As I am sure is the same for many of us in the field, my first exposure to general microbiology occurred in college. In one of the first lab sessions for the microbiology course we were instructed to swab a surface and transfer its contents onto a nutrient agar plate. Being curious college students, we sampled everything from lab bench top surfaces, to plant leaves and clothing. I was more interested in what critters were growing on me, so I swabbed my hands.
Several days later as we were checking our plates, I heard one girl say that she should do her laundry more often because of the mold that grew on her plate. Looking at my plate, I had a mixture of golden yellow and white colonies growing. After a battery of phenotypic tests, I identified these colonies as Staphylococcus aureus and Staphylococcus epidermidis, respectively. These bacteria, as I later learned, are just two of the many microorganisms that are part of the natural human skin flora.
Hmmm. Where else have I heard of Staph? Reruns of House, M.D. or Grey’s Anatomy, maybe? Who hasn’t heard of a Staph infection?
S. aureus is not only a regular resident on our skin, but in certain conditions will sneak through open wounds and cause infections, sometimes serious, especially to immuno-compromised individuals.
Not a week goes by that we don’t hear about superbugs. Staph, or a certain strain of it, are one of these responsible bugs. There is an increase in nosocomial infections worldwide in community and healthcare settings. Formally, this superbug is known as methicillin-resistant Staphylococcus aureus (MRSA) and as its name suggests these strains of S. aureus are resistant to beta-lactam antibiotics, such as penicillin. As a microbiologist, I’m amazed at the ability of these bugs to adapt. As a human, I’m concerned as it is becoming increasingly difficult to treat Staph-related infections. In a study by Klein et al. (2007), between 1995 and 2005, the number of S. aureus-related hospitalizations increased from 295,000 to 478,000 and the number of MRSA-related hospitalizations doubled from 127,000 to 278,000. Initial symptoms of MRSA infections include bumps and blisters at the site of infection. These later become pus-filled boils, which provide a vehicle for transmission, as contact with the pus can cause infection. If untreated, the infection can further advance to widespread infection and toxic shock syndrome (induced by bacterial toxin secretion).
Should you be swabbing your hands and arms everyday to catch Staph? Nah, in most cases, S. aureus, like many microorganisms, are just part of the natural ecosystem that is the human body.
The traditional test for S. aureus includes general incubation of around 2-5 days. The Growth DirectTM System for rapid automated microbial detection visualizes this microbe in 9-12 hours.
Rapid Micro Biosystems
Klein E., Smith D.L., Laxminarayan R. (2007) Hospitalizations and deaths caused by methicillin-resistant Staphylococcus aureus, United States, 1999-2005. Emerg Infect Dis: 13(12): 1840-1846.