Background: Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are common among critically ill patients, leading to increased morbidity and mortality rates. Conventional culture-based diagnostics require 48-72 hours, which delays pathogen identification and prolongs the use of broad-spectrum antibiotics. Multiplex polymerase chain reaction (mPCR) enables the rapid detection of pathogens and resistance genes, but its effects on real-world antibiotic decision-making remain unclear.
Methods: This retrospective study included patients in the intensive care unit who were diagnosed with HAP or VAP at a tertiary medical center between July 2023 and June 2024. All patients underwent both mPCR and respiratory culture. The primary outcome was the time to the first antibiotic modification based on mPCR or respiratory culture. The secondary outcome was the rate of antibiotic de-escalation from carbapenem or teicoplanin/vancomycin based on mPCR findings.
Results: In total, 75 patients were included (median age, 68 years; 61.3% male). mPCR identified bacterial pathogens in 45.3% cases, with a median turnaround time of 281 minutes. The median time to antibiotic modification was 5.8 hours for mPCR versus 122.32 hours for culture (P<0.01). Despite negative mPCR results for gram-negative bacilli, carbapenem therapy was discontinued in only 1 of 24 cases (4.2%). Among 39 patients with negative results for Staphylococcus aureus, vancomycin or teicoplanin was discontinued in only 3 cases (7.7%).
Conclusions: mPCR provided faster pathogen identification and earlier antibiotic modifications than conventional respiratory culture. However, antibiotic discontinuation remained uncommon despite negative mPCR results, highlighting challenges in real-world antimicrobial stewardship.
Keywords: anti-bacterial agents; multiplex polymerase chain reaction; pneumonia.