Higher Cytotoxicity of Methicillin-Resistant Staphylococcus aureus (MRSA) Epidemic Clones Related to the Production Of Αlpha-Toxin

SOLA C; SAKA HA; BOCCO JL

Pinamar

Congreso; SAIB 41st Annual Meeting - XLI Reunión Anual -Argentine Society for Biochemistry and Molecular Biology- -Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2005

SAIB

Infections caused by MRSA are increasingly involved as main healthcompromise in worldwide for hospitalized patients. Some MRSAclones have the ability to spread easier than others within thehospital environment and thereby are frequently implicated inoutbreaks. The specific phenotypic and genetic factors contributingto the epidemic behavior of this bacterium have not been identifieduntil present. We examined the invasion and intracellular survivalof both epidemic and sporadic strains of Staphylococcus aureuswithin epithelial and macrophages cell lines as an essential step tostudy their involvement in the epidemic capacity. Both, epidemicand sporadic S. aureus strains showed similar intracellular growthduring the first 60 min. of infection. Besides to survive within theeukaryotic cells, all epidemic strains but not the sporadic onesinduced a significant necrotic-like cytotoxicity following 12 h. ofinfection. This effect correlates with the production of the α-toxinidentified as a major excreted protein involved in a drastic reductionof cell viability. Thus, S. aureus can persist in clinical setting throughbiofilm formation for which the α-toxin is required. In conclusion,the higher cytotoxicity evidenced in this study reveal a biologicalfeature of these bacteria explaining why some strains can persist inthe environment and disseminate easier that others, conferring theepidemic behavior.