Mutations of gyrA and parC Genes in Ciprofloxacin-Resistance Isolates of Pseudomonas Aeruginosa from Burn Wounds in Yazd City, Iran

Pseudomonas aeruginosa is one of the most important factors for nosocomial infections with percentage of resistance to the drug, particularly in the burn wounds. One of the mechanisms of resistance in these bacteria is chromosomal mutation in the quinolone-resistance-determining region (QRDR) of chromosome gene. The aim of this study was to evaluate gyrA and parC gene mutation in Pseudomonas aeruginosa isolates from burn wound infections resistant to ciprofloxacin.
50 clinical Pseudomonas aeruginosa isolates were identified from patients admitted to burn hospital. Minimum inhibitory concentrations (MICs) of ciprofloxacin were evaluated by E-test method and polymerase chain reaction-sequencing (PCR-sequencing) method was carried out to assess the gyrA and parC mutations in ciprofloxacin-resistant isolates.
Findings: From 50 isolates, 62% were resistant to ciprofloxacin. Mutations were detected in all (100%) and 41 isolates (82%) in gyrA and parC genes, respectively. The most frequent mutations were observed in gyrA gene conversion (T83I) and parC (S87L). No mutation was found in sensitive isolates.
Results indicate that mutations in the quinolone-resistance-determining-region are the major mechanisms for ciprofloxacin resistance in clinical isolates of Pseudomonas aeruginosa. Considering the prevalence of these genes, these mutations play a major role in the development of resistance.