Antibiotic-resistant infections in the critically ill adult.

Intensive care units (ICUs) frequently are the epicenter of nosocomial infections with antibiotic-resistant bacteria. Optimization of antibiotic therapy for seriously ill patients with bacterial infections appears to have a strong influence on outcome. Laboratories can aid in provision of appropriate antibiotic therapy by providing clinicians with "antibiograms" to aid empiric antibiotic choice and by providing minimal inhibitory concentrations of key antibiotics so that antibiotic dosing is optimized to key pharmacodynamic targets. Laboratories also play a crucial role in the prevention of antibiotic resistance in the ICU. Molecular epidemiologic evidence of an oligoclonal outbreak of infections orients prevention measures toward investigation of common environmental sources of infection and prevention of patient-to-patient transmission. In contrast, evidence of polyclonality shifts prevention of antibiotic resistance to antibiotic management strategies.