Value Of T-SPOT.TB For Diagnosing Cutaneous Infections Of Mycobacteria Possessing RD1 And Monitoring Efficacy Of Antibiotic Therapy

Objective:To determine the diagnostic value of interferon-y release assay T-SPOT.TB in cutaneous infections of mycobacteria possessing RD1(Region of Difference 1)and the value in therapeutic evaluation.Methods:Patients suspected cutaneous mycobacterial infections according to clinical manifestations and pathological examination in our hospital during July,2015 to January,2017 were recruited and screened prospectively.Tuberculosis involving other organs,including previous and current infection,was excluded.T-SPOT.TB tests were conducted before antibiotic therapy.The manifestations,laboratory results,diagnoses,treatment,and the therapeutic efficacy of the eligible patients were collected and analyzed.All patients were divided into two groups according to the final diagnosis:the group of cutaneous infections of mycobacteria possessing RD1 and the group of other diseases including cutaneous infections caused by mycobacteria without RD1,fungal infection,and others.T-SPOT.TB were tested again in patients of the former group 3 months after treatment.The potential role of T-SPOT.TB in diagnosing and monitoring therapeutic efficacy of the disease was analyzed.Results:45 eligible patients were enrolled,with 35 cases diagnosed as cutaneous infections of mycobacteria possessing RD1 and 10 cases of other diagnoses.The sensitivity,specificity,positive predictive value,and negative predictive value were 85.7%?90.0%?96.8%.64.3%,respectively.100%of the cutaneous tuberculosis and 70.6%of the cutaneous infections by nontuberculous mycobacteria(NTM)with RD1 had positive T-SPOT.TB results(P=0.013).The median spot forming cells(SFCs)in cutaneous tuberculosis,cutaneous infections by NTM with RD1,and other diagnoses were 26.0,14.0 and 0,respectively(P=0.000).In the group of cutaneous infections of mycobacteria possessing RD1,the positive rate decreased from 88.6%to 46.2%(P=0.000)and the median SFCs decreased from 16.0 to 5.0 after treatment(P=0.000).Conclusions:T-SPOT.TB has favorable functions for diagnosing cutaneous infections of mycobacteria possessing RD1,especially in cutaneous tuberculosis.Combining the manifestations and pathology,T-SPOT.TB may help to diagnosis or exclude the infections.SFCs in T-SPOT.TB correlated well to therapeutic efficacy.Therefore T-SPOT.TB is potential tool for evaluating the therapeutic efficacy in cutaneous infections of mycobacteria possessing RD1.