The Role of Quinolones as Prophylaxis in Neutropenic Patients

Neutropenia and risk of infectious complications It has been appreciated for 50 years that neutropenia predisposes patients to infectious diseases. The degree and duration of neutropenia predict the risk of infectious complications, and resolution of infections is linked to myeloid recovery (1). Chemotherapy-related oral and gastrointestinal mucositis play an important role in contributing to the increased risk of infection among neutropenic patients, predisposing to blood stream infections by α-hemolytic streptococci spp. (2–4), Gram-negative rods (5), and Candida spp. (6). Additional factors that can increase the risk of infectious complications include the use of indwelling venous catheters, use of systemic steroids and other immunosuppressive agents, and co-morbidities such as malnutrition and renal and hepatic impairment. Whereas in the 1960s and 1970s, Gram-negative bacterial pathogens (coliforms and Pseudomonas aeruginosa) were the principal causes of bacteremia, Gram-positive bacterial infections have since become predominant, with approximately two-thirds of nosocomial bloodstream infections in patients with hematological malignancies being Address for correspondence Brahm H. Segal, MD Division of Infectious Diseases, Roswell Park Cancer Institute, Elm & Carlton Streets, Buffalo, New York 14263, USA Phone: 716-845-5721 Fax: 716-845-5777 E-mail: [email protected] Gram-positive (7–9). This shift toward infection by Gram-positive organisms likely reflects the widespread use of implantable venous catheters, more effective agents against Gram-negative pathogens, and more common use of antibacterial prophylaxis. Efforts to reduce the incidence of serious bacterial infections involved the routine use of anti-pseudomonal β-lactam agents as empirical antibacterial therapy at the onset of neutropenic fever (10). Empirical antimicrobial therapy, by definition, denotes therapy for suspected, but not documented, infection. With improvements in antibacterial therapy and the rapid initiation of broad-spectrum antibiotic treatment at the onset of neutropenic fever, mortality from bacterial infections during chemotherapy-induced neutropenia became less common. Indeed, among patients with prolonged neutropenia (e.g., patients receiving induction or re-induction regimens for acute myelogenous leukemia), invasive fungal diseases equaled or exceeded bacterial infections as the predominant causes of infectious-related mortality at several centers (11). Thus, the question is raised regarding the expected benefits versus limitations Brahm H. Segal, MD Head, Division of Infectious Diseases Roswell Park Cancer Institute Buffalo, New York, USA