Objectives: To evaluate burden and predictors of HSV pneumonia among immunocompromised patients not undergoing invasive mechanical ventilation according to a tailored diagnostic algorithm. Methods: This prospective, observational study included immunocompromised adults with pneumonia non-responding to empirical antibiotic therapy. Bronchoalveolar lavage (BAL) specimens were cultured for bacteria, mycobacteria and fungi. Real-time PCR for Herpesviruses and other microorganisms were performed on BAL and other specimens. Cytological examination of BAL samples was carried out for identification of intranuclear inclusion bodies and immunohistochemical staining for HSV. Results: We enrolled 45 patients (mean age 64.6 years) from January 2015 to June 2016. Nineteen (42.2%) cases tested positive for HSV-1 PCR on BAL. According to our definitions, 11 (24.4%) patients had HSV- 1 pneumonia with viral loads ranging between 10 3 copies/mL and 10 7 copies/mL. HSV-1 positive throat swab (OR 85.2, 95% CI 5.83–1245.1, P < 0.001) and solid organ transplant (SOT) (OR 53.3, 95% CI 1.37–2072.8, P < 0.03) as underlying condition were found to be independently associated with HSV pneumonia by multivariable analysis. Conclusions: HSV pneumonia turned out to be relatively common and should be investigated especially in individuals with HSV positive throat swab and SOT. Interventional studies are needed to assess the real clinical impact of HSV pneumonia in immunocompromised patients.
