Virulence-associated characteristics of Enterococcus faecalis strains isolated from clinical sources

Brazilian Journal of Microbiology

Márcia T. Furumura¹  Patricia M.s. Figueiredo¹  Gleize V. Carbonell²  Ana Lucia Da Costa Darini²  Tomomasa Yano¹ 

[1] ,Universidade Estadual de Campinas Instituto de Biologia Departamento de Microbiologia e ImunologiaCampinas SP ,Brasil

关键词: Enterococcus faecalis;    virulence factors;    hemolysin;    proteases;    lipase;    cytotoxin;    biofilm;    Enterococcus faecalis;    hemolisina;    proteases;    lípase;    citotoxina;    fatores de virulência;   

DOI  :  10.1590/S1517-83822006000300007

来源: SciELO

【 摘 要 】

Thirty-two clinical isolates of Enterococcus faecalis were screened for virulence factors. Twenty-four (75%) isolates produced hemolysin on Mueller-Hinton blood agar plates with sheep erythrocytes. However, the cell free heat-stable hemolysin was detected in all isolates (100%) of E. faecalis when grown in BHI-GA (BHI medium supplemented with 1% glucose and 0.03% L-arginine), but not in BHI broth alone. Twenty-four isolates (75%) produced caseinase and 23 (71.9%) lipase, but none of the isolates produced gelatinase. Fifteen (46.9%) culture filtrates caused rounding and membrane alterations with blebbing formation followed by death in HeLa and HEp-2 cells, but not in Vero cells. Thirteen isolates (40.6%) agglutinated rabbit erythrocytes, but did not produce hemagglutination in other bloods, containing or not 1% D-manose. Sixteen (50%) E. faecalis isolates adhered to HeLa cells and thirteen (40.6%) to HEp-2 cells, but all isolates adhered to polypropylene microtiter plates, indicating that clinical E. faecalis possess the ability to form biofilm in vitro. All the isolates were resistant to the bactericidal action of normal serum and did not produce aerobactin. These findings suggest that adherence and consequently biofilm formation on ephitelial host cells are the first steps in the E. faecalis virulence and that hemolysin, lipase, caseinase and other virulence factors act as causative of human epithelial cell damages.

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