Antibiotic Susceptibility Profile and Putative Virulence Genes in Clinical Isolates of Pseudomonas aeruginosa

Abstract

Background: Pseudomonas aeruginosa is a common environmental Gram-negative rod responsible for a wide range of nosocomial infections. The pathogenesis of P. aeruginosa is because of the production of various virulence factors. The present study was carried out to determine the presence of virulence factors and the rate of antibiotic resistance among clinical isolates of P. aeruginosa.

Methods:  This cross-sectional study was performed on 120 clinical isolates of P. aeruginosa collected from a teaching hospital in the south of Iran. All isolates were identified with standard biochemical and microbiological tests. Antibacterial susceptibility was determined by disk diffusion method. The presence of virulence genes was screened by PCR.

Results: From 120 P. aeruginosa isolates, the most common sites of bacterial isolation were pulmonary with frequency 52 (43.3%), followed by urine 28 (23.3%), blood 17 (14.2%), and wound 14 (11.7%). Antibiotic susceptibility patterns revealed that the highest and lowest resistance rates were against ticarcillin-clavulanate (60%) and amikacin (10%), respectively. The majority of meropenem-resistant isolates had a MIC range >32 μg/mL. Among tested virulence genes, lasB gene was detected in the 98.3% of isolates followed by pvdA in 68.3%, pilA in 8.3% and pilB in 5% of isolates.

Conclusion: Results showed a high prevalence of lasB in clinical isolates of   P. aeruginosa. These findings accompanied with remarkable rate of β-lactam-resistance highlights importance of suitable surveillance and control processes to prevent the further spread of these isolates in hospitals.