Investigation of the prevalence of latent tuberculosis infection in different immunosuppressed patient groups during the COVİD-19 pandemic process

Latent Tuberculosis Infection (LTBI) is a form of TB infection caused by dormant bacilli in the host system, which do not have symptoms of active Tuberculosis (TB) disease and do not show any radiological findings. In case of immunosuppression by underlying diseases and immunosuppressive treatments in individuals, there is a risk of reactivation in terms of LTBI. For this reason, it is important to accurately detect LTBI. The diagnostic performance of QuantiFERON-TB Gold Plus (QFT- Gold Plus), one of the tests used in the diagnosis of LTBI, can be affected by any immunosuppressive condition. The aim of our study is to investigate the presence of LTBI under these immunosuppressive conditions and to evaluate possible risk factors in individuals with underlying comorbidities (COVID-19, HIV, diabetes, autoimmune diseases, etc.) and who have been treated with immunosuppressants such as steroids. In this study, which included the samples of 280 patients who applied to Mersin University Medical Faculty Research and Application Hospital between April 2021 and April 2023; In this study, it was aimed to investigate the prevalence of LTBI according to the QFT TB Gold Plus test results in patients with many comorbidities or receiving treatment with immunosuppressive agents. According to these results, we found that the prevalence of LTBI is higher in the patient population who have had COVID-19 (p=0.022). In addition, in the study group with inflammatory autoimmune diseases, although we observed that LTBI results were negative due to the decrease in IFN-Y production as a result of weakened immunity, there was no significant result. No statistical significance was found between other underlying comorbidities and QFT results. In addition, no significant results were found regarding the prevalence of LTBI in individuals receiving treatment with agents such as steroids with immunosuppressive properties (p=0,950). Contrary to expectations, we think that these results we obtained are due to limitations such as insufficient patient population of the study and limited patient data. In addition, in the analyzes we conducted to determine the diagnostic role of biomarkers, our results were not found to be significant due to the fact that the included biochemical tests were not studied in the entire patient population. These findings provide us with different results, as there has not been a similar study conducted in our country on the investigation of LTBI by including many different parameters. However, the results of these studies show that there is a need for studies involving large-scale patient and control groups.