Nosocomial viral pneumonia in the intensive care unit.

The role viruses play in nosocomial ICU pneumonias is not well documented except for outbreaks of influenza and respiratory syncytial virus (RSV) infections. Clinically, viral pneumonias are difficult to differentiate from bacterial pneumonias, and most routine diagnostic tests are able to diagnose viral pathogens. Therefore, the incidence of viral pneumonias is almost certainly underestimated. The likelihood of a viral pneumonia is increased if the patient is not responding to antimicrobial agents, if pneumonia occurs during the winter months, or if there is evidence of viral outbreaks in the hospital or community. In the past few years, new diagnostic tests and a number of effective antiviral agents have been introduced; this makes the rapid diagnosis and treatment of viral pneumonia possible.