Staphylococcus aureus

Staphylococcus aureus

Life History and Characteristics: Staphylococcus aureus is a gram positive bacterium that is usually found in the nasal passages and on the skin of 15 to 40% of healthy humans, but can also survive in a wide variety of locations in the body. This bacterium is spread from person to person or to fomite by direct contact. Colonies of S. aureus appear in pairs, chains, or clusters. S. aureus is not an organism that is contained to one region of the world and is a universal health concern, specifically in the food handling industries.

Diseases: The most common health concern associated with S. aureus is food poisoning caused by the release of enterotoxins, even in small doses, into food. Release of less than 1 microgram of toxin is sufficient to contaminate food enough to illicit symptoms of food poisoning. The infective dose of toxin is generally present when food is contaminated with an excess of 100,000 bacteria per gram of food. The intensity and variety of symptoms resulting from S. aureus food poisoning differ from individual to individual, but some of the most common symptoms are nausea, vomiting, abdominal cramping, and prostration (complete physical or mental exhaustion). It usually takes 2 or 3 days to recover from S. aureus food poisoning, but in some instances individuals will require more time to fully recover.

Even though S. aureus is mainly associated with food poisoning, the bacterium can penetrate the skin or other mucous membranes to invade a range of tissues which will cause a variety of infections. Superficial infection of the skin can cause boils, impetigo, styes (infection of the glands or hair follicles of the eyelids), folliculitis, and furnacles. All of these infections are charac...

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...ood to above 60 degrees C and storing food below 7.2 degees C are two effective ways of controling S. aureus growth in food. The most important recent epidemiological information concerning this organism involves the increasing resistance to antibiotics. Methicillin-resistant S. aureus (MRSA) is the most common of these antibiotic resistant organisms. The effects of MSRA are the same as any other S. aureus infection, however, MSRA infections are a difficult to treat because there are few effective antibiotics available. MSRA infections are generally not life threatening, however in some extreme cases death can occur.

References:

http://www.cdc.gov/ncidod/hip/Aresist/mrsa.htm

http://www.bact.wisc.edu/Bact330/lecturestaph

http://vm.cfsan.fda.gov/~mow/chap3.html

http://www.bacteriamuseum.org/species/staphaureus.shtml

http://www.dermnetnz.org/index.html