Purpose Hashimoto thyroiditis (HT) is one of the most prevalent autoimmune thyroid diseases. Many autoimmune disorders are influenced by gut bacteria. The pathogenic link between dysbiosis and autoimmune thyroid disease is controversial. The current study was conducted to evaluate changes in the microbial inhabitants between HT and healthy individuals to understand the role of gut microbiota in HT. Patients and methods We conducted a case-control study recruiting 20 HT patients and 30 controls. Thyroid hormones and antibodies were measured. Fecal samples were collected to analyze the gut microbiome by real-time PCR of the 16SrRNA gene of selected bacterial species. Results The study showed that the diversity index in HT (1.58 ± 0.15) was not significantly different from controls (1.66 ± 0.17) (P: 0.096), and dysbiosis biomarkers F/B (1 vs. 1.1) and P/B (0.92 vs. 0.4) ratios of gut microbiota were similar in HT and controls. We found that Lactobacilli, L. reuteri, and Bacteroides fragilis were decreased in HT (P: 0.013 and < 0.001, respectively), and microbiota Prevotella copri was significantly increased in comparison to controls (P: 0.004). There was a positive correlation between P. copri and disease duration (rs: 0.576, P = 0.008). Conclusion This study indicates an association between HT and alteration of gut microbiota composition at the species levels but there was no dysbiosis at the phylum level. The link of the gut microbiota to HT remains poorly explored with conflicting results. This highlights the need for further research to examine gut microbiota as a potential trigger for thyroid autoimmunity.
El-Aghoury et al. (Tue,) studied this question.