Herpes simplex virus--the most frequently isolated pathogen in the lungs of patients with severe respiratory distress.

308 consecutive patients with severe or complicated respiratory tract infections underwent fiber-optic bronchoscopy in the search for a microbiological etiology. Protected brush specimens were used for bacterial cultures and bronchoalveolar lavage (BAL) for virus isolation and cytological examination. Herpes simplex virus (HSV) was the most commonly found pathogen and was isolated in 37 patients. 20 (54%) of them also had serological and/or cytological signs of HSV infection. 132 patients required assisted ventilation (AV) and in this group 34 (92%) of the 37 HSV positive patients were found. Isolation of HSV was significantly (p less than 0.001) associated with AV compared to patients not requiring AV. Of all patients treated with AV 26% had positive HSV isolation in conjunction with suspected acute lower respiratory infection. Coinfection with HSV and bacteria occurred in only 8 (22%) patients. HSV was more common in patients with burns (47%) compared to other patient groups such as patients with AIDS (3%) or other immunodeficiencies (9%).