A global proficiency testing programme for Xpert® MTB/RIF using dried tube specimens, 2013–2015

Klein, Katherine A.; DeGruy, Kyle; Rey, Zilma; Hall, Patricia; Kim, Andrea; Gutreuter, Steve; Alexander, Heather

doi:10.4102/ajlm.v9i1.1167

Cited by 4 publications

(4 citation statements)

References 14 publications

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“…We are continuing to study and refine the technique for producing DTS, including the investigation of heat inactivation of M. tuberculosis for improved biosafety, stability and sample accuracy and precision. Since development of this novel PT 24 In addition, in 2016 we began the transfer of DTS technology to countries as part of a PT package that includes feedback and corrective actions to sustainably improve the quality of international diagnostic testing services. In 2019, the scope of the PT programme was increased to include the Xpert MRB/RIF Ultra assay (Cepheid, Sunnyvale, California, United States) where the same panel prepared for Xpert MTB/RIF PT was also successfully validated for use as PT for the Xpert MTB/RIF Ultra assay.…”

Section: Recommendations and Next Stepsmentioning

confidence: 99%

Development of dried tube specimens for Xpert MTB/RIF proficiency testing

et al. 2020

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Background: Proficiency testing (PT) is part of a comprehensive quality assurance programme, which is critical to ensuring patients receive accurate and reliable diagnostic testing. Implementation of the Cepheid Xpert® MTB/RIF assay to aid in the diagnosis of tuberculosis has expanded rapidly in recent years; however, PT material for Xpert MTB/RIF is not readily available in many resource-limited settings.Objective: To develop an accurate and precise PT material based on the dried tube specimen (DTS) method, using supplies and reagents available in most tuberculosis culture laboratories.Methods: Dried tube specimens were produced at the United States Centers for Disease Control and Prevention from 2013 to 2015 by inactivating liquid cultures of well-characterised mycobacterial strains. Ten percent of DTS produced were tested with Xpert MTB/RIF and evaluated for accuracy and precision.Results: Validation testing across eight rounds of PT demonstrated that DTS are highly accurate, achieving an average of 96.8% concordance with the Xpert MTB/RIF results from the original mycobacterial strains. Dried tube specimen testing was also precise, with cycle threshold standard deviations below two cycles when inherent test cartridge variability was low.Conclusion: Dried tube specimens can be produced using equipment already present in tuberculosis culture laboratories, making Xpert MTB/RIF PT scale-up more feasible in resource-limited settings. Use of DTS may fill the gap in tuberculosis laboratory access to external quality assessment, which is an essential component of a comprehensive continuous quality improvement programme.

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Section: Recommendations and Next Stepsmentioning

confidence: 99%

Development of dried tube specimens for Xpert MTB/RIF proficiency testing

et al. 2020

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“…The infectious nature of the pathogen imposes specific infrastructure requirements. A biosafety level III laboratory and associated equipment are prerequisites for preparing these panels (Gumma et al, 2019;Klein et al, 2020), which are not easily accessed in resource-limited settings, hindering the local manufacture of the proficiency test panels, especially in resource-limited regions and countries that are severely affected by TB. In practice, however, local manufactures are encouraged to improve the performance quality of the assay by reducing costs and output time, while ensuring sustainability (Gumma et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Construction and application of a heterogeneous quality control library for the Xpert MTB/RIF assay in tuberculosis diagnosis

Guan

Han

Huang

et al. 2023

Front. Cell. Infect. Microbiol.

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Proficiency testing based on quality control materials is an important component of the quality assurance system for detection methods. However, in the detection of infectious diseases, it is a challenge to use quality control materials derived from clinical samples or pathogens owing to their infectious nature. The Xpert MTB/RIF assay, endorsed by the World Health Organization, is one of the most widely implemented assays in the detection of Mycobacterium tuberculosis along with rifampicin resistance and its heterogeneity. Clinical isolates are typically used as quality controls for this assay, leading to concerns about biosafety, constrained target sequence polymorphisms, and time-consuming preparation. In this study, a heterogeneous quality control library for the Xpert MTB/RIF assay was constructed based on DNA synthesis and site-directed mutation, which provides sufficient rifampicin resistance polymorphisms, enabling monitoring all five probes of Xpert MTB/RIF and its combinations. Escherichia coli and Bacillus subtilis were used as heterogeneous hosts rather than the pathogen itself to eliminate biosafety risks; thus, preparation does not require a biosafety level III laboratory and the production time is reduced from a few months to a few days. The panel was stable for more than 15 months stored at 4°C and could be distributed at room temperature. All 11 laboratories in Shanghai participating in a pilot survey identified the specimens with corresponding probe patterns, and discordant results highlighted inappropriate operations in the process. Collectively, we show, for the first time, that this library, based on heterogeneous hosts, is an appropriate alternative for M. tuberculosis detection.

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“…To overcome the rigorous and expensive biannual preparations processes while maintaining semiannual PT rounds, the Uganda-SRL adopted the use of DTS, a method that had been used by the United States centers for disease control and prevention (CDC) and in other disease PT schemes such as HIV viral load testing [8,10,11]. We designed this study to demonstrate the stability of DTS panels and compatibility with testing protocol when stored under different environmental conditions for one year.…”

Section: Introductionmentioning

confidence: 99%

Advancing proficiency testing for ultra in resource-limited settings using dried tube specimen: A study by SRL-Uganda

Kabugo

Namutebi²,

Adam³

et al. 2023

PLoS ONE

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Background Proficiency testing (PT) has been hard to set up due to cost limitations and technical capacity. Conventional Xpert MTB/RIF PT programs use liquid and culture spots which require stringent storage and transportation conditions with cross-contamination chances prevalent. These setbacks prompted the use of dried tube specimens (DTS) for Ultra assay PT. For continuity of PT provision, stability of DTS and compatibility with testing protocols when kept for a long period needs to be established. Methods DTS were prepared from known isolates inactivated using a hot air oven at 85°C. 100μl of bacterial suspensions were aliquoted and dried inside a Biosafety cabinet. Panel validation was done to establish the baseline Deoxyribonucleic acid (DNA) concentration in terms of cycle threshold (Ct) value. DTS aliquots were shipped to participants to test and report within six weeks. The remaining DTS were kept at 2–8°C and room temperature for one year with testing at six months. Twenty (20) DTS samples per set remaining at one year were heated at 55°C for two weeks before testing. The means of the different samples were compared to validation data using paired t-tests. Boxplots were designed to visualize the differences in the medians of the DTS. Results Overall mean Ct value increased by 4.4 from the validation to testing after one year at the different storage conditions. Samples heated at 55°C showed a 6.4 Ct difference from validation data. Testing done at six months on 2–8°C stored items showed no statistical difference. At all the remaining testing times and conditions, P-values were less than 0.008 although the absolute mean Ct when compared showed slight increments and accommodated differences for the detection of MTB and rifampicin resistance. Median values for samples stored at 2–8°C were lower compared to those at room temperature. Conclusion DTS stored at 2–8°C remain more stable for one year compared to higher temperatures and can be consistently used as PT materials in more than one PT round for biannual PT providers.

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A global proficiency testing programme for Xpert® MTB/RIF using dried tube specimens, 2013–2015

Cited by 4 publications

References 14 publications

Development of dried tube specimens for Xpert MTB/RIF proficiency testing

Development of dried tube specimens for Xpert MTB/RIF proficiency testing

Construction and application of a heterogeneous quality control library for the Xpert MTB/RIF assay in tuberculosis diagnosis

Advancing proficiency testing for ultra in resource-limited settings using dried tube specimen: A study by SRL-Uganda

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