Background: Infants, toddlers, and children of primary-school age without any special risk factors generally have three to ten febrile respiratory infections per year. Most such infections are of viral origin and self-limiting, but viral infection is often hard to distinguish from bacterial infection. The use of a multiplex polymerase chain reaction (PCR) to detect viruses in respiratory secretions is potentially beneficial, as it might help physicians avoid giving antibiotics unnecessarily.
Method: This article is based on a selective review of the literature and on the findings of the authors' own investigations.
Results: Multiplex PCR is a highly sensitive, highly specific test for the detection of viral nucleic acids in respiratory secretions. If PCR reveals the presence of RNA derived from respiratory syncytial virus, human metapneumovirus, parainfluenza virus, or influenza virus, then an acute infection caused by the corresponding pathogen is probably present, and further treatment can be given accordingly. On the other hand, the nucleic acids of adeno-, boca-, rhino- or coronaviruses can be found in relatively trivial infections as well as in asymptomatic persons, probably reflecting either a prior infection or a current subclinical one. For children in particular, upper respiratory infections are so common in the winter months that acute and prior infections with these pathogens cannot be distinguished by multiplex PCR. The use of multiplex PCR in children has not been shown to shorten hospital stays or to lessen antibiotic consumption or overall cost.
Conclusion: The detectability of viral nucleic acids is an important contribution to the diagnostic assessment of children with severe respiratory infection. For these highly sensitive diagnostic tests to be used optimally, primary viral infections must be distinguished from bacterial superinfections.