Global availability of susceptibility testing for second-line anti-tuberculosis agents

BACKGROUND: The continued development of new anti-TB agents brings with it a demand for accompanying treatment regimens to prevent the development of resistance. Effectively meeting this demand requires an understanding of the pathogen´s susceptibility to various treatment options, which in turn makes access to antibiotic susceptibility testing (AST) a paramount consideration in the global treatment of TB.METHODS: A 12-question, quantitative and qualitative survey was developed to gauge global capacity and access to AST. The survey was disseminated to members of the Global Laboratory Initiative, Global Drug-resistant TB Initiative, and the TB section of the International Union Against Tuberculosis and Lung Disease to solicit responses from pertinent stakeholders.RESULTS: A total of 323 complete responses representing 84 countries and all WHO Regions were collected. AST capacity for fluoroquinolones and second-line injectables was high in all WHO Regions. AST capacity for the new and repurposed drugs is highest in the European Region, Region of the Americas and the Western Pacific Region, but quite limited in the African and Eastern Mediterranean Regions. The AST turnaround time for second-line drugs was delayed compared to that for first-line drugs as samples needed to be sent farther for analysis. Common barriers to AST for second-line drugs were lack of specimen transportation infrastructure, high costs, and lack of specialised laboratory workers and specialised laboratory facilities.CONCLUSION: Without expanding global access to AST, the growing availability of new treatment options will likely be threatened by accompanying increase in resistance. There is an earnest and pressing need to improve capacity and access to AST alongside treatment options.

Coronavirus Disease 2019 Diagnosis in Low- and Middle-Income Countries: The Big New Bully Disrupting TB and HIV Diagnostic Services

Coronavirus disease 2019 (COVID-19) undermines control of other infectious diseases. Diagnostics are critical in health care. This opinion paper explores approaches for leveraging diagnostics for COVID-19 while retaining diagnostics for other infectious diseases, including tuberculosis (TB) and HIV. The authors reflect on experiences with GeneXpert technology for TB detection and opportunities for integration with other diseases. They also reflect on benefits and risks of integration. Placement of diagnostics in laboratory networks is largely nonintegrated and designated for specific diseases. Restricting the use of diagnostics leaves gaps in detection of TB, HIV, malaria, and COVID-19. Integrated laboratory systems can lead to more efficient testing while increasing access to critical diagnostics. However, the authors have observed that HIV diagnosis within the TB diagnostic network displaced TB diagnosis. Subsequently, COVID-19 disrupted both TB and HIV diagnosis. The World Health Organization recommended rapid molecular diagnostic networks for infectious diseases and there is a need for more investment to achieve diagnostic capacity for TB, HIV, COVID-19, and other emerging infectious diseases. Integrated laboratory systems require mapping laboratory networks, assessing needs for each infectious disease, and identifying resources. Otherwise, diagnostic capacity for one infectious disease may displace another. Further, not all aspects of optimal diagnostic networks fit all infectious diseases, but many efficiencies can be gained where integration is possible.

Reduction of diagnostic and treatment delays reduces rifampicin-resistant tuberculosis mortality in Rwanda

SETTING: In 2005, in response to the increasing prevalence of rifampicin-resistant tuberculosis (RR-TB) and poor treatment outcomes, Rwanda initiated the programmatic management of RR-TB, including expanded access to systematic rifampicin drug susceptibility testing (DST) and standardised treatment.OBJECTIVE: To describe trends in diagnostic and treatment delays and estimate their effect on RR-TB mortality.DESIGN: Retrospective analysis of individual-level data including 748 (85.4%) of 876 patients diagnosed with RR-TB notified to the World Health Organization between 1 July 2005 and 31 December 2016 in Rwanda. Logistic regression was used to estimate the effect of diagnostic and therapeutic delays on RR-TB mortality.RESULTS: Between 2006 and 2016, the median diagnostic delay significantly decreased from 88 days to 1 day, and the therapeutic delay from 76 days to 3 days. Simultaneously, RR-TB mortality significantly decreased from 30.8% in 2006 to 6.9% in 2016. Total delay in starting multidrug-resistant TB (MDR-TB) treatment of more than 100 days was associated with more than two-fold higher odds for dying. When delays were long, empirical RR-TB treatment initiation was associated with a lower mortality.CONCLUSION: The reduction of diagnostic and treatment delays reduced RR-TB mortality. We anticipate that universal testing for RR-TB, short diagnostic and therapeutic delays and effective standardised MDR-TB treatment will further decrease RR-TB mortality in Rwanda.

Connectivity of diagnostic technologies: improving surveillance and accelerating tuberculosis elimination

In regard to tuberculosis (TB) and other major global epidemics, the use of new diagnostic tests is increasing dramatically, including in resource-limited countries. Although there has never been as much digital information generated, this data source has not been exploited to its full potential. In this opinion paper, we discuss lessons learned from the global scale-up of these laboratory devices and the pathway to tapping the potential of laboratory-generated information in the field of TB by using connectivity. Responding to the demand for connectivity, innovative third-party players have proposed solutions that have been widely adopted by field users of the Xpert(®) MTB/RIF assay. The experience associated with the utilisation of these systems, which facilitate the monitoring of wide laboratory networks, stressed the need for a more global and comprehensive approach to diagnostic connectivity. In addition to facilitating the reporting of test results, the mobility of digital information allows the sharing of information generated in programme settings. When they become easily accessible, these data can be used to improve patient care, disease surveillance and drug discovery. They should therefore be considered as a public health good. We list several examples of concrete initiatives that should allow data sources to be combined to improve the understanding of the epidemic, support the operational response and, finally, accelerate TB elimination. With the many opportunities that the pooling of data associated with the TB epidemic can provide, pooling of this information at an international level has become an absolute priority.

Diagnostic performance of smear microscopy and incremental yield of Xpert in detection of pulmonary tuberculosis in Rwanda

Background

Tuberculosis control program of Rwanda is currently phasing in light emitting diode-fluorescent microscopy (LED-FM) as an alternative to Ziehl-Neelsen (ZN) smear microscopy. This, alongside the newly introduced Xpert (Cepheid, Sunnyvale, CA, USA) is expected to improve diagnosis of tuberculosis and detection of rifampicin resistance in patients at health facilities. We assessed the accuracy of smear microscopy and the incremental sensitivity of Xpert at tuberculosis laboratories in Rwanda.

Methods

This was a cross-sectional study involving four laboratories performing ZN and four laboratories performing LED-FM microscopy. The laboratories include four intermediate (ILs) and four peripheral (PLs) laboratories. After smear microscopy, the left-over of samples, of a single early-morning sputum from 648 participants, were tested using Xpert and mycobacterial culture as a reference standard. Sensitivity of each test was compared and the incremental sensitivity of Xpert after a negative smear was assessed.

Results

A total of 96 presumptive pulmonary tuberculosis participants were culture positive for M. tuberculosis. The overall sensitivity in PL of ZN was 55.1 % (40.2–69.3 %), LED-FM was 37 % (19.4–57.6 %) and Xpert was 77.6 % (66.6–86.4 %) whereas in ILs the same value for ZN was 58.3 % (27.7–84.8 %), LED-FM was 62.5 % (24.5–91.5 %) and Xpert was 90 (68.3–98.8 %). The sensitivity for all tests was significantly higher among HIV-negative individuals (all test p <0.05). The overall incremental sensitivity of Xpert over smear microscopy was 32.3 %; p < 0.0001. The incremental sensitivity of Xpert was statistically significant for both smear methods at PL (32.9 %; p = 0.001) but not at the ILs (30 %; p = 0.125) for both smear methods.

Conclusions

Our study findings of the early implementation of the LED-FM did not reveal significant increment in sensitivity compared to the method being phased out (ZN). This study showed a significant incremental sensitivity for Xpert from both smear methods at peripheral centers where majority of TB patients are diagnosed. Overall our findings support the recommendation for Xpert as an initial diagnostic test in adults and children presumed to have TB.