Comparison of BACTEC MGIT 960 and BACTEC 460 for culture of Mycobacteria

Whyte, Tom; Cormican, Martin; Hanahoe, Belinda; Doran, Geraldine; Collins, Tom; Corbett-Feeney, G.

doi:10.1016/s0732-8893(00)00179-6

Cited by 16 publications

(13 citation statements)

References 8 publications

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“…The concentration of NaOH used in the decontamination was 2% but could be increased up to 4% to attempt to reduce contamination. However, care should be taken to avoid toxicity to mycobacteria, which might cause negative culture results (21). Another important point could be the delay between sputum collection and processing, but in this study, it was only 2 to 3 days and samples were kept at 4°C.…”

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confidence: 94%

Implementation of the Thin Layer Agar Method for Diagnosis of Smear-Negative Pulmonary Tuberculosis in a Setting with a High Prevalence of Human Immunodeficiency Virus Infection in Homa Bay, Kenya

Martin

Waweru²,

Okatch³

et al. 2009

J Clin Microbiol

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The objective of this study was to evaluate the performance of a low-cost method, the thin layer agar (TLA) method, for the diagnosis of smear-negative patients. This prospective study was performed in Homa Bay District Hospital in Kenya. Out of 1,584 smear-negative sputum samples, 212 (13.5%) were positive by culture in Löwenstein-Jensen medium (LJ) and 220 (14%) were positive by the TLA method. The sensitivities of LJ and TLA were 71% and 74%, respectively. TLA could become an affordable method for the diagnosis of smearnegative tuberculosis in resource-limited settings, with results available within 2 weeks.The prevalence of smear-negative pulmonary tuberculosis (TB) has been increasing in countries with a high incidence of human immunodeficiency virus (HIV), especially in low-income countries where many patients are coinfected with HIV and TB and where culture of Mycobacterium tuberculosis is often not available (3,4,5,6,13,15). The incidence of TB in Kenya is estimated at 384/100,000 inhabitants (23). Kenya ranks 13th on the World Health Organization list of 22 highburden countries for TB worldwide, and HIV prevalence in new TB cases is estimated at 52% (23). Culture is more sensitive than smear microscopy (1, 3, 7), but cultivation in Löwenstein-Jensen (LJ) medium is very slow. The thin layer agar (TLA) method has been described as a simple, rapid, and inexpensive method (11,12,18) allowing initial identification of M. tuberculosis based on colony morphology, visualized microscopically, and by incorporation of para-nitrobenzoic acid (PNB) in the medium (10,17,19). We performed a prospective study to evaluate the performance of the TLA method for detection of M. tuberculosis in smear-negative samples compared to cultivation in LJ medium.The study was conducted in Homa Bay District Hospital, Kenya. All smear-negative respiratory samples received between November 2007 and September 2008 from patients suspected of having TB were included. A total of 1,584 smearnegative samples were analyzed. Sputum was digested and decontaminated using the sodium hydroxide-N-acetyl-L-cysteine method (9). LJ cultures were examined twice weekly for up to 8 weeks (22). Cultures were considered positive for M. tuberculosis according to their morphological characteristics, positive acid-fast bacilli staining, and inhibition of growth by PNB on TLA (8). A culture was considered negative if no growth was observed after 8 weeks, and it was considered contaminated if there was growth but it was negative for acidfast bacilli. TLA plates were prepared as previously described (18) with small modifications. One hundred microliters of decontaminated sample was inoculated on a biplate petri dish of 100 mm by 15 mm (Becton Dickinson, Sparks, MD) containing 20 ml of 7H11 agar supplemented with 10% oleic acid-albumin-dextrose-catalase (Becton Dickinson) plus piperacillin, trimethoprim, and amphotericin B (Sigma Aldrich) at 0.05 g/ ml, 0.02 g/ml, and 0.02 g/ml, respectively. PNB at 500 g/ml was incorporated in one compartment. The plates were se...

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confidence: 94%

Implementation of the Thin Layer Agar Method for Diagnosis of Smear-Negative Pulmonary Tuberculosis in a Setting with a High Prevalence of Human Immunodeficiency Virus Infection in Homa Bay, Kenya

Martin

Waweru²,

Okatch³

et al. 2009

J Clin Microbiol

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“…Of the 498 articles identified in the literature search, 24 were reviewed in detail, and data from 14 of these articles (2,3,6,10,13,14,16,21,25,30,(32)(33)(34)(35) were excluded because they used a standard different from the accepted reference or they did not allow the construction of the 2 ϫ 2 table of results. Table 1 summarizes the principal characteristics of the 10 studies included in the metaanalysis (1,11,12,17,18,23,24,27,28,31).…”

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confidence: 99%

Meta-Analysis of BACTEC MGIT 960 and BACTEC 460 TB, with or without Solid Media, for Detection of Mycobacteria

et al. 2004

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In a meta-analysis of 10 studies, the BACTEC 960/MGIT and BACTEC 460 systems showed a sensitivity and specificity in detecting mycobacteria (1,381 strains from 14,745 clinical specimens) of 81.5 and 99.6% and 85.8 and 99.9%, respectively. Combined with solid media, the sensitivity of the two systems increased to 87.7 and 89.7%, respectively.Currently, a combination of conventional solid media with a broth-based method is the accepted reference standard for the diagnosis of mycobacterial infection (5, 26). Among the methods utilizing liquid media, the half-automated radiometric BACTEC 460 TB system (BACTEC 460) is widely accepted as the reference standard. This system, however, is also known for some well-established limitations, which include problems with the use of radioactive material, cumbersome manual loading and unloading, potential hazard of needle stick injury, risk of cross contamination, and lack of computerized data management.Recently, the BACTEC Mycobacteria Growth Indicator Tube System (BACTEC 960/MGIT), a newly developed nonradiometric, fully automated, continuously monitoring system, was introduced as an alternative to the radiometric BACTEC 460 for growth and detection of mycobacteria. The results of several comparative studies show that BACTEC 960/MGIT is a suitable tool for the detection of Mycobacterium tuberculosis and other mycobacterial species, though rather wide variations in diagnostic performance have been reported (1-3, 6, 10-14, 16-18, 21, 23-25, 27, 28, 30-35). To provide an evaluation of the quality of the available reports and an overall summary of the diagnostic accuracy of BACTEC 960/MGIT versus that of BACTEC 460, we performed a systematic review and metaanalysis.Literature search. The literature was searched for the period from January 1990 to June 2003 with the Medline, Embase, and Cochrane libraries. The studies were included for analysis if they compared the results of BACTEC 960/MGIT and BACTEC 460TB with and without solid media, they reported data on false-positive (sample flagged as positive without any microscopic or cultural evidence of acid-fast bacilli by subculture at the end of the incubation period), false-negative (negative test samples found positive on subculture), truepositive, and true-negative results separately; the results of the tests were compared against the reference standard, which was defined as a positive culture with at least one of the three systems used, and the comparison between tests was performed prospectively with the same series of patients from a relevant clinical population, defined as a group of individuals requiring routine microbiologic investigations for suspected pulmonary or extrapulmonary mycobacterial infections.Statistical analysis. To evaluate if variations between primary studies in test threshold had an influence on the accuracy of diagnostic procedures, we used receiver operator characteristic (ROC) curves (9,15,20,22).The common value of noncomparative binary outcomes, as sensitivity and specificity, were obtained by transf...

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“…MGIT 960 system has the advantage of high throughput (960 samples can be tested in one instrument), rapidity (4-13 days) and easier interpretation of results [3]. The technique is based on fluorescence detection of mycobacterial growth in a tube containing a modified Middlebrook 7H9 medium together with fluorescence quenching-based oxygen sensor [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Isolation and Identification of Mycobacterium tuberculosis with Mixed Growth from Positive MGIT 960 Cultures by Re-Decontamination

Ahmad¹,

Hanif²,

Chopra³

et al. 2017

J Biotechnol Biomater

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Tuberculosis (TB) caused by Mycobacterium tuberculosis has been identified as a remerging infectious disease with public health importance globally. Exploitation of better diagnosis techniques for precise isolation of mycobacteria in clinical specimens is of great importance to improve the diagnosis as part of the global TB control efforts. Contamination of broth cultures of acid-fast bacilli (AFB) by bacterial species other than Mycobacterium species frequently occurs. Many of these contaminated cultures require re-decontamination and re-incubation before the appropriate tests can be performed for identification. This study aimed at the isolation/recovery of M. tuberculosis from contaminated MGIT tubes by making minor modification to the standard protocol and access whether the modification has any impact on recovery rate. Among all confirmed 451 mixed growth positive cultures, 89.57% were culture positive (positive for MTBC), 3.80% were culture negative, 4.65% were culture contaminated and 1.99% were found NTM.

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Comparison of BACTEC MGIT 960 and BACTEC 460 for culture of Mycobacteria

Cited by 16 publications

References 8 publications

Implementation of the Thin Layer Agar Method for Diagnosis of Smear-Negative Pulmonary Tuberculosis in a Setting with a High Prevalence of Human Immunodeficiency Virus Infection in Homa Bay, Kenya

Implementation of the Thin Layer Agar Method for Diagnosis of Smear-Negative Pulmonary Tuberculosis in a Setting with a High Prevalence of Human Immunodeficiency Virus Infection in Homa Bay, Kenya

Meta-Analysis of BACTEC MGIT 960 and BACTEC 460 TB, with or without Solid Media, for Detection of Mycobacteria

Isolation and Identification of Mycobacterium tuberculosis with Mixed Growth from Positive MGIT 960 Cultures by Re-Decontamination

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