Gelatinase-associated phenotypes and genotypes among clinical isolates of Enterococcus faecalis in Poland

Enterococcus faecalis is an important nosocomial pathogen causing serious invasive infections. One of the virulence factors of this pathogen, gelatinase GelE, is a protease whose gene expression is regulated by the Fsr quorum sensing system. In this study, we used a well-characterized collection of 153 clinical E. faecalis isolates to investigate the distribution of genes involved in gelatinase expression. Although 140 isolates (91% of the group) harbored the gelE gene, only 81 isolates (53%) produced active gelatinase. The gelatinase-negative phenotype was found in several unrelated clones, and appeared to be caused by various genetic events. Isolates of the hospital-adapted clonal complex 2 (CC2) and of CC40 were uniformly gelatinase-positive, while all the CC87 isolates contained the 23.9 kb deletion encompassing most of the fsr locus and were gelatinase-negative. No significant differences among isolates of different clinical origin and gelatinase activity or presence of the fsr genes were found with the exception of isolates from cerebrospinal fluid, which were more often gelatinase-positive than colonizing isolates.