Occurrence of virulence factors among human intestinal enterococcal isolates
H. Lempia¨inen, K. Kinnunen, A. Mertanen and A. von Wright
Institute of Applied Biotechnology, University of Kuopio, Kuopio, Finland
2003/1200: received 31 December 2003, revised 3 January 2005 and accepted 26 April 2005
ABSTRACT
H. LEMPIA¨ INEN, K. KINNUNEN, A. MERTANEN AND A. VON WRIGHT. 2005.
Aims: The aim of this study was to investigate the frequency of enterococcal virulence factors among human intestinal Enterococcus faecalis strains and to find out whether the pattern differs from that seen in published reports on food and clinical isolates.
Methods and Results: The E. faecalis isolates were cultured from human faecal samples obtained from five ulcerative colitis patients in remission phase. The species identification was based on API120 strips and speciesspecific
PCR primers. The isolates were further characterized using the pulsed-field gel electrophoresis. The presence of seven different known enterococcal virulence factors among the confirmed E. faecalis isolates were screened using PCR techniques and published primers.
Conclusions: Among the 35 isolates representing nine different pulsotypes the most frequent virulence factors were cpd (33 isolates), agg (25 isolates), gelE (22 isolates) and esp (15 isolates). No complete sets of genes associated for the production of functional cytolysin were encountered indicating that intestinal enterococci may differ in this respect from clinical strains.
Significance and Impact of the Study: According to the results, the commensal enterococcal strains appear to differ from clinical isolates in their complement of presumed virulence factors.
Keywords: Enterococcus faecalis, intestinal enterococci, PCR, pulsed-field gel electrophoresis, virulence factors.
INTRODUCTION
Enterococci are normal intestinal commensals. They are also frequently met in foods either as contaminants, as components of spontaneously formed