Staphylococcus aureus is a common bacteria that often lives on the skin without causing harm. When it penetrates the skin through a cut, sore, or surgical intervention, it can cause staph infection.
Methicillin was the preferred antibiotic for decades, but many strains of the bacteria are now resistant. Methicillin resistant Staphylococcus aureus is commonly called MRSA.
Susan J. Rehm of the Cleveland Clinic and Alan Tice of University of Hawaii reported on the emergence of antibiotic resistance in staph bacteria. MRSA was first noted in health care settings, but is now common in the community as well.
Researchers distinguish between health care associated (HA-MRSA) and community acquired (CA-MRSA) types. These are biologically different, suggesting that CA-MRSA is not a descendent of HA-MRSA that escaped from hospitals, but developed independently.
Risk factors for HA-MRSA include:
1. Hospitalization during the previous year
2. Recent surgical procedure
3. Exposure to broad-spectrum antibiotics
4. Residence in a long-term care facility
5. Hemodialysis for kidney failure
6. Medical devices such as catheters
7. Intravenous drug use
HA-MRSA infections usually affect the respiratory tract, bloodstream, urinary tract, or surgical sites.
CA-MRSA is an important cause of infection in the following:
1. Hospital emergency departments
2. Intensive care units
3. Athletic participants
4. Military recruits
5. Persons in prison
CA-MRSA usually infects the skin and soft tissues, causing abscesses, boils, and hair follicle inflammation.
Vancomycin is the standard antibiotic treatment for both types of MRSA. Amy Schilling of The University of Texas Medical Branch and colleagues reported on the optimal use of vancomycin.
“In the past half-century, vancomycin has gone from near-orphan status to being one of the most often used antibiotics in our formulary,” Schilling wrote. Early concerns about kidney damage limited the use to exceptional cases.
“In the 1950's, vancomycin formulations were sometimes called 'Mississippi mud' because of the many impurities they contained,” Schilling explained.