Antimicrobial resistance in the intensive care unit.

Antimicrobial resistance remains a major clinical problem in the intensive care unit despite the introduction of potent new antibiotics and the application of infection control measures. Impaired antibiotic permeability, antibiotic inactivation and alteration of antibiotic target sites, typically in concert, are mechanisms by which this resistance occurs. Resistance traits may be chromosomally mediated, in which case they may be expressed constitutively or inducibly, or may be mediated by plasmids and/or transposons that may confer resistance to multiple drugs and facilitate spread to other organisms. Bacteria in which clinically significant resistance has now become a potential problem include methicillin-resistant staphylococci, enterococci, a wide variety of Enterobacteriaceae, Pseudomonas aeruginosa, Pseudomonas cepacia, and Xanthomonas (Pseudomonas) maltophilia. Judicious limitation in the use of antimicrobials, especially in prophylactic regimens; use of antibiotics in appropriate doses; and, where possible, avoidance of drugs to which resistance has been shown to emerge rapidly in a specific clinical setting will help to minimize the evolution and spread of resistant bacterial isolates.