Syndromic multiplex PCR: the impact on microbial yield in non-ventilator hospital-acquired pneumonia

Abstract Background Non-ventilator hospital-acquired pneumonia (NV-HAP) is a leading cause of hospital-acquired infection, associated with substantial morbidity and mortality. Conventional bacterial cultures from lower respiratory tract specimens, as recommended by current guidelines, have limited sensitivity and frequently fail to identify causative pathogens. This study evaluated a rapid, culture-independent molecular diagnostic approach versus standard methods for identifying microbial etiology, assessing antimicrobial prescribing, and determining NV-HAP incidence in a medium-sized Norwegian hospital. We hypothesized that multiplex polymerase chain reaction (mPCR) would shorten time to diagnosis and increase microbial yield. Methods A screening process twice daily was established to prospectively identify NV-HAP patients eligible for inclusion in a single hospital from June 11, 2021, and November 26, 2024. Lower respiratory tract samples were analyzed using a syndromic multiplex PCR assay and compared with conventional culture methods. Results Eighty-six patients were included, with bacterial pathogens detected in 51.2% of the samples analyzed by mPCR and in 23.5% of cultured samples (p<0.01). Median time to microbiological results were 2.5 (2-10) hours for mPCR and 45.8 (26.9-50.3) hours for bacterial culture (p<0.01). Overall agreement was fair to moderate (κ = 0.39), with an observed agreement of 69%. Antibiotic therapy was modified based on the mPCR in 13 patients (15.1%) and due to culture in 9 patients (10.5%). Conclusion The use of syndromic mPCR provided faster results and a higher detection rate for microbial etiology compared to traditional culture methods.