Oral acyclovir as prophylaxis for bacterial infections during induction therapy for acute leukaemia in adults. The Leukemia Group of Middle Sweden.

We prospectively tested the hypothesis that prevention of herpes simplex virus infection with acyclovir might also reduce the incidence of bacterial infections in adult patients with acute leukaemia. During the first induction therapy a double-blind, randomized and placebo-controlled study was undertaken. Fifty-two patients were treated with 200 mg acyclovir orally four times daily throughout the induction period, whereas 55 patients received placebo. The groups were comparable with regard to age, cytotoxic chemotherapy and duration of neutropenia. Bacteraemias were significantly fewer in the acyclovir group (20 versus 41 episodes; P = 0.007). The number of isolated microorganisms causing bacterial or fungal infections was also lower during acyclovir prophylaxis (52 isolates, versus 93 isolates; P = 0.02). There was no significant difference between the groups with regard to the number of clinically documented infections or fevers of unknown origin. Herpes simplex virus isolations occurred only in the placebo group (P = 0.001). Thus, oral acyclovir prophylaxis was associated with reductions of all microbiologically documented infections suggesting that prevention of herpes simplex virus reactivation in acute leukaemia patients may reduce the occurrence of other infections.