Evaluation of BACTEC MGIT 960 system for recovery of Mycobacterium tuberculosis complex in Pakistan

Malaysian Journal of Microbiology, Vol 6(2) 2010, 01/2010;

ABSTRACT We evaluated the performance of MGIT 960 system in terms of recover rate, detection time of mycobacteria and
contamination rate from various human clinical specimens and compared it with already in use BACTEC 460 TB system
and conventional LJ medium. This is the first reported study on MGIT 960 and its comparison with BACTEC 460 system
in Pakistan. A total of 260 different clinical specimens received for the culture of mycobacteria were dealt during the six
months study period. All the specimens were digested and decontaminated according to the standard N-acetyl-Lcysteine
NaOH method. All the processed specimens were inoculated on both the liquid systems and solid medium and
incubated for six weeks and eight weeks consecutively. A total of 44 mycobacterial isolates (Mycobacterium
tuberculosis, n=43; Mycobacteria other than tuberculosis, n=1) were recovered from 260 clinical specimens. The
recovery rate of M. tuberculosis complex was 97.6% on BACTEC MGIT 960 system and 93.0% on BACTEC 460 system
and 83.7% on LJ medium. The mean detection time of mycobacteria on BACTEC MGIT 960 system was 11.2 days in
smear positive cases, 14.2 days in smear negative cases and 14.8 days in smear positive cases on BACTEC 460
system. Contamination rates were 9.6% and 5.6% and 3.4% for BACTEC MGIT 960, BACTEC 460 system and LJ
medium respectively. The non-radiometric, fully automated BACTEC MGIT 960 system has better diagnostic ability as
compared with radiometric, semi-automated BACTEC 460 system and LJ medium, so it can be used as a reliable
alternative in over burden laboratories.

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    ABSTRACT: Objective: Tuberculosis (TB) caused by Mycobacterium tuberculosis has been identified as a reemerging infectious disease with public health importance globally. Exploitation of new laboratory techniques for precise identification of mycobacteria in clinical specimens is of great importance to improve the diagnosis as part of the global TB control efforts. Methods: The current study was conducted for the evaluation of BACTEC MGIT 960 method in comparison with Lowenstein–Jensen (LJ) culture and light emitting diode (LED) fluorescence microscopy for isolation of mycobacteria among TB suspects from Bangladesh. A total of 421 specimens were tested with these methods. Results: Among the tested samples, 3.6% (n = 15) were LED fluorescence microscopy positive; while 18 (4.2%) and 45 (10.6%) were recovered from LJ and MGIT 960 culture. The relative positivity found through MGIT 960 system were 60% and 66.7% higher than that of LJ culture and LED fluorescence microscopy, respectively. Recovery rate of Mycobacterium tuberculosis complex ([MTC], 21 by MGITand 16 by LJ culture) and non-tubercular mycobacteria ([NTM], 24 by MGITand 2 by LJ culture) by MGIT 960 was 24% and 96% greater, respectively than LJ culture. Moreover, MGIT 960 was found to be highly sensitive (100%), specific (93.3%), accurate (93.6%) and a more rapid method in detecting mycobacteria when compared with LJ culture. Conclusion: Extended recovery of NTM and MTC through MGIT 960 urged frequent application of this method to detect mycobacteria more effectively and rapidly.
    . International Journal of Mycobacteriology. 09/2013;
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    ABSTRACT: We compared Mycobacterium tuberculosis (MTB) sputum culture recovery and contamination rates between the following decontaminants in Löwenstein-Jensen (LJ) media compared to LJ alone: 1) PANTA (n=299), 2) Selectatab-MB (n=299), and 3) penicillin G (n=234). The contamination rate for LJ-alone was approximately 31%, versus 5.0% for PANTA, 2% for Selectatab, and 9% for penicillin-containing media (P<0.001). MTB isolation rates were 9.8%, 17%, 18% and 12% for standard LJ, PANTA, Selectatab and Penicillin cultures respectively.
    Journal of clinical microbiology 04/2014; · 4.23 Impact Factor
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    ABSTRACT: To evaluate the yield of polymerase chain reaction (PCR) for detection of Mycobacterium tuberculosis from different clinical specimens. Observational study. Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from January 2001 to December 2010. Methodology: Different clinical specimens received for Mycobacterium tuberculosis PCR were dealt during the study period. Contaminated samples like sputum were processed by the standard N-acetyl L-cysteine (NALC)-NaOH method. PCR protocols were followed as per manufacturer's manual. PCR was performed using a Thermal Cycler (Master Cycler, Eppendorf, Germany): an initial denaturation step at 94°C for 3 minutes was followed by 40 cycles of denaturation at 94°C for 30 seconds, annealing at 60°C for 30 seconds and extension at 72°C for 30 seconds and a final extension at 72°C for 7 minutes. The products were held at 4°C and later run on 1% agarose gel, stained with Ethidium bromide and visualized in ultraviolet (UV) transilluminator. Out of a total 4620 samples for PCR, 299 were positive for Mycobacterium tuberculosis (6.5%). The percentage of samples from male patients were 63.2%. The mean age of patients was 38+11.5 years. Blood was the most frequent specimen received for PCR (46.66%), followed by body fluids (18.41%) and CSF (10.64%). Yield for different clinical samples was 63/471 for sputum (13.4%), 3/29 for endobronchial washings (10.3%), 59/851 for body fluids (6.9%) and 24/400 for urine (6%). Positive yield from blood was the lowest (101/2156, 4.7%). PCR for Mycobacterium tuberculosis is a rapid and reliable method for the diagnosis of both pulmonary and extrapulmonary tuberculosis. The highest positive yield was obtained from sputum and lowest from blood specimens.
    Journal of the College of Physicians and Surgeons--Pakistan : JCPSP. 05/2012; 22(5):298-301.

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