Pathogens and clinical characteristics of T2DM in patients with CAP via bronchoalveolar lavage fluid (BALF) mNGS: a comparative observational study

Background: Metagenomic next-generation sequencing (mNGS) offers high sensitivity and specificity for pathogen detection. Type 2 diabetes mellitus (T2DM) is a key risk factor for opportunistic infections, including community-acquired pneumonia (CAP). Targeted treatment of the pathogen is beneficial to the prognosis of patients with CAP. This study aimed to explore the pathogen distribution and clinical presentation of CAP in patients with T2DM via bronchoalveolar lavage fluid (BALF) mNGS.

Methods: In this comparative observational study, a total of 285 patients with CAP were enrolled. Ultimately, 117 CAP patients without T2DM and 96 CAP patients with T2DM were included. Demographics, clinical data, laboratory data, and BALF mNGS results were collected. Least absolute shrinkage and selection operator (LASSO) regression was performed to determine potential variables, which were subsequently included in a binary logistic regression model to identify clinical and microbiological features associated with pre-existing T2DM in CAP patients.

Results: Thirteen potential T2DM-associated variables were selected by LASSO regression. Furthermore, binary logistic model identified that higher body mass index (BMI) (OR=1.107, 95% CI: 1.004-1.221), lower rate of connective tissue disease (CTD) (OR=0.046, 95% CI: 0.002-0.935), elevated blood urea nitrogen (BUN) (OR=1.091, 95% CI: 1.003-1.187), the presence of COVID-19 (OR=6.582, 95% CI: 1.244-34.829) and Aspergillus (OR=2.909, 95% CI: 1.018-8.311) were independent variables for T2DM in CAP patients.

Conclusions: Collectively, our analysis revealed that CAP patients with T2DM had a distinct clinical profile and pathogen spectrum, characterized by a higher prevalence of COVID-19 and Aspergillus infection, a greater tendency for renal dysfunction, and a higher BMI but a lower rate of CTD. These findings underscore T2DM as a significant risk factor for COVID-19 and Aspergillus pneumonia. In clinical practice, stricter infection screening strategies should be implemented for this population, along with targeted anti-infective therapy and enhanced dynamic assessment of renal function, weight management, and blood glucose control, will help improve outcomes.

Keywords Community-acquired pneumonia (CAP); Type 2 diabetes mellitus (T2DM); Metagenomic next-generation sequencing (mNGS); Pathogen; Risk factor