FREQUENCY OF BAP AND CPAA VIRULENCE GENES IN DRUG RESISTANT CLINICAL ISOLATES OF ACINETOBACTER BAUMANNII AND THEIR ROLE IN BIOFILM FORMATION

摘要

Objective(s): Acinetobacter baumannii has a high propensity to form biofilm and frequently causes medical device-related infections with multiple-drug-resistance in hospitals. The aim of this work is to study antimicrobial resistance and the role of bap and cpa A genes in biofilm formation by A. baumannii to understand how this pathogen persists in the hospital environment.Materials and Methods: The antibiotic resistance profile and in vitro biofilm-forming ability of one hundred clinical isolates of A. baumannii was evaluated by disc diffusion and crystal-violet staining methods, respectively. Isolates were tested for the presence of bap and cpaA genes.Results: The isolates were highly resistant to cefepime, third-generation cephalosporins, ciprofloxacin, cotrimoxazole, aminoglycosides and carbapenems. Moreover, four isolates were resistant to colistin. Quantification of biofilm showed that 43% of the isolates were strong biofilm-producer. Furthermore, 32% of the isolates exhibited moderate biofilm-formation and showed initial binding activity. Frequency of bap and cpaA were determined 92% and 36%, respectively.Conclusion: There was strong association between the presence of bap gene and biofilm formation by A. baumannii isolates (P=0.003). In addition, multidrug resistant isolates produced stronger biofilm than other isolates (P=0.0001). These results indicate importance of biofilm in resistance of isolates and effect of presence of bap gene in biofilm formation by A. baumannii strains.