ABSTRACT
Methicillin resistance in Staphylococcus aureus (MRSA) and the coagulase-negative staphylococci (MRCNS) is widespread and continues
to increase in prevalence, particularly in the health care setting. The clinical significance
of methicillin resistance for patients with staphylococcal infections is not clear:
studies in patients with bacteremia, pneumonia, and mediastinitis show a higher mortality
with MRSA infection compared to methicillin-sensitive Staphylococcus aureus (MSSA) infection, though this may be due to underlying patient, pharmacodynamic,
or microbiological differences. For serious methicillin-resistant staphylococcal infections,
vancomycin-based regimens are preferred. Treatment alternatives for patients with
severe methicillin-resistant infections who are unable to tolerate vancomycin include
linezolid and quinupristin/dalfopristin; these agents should be considered second-line
options, given the relative lack of clinical experience and the nonsignificant but
consistent trends toward worse outcomes in bacteremia and pneumonia with these agents
compared to vancomycin. For less severe infections, treatment options also include
trimethoprim-sulfamethoxazole, or fluoroquinolones in combination with rifampin.
KEYWORDS
Staphylococcus aureus, coagulase-negative staphylococci - methicillin resistance
