Diabetes-associated Parvimonas enrichment and altered lung microbiota profiles in lower respiratory tract infection: an analysis of 632 metagenomes.

The homeostasis of pulmonary microbiota is crucial in maintaining human health and modulating disease progression. The stability of pulmonary microbial flora may be associated with diabetes, yet the specific alterations remain poorly characterized. This retrospective observational study aims to analyze the profiles in pulmonary microbiota between individuals with and without diabetes, using metagenomic next-generation sequencing (mNGS). A total of 632 patients were sequentially enrolled, including 77 patients with both pneumonia and diabetes, 46 patients without either pneumonia or diabetes, 499 patients with pneumonia but without diabetes, and 10 diabetic patients without pneumonia. Pathogens in bronchoalveolar lavage fluid (BALF) specimens were detected using mNGS (DNA). The lung microbiota of diabetic individuals significantly differs from that of non-diabetic individuals in the non-lower respiratory tract infection (non-LRTI) cohort. Parvimonas was more abundant in the diabetic group. Compared to non-diabetic patients with LRTI, those with diabetes and LRTI showed an increased relative abundance of Parvimonas, but decreased relative abundances of Prevotella and Malassezia. Our analysis revealed a negative correlation between Parvimonas and Malassezia, alongside a positive association of Parvimonas with the expression of antimicrobial resistance genes ICR-Mc and RbpA. This suggests a potential association between Parvimonas enrichment and microbial dysbiosis during infection, although the underlying host-microbe interactions require further validation. Interestingly, Parvimonas abundance showed no significant association with HbA1c levels. Our findings suggest that Parvimonas enrichment is associated with diabetes-related alterations in lower respiratory tract microbiota. Whether microbiota-associated alterations represent clinically actionable targets in diabetic patients with pulmonary infections remains to be determined in prospective and interventional studies.IMPORTANCEThis study reveals significant differences in lung microbiota between diabetic and non-diabetic individuals. Parvimonas was enriched in the diabetic lung, and its abundance correlated with the expression of antimicrobial resistance genes, such as ICR-Mc and RbpA. Surprisingly, microbial dysbiosis was independent of HbA1c levels, indicating that mechanisms other than glycemic control contribute to infection progression. This study suggests that Parvimonas enrichment may be a diabetes-associated microbial feature in bronchoalveolar lavage fluid (BALF) microbiota, but its potential diagnostic or clinical relevance requires validation in future studies. Our work provides a scientific foundation for optimizing infection prevention and advancing precision anti-Parvimonas therapies.