Strong biofilm production, antibiotic multi-resistance and high gelE expression in epidemic clones of Enterococcus faecalis from orthopaedic implant infections.

Enterococcus faecalis is an opportunistic pathogen, which today represents one of the leading aetiologic agents of nosocomial infections and, increasingly, of implant infections. Here, in a collection of 43 E. faecalis isolated from implant orthopaedic infections, virulence-related phenotypes (biofilm and gelatinase production) and genotypes (gelE and esp) were studied to characterize epidemic clones identified and grouped by ribotyping. The presence of the esp gene and a marked and steady biofilm formation ability appeared to be the features associated with the clonal spreading, as well as a conspicuous gelatinase production, whereas the simple presence of gelE appeared non-specific of the epidemic clones. Antibiotic multi-resistance and strong biofilm production abilities together with a high phenotypic expression of gelatinase are an important equipment of E. faecalis to colonize peri-prosthesis tissues and to spread out as causative agents of implant orthopaedic infections.