Etiology of Mrsa

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that causes infections in the body. "MRSA, like other multidrug resistant organisms (MDR) really seem to be gathering pace, no doubt fuelled by intensive broad-spectrum antibiotic use, poor infection control, highly immunosuppressed patients, and rapid and frequent air travel". When MRSA occurs in a healthcare setting such as a hospital, it is referred to as HA-MRSA, and when this occurs in a community, "among healthy people," it is referred to as CA-MRSA. HA-MRSA is a growing "endemic" throughout the whole world while CA-MRSA is prevalent in less countries, the U.S. being one where it is very high.

Infection occurs with HA-MRSA when "[a] doctor, nurse, other health care provider, or visitors may have staph germs on their body that can spread to a patient;" or when the patent is exposed to "intravenous catheters, surgical procedures like joint replacement, and contact with devices found in a hospital setting". Infection occurs with CA-MRSA in "conditions of close personal contact, poor hygiene, and exposure to contaminated objects". "At-risk populations include groups such as high school wrestlers, child care workers and people who live in crowded conditions".

In general, CA-MRSA has fewer "risk-factors" than HA-MRSA. While HA-MRSA "has traditionally been resistant to other anti-staphylococcal agents, such as clindamycin, erythromycin, and tetracycline, with variable resistance to gentamicin and trimethoprimsulfamethoxazole (SXT)"; CA-MRSA has "typically been susceptible to clindamycin, SXT, and gentamicin". This makes HA-MRSA more dangerous and difficult to treat.