Herpes simplex virus infection of respiratory tract in intensive care unit

Abstract

Background Herpes Simplex virus (HSV) is commonly isolated from the specimen of respiratory tract in hospitalized patients. It can indicate asymptomatic shedding from respiratory epithelium, viral reactivation with macroscopic airway lesion, or even pneumonia. There are significant differences in the awareness, interpretation and management strategies of the condition among departments and hospitals. Objective A retrospective case review of clinical features, management and outcomes of hospitalized subjects from whom HSV is detected in the bronchoalveolar lavage specimen Method The medical records of all the patients with pneumonia and bronchoalveolar lavage (BAL) being positive for HSV culture, who were admitted between 2004 and 2011 to Queen Mary Hospital, were retrieved from the clinical management system or record folders. Their demographic data, laboratory results, progress and outcomes were recorded. Results A total of 32 patients were identified over the period of seven years. 81.3% of them were emergency admission while 18.8% were elective admission. Most of them (90.6%) required admission to the Adult Intensive Care Unit. 59.3% (n=19) required intubation and mechanical ventilation during hospitalization. The mean age was 57.1 (SD 13.8) year old. 71.9% were male patients. No patients with HSV detected in BAL had macroscopic lesion on bronchoscopy. No cytological examination on the BAL was performed. HSV reactivation is commonly associated other opportunistic pathogens such as Pneumocystis jivoreci (21.9%) and cytomegalovirus antigenemia (18.8%). Majority of the subjects (90.6%, n=29) with HSV infection were lymphopenic (absolute lymphocyte count <1 x 109/L) which could indicate underlying impairment in cell-mediated immunity related to malnutrition, hematological disorders, use of immunosuppressants. Similar proportion in the surviving group received anti-viral treatment as compared to the mortality group (53.8% versus 66.7%, respectively), implicating that treatment with anti-viral medication might not have important impact on mortality rate. Conclusion The awareness of significance of HSV reactivation in lower respiratory tract is highly variable. Lymphopenic patients are at high risk of HSV reactivation or HSV pnemonitis. The presence of lymphopenia, or other immunocompromised state should prompt the physicians to perform a thorough work-up for HSV infection even in the absence of macroscopic lesions.