Nucleic acid testing for viral pathogens in community-acquired pneumonia

 

The American thoracic Society has published a guideline for this in the American Journal of Respiratory and Critical Care Medicine. These are soft recommendations based on low-level evidence.

The guideline does not address influenza or covid.  For influenza, the IDSA community-acquired pneumonia guidelines recommend influenza PCR testing during flu season (in preference to antigen testing ). The  guidelines did not address covid-19 as there was insufficient data at the time of the literature review.

The guideline calls for viral PCR panel testing in the following groups of patients: those with neutropenia, those undergoing active cancer therapy, those with a transplant history, those with advanced HIV,  those with a history of chronic immunosuppression including systemic corticosteroids, and those whose community-acquired pneumonia is classified as severe.

Criteria for severity overlap with some of those just mentioned and include the presence of septic shock or need for mechanical ventilation. Absent these two conditions three of the following minor criteria denote severity: impaired respiratory physiology in the form of either a respiratory rate greater than 30 or a PO2 to Fio2 ratio below 250, multilobar infiltrates, altered mental status, BUN greater than 20, white blood cell count less than 4,000, platelet count less than 100,000,  hypothermia less than 36.8 centigrade or hypotension requiring aggressive fluid resuscitation.