Bacterial Causes of Tonsillitis among Adults and Their Relationship with Oxidative Stress Markers

Background: Tonsillitis in adults is often caused by Streptococcus pyogenes, and is accompanied by oxidative stress, which affects inflammation and the development of the disease. Aims of the study: This research proposes to determine the bacteria responsible for adult tonsillitis and to assess their association with oxidative stress markers to understand their impact on disease pathogenicity and disease course. Methodology: In this case-control study, 150 patients (100 cases and 50 controls) were enrolled at University of Babylon faculty of dentistry between August 10, 2025 and April 20, 2026. Participants were diagnosed with symptoms and throat culture. Participants were adults (≥18 years) without chronic illness, prior antibiotic use, or pregnancy. Blood (5 ml) was taken, centrifuged and frozen at -20°C. Oxidative stress markers were measured by ELISA (BioTechne, USA). Data were analyzed via SPSS version 26, p < 0.05 was used as cut off value. Result: Age (p = 0.38), sex (p = 0.82) and smoking (p = 0.36) were not significantly different, but recurrent tonsillitis was significantly increased in patients (p = 0.001). Significant symptoms were found (p < 0.001). The most prevalent bacteria was Streptococcus pyogenes. Oxidative stress parameters were elevated MDA and low antioxidants (p < 0.001). There were significant differences among bacteria (p = 0.041-0.048) and varying antibiotic sensitivities. MDA was positively correlated and antioxidants negatively (p < 0.001). Conclusions: Oxidative stress, with elevated MDA and decreased antioxidant status is seen in bacterial tonsillitis, probably caused by excessive production of reactive oxygen species in response to infection. Streptococci induce more inflammation, leading to more oxidative stress and severity of disease.