Bacterial Biofilm in Ventilator-Associated Pneumonia: A Clinical Concern
Author(s): Elnaz Shahrokhi, Alka Hasani, Khalili Ansarin, Halah Mikaili, Akbar Hasani, Mohammad Aghazadeh, Saeed Mosavi, Akbar Sharifi
Introduction: Development of Ventilator-associated pneumoniae (VAP) presents an intricate chemistry comprising of intubation and invading bacteria which often are tied up with biofilm production.
Aim: To assess the phenotypic and genetic basis of biofilm formation by gram negative bacilli isolated from mechanically ventilated and VAP developed patients.
Materials and Methods: Endotracheal aspirate obtained from 40 mechanically ventilated patients was inoculated by a semi quantitative method. Isolation and identification of gram negative bacilli was done according to standard bacterial protocol followed by antibiotic susceptibility test and biofilm assessment by micro titer method. Presence of biofilm genes was studied by molecular method.
Result: Amongst 40 enrolled hospitalized patients, 12.5% of them developed VAP. A. baumannii (n=68) was the commonest organism followed by P. aeruginosa (n=18), K. pneumoniae (n=32) and E. coli (n=12). Presence of multi drug (MDR) and extensive drug resistance (XDR) was evident in A. baumannii and P. aeruginosa comparative to K. pneumoniae and E. coli isolates. Moderate or strong biofilm production was an overt feature. Presence of bap gene was marked in 57.4% A. baumannii whereas, 11.1% P. aeruginosa displayed algC gene. Manifestation of genes fimH, ang43 and csgA was evident in 33.3%, 66.7% and 25% E. coli isolates respectively. Gene type 3 was present in all K. pneumoniae isolates while, mrkA and fimK genes were shown in 65.6% and 81.2% isolates respectively by multiplex PCR.
Conclusion: Drug resistance phenotypes require specific national and regional therapeutic studies focusing on antimicrobial stewardship programs. Presence of biofilm requires routine surveillance of VAP, to track endemic VAPs.