ABSTRACT
BACTEC 460 has now been phased out, so the search for an alternative is imperative. We have determined the activity of standard anti-tuberculosis drugs against intramacrophage Mycobacterium tuberculosis, in vitro, by using BACTEC 460 and MGIT 960 methods. The minimum inhibitory concentrations of isoniazid, rifampicin, ethambutol and streptomycin against intracellular M. tuberculosis H37Rv were found to be 0.2, 0.8, 8.0, and 5.0 µg/mL, respectively, by both methods. These results show a significant (p<0.001) concordance between minimum inhibitory concentrations obtained by these two different methods. MGIT 960 system uses a robust florescence quenching-based oxygen sensor, requires no radioisotope, is safe, and relatively easy to operate. Apparently, this is the first report wherein MGIT 960 has been validated for anti-tubercular susceptibility testing against intracellular M. tuberculosis H37Rv. Our preliminary data thus clearly demonstrate that the MGIT 960 method can be considered as a promising alternative to BACTEC 460 method.
Subject(s)
Antitubercular Agents/pharmacology , Macrophages/microbiology , Microbial Sensitivity Tests/methods , Mycobacterium tuberculosis/drug effects , Animals , Female , Male , Mice , Reproducibility of ResultsABSTRACT
Genitourinary tuberculosis is a disease of the genitourinary system which includes the entire urinary tract and reproductive system. Genital tuberculosis is an important cause of female infertility, especially in developing nations like India. In the present study, a total of 257 clinical specimens comprising of endometrial biopsy (109), endometrial curetting (42), menstrual blood (8), semen (17), placenta (11) and urine (70) were collected from patients and subjected for PCR, Culture and AFB detection. The endometrial biopsy, endometrial curetting, menstrual blood, semen, placenta, urine showed 30.2, 45.2,12.5, 5.8, 27.2, 31.4 %, positivity rate for tuberculosis by PCR, 7.3, 9.5, 25.0, 0, 9, 8.5 % by culture and 1.8, 2.3, 0, 0, 0, 2.8 % respectively by AFB smear. Being a novel, rapid technique, PCR is the method of choice for rapid diagnosis and management of genitourinary tuberculosis shared with the other concerned tests. This study reveals that genital tuberculosis can occur in any age group, however, the majority of patients were from reproductive age (nearly 75 % of them were from 20-45 years of age) group.
ABSTRACT
BACKGROUND: Tuberculosis (TB), declared a global emergency in 1993 by the WHO, remains a worldwide public health problem. Rapid diagnosis is required for treatment and prevention. This study compares genotypic methods using two gene targets [IS6110 and 'short fragment' devR (Rv3133c)] with phenotypic methods [Lowenstein Jensen (LJ) and BACTEC 460] for the diagnosis of TB while using Ziehl Neelsen (ZN) staining as the gold standard. METHODS: 56 clinical TB samples from a tertiary care apex center along with 50 healthy control samples, excluding samples from patients already on ATT were processed by routine USP methodology. Smears were graded by ZN stain. Solid media (LJ) and liquid media (BACTEC 460) were used along with IS6110 and 'short fragment' devR (Rv3133c) specific gene amplification and comparatively analyzed. RESULTS: 50/56 samples were positive by phenotypic methods, 53 by IS6110 and 45 by devR (Rv3133c) amplification. 38 samples were positive by both phenotypic and genotypic methods. IS6110 detected six and devR (Rv3133c) detected five phenotypically negative samples. Both IS6110 and devR (Rv3133c) were positive in 42 samples. 11 devR (Rv3133c) negative samples were positive by IS6110 and three IS6110 negative samples were positive by 'short fragment' devR (Rv3133c). Compared to phenotypic methods, the sensitivity, specificity, positive and negative predictive values of IS6110 was 94%, 89.29%, 88.68% and 94.34% while that of devR (Rv3133c) was 80%, 91.07%, 88.89% and 83.61% respectively. CONCLUSION: Simultaneous use of both phenotypic and genotypic methods increases the yield of positive results.
ABSTRACT
BACKGROUND: BACTEC MGIT 960 system(Becton Dickinson, USA; MGIT 960) is a fully automated, noninvasive culture system for mycobacteria, which has been regarded as a sensitive and least labor-intensive method. This study was purposed to evaluate the performance of MGIT 960 compared to BACTEC 460 TB radiometric system(Becton Dickinson, USA; BACTEC 460) and Ogawa media. METHODS: A total of 1,067 clinical specimens submitted from April to June in 1999 was cultured for acid fast bacilli(AFB). All specimens were digested, decontaminated by the 6% sodium hydroxide(final concentration of 1.5%) and 0.5% N-acetyl-L-cysteine method. All specimens were inoculated into three kinds of media: a MGIT, a BACTEC 12B, and an Ogawa medium. The AFB recovered from cultures were identified to M. tuberculosis complex and MOTT by NAP test. RESULTS: Of 106 isolates of M. tuberculosis recovered from all culture systems, 101(95.3 %) were detected in the MGIT 960, 95(89.6%) in the BACTEC 460 and 76(71.7%) on Ogawa media. MGIT 960 plus Ogawa media detected 104(98.1%) isolates and BACTEC 460 plus Ogawa media recovered 96(90.6%) isolates. The mean time required for detection of M. tuberculosis was 12.7+/-5.8 days with MGIT 960, 16.2+/-7.7 days with BACTEC 460, and 22.8+/-9.5 days with Ogawa media. The contamination rate were 5.1% for MGIT 960, 2.7% for BACTEC 460, and 6.7% for Ogawa media. CONCLUSIONS: MGIT 960 is a sensitive and rapid method to isolate M. tuberculosis.