What is Staphylococcus aureus?
Staphylococcus aureus or “Staph” for short, are spherical bacteria carried mainly on human skin and nose. They are found among 25-30% of population but do not cause infection unless they find a way inside the skin through a cut for example. Staphylococcus aureus can also cause foodborne illness if it is transferred to food. When transferred to food, S. aureus can quickly produce a toxin that is extremely heat resistant and, if consumed, will cause foodborne illness. Staphylococcal infections can produce very serious complications including: wound infections, bloodstream infections, pneumonia and meningitis. What is MRSA? Methicillin-resistant Staphylococcus aureus (MRSA) is a type of staphylococcal bacteria that is resistant to most antibiotics used to treat infections. It is a growing concern in many hospitals and health care facilities. Where is Staph. aureus found? Human skin and nose are the main reservoirs for S. aureus; however, it has also been found on some animals (chicken and pig) and in the environment including places that are hard to clean such as ventilation systems.
What kind of environmental conditions can it survive? Staphylococcus aureus can grow in a wide range of temperatures (6 to 48°C) but grows best at 37°C. It can also grow at pH levels of 4.2 to 9.3 but grows best at pH levels of 7-7.5.Staphylococcus aureus can grow in salt concentrations of about 7-25%. While S. aureusprefers to grow in the presence of oxygen they are also capable of growing without it. Staphylococcus aureus do not compete well with other bacteria and is, therefore rarely the cause of foodborne illness in raw foods. The bacterial cells are destroyed by heat but the toxin that they leave behind in the food they have contaminated is extremely heat resistant.Staphylococcus aureus can also survive drying. What foods are involved?
Foods that are cooked, salty, and high in protein are most commonly implicated in foodborne illness caused by S. aureus, such foods include:
- Abdominal cramps
- Areas that are red, painful and swollen.
- Sweating heavily
New Zealand Food Safety Authority. (2001). Microbial Pathogen Data Sheets: Staphylococcus aureus. Retrieved from www.nzfsa.govt.nz/science/data-sheets/staphylococcus-aureus.pdf Public Health Agency of Canada. (2001). Staphylococcus aureus. Retrieved from www.phac-aspc.gc.ca/msds-ftss/msds143e-eng.php