Influence of isolate origin and presence of various genes on biofilm formation by Enterococcus faecium

Abstract

Enterococcus faecium, a major cause of nosocomial infections, is often isolated from conditions where biofilm is considered to be important in the establishment of infections. We investigated biofilm formation among E. faecium isolates from diverse sources and found that the occurrence and amount of biofilm formation were significantly greater in clinical isolates than fecal isolates from community volunteers. We also found that the presence of the empfm (E. faecium pilus) operon was associated with the amount of biofilm formation. Furthermore, we analyzed the possible association between the distribution of 16 putative virulence genes and the occurrence of biofilm production. Even though the prevalence of these virulence genes was significantly higher in clinical isolates, we did not observe any correlation with the occurrence of biofilm formation.

Keywords: Enterococcus faecium; biofilm; virulence.

Figure 1. Analysis of biofilm formation among E. faecium isolates from diverse sources

Circles and squares represent clinical isolates and community stool isolates respectively. The horizontal line indicates the median OD₅₇₀ of biofilm formation of each group. Each point represents the average OD₅₇₀ values from two independent experiments with 8 replicates each.