Methicillin-Resistant Staphylococcus Aureus
MRSA is a mutation of a very common bacterium that’s easily spread by direct person-to-person contact. Previously limited to large teaching hospitals and tertiary care centers, MRSA is now endemic in nursing homes, long-term care facilities,
and community hospitals. Patients most at risk for MRSA infection include immunosuppressed patients, burn patients, intubated patients, and those with central venous catheters, surgical wounds, or dermatitis. Others at risk include those with prosthetic devices, heart valves, and postoperative wound infections. Also at risk are patients with acute endocarditis, bacteremia, cervicitis, meningitis, pericarditis, and pneumonia. Other risk factors include prolonged hospital stays, extended therapy with multiple or broad-spectrum antibiotics, and close proximity to those colonized or infected with MRSA.
and community hospitals. Patients most at risk for MRSA infection include immunosuppressed patients, burn patients, intubated patients, and those with central venous catheters, surgical wounds, or dermatitis. Others at risk include those with prosthetic devices, heart valves, and postoperative wound infections. Also at risk are patients with acute endocarditis, bacteremia, cervicitis, meningitis, pericarditis, and pneumonia. Other risk factors include prolonged hospital stays, extended therapy with multiple or broad-spectrum antibiotics, and close proximity to those colonized or infected with MRSA.
Causes
MRSA enters health care facilities through an infected or colonized patient or colonized health care worker. Although MRSA has been recovered from environmental surfaces, it’s transmitted mainly on health care workers’ hands. Many colonized individuals become silent carriers. The most frequent site of colonization is the anterior nares (40% of adults and most children become transient nasal carriers). Other sites include the groin, axilla, and the gut; however, these sites aren’t as common. Typically, MRSA colonization is diagnosed by isolating bacteria from nasal secretions.
In individuals where the natural defense system breaks down, such as after an invasive procedure, trauma, or chemotherapy, the normally benign bacteria can invade tissue, proliferate, and cause infection. Today, up to 90% of S. aureus isolates or strains are penicillin-resistant, and about 27% of all S. aureus isolates are resistant to methicillin, a penicillin derivative. These strains may also resist cephalosporins, aminoglycosides, erythromycin, tetracycline, and clindamycin.
MRSA has become prevalent with the overuse of antibiotics. Over the years, overuse has given once-susceptible bacteria the chance to develop defenses against antibiotics. This new capability allows resistant strains to flourish when antibiotics knock out their more sensitive cousins.
Complications
This infection can lead to sepsis and resultant death in severely affected individuals.
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