Estudo da atividade gelatinolítica em amostras clínicas de Enterococcus faecalis

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Gelatinase is a potential virulence factor in Enterococci which are opportunistic pathogens that cause various types of infections in humans. The production of gelatinase was studied in 95 Enterococcus faecalis strains isolated from different types of clinical sources. Various environmental parameters including culture medium, temperature, pH, divalent cations, and carbon sources were examined for their effect on production of gelatinase. Enzyme activity was determined based on gelatin degradation in agar plates by filter-paper disks impregnated with bacterial cells, as evidenced by the formation of an opaque halo. Gelatinase production was sensitive to heat at a temperature greater than 50 °C, showing to associate with time of heat treatment. A greater number of enterococcal strains produced gelatinase when grown in medium containing beef extract and peptone as nutrient agar. Gelatinase activity was detected over wide pH range with an optimum at pH 8. Ca2+ and Zn2+ caused a reduction in gelatinase production while other common divalent cations (Fe2+ and Cu2+) inhibited it or had no effect (Mg2+). Gelatinolytic activity varied greatly when bacterial cells were supplemented with different carbohydrates as the carbon source, increasing with arabinose, xylose, glucose, maltose and mannose, while unchanged or decreasing with various other sugars. The results show that gelatinase production is strongly influenced by different environmental factors. Further studies are warranted to determine the mechanisms controlling the production of this potential virulence factor in Enterococci.

ASSUNTO(S)

bactérias gram-positivas bacteriologia microbiologia gram-positive bacteria bacteriology microbiology

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