PHENOTYPIC AND GENETIC BASIS OF BIOFILM FORMATION BY ESCHERICHIA COLI AND PSEUDOMONAS AERUGINOSA IN MECHANICALLY VENTILATED AND VAP DEVELOPED PATIENTS

Background and Aim:VAP is the second most common nosocomial infection in the intensive care unit (ICU). We aimed to study the phenotypic and genetic basis of biofilm formation by Escherichia coli and Pseudomonas aeruginosa isolated from mechanically ventilated and VAP developed patients.Methods:The study was conducted from May 2015 to March 2016, in a respiratory ICU of a University Teaching hospital. Endotracheal from 40 patients were collected for culture at least in four episodes including, 48 hours, 72 hours, 7 days and 10 days after being ventilated. The bacterial culture was performed quantitatively and colonies more than 105 CFU/ml were considered pathogens. The ability of isolates to form biofilms was evaluated quantitatively using micro titer plate method and finally, the presence of biofilm genes was investigated by PCR method.Results:The prevalence of VAP was 15%. Among 148 bacterial isolates obtained from ventilator patients included Pseudomonas aeruginosa (n=18) Escherichia coli (n=12). Escherichia coli)100%) and Pseudomonas aeruginosa (83.4 %) were able to form biofilms on micro titer plate method. Frequency of pslA and algC genes in Pseudomonas aeruginosa isolates was 50%, 11.1%, respectively and papC, pgaA, ang43, csgA, genes in Escherichia coli isolates were observed in 33.3%, 100%, 66.7%, 25% of isolates respectively.Conclusion:Biofilm genes in organisms contributed to biofilm formation. This feature triggers strong multi-drug resistance and their dissemination in the hospital environment.

کلیدواژه ها:

Ventilator-induced pneumonia ، Biofilm