Severe bacterial infection in thalassemia patients: prevalence, predisposing factors, causative organisms and outcomes

Abstract

Introduction: Thalassemia is one of the most common genetic blood disorders globally. Bacterial infections remain a major cause of death among affected patients. To determine prevalence, predisposing factors, causative organism, and outcomes of severe bacterial infection in thalassemia patients. Methods: This retrospective study analyzed data from the Thalassemia Registry of the Division of Hematology, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University (September 2013–September 2023). Thalassemia patients aged >15 years were included. Risk factors for severe bacterial infection were identified using multivariate logistic regression. Severe bacterial infection was defined as community-acquired involving a major organ, requiring parenteral antibiotics and/or surgery, and associated with a National Early Warning Score (NEWS) > 4. Results: A total of 208 patients were enrolled (mean age 45.3 ± 16.0 years; 62.0% female; 56.7% transfusion-dependent; 36.1% splenectomy). Severe bacterial infection occurred in 43 patients (20.7%). Primary bacteremia was the most common (23.2%), with Klebsiella pneumoniae (20.9%) and Escherichia coli (13.9%) as the leading pathogens. Infection-related mortality rate was 9.3%. Significant risk factors included hematocrit <21% (OR = 3.15; 95% CI 1.32–7.50; p = 0.01), splenectomy >10 years (OR = 2.46; 95% CI 1.07–5.69; p = 0.035), diabetes mellitus (OR = 10.42; 95% CI 2.21–49.12; p = 0.03), and liver hemochromatosis (OR = 3.76; 95% CI 1.64–8.63; p = 0.002). Conclusion: Severe bacterial infections affected 20.7% of thalassemia patients in this cohort, mainly bacteremia due to Klebsiella pneumoniae and Escherichia coli. Major risk factors were severe anemia, prolonged splenectomy, diabetes mellitus, and iron overload with liver hemochromatosis.