Overview of resistance in the 1990s.

The tremendous therapeutic advantage afforded by antibiotics is being threatened by the emergence of increasingly resistant strains of microbes. Selective pressure favoring resistant strains arises from misuse and overuse of antimicrobials (notably extended-spectrum cephalosporins), increased numbers of immunocompromised hosts, lapses in infection control, increased use of invasive procedures and devices, and the widespread use of antibiotics in agriculture and animal husbandry. Outside the hospital, penicillin-resistant Streptococcus pneumoniae is of greatest concern; recent reports also indicate the appearance of outpatient methicillin-resistant Staphylococcus aureus (MRSA) infections. MRSA is a significant problem in the hospital, as are vancomycin-resistant Enterococcus, oxacillin-resistant S aureus, and multidrug-resistant Gram-negative bacilli. Owing to the high rate of antibiotic use and other risk factors, a person is more likely to acquire an antibiotic-resistant infection in the ICU than anywhere else, either inside or outside the hospital. Responsible antibiotic use and stringent infection-control policies are needed to discourage the development of resistant strains.