The Application And Evaluation Of The Microscopic Observation Drug Susceptibility Assay For Rapid Diagnosis Of Tuberculosis

Objective:1.This research is to understand the diagnostic value of microscopic observation drug-susceptibility assay(MODS) for intrapulmonary tuberculosis mainly through the comparison microscopic observation drug-susceptibility assay 、 smear acid fast method with Lowenstein-Jensen culture method detecting Mycobacterium tuberculosis from sputum specimens.2.This research is to investigate the diagnostic value of microscopic observation drug-susceptibility assay(MODS) for extrapulmonary tuberculosis mainly through the comparison microscopic observation drug-susceptibility assay、Ziehl-Neelsen smear method with Lowenstein-Jensen culture method detecting Mycobacterium tuberculosis from pleural fluid and cerebrospinal samples.Methods:1.Pulmonary tuberculosis group:MODS technology was constructed by using24-well culture plate and liquid culture.A total of 264 consecutive sputum samples collected from 264 individuals suspected of TB were tested by Ziehl-Neelsen smear,Lowenstein-Jensen culture and MODS assay after the initial sample submission. The immunochromatography was used to distinguish Mycobacterium tuberculosis from nontuberculosis mycobacteria.Using MODS assay for detecting Mtb underwent a90-day follow-up.According to the results of follow-up,the finally diagnosis could be done by specialists.The result of microscopic observation drug-susceptibility assay were compared with that of conventional microbiology diagnosis methods against the clinical gold standard.Comparing and analyzing the detection performance of the three methods is to evaluate the value of MODS technique in the diagnosis oftuberculosis.2.Extrapulmonary tuberculosis group:MODS assay was constructed by using24-well culture plate and liquid culture.A total of 173 samples were collected from173 individuals of extrapulmonary TB including 112 pleural fluid samples collected from patients with tuberculous pleurisy,61 cerebrospinal fluid samples collected from patients with tuberculous meninggitis,In addition,18 samples were collected from non-tuberculosis suspects.According to the results of follow-up,the finally diagnosis could be done by specialists.The result of microscopic observation drug-susceptibility assay(MODS) were compared with that of conventional microbiology diagnosis methods against the clinical gold standard.All of them were detected by Ziehl-Neelsen smear, Lowenstein-Jensen culture and MODS assay.The immunochromatography was used to distinguish Mycobacterium tuberculosis from nontuberculosis mycobacteria.Using MODS assay for detecting Mtb underwent a90-day follow-up.According to the results of follow-up,the finally diagnosis could be done by specialists.The results of MODS,Ziehl-Neelsen smear and Lowenstein-Jensen culture were compared by chi-square test.Comparing and analyzing the detection performance of the three methods is to evaluate the value of MODS technique in the diagnosis of extrapulmonary tuberculosis.Results:1.Pulmonary tuberculosis group:Twenty sputum samples which collected from non-TB suspects were confirmed to have no Mtb by ZN smear,L-J culture and MODS assay.Of the 264 sputum samples collected from TB suspects,the detection rates of were 28.8%,36.0% and 42.8%,respectively ZN smear,L-J and MODS culture.Of the total of 102 smear or L-J culture positive sputum samples.MODS assay detected97(95.1%).Of 162 ZN smear and L-J smear and L-J culture negative sputum samples,MODS detected 16 positive results.When clinic diagnosis was considered as gold standard,the sensitivity of microscopic observation drug-susceptibility assay(MODS),L-J method and ZN smear against clinical diagnosis as the gold standard were 63.4% and 97.8%,54.3% and 100%,43.4% and 100%,respectively.The sensitivity of detection for MODS assay was significantly higher than for L-J culture or ZN smear(P<0.01).The median time of detection for MODS and L-J culture was10 days and 25 days,respectively(P<0.01).2.Extrapulmonary tuberculosis group:The results of Ziehl-Neelsen smear,Lowenstein-Jensen culture and MODS assay were 1.3%(1/78),6.4%(5/78)and20.5%(16/78),respectively in tuberculous pleurisy patients;3.1%(1/32, 18.8%(6/32)and 37.5%(12/32),respectively in tuberculous meninggitis patients.The positive rate of MODS assay was significantly higher than that of Lowenstein-Jensen culture in tuberculous pleurisy patients(P<0.01) and tuberculous meninggitis tuberculous meninggitis(P<0.01).Every Mycobacterium obtained from MODS and Lowenstein-Jensen culture was identified as Mycobacterium tuberculous by immunochromatography.All of the 18 pleural fluid and cerebrospinal fluid samples collected from non-tuberculosis suspects were all negative tested by MODS,Ziehl-Neelsen smear and Lowenstein-Jensen culture.The median time to culture positive of MODS was 9 days in cerehrospinal fluid and 14 days in pleural fluid samples,which were both significantly shorter than that of Lowenstein-Jensen culture(31 days in both cerebrospinal fluid and pleural fluid samples).Conclusion:Microscopic observation drug-susceptibility assay(MODS) compared with the traditional detection methods has a rapid,sensitive technique which is appropriate for diagnosis of TB.