Dissecting the effect of single- and co-infection of TB and COVID-19 pathogens on the sputum microbiomeOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study asked how COVID-19 co-infection changes the sputum microbiome of tuberculosis (TB) patients. It is described as the first metagenomic analysis of TB and COVID-19 co-infection. Researchers sequenced the 16S rRNA V3-V4 region of sputum and ran whole-genome sequencing on a subset of TB-positive samples. They compared microbial composition, diversity, differential abundance, and PICRUSt2-inferred pathways across four groups.
Who was studied?
Participants were sputum donors in India across four groups: TB only, COVID-19 only, TB plus COVID-19 (TBCOVID), and uninfected controls. From 1,132 screened samples, the team selected 24 each for TB, TBCOVID, and control, plus 10 COVID-only. With technical replicates, 82 samples underwent metagenomic sequencing. TB and TBCOVID patients were matched by propensity scoring on 21 covariates. Most were male (85 percent), newly diagnosed, and HIV-negative. Whole-genome data came from 20 TB isolates (9 TB, 11 TBCOVID).
What were the most important findings?
Mycobacterium tuberculosis reads appeared in 66 percent of TB and 79 percent of TBCOVID samples, and were absent in COVID and control groups. Microbial composition differed at the species level for TB versus TBCOVID (PERMANOVA p equal to 0.006). Several inflammation-linked and opportunistic species were enriched in TBCOVID compared with TB alone, while seven genera were depleted. PICRUSt2 flagged 30 upregulated pathways in TBCOVID, including pulmonary surfactant lipid metabolism (fold change 7.46). Whole-genome sequencing showed no genetic difference between TB and TBCOVID isolates, which were mostly lineage 1.
What are the greatest implications of this study?
The results suggest COVID-19 co-infection accelerates airway dysbiosis in TB by favoring pathogenic and inflammatory bacteria. This could help explain worse lung outcomes in co-infected patients. Detecting concomitant respiratory pathogens in sputum may allow more personalized antibiotic choices for high-risk TB patients. The authors stress the cohort was small and single-region, so associations need validation in larger, longitudinal, multi-center studies before guiding treatment.