Comparison of antibiotic resistance, virulence determinants, and biofilm formation in Pseudomonas aeruginosa isolated from intestinal carriers and clinical samples.

Pseudomonas aeruginosa is an important opportunist pathogen responsible for community-acquired and nosocomial infections. The intestinal carriage of P. aeruginosa is likely due to its opportunistic nature. The aim of this study was to compare phenotypic and genotypic characteristics of P. aeruginosa recovered from stool of intestinal carriers with those isolated from various clinical specimens. Twenty- four fecal P. aeruginosa isolates obtained from 148 stool samples (74 healthy individuals and 74 patients with colonic disease) and 26 clinical P. aeruginosa isolates recovered from various clinical specimens other than stool, were investigated. Antimicrobial susceptibility, biofilm-forming ability using phenotypic methods and presence the exoY, algD, toxA, exoS, exoU, lasB, exoT genes were determined using polymerase chain reaction. The frequency of fecal carriage of P. aeruginosa was determined 16.2%. All fecal isolates were susceptible to ceftazidime and colistin, whereas all clinical isolates were susceptible only to colistin. There were no significant differences in multidrug- resistant (MDR) phenotypes between the clinical and fecal isolates. No significant differences in biofilm production were observed among isolates from healthy individuals compared with those from patients with colonic disease. However, differences were observed between clinical and fecal isolates regarding the presence of the algD and exoU genes (P ≤ 0.05). A significant difference was also found in the present of the exoU gene between MDR fecal and MDR clinical isolates (P = 0.007). The high prevalence of virulence factors in both fecal and clinical isolates emphasizes the importance of fecal P. aeruginosa as same as clinical isolates.