Seda YAYLA, Sami DENİZ, Onur KARAMAN, Görkem VAYISOĞLU ŞAHİN
Eurasian Journal of Pulmonology - 2026;28(2):111-118
BACKGROUND AND AIM: Eosinophilia, defined by an absolute eosinophil count (AEC) >=500 cells/µl, is a common finding associated with various conditions, including mycobacterial infections, and can rarely be induced by standard anti-tuberculosis (TB) drugs such as isoniazid, ethambutol, and rifampin. While in vitro studies suggest that eosinophil products, such as eosinophil peroxidase, possess mycobactericidal activity, the clinical impact of eosinophilia on TB outcomes is unknown. This study aimed to analyze the association between eosinophilia development during treatment and the duration of therapy in a retrospective cohort of patients newly diagnosed with drug-sensitive pulmonary TB. METHODS: This was a retrospective cohort study conducted at a tertiary center. A total of 6,045 patients with drug-sensitive pulmonary TB treated between 2017 and 2022 were screened. Patients were excluded if they had conditions that could confound eosinophilia or treatment duration, including allergic diseases, drug-resistant TB, severe comorbidities, and an AEC >=1500 cells/muL. The final cohort included 121 contemporary non-eosinophilic controls (Group 1) and 119 patients who developed eosinophilia with no identifiable cause (Group 2). RESULTS: The median age was comparable between Group 1 (43 years, range: 18-82) and Group 2 (45 years, range: 18-84; p=0.485). A statistically significant difference was observed in the duration of anti-TB treatment (p=0.013). The median treatment duration for the control group (Group 1) was 7 months (range: 6-9 months), whereas the median duration for the eosinophilia group (Group 2) was 6 months (range: 6-9 months). Logistic regression analysis confirmed that eosinophilia was significantly associated with treatment duration (odds ratio: 2.06, (95% confidence interval: 1.14-3.71; p=0.017). CONCLUSIONS: The development of eosinophilia during treatment for drug-sensitive pulmonary TB was associated with a significantly shorter treatment duration. Conversely, the absence of eosinophilia is an independent risk factor for prolonged therapy. These findings suggest that eosinophils may contribute to a more effective host immune response against Mycobacterium tuberculosis, serving as a potential positive prognostic indicator in clinical practice.
