Prevention of lower respiratory herpes simplex virus infection with acyclovir in patients with the adult respiratory distress syndrome.

Herpes simplex virus (HSV) type I commonly occurs in the lower respiratory tract (LRT) of seriously ill patients, particularly those with the adult respiratory distress syndrome (ARDS), but it is not known whether HSV is a benign mucosal colonizer or a pathogen. The aims of this study were to determine whether the antiviral agent acyclovir could prevent this occurrence, and if so, whether prevention improved the outcome. Forty-five patients with ARDS underwent double-blind randomization into a treatment group (22 subjects) who received prophylactic acyclovir intravenously, 5 mg/kg every 8 h, and a control group (23 subjects). Upper and lower respiratory secretions were examined for the presence of HSV before randomization and twice weekly thereafter. Seven patients were excluded because of HSV detection prior to treatment. There were no significant differences between the remaining 17 acyclovir and 21 control patients in age, sex, distribution of primary diagnostic categories, and severity of primary illness. Only 1 patient (6%) in the acyclovir group developed HSV after treatment compared with 15 (71%) in the control group (p less than 0.001), but there was no improvement in the acyclovir group in the severity of respiratory failure, the duration of ventilator support (acyclovir, 20 +/- 19 days; control, 14 +/- 11 days), or mortality (acyclovir, 8 of 17, 47%; control, 9 of 21, 43%). We conclude that acyclovir is effective in preventing the high incidence of HSV in patients with ARDS, but that this prevention does not improve outcome. Routine prophylaxis of HSV is not recommended.