The Value Of Different Methods To Detect Mycobacterium Tuberculosis In Sputum And Bronchoalveolar Lavage Fluid

Objective:To evaluate the diagnostic value of different specimens and methods for pulmonary tuberculosis,and to provide a theoretical basis for clinical diagnosis.Methods:A total of 13306 patients who were admitted to Tianjin Haihe Hospital from September 2017 to November 2019 and finally diagnosed with tuberculosis were enrolled.Their general informations and the results of smear,MTB culture,Xpert Mtb/RIF,and MTBDRplus were collected to be analyzed retrospectively.Comparing the positive rates of sputum and BALF for each method to evaluate the diagnostic value of BALF.Evaluate the value of BALF in patients with negative sputum smears and negative sputum.Evaluate the diagnostic value of different methods by comparing the positive rates of the various methods and the combined detections in all specimens,which were examined by smear,MTB culture,Xpert Mtb/RIF and MTBDRplus at the same time.Results:1.Comparison of sputum and BALF:The positive rate of sputum smear was9.8%,and the positive rate of BALF was 12.8%.The difference was statistically significant(X~2 30.456,P<0.05);The positive rate of sputum MTB culture was 28.3%,and the positive rate of BALF was 28.9%.There was no significant difference between the two specimens(X~2 0.466,P>0.05);The positive rate of sputum Xpert Mtb/RIF was 18.6%,and the positive rate of BALF was 29.7%.The difference was statistically significant(X~2 102.671,P<0.05);The positive rate of sputum MTBDRplus was 33.5%,and the positive rate of BALF was 38.2%.There was no significant difference between the two specimens(X~2 2.521,P>0.05).2.Among patients with negative sputum smears,the positive rates of BALF smear microscopy,MTB culture,Xpert Mtb/RIF,MTBDRplus,and the four test methods were 7.3%,21.7%,25.3%,24.9%,and 31.5%,respectively.Among sputum-negative patients,the positive rates of BALF smear microscopy,MTB culture,Xpert Mtb/RIF,MTBDRplus,and the four test methods were 3.5%,10.0%,12.9%,8.7%,and 20.9%,respectively.3.In the group of sputum+BALF,the positive rates of Smear microscopy,MTB culture,Xpert Mtb/RIF,MTBDRplus,smear&culture,smear&Xpert,smear&MTBDRplus,culture&Xpert,culture&MTBDRplus,Xpert&MTBDRplus,smear&culture&Xpert,smear&culture&MTBDRplus,smear&Xpert&MTBDRplus,culture&Xpert&MTBDRplus,smear&culture&Xpert&MTBDRplus were 31.20%,45.75%,46.22%,44.83%,47.49%,49.22%,47.89%,54.94%,54.88%,52.57%,55.11%,55.11%,54.13%,58.46%,58.64%,respectively.The positive rates in sputum specimens were 41.24%,55.52%,54.20%,55.34%,57.71%,58.06,58.76%,63.57%,64.80%,61.82%,63.84%,65.15%,63.66%,67.34%,67.60%;The positive rates in BALF were 11.71%,26.83%,30.73%,24.45%,27.67%,32.09%,26.83%,38.20%,35.65%,34.63%,38.20%,35.65%,35.65%,41.26%,41.26%,respectively.4.The positive rates of MTB culture,Xpert Mtb/RIF,and MTBDRplus were significantly higher than those of smear microscopy.However,there were no significant difference between the MTB culture,Xpert Mtb/RIF,and MTBDRplus.In different specimens,not all the differences between the different combined detections are statistically significant.Conclusions:1.BALF can significantly increase the positive rate of smear microscopy and Xpert Mtb/RIF compared with sputum specimens,and it is helpful for the early diagnosis of tuberculosis.However,it cannot significantly increase the positive rate of MTB culture and MTBDRplus;2.Using BALF can significantly increase the detection rate of MTB in sputum smear-negative patients/sputum-negative patients,which is helpful for the diagnosis of these patients.3.When different methods are applied separately,the positive rate of smear microscopy is the lowest,and it is significantly lower than that of MTB culture,Xpert Mtb/RIF,MTBDRplus.While the positive rates of culture and molecular biology examinations are not significantly different.4.Although the combined detections can improve the positive rate,the combined detections of four methods is not better than the combined detections of three methods in terms of cost-effectiveness.5.The smear microscopy&MTB culture&MTBDRplus scheme has the highest diagnostic value in sputum specimens;the smear microscopy&MTB culture&Xpert Mtb/RIF scheme has the highest diagnostic value in BALF.