Download Staphylococcus aureus

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: 0.5-1.5 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.
Scanning electron micrograph of a cluster of Staphylococcus aureus.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3002151/
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).
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 3 2012 194 -
Staphylococcus aureus virulence factors
A. Del Sol F2013
Modified by DYH
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.
http://www.news-medical.net/health/What-is-Staphylococcus-Aureus.aspx
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.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3002151/