Lower respiratory tract viral infections in hospitalized adult patients.

Aim. The epidemiology of lower respiratory tract (LRT) viral infections in adults is probably underestimated and the high frequency of multiple viral infections complicates the evaluation of the possible role of the single viruses. The aim of this study was to investigate die clinical epidemiology and impact of respiratory viral pathogens, in particular of those singularly detected, in bronchoalveolar lavage (BAL) specimens from hospitalized adult patients. Methods. A panel for the detection of 16 respiratory viruses was used to prospectively evaluate 324 consecutive specimens obtained from 219 patients over a full-year period. Results. Two-hundred-twenty-one specimens (68.2%) were positive for at least one virus, 119/324 (36.7%) to a single viral agent. The most commonly detected viruses were herpesviruses HHV-7 (26.2%), human cytomegalo-virus (HCMV, 22.2%), HHV-6 (19.8%), EBV (12.7%), enteroviruses and rhinoviruses (both 11.7%), parainfluenza viruses (4.9%), and metapneumovirus (4.0%). Human cytomegalo-virus was significantly more prevalent as single viral pathogen with a viral load >10(5) copies/ml associated to pneumonia in solid organ transplant recipients. Other viral pathogens might account for some cases of pneumonia or respiratory insufficiency, although multiple infections were common. Conclusion. The use of a comprehensive diagnostic panel for respiratory viral infections may be useful to clarify the epidemiology and clinical impact of viral pathogens in hospitalized adult patients. The occurrence of multiple infections is a common finding and results should be interpreted taking into account the clinical context as well as viral load and the biological characteristics of each virus.