The prevalence of biofilm encoding genes in multidrug-resistant Acinetobacter baumannii isolates

Background: Increasing prevalence of multidrug-resistant (MDR) A. baumannii isolates coupled with survival ability in adverse conditions has made this pathogen a serious threat to global health. A cross-sectional study was conducted to examine biofilm forming genes and antibiotic resistance profiles of A. baumannii clinical isolates in Tabriz, North-west Iran. Methods: A total of 100 A. baumannii strains were isolated from hospitalized patients in Tabriz city, northwest of Iran. The isolates were detected through standard microbiological and biochemical tests and blaOXA-51 detection. After the examination of antibiotic resistance profile, the biofilm formation capacity was investigated by a microtitre plate assay. The presence of bap and ompA genes related to biofilm-forming was examined by PCR reaction. Results: The highest resistance rate was observed against meropenem (100%), tigecycline (100%), and ceftizoxime (99%), respectively. Analysis for resistance to different antibiotic classes revealed that 100% of the isolates were multidrug-resistant (MDR), and 79% of them were extensively drug-resistant (XDR). Overall, 84% of the isolates were able to produce biofilm that 3.57% (3/84) of them were strongly capable to form a biofilm. All of the strong biofilm-forming A. baumannii isolates were found as XDR. Also, 100% of the isolates had the ompA gene, and 89% of them were positive for the bap gene. Conclusion: Our findings revealed a high prevalence of biofilm-forming and biofilm-related genes of bap and ompA in MDR A. baumannii strains in the study region. Based on our results, there is a correlation between the presence of the bap gene and biofilm formation.