Investigation of Microbial Etiology in Endotracheal Aspirate Samples of Severe Pneumonia Patients by Multiplex PCR and Culture Method

Abstract

Objectives: The probability of detecting viral and atypical agents in pneumonia patients has increased with the molecular methods used in recent years. We aimed to investigate pneumonia pathogens in endotracheal aspiration samples (ETA) of patients with severe community-acquired (CAP), hospital-acquired pneumonia (HAP), and ventilator-associated pneumonia (VAP) by multiplex polymerase chain reaction (m-PCR) and culture method. Methods: A prospective study was performed between December 2019 and October 2020. Patients 18 years and older with pneumonia followed in ICU on the mechanical ventilator were included. COVID-19 patients were excluded. Patients were grouped as CAP, HAP, and VAP. Two ETA samples were obtained from patients within 48 hours of the pneumonia diagnosis. Respiratory pathogens were investigated in samples by viral-bacterial m-PCR and bacterial culture methods. Results: 74 patients were included in the study. m-PCR of ETA samples achieved pathogen detection in 87.8% of patients compared with 58.1% with culture methods. The most common pathogen detected by m-PCR was Streptococcus pneumoniae in both CAP and HAP patients and Klebsiella spp. in VAP patients. The most common pathogen isolated by culture was Staphylococcus aureus in both CAP and HAP patients and Klebsiella spp. in VAP patients. Atypical pneumonia pathogens were positive for 14.9% of the patients. Atypical pathogens were recovered from 28.5% of CAP patients and 23.1% of HAP patients. Viruses constituted all of the atypical pathogens recovered from HAP patients. No atypical pathogen was found in VAP patients. Conclusion: In this study, S. pneumoniae was the most common pathogen detected with m-PCR, and S. aureus and Klebsiella spp. were the most common pathogens detected with culture. Determination of microbial etiology of lower respiratory tract samples by molecular methods for diagnosing severe CAP and HAP may be beneficial in terms of treatment. Keywords: pneumonia, multiplex PCR, endotracheal aspirate, conventional methods