to quinolone. Rapid detection of quinolone resistant A. baumannii isolates can help physicians to determine effective treatment for these infections.