Investigation of immuno-regulatory mechanisms during Staphylococcus aureus colonisation and infection

Abstract

1.1 Staphylococcus aureus infections and treatment options Staphylococcus aureus: (S. aureus) is a Gram-positive coccal bacterium. It is a facultative anaerobe which can be distinguished from other such staphylococci due to its gold pigmentation and ability to ferment mannitol. S. aureus is one of the leading causes of a variety of community-acquired and hospital-acquired bacterial infections. It is one of the most prominent causes of bacteraemia, carrying a greater mortality than any other bacterium - currently 20-40% mortality at thirty days despite appropriate treatment (1, 2). It is also a contributing cause for other deep-seated infections including osteomyelitis, septic arthritis, endocarditis, device-related infections and pneumonia. S. aureus is unique for its ability to cause primary bacteraemia and serious infections in young, otherwise healthy people, as well as in those with known risk factors (3). Invasive disease is by far the most acute and severe, however, the greatest burden of morbidity is due to chronic and recurrent skin and soft tissue infections (SSTIs), which are extremely common (4). <-. Methicillin resistant S. aureus (MRSA) strains are now a major cause of concern in the healthcare associated (HA) environment, particularly in Western Europe and North America. Lately, there have been reports of S. aureus resistance to vancomycin, a glycopeptide antibiotic, considered by many as the last resort of antibiotic treatment to treat infections caused by this bacterium (5). Of further alarm, is the more recent outbreak of community associated (CA)-MRSA among healthy individuals outside the healthcare realm. These CA-MRSA strains can be characterised by distinct genotypes and distinct determinants of virulence, which are often more virulent than HA MRSA strains (6, 7).