ICU · Infectious Diseases

Acute severe community-acquired pneumonia: respiratory virus panel

Also known as Viral pneumonia · Respiratory virus PCR · Influenza, RSV, COVID-19 · Viral-bacterial co-infection · Multiplex respiratory virus panel · FilmArray / BioFire respiratory panel · Syndromic respiratory PCR

Respiratory viruses are increasingly recognised as a cause — or co-pathogen — in severe community-acquired pneumonia (15-30% of cases). The common ICU viruses are influenza A/B, RSV, SARS-CoV-2 (COVID-19), adenovirus, rhinovirus, parainfluenza, human metapneumovirus (hMPV), coronavirus, enterovirus and bocavirus. Diagnosis rests on the multiplex respiratory virus PCR panel performed on a nasopharyngeal swab / BAL, which detects many viruses simultaneously and returns a result within ~1 hour (syndromic testing). Clinical utility spans aetiological diagnosis, infection-control / isolation decisions, antiviral therapy selection (oseltamivir for influenza, remdesivir for COVID-19, ribavirin for RSV in the immunocompromised) and antibiotic stewardship (a confident viral diagnosis may permit earlier antibiotic de-escalation). Critical limitations: detecting viral nucleic acid does NOT prove the virus is causing the pneumonia — asymptomatic shedding, prolonged shedding post-infection and bacterial co-infection (30-50%) are all common, so antibiotics must always be covered empirically until bacterial infection is excluded. Procalcitonin is a useful bacterial biomarker adjunct (low in pure viral disease). The immunocompromised require more aggressive and broader viral testing (CMV, HSV).