The dissemination among Staphylococcus aureus of the Staphylococcal Chromosome Cassette mec (SCCmec) which confers multiresistance

Abstract

Staphylococci are gram-positive bacteria present on the skin of most healthy humans. Although majority of coagulase-negative staphylococci (CNS) are commensals that generally do not cause severe clinical problems, some, including Staphylococcus epidermidis and Staphylococcus haemolyticus, may cause clinically relevant infections and bactereamia related to indwelling devices. In addition, one third of healthy humans carry Staphylococcus aureus, which may cause severe invasive disease. S. aureus accounts for the majority of nosocomial infections around the world, causing high mortality when untreated. Several types of antibiotics, directed to different targets in bacterial metabolism, were employed to fight infections caused by S. aureus. However, S. aureus has acquired resistance to most extant antibiotics, including vancomycin, and evolved to be one of the most difficult-to-treat pathogens in hospitals. This thesis describes the essential role of horizontal gene transfer between the chromosomes of different staphylococci in the dissemination of resistance genes.