Assessment of biofilm formation by enterococci isolates from urinary tract infections with different virulence profiles

Abstract

This study aimed to investigate possible associations between virulence profiles and biofilm formation in Clinical UTI isolates. Isolates were collected from five university hospitals and identified and characterized for the presence of virulence factors by PCR. Biofilm assays were conducted in 96 well microtiter plates by reading the OD570 after crystal violet staining. 75% of isolates had esp gene, 38.77% had asa1, 84.18% had ace, 81.63% had efaA, 93.36% had ebpR, 34.18% had cylA, 81.63% had gelE and 17.35% had hyl. Biofilm experiences were done and isolates having asa1 or efaA genes produced more biofilms than negative ones (P = 0.011, P = 0.008), but the presence of esp, ace, cylA or gelE genes in isolates had no effect on biofilm formation. Isolates possessing hyl had much lower biofilm formation (P = 0.000). Present study showed that the esp, ace, gelE and cylA genes do not seem to be necessary nor sufficient for the production of biofilm in enterococci but the presence of efaA and asa1 correlates with increased biofilm formation of urinary tract isolates. Also the low prevalence of hyl among enterococci isolated from UTIS and its association with poor biofilm production indicate that the absence of this gene can be an advantage in the pathogenesis of UTIs.

Keywords

• Enterococci
• Biofilm
• UTIs
• Virulence genes
• Colonization
• Secretory factors