Systemic infection and colonization with and without prophylactic norfloxacin use over time in the granulocytopenic, acute leukemia patient.

Patients undergoing intensive antileukemic chemotherapy and profound granulocytopenia are susceptible to overwhelming infections, particularly those arising from disease- and therapy-related gastrointestinal tract damage. We have previously demonstrated that the ability to suppress bacterial colonization of this site with oral norfloxacin prophylaxis (400 mg every 12 h) affects the incidence and distribution of aerobic gram-negative bacterial infections and the overall management of infectious complications in this patient population. We have now determined the broad impact of continuous, long-term use of oral norfloxacin on aerobic gram-negative bacterial infection and colonization, overall management of presumed and documented infections during marrow aplasia and emergence of clinically significant antibiotic resistant pathogens during intensive antileukemic chemotherapy. Oral norfloxacin prophylaxis administered throughout the course of induced granulocytopenia continues to afford effective protection by suppressing the development of aerobic gram-negative infections, particularly those arising from the gastrointestinal tract, and preventing the acquisition or emergence of multiply resistant pathogens. A long-range effect of norfloxacin on pathogens colonizing the respiratory tract is also detected, with inhibition of acquired drug resistance occurring at that site as well. For these reasons, norfloxacin continues to be an excellent agent for oral prophylactic use in this patient population.