Biofilm formation ability and swarming motility are associated with some virulence genes in Proteus mirabilis.

Proteus mirabilis (P. mirabilis) is one of the frequent causes of urinary tract infection in humans. This pathogen armed by diverse virulence associated factors. Biofilm formation and swarming motility are two surface living behaviors of P. mirabilis and their association with virulence associated genes was investigated in the present study. Biofilm formation ability and swarming motility were evaluated by microtiter plate assay and top-agar travel tracking in 91 P. mirabilis isolates respectively. The polymerase chain reaction method was used for screening of 10 virulence associated genes. Association of virulence associated genes with biofilm formation ability and also swarming motility was analyzed statistically. The zapA (100%) and hlyA (41.8%) genes had maximum and minimum frequency respectively. Forty-one, 35 and 15 isolates were categorized as weak, intermediate and strong biofilm producers respectively. While, 11%, 38.5% and 50.5% of isolates were grouped as weak, intermediate and strong swarmers respectively. Adhesin encoding genes such as mrpA were more prevalent in strong biofilm producers in comparison to the other isolates. Reversal association of rsmA gene with swarming motility was detected. The frequency of hlyA gene was associated directly with swarming motility and in opposite way with biofilm formation. Reverse correlation of biofilm formation ability and swarming motility was estimated. Based on the study findings it is hypothesized that P. mirabilis benefited from adhesins such as MR/P fimbriae for production of biofilm and successful colonization and then they shift from biofilm formers to strong swarmers in order to reach deeper urinary organs and HlyA toxin is used to overcome the immune system cells. However, it has to confirmed trough future studies.