Dataset Information

Performance of the Abbott RealTime MTB and MTB RIF/INH Assays in a Setting of High Tuberculosis and HIV Coinfection in South Africa.

ABSTRACT: South Africa is a country with a high incidence of tuberculosis (TB), complicated by coinfection with human immunodeficiency virus (HIV). The Xpert MTB/RIF (Cepheid, Sunnyvale, CA, USA) is used in South Africa as the test for the initial diagnosis of TB, and other molecular platforms such as the m2000 (Abbott Molecular, Des Plaines, IL, USA) are widely used for molecular monitoring of HIV load. The latter platform is now also equipped with the RealTime (RT) MTB and RealTime MTB RIF/INH assays for TB and first-line drug resistance screening but has not been evaluated in settings of HIV and TB coinfection. A prospective clinical validation study was conducted at a community health center in Johannesburg, South Africa, and consenting individuals with presumptive pulmonary TB were enrolled. The performance of the Abbott assays was compared with those of the Xpert MTB/RIF, liquid culture, drug susceptibility testing, and clinical case definitions. A statistical analysis was performed on 206 individuals (73% were HIV positive). The sensitivity and specificity of the RT MTB were 82.5% (confidence interval [CI], 67.2 to 92.7) and 93.1% (CI, 86.2 to 97.2) on raw sputum and 77.5% (CI, 61.5 to 89.2) and 95.1% (CI, 88.9 to 98.4) on concentrated sputum, respectively, compared with those from liquid culture. The RT MTB correctly identified 17/35 more smear-negative culture-positive specimens than the Xpert MTB/RIF. Both the RT MTB and the Xpert MTB/RIF displayed sensitivities >70% and specificities >90% in HIV-positive individuals. The available drug resistance results concurred with MTBDRplus and drug susceptibility profiles. The RT MTB assay has similar diagnostic performance to the Xpert MTB/RIF and is suited to testing presumptive TB patients coinfected with HIV. The existing laboratory information system connectivity, training, and technical support make this a viable polyvalent option to scale up TB alongside HIV laboratory testing services in South Africa.

SUBMITTER: Scott L

PROVIDER: S-EPMC5527428 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Performance of the Abbott RealTime MTB and MTB RIF/INH Assays in a Setting of High Tuberculosis and HIV Coinfection in South Africa.

Scott Lesley L David Anura A Noble Lara L Nduna Matilda M Da Silva Pedro P Black Andrew A Venter Francois F Stevens Wendy W

Journal of clinical microbiology 20170607 8

South Africa is a country with a high incidence of tuberculosis (TB), complicated by coinfection with human immunodeficiency virus (HIV). The Xpert MTB/RIF (Cepheid, Sunnyvale, CA, USA) is used in South Africa as the test for the initial diagnosis of TB, and other molecular platforms such as the m2000 (Abbott Molecular, Des Plaines, IL, USA) are widely used for molecular monitoring of HIV load. The latter platform is now also equipped with the RealTime (RT) MTB and RealTime ...[more]

PMID: 28592547

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Project description:BackgroundThe Abbott RealTime MTB is an assay for the detection of Mycobacterium tuberculosis (MTB) complex DNA from respiratory specimens in combination with the Abbott RealTime RIF/INH assay for the detection of genetic resistance markers for isoniazid (INH) and rifampicin (RIF) from MTB positive isolates. Hence, this study aimed to evaluate the performance of the Abbott RealTime MTB and RIF/INH assays.MethodsA cross-sectional study was conducted on 289 study subjects presumptive to have pulmonary tuberculosis at Nigist Eleni Mohammed Memorial Hospital, South Ethiopia from April 2017 to June 2018. Two morning expectorated sputum specimens were collected from each study participant. One sample was tested directly by Xpert MTB/RIF assay at Nigist Eleni Mohammed Memorial Hospital and the other sample was used for smear microscopy, TB culture, Abbott RealTime MTB, and Abbott RealTime INH/RIF assays at International Clinical Laboratories, Addis Ababa, Ethiopia. The diagnostic performance of the Abbott RealTime MTB and INH/RIF assays were calculated against MGIT liquid culture and phenotypic drug susceptibility testing (DST) as the gold standard.ResultsFor the detection of MTB the Abbott RealTime MTB assay exhibited sensitivity 92.4% (95% CI 83.6-96.9), specificity 95.4% (95% CI 91.1-97.7), PPV 89.0% (95% CI 79.7-94.5) and NPV 96.9% (95% CI 93.0-98.7). For the detection of RIF resistance MTB, Abbott RealTime MTB RIF/INH concurred with phenotypic DST and Xpert MTB/RIF, while for the detection of INH resistance MTB, the sensitivity, specificity, PPV and NPV of the Abbott MTB RIF/INH assay was 84.2% (95% CI 60.4-96.6), 100% (95% CI 89.7-100), 100% and 91.9% (95% CI 80.0-96.9), respectively.ConclusionsThe Abbott RTMTB and RIF/INH assays revealed high sensitivity and specificity in MTB diagnosis and provided reliable INH and RIF resistance profiles. This assay has a similar diagnostic performance to the Xpert MTB/RIF assay with the advantages of high-throughput.

Project description:The aim of this study was to evaluate the performance of Xpert MTB/RIF Ultra (Ultra) compared with its predecessor, Xpert MTB/RIF (Xpert), in the diagnosis of tuberculosis (TB) in a low TB incidence country. Retrospective analysis was performed on 689 clinical samples received between 2015 and 2018, on which Xpert was performed, and on 715 samples, received between 2018 and 2020, on which Ultra was performed. Samples were pulmonary (n = 830) and extrapulmonary (n = 574) in nature, and a total of 264 were culture positive for Mycobacterium tuberculosis complex (MTBC). The diagnostic performance of both assays was analyzed using culture as the reference standard. The sensitivity of Ultra for culture positive (smear positive and smear negative) MTBC samples, was 93.2% (110/118) compared with 82.2% (120/146) for Xpert (P = 0.0078). In smear negative-culture positive samples, Ultra had a sensitivity of 74.2% (23/31) versus 36.11% (13/36) for Xpert (P = 0.0018). Specificity of both assays was comparable at 94.8% (566/597) for Ultra and 95.8% (520/543) for Xpert (P = 0.4475). The sensitivity of Ultra and Xpert assays among exclusively pulmonary samples was 95.3% (82/86) and 90.3% (84/93), respectively (P = 0.1955), and 87.5% (28/32) and 67.9% (36/53), respectively, among extrapulmonary samples (P = 0.0426). Ultra showed improved performance compared with Xpert in a low TB incidence setting, particularly in smear negative and extrapulmonary MTBC disease. The specificity of Ultra was lower than Xpert, however, this was not statistically significant. IMPORTANCE The study demonstrates the improved sensitivity of the Ultra compared with the Xpert, particularly in smear negative TB disease, for both pulmonary and extrapulmonary samples in a low TB incidence setting. Cycle threshold (Ct) value for both assays was found to positively correlate with time to TB culture positivity, suggesting that Ct and semiquantitative results could be used as indicators of sample MTBC bacillary burden, and thus, perhaps, of transmission potential. This may have implications for the designation of patient isolation precautions.

Dataset Information

Performance of the Abbott RealTime MTB and MTB RIF/INH Assays in a Setting of High Tuberculosis and HIV Coinfection in South Africa.

Publications

Performance of the Abbott RealTi<i>m</i>e MTB and MTB RIF/INH Assays in a Setting of High Tuberculosis and HIV Coinfection in South Africa.

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