Detection of Genes Involved in Biofilm Formation in MDR and XDR Acinetobacter baumannii Isolated from Human Clinical Specimens in Isfahan, Iran

Acinetobacter baumannii is capable of forming biofilms that may be responsible for the survival of this pathogen in the hospital environment as well as antibiotic resistance. In this study, considering the importance of genes bap, blaPER-1, and csuE in the formation of biofilms and resistance to antimicrobial drugs, we aimed to investigate the frequency of these genes and also the relationship between these genes and the biofilm formation. One hundred and eighteen clinical strains of the A. baumannii were collected and identified using standard microbiological methods. Antibiotic susceptibility was evaluated by microdilution broth and disk diffusion methods according to the Clinical and Laboratory Standards Institute (CLSI). Biofilm formation assay was performed by microtiter plate method. Then the bap, blaPER-1, and csuE genes were detected by PCR. The rate of XDR and MDR were 16.1% and 83.9%, respectively. Moreover, 9 (7.6%) isolates were resistant to colistin. The results of biofilm formation revealed that 32 (27.1%), 33 (28.0%), 37 (31.4%), and 16 (13.6%) of the isolates had non-biofilm, weak, moderate, and strong activities, respectively. The association between the formation of biofilm and amikacin resistance was found (P < 0.05). In the isolates, the frequencies of bap, blaPER-1, and csuE genes were 70.3%, 54.2%, and 93.2%, respectively. Statistical analysis showed a significant correlation between the frequency of blaPER-1 and bap genes and the ability to form biofilms (P < 0.05). This study shows the high tendency among the clinical isolates of A. baumannii to form a biofilm. It also shows the correlation between the presence of blaPER-1 and bap genes with the capacity of biofilm formation. Moreover, the majority (92.4%) of the A. baumannii isolates from Isfahan were susceptible to colistin. Therefore, providing new and effective strategies is essential for the prevention and treatment of infections caused by biofilm-forming A. baumannii strains.