ABSTRACT
Objective To test the drug susceptibilities in Mycobacterium tuberculosis by microscopic observation drug susceptibility(MODS)and evaluate the method for the detection susceptibility in second-line drugs.Methods To set up the MODS method.the drug susceptibilities of 4 second-line drugs in Mycobacterium tuberculosis were tested in 24 well plates.The test conditions were discussed.The resistance to protionamide(PTH),amikacin(AMK),capreomycin(CPM)and levofloxacin(LVF)of 60 MTB isolated from 2007 to 2008 in Shanghai Pulmonary Hospital were detected and compared with that of L-J method.The isolates were tested by minimum inhibitory concentration(MIC)method when the drug susceptibilities were not consistent.Results Among the 60 Mycobacterium tuberculosis clinical isolates.the results of drug susceptibility were confirmed by MODS,absolute concentration method and the accordance rate of PTH,AMK,CPM and LVF were 96.7%(58/60),98.3%(59/60),91.7%(55/60)and 96.7%(58/60),respectively.If the result of absolute concentration method was as the standard.the sensitivity.specificity.positive and negative predictive value as well as accuracy were 100%,87.5%,87.5%,100%and 96.7%in PTH;100%,90.0%,90.0%,100%and 98.3% in AMK;76.9%,95.7%,83.3%,93.8%,91.7% in CPM;100%,96.0%,83.3%,100% and 96.7% in LVF respectively detected by MODS assay.Conclusion MODS is a rapid and simple method for susceptibility testing of second-line drug in Mycobacterium tuberculosis.
ABSTRACT
OBJECTIVE To set up and evaluate the microscopic observation drug susceptibility assay(MODS)technology and use it to detect rapidly Mycobacterium tuberculosis(MTB).METHODS The 24-hole cell culture plate method of liquid culture were used to set up MODS technology.The MODS technology was used to detect MTB and non-M.tuberculosis(NMT)isolates comparing with Lowenstein-Jensen(L-J) method.RESULTS When bacterial concentration was 3?103 CFU/ml,the time of reading test-result was the seventh day by MODS;four kinds of NMT(M.phlei,M.kansasii,M.chelonaeand M.marinum) in the liquid medium in the observation was similar to the growth of cording,it was difficult to distinct from the cording of MTB in the liquid medium;When using the 4-Nitro-benzoic acid 800 ?g/ml,thiophene-2-carboxylic acid hydrazine 2.5 ?g/ml for testing conditions,the correct diagnosis can be improved;the test results of clinical isolates by MODS were highly concordance rate with the results of L-J.If the results of L-J was the golden standard,the sensitivity,specificity,positive and negative predictive value as well as accuracy by MODS was 95.7%,100%,100%,99.9% and 97% respectively.CONCLUSIONS The results of MODS in detection of MTB are highly concordance wih the results of L-J method;MODS assay can be used for rapid detection of tuberculosis,with a rapid,simple,inexpensive,and other advantages.