Tuberculosis (TB) is the most common opportunistic infection in HIV-infected patients and the emergence of drug-resistant tuberculosis (DR-TB) is a growing problem in resource-limited settings (RLS). TB diagnosis in most RLS still depends on smear microscopy for acid-fast bacilli (AFB) while adequate infrastructure for testing drug sensitivity is unavailable. However, molecular diagnostics that detect Mycobacterium tuberculosis (Mtb) DNA and its genetic markers of drug resistance were recently developed. In this thesis I describe the use of a molecular diagnostic, Genotype MTBDRplus, for characterizing DR-TB and patterns of tuberculosis-like infection in two cities in south-west and north-central Nigeria. I found high rates of DR-TB in Nigerian HIV-infected individuals (9.3% for RIF or INH) with significantly different amounts by location (18.18% in south-west vs. 3.91% in north-central Nigeria, p=0.01). RIF resistance, indicative of MDR-TB, was found in 5.52% treatment-naïve patients, far exceeding the WHO predictions (0-4.3%). Furthermore, RIF resistance was genetically distinct, suggesting location-specific transmission of drug resistance (p=0.04). Genotype MTBDRplus correctly identified the drug-resistant samples compared to sequencing in 96.8% of cases. Mtb was confirmed in 56% of patients and was less likely to be found in patients on ART, while controlling for other relevant demographic characteristics (OR 0.29, P=0.02). Only abnormal respiratory findings on auscultation and the direct sputum smear grade greater than 3/100 were significant predictors of Mtb infection (OR 3.28, P=0.03; OR 6.40, p<0.01 respectively). Concentrated sputum smear was not significantly correlated with Mtb infection, except at the highest grades (>2+). Furthermore, in 49% of samples that were not confirmed for Mtb other actinomycetes were found: atypical Mycobacteria (ATM), Rhodococcus spp., Nocardia spp., Corynebacterium spp. I conclude that concentrated sputum AFB smears may misidentify bacteria as Mtb in a subset of HIV-infected patients. These individuals may have a different, even uncharacterized, actinomycete infection in the respiratory tract. Furthermore, total DR-TB in HIV-infection is high and transmission of DR-TB in HIV-infected patients in Nigeria is higher than estimated by the WHO. Molecular diagnostics are a rapid method for identifying Mtb and monitoring DR-TB, and can guide appropriate treatment decisions for respiratory infections in RLS with a high HIV burden.

Tuberculosis remains a major public health issue globally, with an estimated 9.2 million new cases in 2006. A new threat to TB control is the emergence of drug resistant strains. These strains are harder to cure as standard anti-tuberculosis first line treatments are ineffective. Multi Drug Resistant Tuberculosis (MDR-TB) is defined as Mycobacterium tuberculosis that has developed resistance to at least rifampicin and isoniazid, and these strains now account for greater than 5% of worldwide cases. Mutations within the Rifampicin Resistance Determining Region (RRDR) of the rpoB gene are present in greater than 95% of strains that show rifampicin resistance by conventional drug susceptibility testing. As rifampicin mono resistance is extremely rare, and rifampicin resistance is usually associated with isoniaizd resistance, the RRDR region of the rpoB gene is a very useful surrogate marker for MDR-TB. Many molecular assays have been attempted based on this theory and have had varied levels of success. The three methods evaluated in this study are DNA sequencing of the rpoB, katG and inhA genes, the Genotype MTBDRplus line probe assay (Hain Lifesciences) and a novel method incorporating Real-Time PCR with High Resolution Melt analysis targeted at the RRDR using the Rotorgene 6000 (Corbett Lifesciences). The sensitivity for the detection of rifampicin resistance was far better using DNA sequencing or the commercially available line probe assay than detection by the Real-Time PCR method developed in this study.

Yes / Background: Tuberculosis (TB) is the highest-mortality infectious disease in the world and the main cause of death related to antimicrobial resistance, yet its surveillance is still paper-based. Rifampicin-resistant TB (RR-TB) is an urgent public health crisis. The World Health Organization has, since 2010, endorsed a series of rapid diagnostic tests (RDTs) that enable rapid detection of drug-resistant strains and produce large volumes of data. In parallel, most high-burden countries have adopted connectivity solutions that allow linking of diagnostics, real-time capture, and shared repository of these test results. However, these connected diagnostics and readily available test results are not used to their full capacity, as we have yet to capitalize on fully understanding the relationship between test results and specific rpoB mutations to elucidate its potential application to real-time surveillance. Objective: We aimed to validate and analyze RDT data in detail, and propose the potential use of connected diagnostics and associated test results for real-time evaluation of RR-TB transmission. Methods: We selected 107 RR-TB strains harboring 34 unique rpoB mutations, including 30 within the rifampicin resistance–determining region (RRDR), from the Belgian Coordinated Collections of Microorganisms, Antwerp, Belgium. We subjected these strains to Xpert MTB/RIF, GenoType MTBDRplus v2.0, and Genoscholar NTM + MDRTB II, the results of which were validated against the strains’ available rpoB gene sequences. We determined the reproducibility of the results, analyzed and visualized the probe reactions, and proposed these for potential use in evaluating transmission. Results: The RDT probe reactions detected most RRDR mutations tested, although we found a few critical discrepancies between observed results and manufacturers’ claims. Based on published frequencies of probe reactions and RRDR mutations, we found specific probe reactions with high potential use in transmission studies: Xpert MTB/RIF probes A, Bdelayed, C, and Edelayed; Genotype MTBDRplus v2.0 WT2, WT5, and WT6; and Genoscholar NTM + MDRTB II S1 and S3. Inspection of probe reactions of disputed mutations may potentially resolve discordance between genotypic and phenotypic test results. Conclusions: We propose a novel approach for potential real-time detection of RR-TB transmission through fully using digitally linked TB diagnostics and shared repository of test results. To our knowledge, this is the first pragmatic and scalable work in response to the consensus of world-renowned TB experts in 2016 on the potential of diagnostic connectivity to accelerate efforts to eliminate TB. This is evidenced by the ability of our proposed approach to facilitate comparison of probe reactions between different RDTs used in the same setting. Integrating this proposed approach as a plug-in module to a connectivity platform will increase usefulness of connected TB diagnostics for RR-TB outbreak detection through real-time investigation of suspected RR-TB transmission cases based on epidemiologic linking. / KCN was supported by Erasmus Mundus Joint Doctorate Fellowship grant 2016-1346, and BCdJ, LR, and CJM were supported by European Research Council-INTERRUPTB starting grant 311725.