Prevention of infections in the neutropenic patient.

Infections are still a frequent cause of morbidity in patients with hematologic malignancies. Until 10 years ago the microorganisms most frequently encountered were aerobic gram-negative bacilli, which in many centers were responsible for, on average, one infection per neutropenic period. Many different approaches to the prevention of these infections have been designed. Patients have been kept in strict isolation and given broad-spectrum antibiotics prophylactically. This approach has led to a decrease in the incidence of infections in these patients, but compliance and emergence of resistance have been important limiting factors. The rationale of selective decontamination with trimethoprim-sulfamethoxazole or quinolones was that the elimination of potentially pathogenic aerobic gram-negative bacilli from the gastrointestinal tract would prevent colonization and subsequent infection. The use of these antibiotics has led to a shift in the spectrum of infections. Infections due to gram-negative bacilli have been virtually eliminated, but the number of infections caused by gram-positive bacteria is rapidly increasing; however, the latter infections are most often only minor. In some centers quinolones are now used together with agents active against these gram-positive bacteria. The approach of selective decontamination has not led to fewer febrile episodes or to a lower mortality in neutropenic patients. Future studies should be directed towards identifying the cause of febrile episodes and the epidemiology of gram-positive bacterial infections.