ABSTRACT
Linda M. McKinley Department of Infection Control, William S. Middleton Veterans Affairs Medical Center, Madison, Wisconsin, U.S.A.
INTRODUCTION
Methicillin-resistant Staphylococcus aureus (MRSA), a major cause of
infections in healthcare institutions (1) and more recently in the community
(2,3), was first reported in 1961, two years after the introduction of
methicillin for treatment of penicillin-resistant S. aureus infections (4,5).
Since then, despite extensive infection control efforts, methicillin resistance
among isolates of S. aureus has steadily increased. Data from the National
Healthcare Safety Network (NHSN) at the Centers for Disease Control
and Prevention (CDC) show that 50% to 60% of healthcare-associated
S. aureus isolates from ICUs are now resistant to methicillin. Figure 1
shows resistance trends in S. aureus over time (6). Multidrug-resistant
strains of staphylococci are also being reported with increasing frequency
worldwide, including isolates that are resistant to methicillin, lincosamides,
macrolides, aminoglycosides, fluoroquinolones, or combinations of these
antibiotics (7). Recently, the emergence of S. aureus strains with inter-
mediate resistance to vancomycin has been reported (8-10). For decades,
vancomycin has been the only uniformly effective treatment against serious
MRSA infections and the development of resistance to it is deeply con-
cerning. MRSA infections are associated with prolonged hospitalization
