Investigating Two-stage Tuberculin Skin Test for Screening Latent Tuberculosis Infections in Diabetic Patients: A Regional Study in Khorramabad, Iran

Introduction: latent tuberculosis infections (LTBI) are not detectable by a single-stage tuberculin test and maybe detected after repeating tests ۷-۲۱ days later. This phenomenon, called the boosting phenomenon, supports a two-stage test to identify false negatives in a single-stage test. The present study investigates the value of a two-stage tuberculin test in diabetic patients. Methods: We performed a tuberculin test for ۱۹۵ diabetic patients. The patients with induration > ۱۰ mm were subjected to a second tuberculin test ۷-۲۱ days later. Results: Of ۱۹۵ patients, ۱۱۵ came for measuring the tuberculin test induration, which was positive in ۳ out of ۱۱۵ patients (۲.۶۱%). Of the remaining ۱۱۲ patients, ۵۳ patients were subjected to the second test, and ۳۸ patients came back for measuring the induration, which became positive in ۴ (۱۰.۵۲%) patients. Conclusion: The increased LTBI rate from ۲.۶۱% to ۱۰.۵۲% following the second tuberculin test indicates a boosting phenomenon due to a delayed hypersensitivity reaction. Hence, patients with latent tuberculosis who had a false negative test in the first stage were identified.

کلیدواژه ها:

Tuberculosis ، Latent tuberculosis ، Type ۲ diabetes mellitus ، Two-stage tuberculin test ، Boosting phenomenon