The prevalence of some Pseudomonas virulence genes related to biofilm formation and alginate production among clinical isolates

Chronic infections caused by Pseudomonas aeruginosa (P. aeruginosa) isolates are mainly related to resistance to antimicrobials and the production of certain virulence factors. The purpose of this study was twofold: to investigate the prevalence of virulence genes and to study the relationship between biofilm formation/alginate production/antibiotic resistance and the presence of genes associated with biofilm, alginate, flagella and exotoxin A in clinical isolates of P. aeruginosa.Microtiter plate biofilm assay and Carbazole method were used to examine the biofilm formation and alginate production ability of the isolates, respectively. The genes, ppyR, pslA, pelA (biofilm formation), algD, algU, algL (alginate production), fliC (flagella) and exoA (exotoxin A) were detected by PCR.Biofilm formation as well as alginate production ability was found in 47.1% of the clinical isolates. Based on PCR data, the frequency distribution of the genes in the clinical isolates was as follows: ppyR (99%), pslA (83.7%), pelA (45.2%), algU (90.4%), algL (73.1%), algD (87.5%), exoA (84.6%) and fliC (70.2%). Biofilm formation ability of the isolates was significantly correlated with the presence of the genes, pelA and fliC (statistically significant). In addition, 58.65% of the isolates were resistant to three or more different classes of antibiotics.