naLD mutations in ciprofloxacin resistant isolates of Pseudomonas aeruginosa in Guilan hospitals

Pseudomonas aeruginosa is a gram-negative bacterium that continues to be a major cause of opportunistic nosocomial infections. In pseudomonas aeruginosa, several quinolone resistance mechanisms have been proposed such as mexAB-oprM overexpression. nalD is a regulatory gene of the mexAB-oprM operon that mutations in this gene have been observed in clinical isolates overexpressing MexAB-OprM. The aim of this study investigation of naLD mutations in ciprofloxacin resistant pseudomonas aeruginosa isolated from patients in Guilan hospitals.Materials and Methods: In this study, forty-eight pseudomonas aeruginosa, isolated from different clinical isolates identified by biochemical tests. The ciprofloxacin resistance and susceptibility of strains was determined by disc diffusion and MIC methods. After DNA extraction, PCR and sequencing was performed to evaluate naLD mutations in resistant isolates.Results: eighteen strains (%37.5) showed resistance to ciprofloxacin. MIC range in pseudomonas aeruginosa resistant strains were between 32 to 1024μg/ml. PCR-sequencing revealed that some isolates had mutation in naLD.Conclusions: Ciprofloxacin resistance results in overexpression of efflux pumps and inhibiting the target enzymes. Mutation in nalD in some isolates of Guilan hospital can be a reason of ciprofloxacin resistance in these isolates by upregulation of mexAB-oprM. NalD mutation usually observed in drug resistant isolates by low prevalence that our study confirmed this.

Keywords:

naLD , Pseudomonas aeruginosa , ciprofloxacin resistance , sequencing