Study of Pathogenicity of Various Serovars of Enterococcus faecalis

: Using a mouse experimental UTI (urinary tract infection) model, a study was conducted to find the pathogenicity of various serovars of E. faecalis. On the basis of studies employing serovar-specific factor sera prepared with E. faecalis type strains, serovar 2, 3, 4 and 10 strains showed a high incidence of involvement in pyelonephritis: 90.3%, 85.7%, 85% and 73.3%. Serovar 1, 6 and 7 strains each showed a 63.6% incidence of involvement in pyelonephritis, indicating that they have a moderate pathogenicity. The pathogenicity of the other serovar strains was not very strong, with a low incidence of 40-59.1%. These results were thus in good agreement with the findings of the study using the mouse experimental UTI model infected with clinical isolates. Serotyping was performed of E. faecalis clinical isolates obtained from patients with pyelonephritis or urosepsis. Serovars 2 and 4 comprised 75.1% of these isolates. It was surmised that E. faecalis serovars 2 and 4 tend to have strong pathogenicity. Thus, there were quite a few differences in pathogenicity of E. faecalis according to each kind of serovar.