Prevalence of flmA, flmH, mrkA, ecpA, and mrkD virulence genes affecting biofilm formation in clinical isolates of K. pneumonia

Klebsiella pneumoniae is an opportunistic microorganism causing nosocomial infection all over the world .This study aimed to investigate the prevalence of biofilm formation in K. pneumoniae isolated from patients and its correlation with the virulence factors. Biochemical tests were used for the identification of K. pneumonia isolated from patients referred to Motahari and Milad hospitals in Tehran, Iran, from October 2015 to June 2016. Kirby-bauer test was performed and biofilm formation was assessed phenotypically. Finally, virulence genes were detected by the PCR method. The highest resistance rate was against ceftazidime and cefotaxime (67%) and the least resistance rate was against imipenem and meropenem (39%). In addition, 81% of the isolates were biofilm producers according to the results of biofilm formation assay. Also, the results of PCR showed that all 57 biofilm producer isolates harbored fimA, mrkA, ecpA, and fimD virulence genes and 92% of these isolates harbored fimH virulence gene. Among non-biofilm producer isolates, 36% had fimA gene, 29% had ecpA gene, and none of these isolates carried mrkA and fimH genes. It seems that antibacterial resistance has a significant association with biofilm formation in K. pneumoniae isolates. Therefore, understanding resistance pattern and mechanisms leading to biofilm formation can facilitate efficient treatment of infections caused by this bacterium.