Gut microbial signatures across nutritional status in Indian school-aged children: a qPCR-based case-control study

Gut dysbiosis is a characteristic feature of malnutrition; however, a standardized microbial index for assessing gut health in community settings is lacking. This study aimed to assess the relative abundance of key bacterial communities in underweight, obese, and normal-weight children and adolescents using quantitative polymerase chain reaction (qPCR).

We conducted a 12-month case-control study (February 2023-February 2024) in Hyderabad, India, involving 70 children aged 8-18 years. Participants were categorized as thin (Body Mass Index-for-age Z-score (BAZ) < -2 SD; n = 23), normal-weight (n = 24), or obese (BAZ > +2 SD; n = 23). Socio-demographic and anthropometric data were collected. Fecal samples were analyzed for relative abundance of target bacteria species using quantitative PCR (Roche Light Cycler 480). Conditional and unconditional logistic regression models were used to assess associations between bacterial abundance and nutritional status.

Obese children had higher odds of Lactobacillus spp. (matched odds ratio [mOR] 12.92, 95% CI 1.48-112.86; p = 0.02) and Faecalibacterium prausnitzii (mOR 5.49, 95% CI 1.06-28.49; p = 0.04) compared with normal-weight children. Bacteroides spp. were more abundant in obese (mOR 11.10, 95% CI 1.15-107.20; p = 0.04) and thin children (mOR 8.10, 95% CI 0.87-75.99; p = 0.07). In contrast, Bifidobacterium spp. showed lower abundance in both obese (mOR 0.006, 95% CI 0.00-0.07) and thin children (mOR 0.54, 95% CI 0.01-0.47) relative to normal-weight peers.

This study identified distinct patterns of gut bacterial dysbiosis, characterized by altered relative abundances of Lactobacillus, Faecalibacterium prausnitzii, Bacteroides, and Bifidobacterium, among children and adolescents across different nutritional statuses. These microbial signatures may serve as potential early indicators of malnutrition-related dysbiosis and warrant further investigation.