Objective: Severe pneumonia is a common infectious disease with high morbidity and mortality. Early etiological diagnosis is crucial for improving the prognosis. The aim of this study is to evaluate the clinical value of sampling time of mNGS in patients with severe pneumonia.
Methods: This retrospective study enrolled 105 patients with severe pneumonia. mNGS was performed on bronchoalveolar lavage fluid (BALF). Patients were divided into the sampling time ≤ 72h vs sampling time > 72h groups and survivors vs non-survivors groups according to their sampling time and prognosis. Clinical characteristics, the adjustment of antibiotics and clinical prognostic value were evaluated.
Results: Our study showed that, early sampling of mNGS can significantly shorten the mechanical ventilation time (p = 0.007) and hospitalization time (p = 0.004). In the non-survivors group, CURB-65, SOFA, and APACHE II scores were higher. Age (OR: 1.051, 95% CI: 1.004– 1.100, p = 0.034), chronic respiratory diseases (OR: 4.639, 95% CI: 1.260– 17.082, p = 0.021), immunosuppression (OR: 5.008, 95% CI: 1.617– 15.510, p = 0.005) and SOFA score on the day of mNGS sampling (OR: 1.492, 95% CI: 1.212– 1.837, p < 0.001) were independent risk factors of in-hospital mortality. The most common pathogens were Klebsiella pneumoniae and Human gammaherpesvirus 4. The proportion of appropriate and targeted antibiotics adjusted was significantly higher than that in the sampling time > 72h group, and the proportion of antifungal and antiviral agents adjusted was lower. In the early sampling group, it was significantly decreased in the CRP, PCT level and NEU% at discharge.
Conclusion: This study demonstrated that early sampling of mNGS could shorten the time of mechanical ventilation and hospitalization of patients with severe pneumonia. Patients with higher SOFA score on the day of sampling had a poorer prognosis. It emphasizes that early sampling of mNGS has a positive value.
Keywords: metagenomic next generation sequencing, severe pneumonia, sampling time, mortality