Abstract

Considering the great diversity and prevalence of opportunistic pathogens as well as the medical consequences arising from increasingly frequent cases of infections with resistant pathogens, the aim of this study was to analyze and compare the virulence profiles of some recent isolates of the most frequently encountered human pathogens,Staphylococcus aureus and Pseudomonas aeruginosa. We screened for the production of seven soluble virulence factors (hemolysins, caseinases, amylases, DNA-se, gelatinase, lipase and lecithinase) in 181 clinical isolates, using a method of culturing on specific substrates. Adherence to host cells was analyzed using Cravioto’s adapted method, and invasive potentials were established by an antibiotic protection assay. The results demonstrated that these pathogens may act differently when they are the protagonists of infections and may occur in different clinical condition. We revealed that the analyzed strains display different patterns of soluble virulence factors and different invasive capacity, according to the isolation source; many of the observed differences are statistically significant. By investigating the development of infectious process in variousclinical conditions, our studies provide a high contribution to the development ofpersonalized anti-infectious therapies.

Key words: Opportunistic pathogens, soluble virulence factors, adherence and invasion.