Current guidelines on the use of antibacterial drugs in patients with malignancies.

Patients with malignant disease may be predisposed to bacterial infections because of neoplastic disruption of normal tissue barriers, exogenous immunosuppressive therapy (drugs with or without radiation), and intrinsic host immune deficits secondary to these diseases. Diminished polymorphonuclear leucocyte numbers or function and impaired humoral immunity are highly correlated with the development of serious bacterial infections. The usual signs and symptoms of infection may be absent or altered in a compromised host. Therapy must be instituted promptly upon clinical suspicion of bacterial infection, and empirical choices should usually include combinations that are synergistic for likely pathogens based on knowledge of the local predominant flora and susceptibility data. Synergism has most often been demonstrated in combinations that utilise a beta-lactam (semisynthetic penicillin or cephalosporin) and an aminoglycoside. Triple drug therapy has not been shown to be advantageous. Monotherapy with third generation cephalosporins, carbapenems, monobactams, or ureidopenicillins has not been proven to offer advantages over 2-drug regimens for these patients. Granulocytopenic patients who respond to 2-drug therapy but remain neutropenic may need continued treatment until the neutropenia subsides. Those who do not respond and remain febrile with an unclear focus may need to be started on antifungal therapy in addition to the antibacterial agent. The use of oral agents for the prophylaxis of neutropenic patients against bacteraemia remains controversial. If drugs are used, co-trimoxazole and nystatin suspension may be preferable.