综合医院GeneXpert MTB/RIF检测支气管肺泡灌洗液极低结核分枝杆菌诊断肺结核的准确性

Diagnostic accuracy of GeneXpert MTB/RIF in detecting pulmonary tuberculosis with extremely low loads of MTB in bronchoalveolar lavage fluid in general hospitals

目的:评价武汉市综合医院行支气管肺泡灌洗液GeneXpert MTB/RIF(简称“BALF-Xpert”)检出极低(Ct值>28)结核分枝杆菌(MTB)诊断肺结核的准确性。方法:采用前瞻性研究方法,参照入组标准顺序纳入2019年1月1日至2022年12月30日武汉市肺科医院呼吸与危重症医学科收治的来自12家综合医院以BALF-Xpert检出MTB极低诊断的肺结核患者为研究对象。统计并分析所有入组患者复查BALF-Xpert、抗酸杆菌涂片镜检、分枝杆菌培养、TB-RNA和TB-DNA的检测结果,并最终经3名以上副主任医师综合进行临床诊断,且随访至少1年,以评估综合医院BALF-Xpert检出极低MTB诊断肺结核的准确性。结果:共纳入67例患者,经BALF-Xpert复查,发现MTB检出率为38.81%(26/67),其中MTB极低、低、中和高拷贝量分别为20例(76.92%)、5例(19.23%)、1例(3.85%)和0例。而且,BALF-Xpert检测阳性率分别高于涂片[4.48%(3/67)]和TB-RNA[17.91%(12/67)],差异均有统计学意义(χ^(2)=23.280,P=0.001;χ^(2)=7.200,P=0.007);但与培养[29.85%(20/67)]和TB-DNA[25.37%(17/67)]检测阳性率差异均无统计学意义(χ^(2)=1.192,P=0.275;χ^(2)=2.774,P=0.096)。联合5种检测方法的总阳性率为40.30%(27/67)。最终诊断为肺结核43例,非肺结核24例,误诊率高达35.82%。结论:以BALF-Xpert检出极低MTB诊断肺结核存在较高假阳性率,需结合患者临床表现、影像学表现、结核感染免疫学结果进行综合诊断,必要时需复查。

Objective:To evaluate the accuracy of diagnosing pulmonary tuberculosis(PTB)with extremely low loads of Mycobacterium tuberculosis(MTB)(Ct value>28)in bronchoalveolar lavage fluid by GeneXpert MTB/RIF(BALF-Xpert)in Wuhan general hospitals.Methods:A prospective study was conducted on PTB patients admitted to the Department of Respiratory and Critical Care Medicine of Wuhan Pulmonary Hospital from January 1,2019 to December 30,2022,who were referred from 12 general hospitals with extremely low loads of MTB detected by BALF-Xpert.The results of retesting BALF-Xpert,acid-fast bacilli smear microscopy,mycobacterial culture,TB-RNA,and TB-DNA were analyzed.All patients were clinically diagnosed by 3 or more associate professors and followed up for at least 1 year to evaluate the accuracy of BALF-Xpert in detecting MTB with extremely low loads in general hospitals.Results:A total of 67 patients were included.After retesting with BALF-Xpert,38.81%(26/67)were detected as MTB positive,including 20 cases(76.92%)with extremely low loads,5 cases(19.23%)with low loads,1 case(3.85%)with medium loads,and 0 case with high loads of MTB.The positive rate of BALF-Xpert was higher than that of smear microscopy(4.48%(3/67))and TB-RNA(17.91%(12/67)),with statistically significant difference(χ^(2)=23.280,P=0.001;χ^(2)=7.200,P=0.007).There was no significant difference between BALF-Xpert and culture(29.85%(20/67))and TB-DNA(25.37%(17/67))(χ^(2)=1.192,P=0.275;χ^(2)=2.774,P=0.096).The total positive rate of combining 5 diagnostic methods was 40.30%(27/67).Forty-three patients were finally diagnosed with tuberculosis and 24 patients were diagnosed as non-tuberculosis disease,with a misdiagnosis rate of 35.82%.Conclusion:BALF-Xpert has a high false positive rate for detection of PTB cases with extremely low loads MTB.A comprehensive diagnosis should be made based on the patient’s clinical manifestations,imaging findings,and immunological results for MTB infection and re-examination is recommended,if necessary.