1. Staphylococcus aureus
A. Del Sol F2013
Modified by DYH
It is a non-moving, spherical, Gram-positive bacteria , usually found in grape-like clusters.
Size: microns.
About 30% of people have this bacteria in their nose, skin and back of their throat.
One of the five most common causes of infections is after injury or surgery, affecting around 500,000 patients in American hospitals.
It affects all known mammalian species, including humans. It causes:
-Skin infections such as impetigo, abscesses and folliculitis
Infections of organs such as pneumonia, osteomyelitis, endocarditis, etc (most common
in hospitalized patients).
Scanning electron micrograph of a cluster of Staphylococcus aureus.
Fig 2 MRSA prevalence rate per 1,000 inpatients by state.National prevalence of methicillin-resistant Staphylococcus aureus in inpatients at United States health care facilities, 2010
American Journal of Infection Control Volume 40, Issue http://

2. Staphylococcus aureus virulence factors
A. Del Sol F2013
Modified by DYH
Staphylococcus aureus virulence factors
Adhesins- Aid S. aureus to attach to the host cell surface. It uses microbial surface components recognizing adhesive matrix molecules (MSCRAMMS)
Exoproteins- Exotoxins and enzymes, including nucleases, proteases, lipases, hyaluronidase, and collagenase that convert local host tissue into nutrients required for bacterial growth.
Coagulase and catalase are enzymes that protect S. aureus from the host immune system.
Exfoliative toxins induce erythema as well as skin exfoliation, and enterotoxin results in a self-limited food poisoning
S. aureus can be resistant to penicillin by producing enzymes like penicillinase that destroys the antibiotic.