Herpes simplex and intensive care medicine: an underestimated problem?

Herpes Simplex Virus (HSV) infection may cause different disorders in patients hospitalised in intensive care. Bronchoalveolar lavage (BAL is a procedure performed almost as a routine in patients with unexplained respiratory insufficiency in our department. During the last 10 years, HSV has been isolated frequently from the respiratory tract at our 30 beds intensive care unit. The objectives of this retrospective study were to define risk factors of the population in whom HSV virus was isolated.

The study concerned patients with an isolation of HSV from either bronchial aspiration (BA) or BAL in the past 5 years (1992–1997). HSV was isolated by culture on shell vials and identified by immunofluorescence after staining with monoclonal antibodies or by the conventional culture and cytopathogenic effect on Vero-cells. From the 64 cases observed, 47 HSV isolations originated from BA, 13 from BAL (of which 9 with simultaneously negative BA) and 4 from both BA and BAL. The mean age of the patients was 62 years (range from 16 to 82). Only 50% of the patients had fever at the time of the investigation. The majority of the patients (94.9%) was intubated before the isolation. The role of immunosuppression, previously recognized as a risk factor for herpes infection, was not confirmed in this study: only 20.4% had received cither corticosteroids or immunosuppressive agents. Striking is that 73.4% had undergone a surgical procedure before the isolation, mainly coronary bypass grafting or other thoracic operations. Daily chest X-rays from 2 days before till 2 days after virus isolation were reviewed blindly by the same radiologist. There was no pathognomonic image at the chest X-ray: a localized infiltrate resembling pneumonia, diffuse alveolar infiltrates or an interstitial pattern were observed and 14% of the chest X-rays were even defined as normal. Lung injury was severe: almost 60% had a PaO₂/FiO₂ less than 200. 28 patients received aciclovir therapy once herpes was isolated, without an effect on the outcome: 48.4% of all patients and 42.8% of those receiving aciclovir therapy (28) died.

Isolation of HSV in respiratory samples from critically ill patientsis therefore more frequent than previously known. Whether these isolates contribute to illness and its evolution remains to be determined.