Virulence Gene Profiles of Multidrug-Resistant Pseudomonas aeruginosa Isolated From Iranian Hospital Infections

BACKGROUND: The most common hospital-acquired pathogen is Pseudomonas aeruginosa. It is a multidrug resistant bacterium causing systemic infections. OBJECTIVES: The present study was carried out in order to investigate the distribution of virulence factors and antibiotic resistance properties of Pseudomonas aeruginosa isolated from various types of hospital infections in Iran. PATIENTS AND METHODS: Two-hundred and seventeen human infection specimens were collected from Baqiyatallah and Payambaran hospitals in Tehran, Iran. The clinical samples were cultured immediately and samples positive for P. aeruginosa were analyzed for the presence of antibiotic resistance and bacterial virulence genes using PCR (polymerase chain reaction). Antimicrobial susceptibility testing was performed using disk diffusion methodology with Müeller–Hinton agar. RESULTS: Fifty-eight out of 127 (45.66%) male infection specimens and 44 out of 90 (48.88%) female infection specimens harbored P. aeruginosa. Also, 65% (in male specimens) and 21% (in female specimens) of respiratory system infections were positive for P. aeruginosa, which was a high rate. The genes encoding exoenzyme S (67.64%) and phospholipases C (45.09%) were the most common virulence genes found among the strains. The incidences of various β-lactams encoding genes, including bla(TEM), bla(SHV), bla(OXA), bla(CTX-M), bla(DHA,) and bla(VEB) were 94.11%, 16.66%, 15.68%, 18.62%, 21.56%, and 17.64%, respectively. The most commonly detected fluoroquinolones encoding gene was gyrA (15. 68%). High resistance levels to penicillin (100%), tetracycline (90.19%), streptomycin (64.70%), and erythromycin (43.13%) were observed too. CONCLUSIONS: Our findings should raise awareness about antibiotic resistance in hospitalized patients in Iran. Clinicians should exercise caution in prescribing antibiotics, especially in cases of human infections.