Beta-lactamase-producing Pseudomonas aeruginosa: Phenotypic characteristics and molecular identification of virulence genes

Background: Pseudomonas aeruginosa causes common infections in immunocompromised and cystic fibrosis patients. However, drug resistance capability and release of virulence factors play a key role in bacterial pathogenicity. Methods: Beta-lactamase-producing clinical isolates of P. aeruginosa were screened for biofilm formation and pigment production. Subsequently, all the isolates were subjected to the detection of six virulence genes (OprI, OprL, LasB, PlcH, ExoS, and ToxA). Results: Among beta-lactamase-producing isolates (n = 54), about 85.18% (n = 46) were biofilm producers. Pigment production was observed in 92.59% (n = 50) isolates. Clinical samples were subsequently screened for detection of virulence factors. Among them, 40.74% (n = 22) isolates were found to be OprI positive, while 29.62% (n = 16) were OprL producers. In the case of LasB and PlcH, 24% (n = 13) and 18.5% (n = 10) isolates produced these virulence genes, respectively. Among the isolates, 37.03% (n = 20) and 33.33% (n = 18) expressed virulence factors ExoS and ToxA, respectively. Furthermore, 42.59% (n = 23) isolates coproduced more than one type of virulence factors. Conclusion: In the current study, pigment display, biofilm formation, and virulence genes were detected in P. aeruginosa clinical isolates. Such factors could be crucial in the development of drug resistance. Copyright (C) 2016, the Chinese Medical Association. Published by Elsevier Taiwan LLC.