# Multiplex Polymerase Chain Reaction (PCR) and Conventional Methods for Diagnosing Ventilator-Associated Pneumonia in ICU Settings: A Systematic Review

## TL;DR

This systematic review compares mPCR with conventional methods for diagnosing VAP in ICUs, highlighting mPCR's faster results and high accuracy in ruling out infection.

## Contribution

The study provides a systematic comparison of mPCR and conventional methods for VAP diagnosis, emphasizing mPCR's clinical utility and antimicrobial stewardship benefits.

## Key findings

- mPCR showed high pooled sensitivity and specificity with a near 100% negative predictive value.
- mPCR significantly reduced turnaround time, enabling faster antibiotic adjustments in ICU patients.
- Positive predictive value was variable, highlighting the need for clinical context in interpreting mPCR results.

## Abstract

Ventilator-associated pneumonia (VAP) is a prevalent and serious infection in intensive care units (ICUs), with timely and accurate diagnosis being crucial for patient outcomes. Conventional diagnostic methods, primarily culture-based, are hampered by long turnaround times and limited sensitivity. Multiplex polymerase chain reaction (PCR) (mPCR) offers rapid detection of multiple pathogens and resistance genes, potentially revolutionizing VAP diagnosis and antimicrobial stewardship. This systematic review aims to compare the diagnostic performance and clinical impact of mPCR versus conventional methods for diagnosing VAP in ICU settings. This review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. A comprehensive search of PubMed/MEDLINE, Embase, Web of Science, Scopus, and the Cochrane Library was performed for studies published between 2020 and 2025. Eligible studies compared mPCR with conventional culture in ICU patients with suspected VAP and reported diagnostic accuracy metrics. Study quality was assessed using the QUADAS-2 tool. A qualitative synthesis was performed due to significant heterogeneity among the included studies. Fifteen studies were included. mPCR demonstrated high pooled sensitivity and specificity, with a consistently high negative predictive value (NPV) frequently approaching 100%. This high NPV provides a strong rationale for discontinuing unnecessary antibiotics when results are negative. However, positive predictive value (PPV) was more variable and often lower, reflecting the challenge of differentiating true infection from colonization. The most significant advantage of mPCR was its drastically reduced turnaround time compared to conventional culture. This rapidity facilitated earlier antibiotic modifications, including de-escalation and targeted therapy, as demonstrated in several studies. mPCR represents a significant advancement for the rapid microbiological diagnosis of VAP, offering high NPV and dramatically faster results than conventional culture. These attributes make it a powerful tool for enhancing antimicrobial stewardship in ICUs. However, its optimal use requires integration into clinical practice with careful interpretation of positive results within the context of clinical signs to distinguish infection from colonization. mPCR should be viewed as a complementary diagnostic tool that augments, rather than replaces, conventional microbiology. Limitations include potential omission of relevant studies due to database restrictions, language barriers, and paywalled articles, which may have influenced the comprehensiveness of study retrieval. Future research should focus on measuring its impact on hard clinical outcomes and conducting formal cost-effectiveness analyses.