Infections in cancer patients: some controversial issues.

Despite more than two decades of clinical research into the management of infections in the neutropenic cancer patient, many patients still develop serious morbidity from infection and all too many still die. A number of controversies surround (a) the use of combination versus monotherapy for initial empiric administration; (b) the use of vancomycin as part of the initial regimen; (c) the origin of Staphylococcus epidermidis infections (i.e., mostly from vascular catheters or mostly from the alimentary canal); (d) the use of acyclovir for herpes simplex prophylaxis during remission induction for acute leukemia patients not undergoing bone marrow transplantation; (e) the use of alimentary canal microbial suppression or reverse isolation in a room with laminar air flow, or both, as infection prevention techniques. Current recommendations and observations include the following. (a) Monotherapy with ceftazidime or imipenem is effective and appropriate for patients with moderate granulocytopenia at limited risk for infection with a resistant organism. Combination therapy is recommended for patients with profound, persistent granulocytopenia who are at high risk for gram-negative bacteremia; such bacteremic patients have a better prognosis with combined-modality therapy. (b) Vancomycin need not be included in the initial regimen although some centers may choose to do so because of the high prevalence of gram-positive bacteremias. (c) Despite the ubiquitous presence of indwelling vascular catheters, most S. epidermidis infections among neutropenic patients originate from along the alimentary canal. (d) Herpes simplex infection is much more common following standard remission induction chemotherapy than previously recognized. Acyclovir will reduce these infections and concurrently probably reduce the likelihood of resultant bacterial/fungal co-infections and superinfections. (e) Selective microbial suppression is appropriate for patients expected to experience prolonged (more than 2 weeks) or profound (below 100 granulocytes/microliters) granulocytopenia. Agents chosen should suppress aerobic but not anaerobic flora (maintain colonization resistance) and need to have an effect on both the oral cavity and esophagus as well as the intestines.