Résumé
Hospital-acquired pneumonia is common. Improvements of molecular biology techniques such as multiplex polymerase chain reaction (mPCR) have greatly enhanced our ability to detect respiratory viruses that are estimated to count for 22-32% of episodes. Immunocompromised patients are probably the most at risk population. The clinical and radiological presentation does not differ between bacterial, viral and mixed pneumonias (virus-bacteria). Prolonged excretion of respiratory viruses in the airways has been reported in immunocompromised patients. It could promote bacterial co-infection, associated with a prolonged hospital stay. Intra-hospital acquisition has been demonstrated in all respiratory viruses. It encourages the implementation and respect of preventive measures in order to protect healthcare workers, visitors and patients. Many points remain largely unknown, regarding the interactions between respiratory viruses and non-viral pathogens, incubation periods and duration of viral excretion. The improvement of diagnostic techniques and the accumulation of epidemiological and clinical data may allow a better understanding of the role of respiratory viruses in hospital-acquired pneumonia. This improved knowledge will help streamline the use of detection tests and facilitate its interpretation. It will also guide the clinician in the use of the new antiviral molecules that are expected in the upcoming years.