Bacterial multiplex polymerase chain reaction tests for the diagnosis and management of pneumonia: ready for prime time?

Background: The diagnosis and management of pneumonia is often challenging due to its overlapping clinical presentations with other respiratory illnesses, low pathogen identification rates, and slow turnaround time of conventional bacterial cultures. These factors contribute to both inadequate empiric therapy and overuse of broad-spectrum antibiotics, which can negatively impact outcomes. Recently, multiplex polymerase chain reaction (mPCR) assays capable of rapidly detecting multiple bacterial respiratory pathogens and resistance genes have emerged. However, their clinical utility in pneumonia management remains uncertain.

Objective: To assess the utility of bacterial mPCR assays in pneumonia diagnosis, their impact on antimicrobial usage, and their effect on patient outcomes.

Methods: A comprehensive literature review was conducted using MEDLINE to identify observational studies and randomised controlled trials (RCTs) evaluating the accuracy and clinical impact of bacterial mPCR tests for pneumonia.

Results: Bacterial mPCR assays demonstrate high sensitivity for pathogen detection, rapid turnaround compared to conventional cultures, and the ability to identify many common resistance genes. They may also improve pathogen detection in patients who received empirical antibiotics prior to specimen collection. However, mPCRs do not detect all potential pathogens, cannot reliably differentiate colonisation from infection, and may show discordance between genetic and phenotypic resistance. mPCR panels also generally require lower respiratory tract specimens, limiting their utility since many pneumonia patients cannot produce adequate sputum. Observational studies and RCTs suggest that mPCR may help optimise antibiotic selection, but RCTs have not clearly demonstrated reductions in overall antibiotic use or improved clinical outcomes including mortality. Implementation of mPCR without structured antimicrobial stewardship may limit clinical impact.

Conclusions: Bacterial mPCR assays offer rapid and sensitive pathogen detection, but their integration into pneumonia management requires careful consideration of clinical context and expert antimicrobial stewardship guidance. Future research should focus on optimising their diagnostic and therapeutic applications, evaluating cost-effectiveness, and assessing patient-centered outcomes.