Clinical evaluation of the Mycobacteria Growth Indicator Tube (MGIT) compared with radiometric (Bactec) and solid media for isolation of Mycobacterium species

Chew, William; Lasaitis, R. M.; Schio, F. A.; Gilbert, G. L.

doi:10.1099/00222615-47-9-821

Cited by 47 publications

(34 citation statements)

References 6 publications

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“…[20] Chew et al had shown the mean detection time to be 27 days with LJ medium. [18] Our findings were in agreement to other studies.…”

Section: Totalsupporting

confidence: 83%

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A COMPARATIVE EVALUATION OF PETROFF’S METHOD AND NALC-NaOH DIGESTION DECONTAMINATION PROCEDURE FOR THE ISOLATION OF MYCOBACTERIA FROM CLINICAL SPECIMENS IN A TERTIARY CARE HOSPITAL

Kaur¹,

Simar²,

Setia³

et al. 2017

jemds

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BACKGROUNDTuberculosis is the leading cause of death from a curable infectious disease. [1] Examination by mycobacterial culture provides the only definitive diagnosis of tuberculosis. [3] Isolation of Mycobacteria from specimens contaminated with normal flora like sputum poses a problem in view of high nutritive value of the egg media used for mycobacterial culture. Different laboratories use different decontamination techniques. No single technique is entirely satisfactory. Hence, this study was conducted to compare the Petroff's method and NALC-NAOH (N-Acetyl-L-cysteine NaOH) method digestion decontamination procedures.

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“…[20] Chew et al had shown the mean detection time to be 27 days with LJ medium. [18] Our findings were in agreement to other studies.…”

Section: Totalsupporting

confidence: 83%

“…However, in literature sensitivity of LJ medium had been reported to be 59.7%, 76.9% and 87%. [17,18,19] The mean detection time for isolation of mycobacteria on LJ media was 32.88 ± 12.07 days. It was then separately computed for AFB smear negative and AFB smear positive specimens.…”

Section: Totalmentioning

confidence: 99%

A COMPARATIVE EVALUATION OF PETROFF’S METHOD AND NALC-NaOH DIGESTION DECONTAMINATION PROCEDURE FOR THE ISOLATION OF MYCOBACTERIA FROM CLINICAL SPECIMENS IN A TERTIARY CARE HOSPITAL

Kaur¹,

Simar²,

Setia³

et al. 2017

jemds

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“…One of them could be the use of a solid culture medium, which has a lower sensitivity than liquid media such as MGIT (20). Second, quality control of the SMF readings was not performed mainly because the bacillus staining of the SMF fades away after 24 h. As the two staining methods use the same stain, it might be possible that the remaining hypochlorite and/or Triton X-100 in the membrane fades the stain.…”

Section: Discussionmentioning

confidence: 99%

Increased Sensitivity in Diagnosis of Tuberculosis in HIV-Positive Patients through the Small-Membrane-Filter Method of Microscopy

et al. 2013

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The sensitivity of microscopy for the diagnosis of tuberculosis (TB) is around 50% but decreases by about 15% in patients with suspected TB who are coinfected with HIV. Here, we compared the accuracies of three microscopy methods for processing sputum smears (concentration by centrifugation with or without N-acetyl-L-cysteine [NALC] and concentration by filtration on a polycarbonate membrane) to that of culture on Ogawa-Kudoh medium as the gold standard method. Sputum samples were obtained from 432 patients with suspected pulmonary TB, of whom 60% were infected with HIV. Analysis was performed using the first specimen. Compared to the gold standard culture, the small-membrane-filter (SMF) method was the most sensitive microscopic method. In HIV-infected TB patients, the sensitivity of the SMF method was significantly higher than those for centrifugation of sputum samples with or without NALC treatment (61.9%, 47.6%, and 45.2%, respectively; P ‫؍‬ 0.001). Similarly, in TB patients without HIV infection, the sensitivity of the SMF method was significantly higher than those for centrifugation of sputum samples with or without NALC treatment (81.8%, 63.6%, and 57.5%, respectively; P ‫؍‬ 0.001). In the two study groups, TB patients with or without HIV, no significant differences between the specificities of the three methods were observed. Handling of the second sputum sample similarly by centrifugation with or without NALC and by the SMF method increased positivities by 13%, 11%, and 4%, respectively. The overall agreement between microscopy and culture was above 90% for all groups. Microscopic evaluation of the sputum samples treated with NALC compared to those not treated with NALC did not show any increase in sensitivity. Altogether, the sensitivity of the SMF method is higher than those of the other two microscopic methods studied without a loss of specificity. Diagnosing tuberculosis (TB) in HIV-infected patients still presents a major challenge since clinical and radiological findings are often atypical (1, 2), and many cases of smear-negative pulmonary TB are undiagnosed (3). Sputum smear microscopy, a low-cost method, is important in resource-limited scenarios, where cultures are not available, but it provides a lower sensitivity in HIV-infected patients with suspected TB (4-6).Filtration on a polycarbonate membrane, the small-membrane-filter (SMF) method, was proved to have greater sensitivity and specificity than direct microscopy, even after centrifugation of sputum samples (7,8), but the HIV status of the populations was not reported in those studies.Under the routine conditions of a bacteriology laboratory, we evaluated this method in patients with suspected TB, most of whom were infected with HIV, along with bacilloscopy after centrifugation with or without decontamination. The three methods were compared to culture on solid medium (Ogawa-Kudoh [OK]), considered the gold standard for TB diagnosis in our setting, and their sensitivities, specificities, and Cohen's kappa coefficients were calculated. MAT...

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“…In most of the research studies published two culture media were used to assess the performance of the Xpert MTB/RIF® test: the Löwenstein-Jensen solid medium and the BACTEC MGIT automated liquid medium; however, many hospitals only have the Ogawa-Kudoh solid medium. It is known that the use of solid and liquid culture media can increase the sensitivity by 11% or more (16,17). The conventional culture medium requires 10 2 mycobacteria to detect positivity and the PCR requires only 10 or more mycobacteria.…”

Section: Discussionmentioning

confidence: 99%

Rendimiento de la prueba Xpert MTB/RIF en muestras respiratorias en un escenario real de trabajo de un país en desarrollo

Atehortúa

Ramírez²,

Echeverri

et al. 2014

biomedica

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Site where the research was conducted: Hospital Universitario San Vicente Fundación, Medellín, Colombia Introduction: The Xpert MTB/RIF test detects DNA from Mycobacterium tuberculosis complex and susceptibility to rifampin. It has been evaluated repeatedly under "ideal" conditions including centrifugation of sputum and bronchoalveolar lavage, Ziehl Neelsen (ZN) and auramine/rhodamine staining, as well as with solid and liquid automated culture methods. Results from such evaluations cannot be extrapolated to low-income countries that do not routinely use all these processes. Objective: To assess the performance of the Xpert MTB/RIF test in respiratory samples under "real" conditions of work in a low-income country and its correlation with phenotypic susceptibility testing. Materials and methods: We conducted a cross-sectional study to assess the performance of the Xpert MTB/RIF test in ≥12 year-old patients with suspected pulmonary tuberculosis. In routine sample processing at the Hospital we do not use sputum centrifugation, staining with auramine/rhodamine or automated liquid culture. Results: We screened 152 patients of whom 108 were eligible for the study and 103 were included in the analysis; 34% of the samples were positive. The overall test sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 91%, 92%, 83% and 96%, respectively. In ZNnegative samples the sensitivity, specificity, PPV and NPV were 87%, 91%, 68% and 97%, respectively. The results of sensitivity and resistance to rifampin were concordant with susceptibility testing using the multiple proportions method (kappa=1, p<0.0001). Conclusions:The Xpert MTB/RIF test overall performance was similar to the one achieved under ideal conditions. Its performance in ZN-negative samples was better under "real" conditions of work in a low-income country.

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Clinical evaluation of the Mycobacteria Growth Indicator Tube (MGIT) compared with radiometric (Bactec) and solid media for isolation of Mycobacterium species

Cited by 47 publications

References 6 publications

A COMPARATIVE EVALUATION OF PETROFF’S METHOD AND NALC-NaOH DIGESTION DECONTAMINATION PROCEDURE FOR THE ISOLATION OF MYCOBACTERIA FROM CLINICAL SPECIMENS IN A TERTIARY CARE HOSPITAL

A COMPARATIVE EVALUATION OF PETROFF’S METHOD AND NALC-NaOH DIGESTION DECONTAMINATION PROCEDURE FOR THE ISOLATION OF MYCOBACTERIA FROM CLINICAL SPECIMENS IN A TERTIARY CARE HOSPITAL

Increased Sensitivity in Diagnosis of Tuberculosis in HIV-Positive Patients through the Small-Membrane-Filter Method of Microscopy

Rendimiento de la prueba Xpert MTB/RIF en muestras respiratorias en un escenario real de trabajo de un país en desarrollo

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