OmpA and Bap Genes as Virulence Genes Involved in Biofilm Formation of Acinetobacter baumannii

Abstract

Background: Multiple virulence genes involved in biofilm development by Acinetobacter Baumannii (A. baumannii) like ompA and bap genes. These genes may be analyzed to establish their relevance in biofilm formation or antibiotic resistance phenotypes. This research objects to study virulence genes involved in biofilm formation of A. baumannii to be taken in consideration in prophylactic approaches, treatment, and infection control program. Methods: The prospective study contained 100 isolates including (sputum, endotracheal aspirate, pus from open wounds or open abscesses, mid-stream urine from non-catheterized subjects and catheter-stream urine in catheterized subjects, blood samples and body fluids) were collected from different ICUs. The BD Phoenix Automated System was used to identify the isolates and assess their susceptibility to 21 antibiotics. Biofilm formation was measured by microtiter plate for all isolates, then conventional PCR was done for detection of ompA and bap genes. Results: The comparison of biofilm strength and MDR revealed significant variance among different groups (P<0.05). The presence or absence of OmpA and bap genes was associated with biofilm biomass (with a P value <0.001). Among the 100 A. baumannii isolates, both genes were found in 44 isolates (44%). The strains having both OmpA and Bap genes (27/27) produce stronger biofilms (100%) than those with just one gene only one gene only (P <0.001). The association among the presence of virulence genes and MDR status was measured. The genes encoding OmpA were found at a higher frequency in MDRAB than in non-MDRAB strains (P=0.014). Bap gene was found in 48/90 (53.3%) MDRAB isolates versus only 2/10 (20%) of non-MDRAB strains (P=0.046). Conclusions: There is a significant association among MDR and the biofilm-forming ability of A. baumannii. Biofilm-related genes (ompA and bap) are connected with multidrug-resistant A. baumannii strains and affect the intensity of biofilm formation.