MULTIDRUG-RESISTANT TUBERCULOSIS (MDR-TB): AN EMERGING PROBLEM IN WEST AFRICA

Phenotypic Drug Resistance Pattern and Mutation Characteristics of Mycobacterium tuberculosis from Different Body Fluids Among Extra Pulmonary Patients Presented in Selected Hospitals in Addis Ababa, Ethiopia

Background

Drug resistance in tuberculosis poses challenges to both the control and prevention of the disease. The extent of resistance is not well known in developing countries, including Ethiopia. This study was conducted to determine the drug resistance patterns and mutation characteristics of Mycobacterium tuberculosis among extra pulmonary tuberculosis patients in selected health facilities in Addis Ababa.

Material and Methods

A cross-sectional study was conducted from February 2022 to August 2022 in selected hospitals in Addis Ababa. Socio-demographic and clinical data were collected using structured questionnaire. Mycobacterium tuberculosis complex (MTBC) isolates were tested for phenotypic drug susceptibility patterns using the Mycobacterium growth indicator tube (MGIT) method for first-line drugs and mutation characteristics using the Line Probe Assay (LPA) method. The data were analyzed using: SPSS version 23, and a P-value ≤ 0.05 was considered statistically significant.

Results

From a total of 308 patient samples from presumptive extra pulmonary patients, 44 (14.3%) were positive for MTBC. Any drug resistance was discovered in 25% of 44 MTBC isolates evaluated for five first-line drugs phenotypically, with isoniazid (INH) and pyrazinamide (PZA) resistance accounting for a greater proportion with 13.6% and 11.4% of the isolates, respectively. Two (4.5%) of the isolates were MDR-TB. Out of 44 isolates tested using the Geno Type MTBDRplus assay, 5 (11.4%) showed mutations at katG and 2 (4.5%) showed mutations in the rpoB genes.

Conclusion

Both the phenotypic and genotypic drug susceptibility test results showed a high proportion of INH resistance. All INH resistance-conferring mutations were identified from katG gene. The overall prevalence of MDR-TB was also high. For early case detection and treatment, expanding diagnostic capacity for first-line DST is a vital step to limit further spread of drug resistant TB strains in the study area.

The Relevance of Genomic Epidemiology for Control of Tuberculosis in West Africa

Tuberculosis (TB), an airborne infectious disease caused by Mycobacterium tuberculosis complex (MTBC), remains a global health problem. West Africa has a unique epidemiology of TB that is characterized by medium- to high-prevalence. Moreover, the geographical restriction of M. africanum to the sub-region makes West Africa have an extra burden to deal with a two-in-one pathogen. The region is also burdened with low case detection, late reporting, poor treatment adherence leading to development of drug resistance and relapse. Sporadic studies conducted within the subregion report higher burden of drug resistant TB (DRTB) than previously thought. The need for more sensitive and robust tools for routine surveillance as well as to understand the mechanisms of DRTB and transmission dynamics for the design of effective control tools, cannot be overemphasized. The advancement in molecular biology tools including traditional fingerprinting and next generation sequencing (NGS) technologies offer reliable tools for genomic epidemiology. Genomic epidemiology provides in-depth insight of the nature of pathogens, circulating strains and their spread as well as prompt detection of the emergence of new strains. It also offers the opportunity to monitor treatment and evaluate interventions. Furthermore, genomic epidemiology can be used to understand potential emergence and spread of drug resistant strains and resistance mechanisms allowing the design of simple but rapid tools. In this review, we will describe the local epidemiology of MTBC, highlight past and current investigations toward understanding their biology and spread as well as discuss the relevance of genomic epidemiology studies to TB control in West Africa.

Multidisciplinary management of difficult-to-treat drug resistant tuberculosis: a review of cases presented to the national consilium in Uganda

BACKGROUND

Patients with drug resistant tuberculosis (DR-TB) with comorbidities and drug toxicities are difficult to treat. Guidelines recommend such patients to be managed in consultation with a multidisciplinary team of experts (the "TB consilium") to optimise treatment regimens. We describe characteristics and treatment outcomes of DR-TB cases presented to the national DR-TB consilium in Uganda between 2013 and 2019.

METHODS

We performed a secondary analysis of data from a nation-wide retrospective cohort of DR-TB patients with poor prognostic indicators in Uganda. Patients had a treatment outcome documented between 2013 and 2019. Characteristics and treatment outcomes were compared between cases reviewed by the consilium with those that were not reviewed.

RESULTS

Of 1,122 DR-TB cases, 189 (16.8%) cases from 16 treatment sites were reviewed by the consilium, of whom 86 (45.5%) were reviewed more than once. The most frequent inquiries (N = 308) from DR-TB treatment sites were construction of a treatment regimen (38.6%) and management of side effects (24.0%) while the most frequent consilium recommendations (N = 408) were a DR-TB regimen (21.7%) and "observation while on current regimen" (16.6%). Among the cases reviewed, 152 (80.4%) were from facilities other than the national referral hospital, 113 (61.1%) were aged ≥ 35 years, 72 (40.9%) were unemployed, and 26 (31.0%) had defaulted antiretroviral therapy. Additionally, 141 (90.4%) had hepatic injury, 55 (91.7%) had bilateral hearing loss, 20 (4.8%) had psychiatric symptoms and 14 (17.7%) had abnormal baseline systolic blood pressure. Resistance to second-line drugs (SLDs) was observed among 9 (4.8%) cases while 13 (6.9%) cases had previous exposure to SLDs. Bedaquiline (13.2%, n = 25), clofazimine (28.6%, n = 54), high-dose isoniazid (22.8%, n = 43) and linezolid (6.7%, n = 13) were more frequently prescribed among cases reviewed by the consilium than those not reviewed. Treatment success was observed among 126 (66.7%) cases reviewed.

CONCLUSION

Cases reviewed by the consilium had several comorbidities, drug toxicities and a low treatment success rate. Consilia are important "gatekeepers" for new and repurposed drugs. There is need to build capacity of lower health facilities to construct DR-TB regimens and manage adverse effects.