Detection and characterization of drug-resistant conferring genes in Mycobacterium tuberculosis complex strains: A prospective study in two distant regions of Ghana

Addressing key risk factors hindering tuberculosis control activities in West Africa - progress in meeting the UN sustainable development goals

Tuberculosis (TB) remains a significant public health challenge in West Africa, exacerbated by factors such as HIV, malnutrition, non-communicable diseases, drug-resistant TB, and under-resourced health systems. Addressing these challenges is essential to achieving the World Health Organization's End TB Strategy and Universal Health Coverage goals. This paper explores key strategies for tackling TB and its associated risks in the region. Malnutrition, non-communicable diseases such as hypertension, chronic respiratory diseases, and substance abuse amplify TB burdens. Health system strengthening is pivotal for early TB detection and management. Expanding diagnostic capabilities, particularly through the GeneXpert MTB/RIF assay and Hub-and-Spoke models, alongside workforce development and retention, is crucial. Regional collaborations such as the West African Network of Excellence for Tuberculosis, AIDS, and Malaria (WANETAM) and the Pan-Africa Network for Genomic Surveillance of Poverty-Related Diseases and Emerging Pathogens (PANGenS) demonstrate the importance of collective efforts in research and genomic surveillance. Our article highlights the importance of integrated healthcare approaches, regional partnerships, and community engagement in reducing TB prevalence and improving outcomes. These strategies will not only combat TB but also address its social determinants, advancing health equity in West Africa. By adopting these measures, the region can make significant strides toward UN TB SDG goals.

Trends of Mycobacterium tuberculosis and rifampicin resistance at the Ho Teaching Hospital in Ghana

BACKGROUND

Tuberculosis remains a major public health threat worldwide, causing significant morbidity and mortality, particularly in low- and middle-income countries. In recent years, efforts to combat tuberculosis have focused on strengthening healthcare systems and increasing access to diagnostics and treatment services. There is scarcity of data on the prevalence of Mycobacterium tuberculosis and rifampicin-resistant tuberculosis in the Volta region of Ghana. Therefore, the aim of this study was to determine the trends of Mycobacterium tuberculosis and rifampicin resistance in a major teaching hospital in Ghana spanning a six-year period.

METHODOLOGY

A retrospective cross-sectional hospital study was conducted at Ho Teaching Hospital, Ho, Ghana. Study data included archived results on tuberculosis testing using GeneXpert from 2016-2021. Archived data on tuberculosis testing were collected and entered using Microsoft Excel 2019. IBM SPSS (v26) was used for a statistical analysis of the prevalence of tuberculosis. P-value <0.05 was considered statistically significant.

RESULTS

The study included 5128 presumptive tuberculosis cases from 2016 to 2021, of which 552 were positive, revealing an overall prevalence of 10.76%. Males exhibited a significantly higher prevalence of tuberculosis (14.20%) compared to females (7.48%), with a male-to-female ratio of 2:1. The burden of tuberculosis varied significantly between age groups, with those aged 30-45 years and 46-60 years facing twice the risk compared to those under 15 years (p<0.001). Rainy seasons correlated with heightened tuberculosis occurrences (12.12%) compared to dry seasons (8.84%) (p = 0.008). Rifampicin-resistant tuberculosis was prevalent at 3.45%, slightly higher in women, particularly in the 45-59 age group (5.97%). In particular, tuberculosis prevalence exhibited fluctuations, peaking in 2016 (17.1%) and 2020 (11.5%), with a trough in 2019 (4.6%).

CONCLUSION

The overall prevalence of laboratory confirmed tuberculosis was 10.76%, and resistance to rifampicin, 3.45%, indicating high infection and possible treatment failure. Considering its infectious nature, this calls for concerted efforts to curb the spread of the infection.

Opinion review of drug resistant tuberculosis in West Africa: tackling the challenges for effective control

Drug-resistant (DR) tuberculosis (TB) is a major public health concern globally, complicating TB control and management efforts. West Africa has historically faced difficulty in combating DR-TB due to limited diagnostic skills, insufficient access to excellent healthcare, and ineffective healthcare systems. This has aided in the emergence and dissemination of DR Mycobacterium tuberculosis complex (MTBC) strains in the region. In the past, DR-TB patients faced insufficient resources, fragmented efforts, and suboptimal treatment outcomes. However, current efforts to combat DR-TB in the region are promising. These efforts include strengthening diagnostic capacities, improving access to quality healthcare services, and implementing evidence-based treatment regimens for DR-TB. Additionally, many West African National TB control programs are collaborating with international partners to scale up laboratory infrastructure, enhance surveillance systems, and promote infection control measures. Moreso, novel TB drugs and regimens, such as bedaquiline and delamanid, are being introduced to improve treatment outcomes for DR-TB cases. Despite these obstacles, there is optimism for the future of DR-TB control in West Africa. Investments are being made to improve healthcare systems, expand laboratory capacity, and support TB research and innovation. West African institutions are now supporting knowledge sharing, capacity building, and resource mobilization through collaborative initiatives such as the West African Network for TB, AIDS, and Malaria (WANETAM), the West African Health Organization (WAHO), and other regional or global partners. These efforts hold promise for improved diagnostics, optimized treatment regimens, and provide better patient outcomes in the future where drug-resistant TB in WA can be effectively controlled, reducing the burden of the disease, and improving the health outcomes of affected individuals.

Molecular determinants of multidrug-resistant tuberculosis in Sierra Leone

Multidrug-resistant tuberculosis (MDR-TB) management has become a serious global health challenge. Understanding its epidemic determinants on the regional level is crucial for developing effective control measures. We used whole genome sequencing data of 238 of Mycobacterium tuberculosis complex (MTBC) strains to determine drug resistance profiles, phylogeny, and transmission dynamics of MDR/rifampicin-resistant (RR) MTBC strains from Sierra Leone. Forty-two strains were classified as RR, 196 as MDR, 5 were resistant to bedaquiline (BDQ) and clofazimine (CFZ), but none was found to be resistant to fluoroquinolones. Sixty-one (26%) strains were resistant to all first-line drugs, three of which had additional resistance to BDQ/CFZ. The strains were classified into six major MTBC lineages (L), with strains of L4 being the most prevalent, 62% (n = 147), followed by L6 (Mycobacterium africanum) strains, (21%, n = 50). The overall clustering rate (using ≤d12 single-nucleotide polymorphism threshold) was 44%, stratified into 31 clusters ranging from 2 to 16 strains. The largest cluster (n = 16) was formed by sublineage 2.2.1 Beijing Ancestral 3 strains, which developed MDR several times. Meanwhile, 10 of the L6 strains had a primary MDR transmission. We observed a high diversity of drug resistance mutations, including borderline resistance mutations to isoniazid and rifampicin, and mutations were not detected by commercial assays. In conclusion, one in five strains investigated was resistant to all first-line drugs, three of which had evidence of BDQ/CFZ resistance. Implementation of interventions such as rapid diagnostics that prevent further resistance development and stop MDR-TB transmission chains in the country is urgently needed.

IMPORTANCE

A substantial proportion of MDR-TB strains in Sierra Leone were resistant against all first line drugs; however this makes the all-oral-six-month BPaLM regimen or other 6-9 months all oral regimens still viable, mainly because there was no FQ resistance.Resistance to BDQ was detected, as well as RR, due to mutations outside of the hotspot region. While the prevalence of those resistances was low, it is still cause for concern and needs to be closely monitored.

The Detection of Mutations and Genotyping of Drug-Resistant Mycobacterium tuberculosis Strains Isolated from Patients in the Rural Eastern Cape Province

Drug-resistant tuberculosis (DR-TB) is still a major public health concern in South Africa. Mutations in M. tuberculosis can cause varying levels of phenotypic resistance to anti-TB medications. There have been no prior studies on gene mutations and the genotyping of DR-TB in the rural Eastern Cape Province; hence, we aimed to identify DR-TB mutations, genetic diversity, and allocated lineages among patients in this area. Using Xpert^® MTB/RIF, we assessed the rifampin resistance of sputum samples collected from 1157 patients suspected of having tuberculosis. GenoType MTBDR plus VER 2.0 was used for the detection of mutations causing resistance to anti-TB medications. The next step was to spoligotype 441 isolates. The most prevalent rifampin resistance-conferring mutations were in rpoB codon S531L in INH-resistant strains; the katG gene at codon S315TB and the inhA gene at codon C-15TB had the most mutations; 54.5% and 24.7%, respectively. In addition, 24.6% of strains showed mutations in both the rpoB and inhA genes, while 69.9% of strains showed mutations in both the katG and rpoB genes. Heteroresistance was seen in 17.9% of all cases in the study. According to spoligotyping analysis, Beijing families predominated. Investigation of the evolutionary lineages of M. tuberculosis isolates can be carried out using the information provided by the study's diversity of mutations. In locations wherein these mutations have been discovered, decision-making regarding the standardization of treatment regimens or individualized treatment may be aided by the detection frequency of rpoB, katG, and inhA mutations in various study areas.

Capacity building through comprehensive implementation research training and mentorship: an approach for translating knowledge into practice

BACKGROUND

Implementation research (IR) is increasingly gaining popularity as the act of carrying an intention into effect. It is thus an important approach to addressing individual practices, policies, programmes and other technologies to solving public health problems. Low- and middle-income countries (LMICs) continue to experience public health problems which could be addressed using implementation research. These countries however fall behind prioritizing implementation research due to the disorganized approach used to providing knowledge about the value and scope of implementation research. This paper seeks to explain steps taken to resolve this by capacity strengthening activities through a comprehensive implementation research training and mentorship programme which was informed by needs assessment.

METHODS

The roll-out of the comprehensive implementation research training and mentorship was done in phases, including engaging the implementation research community through TDR Global, competency building for programme officers and ethical review board/committee members, and practical guidance to develop an implementation research proposal. The Bloom taxonomy guided the training whilst the Kirkpatrick Model was used for the evaluation of the effectiveness of the capacity building.

RESULTS

The findings identified critical areas of mentors and how mentorship should be structured and the most effective ways of delivering mentorship. These findings were used to develop a mentorship guide in IR. The mentorship guidance is to be used as a check-tool for mentoring participants during trainings as part of the package of resources in implementation research. It is also to be used in equipping review board members with knowledge on ethical issues in implementation research.

CONCLUSION

The approach for providing comprehensive implementation research training and mentorship for programme personnel has provided an opportunity for both potential mentors and mentees to make inputs into developing a mentorship guidance for LMICs. This guidance would help address mentorship initiation and implementation challenges in IR.

Analysis of drug resistance among difficult-to-treat tuberculosis patients in Ghana identifies several pre-XDR TB cases

Background

Resistance to tuberculosis (TB) drugs has become a major threat to global control efforts. Early case detection and drug susceptibility profiling of the infecting bacteria are essential for appropriate case management. The objective of this study was to determine the drug susceptibility profiles of difficult-to-treat (DTT) TB patients in Ghana.

Methods

Sputum samples obtained from DTT-TB cases from health facilities across Ghana were processed for rapid diagnosis and detection of drug resistance using the Genotype MTBDRplus and Genotype MTBDRsl.v2 from Hain Life science.

Results

A total of 298 (90%) out of 331 sputum samples processed gave interpretable bands out of which 175 (58.7%) were resistant to at least one drug (ANYr); 16.8% (50/298) were isoniazid-mono-resistant (INHr), 16.8% (50/298) were rifampicin-mono-resistant (RIFr), and 25.2% (75/298) were MDR. 24 (13.7%) of the ANYr were additionally resistant to at least one second line drug: 7.4% (2 RIFr, 1 INHr, and 10 MDR samples) resistant to only FQs and 2.3% (2 RIFr, 1 INHr, and 1 MDR samples) resistant to AMG drugs kanamycin (KAN), amikacin (AMK), capreomycin (CAP), and viomycin (VIO). Additionally, there were 4.0% (5 RIFr and 2 MDR samples) resistant to both FQs and AMGs. 81 (65.6%) out of 125 INH-resistant samples including INHr and MDR had katG-mutations (MT) whereas 15 (12%) had inhApro-MT. The remaining 28 (22.4%) had both katG and inhA MT. All the 19 FQ-resistant samples were gyrA mutants whereas the 10 AMGs were rrs (3), eis (3) as well as rrs, and eis co-mutants (4). Except for the seven pre-XDR samples, no sample had eis MT.

Conclusion

The detection of several pre-XDR TB cases in Ghana calls for intensified drug resistance surveillance and monitoring of TB patients to, respectively, ensure early diagnosis and treatment compliance.

Genetic diversity and drug resistance profiles of Mycobacterium tuberculosis complex isolates from patients with extrapulmonary tuberculosis in Ghana and their associated host immune responses

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Pleural TB and TB lymphadenitis are the most common forms of extrapulmonary TB in Ghana.

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M. tb sub-lineage Cameroon is associated with decreased serum IL-1β, IL-17A, and IFN-α.

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A significant association was observed between age and M. tb complex lineages.

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Generally, M. bovis contributes minimally to human extrapulmonary TB in Ghana.

Objectives

This study sought to determine the genetic diversity and drug resistance profiles of Mycobacterium tuberculosis complex (MTBC) isolates from extrapulmonary tuberculosis (EPTB) patients in Ghana, and their associated immune responses.

Methods

Spoligotyping was performed on 102 MTBC isolates from EPTB patients. Lineages/sub-lineages were assigned by comparing spoligotyping patterns primarily with the SITVIT2 database and subsequently with the TB-Lineage online tool for unknown isolates in SITVIT2. Drug susceptibility testing was performed using MGIT (BD BACTEC 960), Lowenstein-Jensen media (indirect proportion method), and GenoType MTBDRplus/MTBDRsl assays. Differential cytokine levels in the serum of 20 EPTB patients infected with MTBC lineage 4 were determined using the Luminex multiplex immunoassay.

Results

Around 95% (97/102) of isolates were Mycobacterium tuberculosis, predominantly lineage 4 (95%; 92/97). Of the lineage 4 isolates, the majority were sub-lineage Cameroon (37%, 34/92). Prevalence was significantly higher in the 15–34 years age group among EPTB patients infected with lineage 4 strains (p = 0.024). Fifteen isolates were resistant to at least one anti-TB drug tested. Decreased levels of IL-1β, IL-17A, and IFN-α were observed in individuals infected with Cameroon sub-lineages compared with other lineage 4 sub-lineages.

Conclusions

Our study confirms Cameroon (SIT61) as the most common spoligotype causing human EPTB in Ghana, and that it is associated with decreased serum IL-1β, IL-17A, and IFN-α.

Treatment outcomes and associated factors among patients with multidrug-resistant tuberculosis in Ashanti Region, Ghana: a retrospective, cross-sectional study

OBJECTIVE

Although several studies have assessed treatment outcomes of drug-susceptible tuberculosis (TB) in Ghana, very little has been done in the area of multidrug-resistant TB (MDR-TB). The aim of this study was to determine treatment outcomes and associated factors among patients treated for MDR-TB in the Ashanti Region, Ghana.

DESIGN

A retrospective, cross-sectional analysis.

SETTING

The study was conducted in the Ashanti Region, the second most populous region in Ghana. The regional MDR-TB register, which contains information on all patients with MDR-TB being treated at the various TB centres in the region, was analysed between February and May 2021.

PARTICIPANTS

The participants consisted of all registered patients with MDR-TB who were placed on treatment between 1 January 2015 and 31 December 2020. Patients were included in the analysis if their treatment outcome had been assigned. Patients with no record of treatment outcome were excluded from the study.

OUTCOME MEASURES

The main outcome variable for the study was MDR-TB treatment outcome, standardised as 'cured', 'treatment completed', 'treatment failure', 'died' and 'lost to follow-up'. A logistic regression model was fitted for factors associated with the outcome measure.

RESULTS

Out of 159 patients included in the analysis, 86 (54.1%) were declared cured, 28 (17.6%) completed their treatment successfully, 6 (3.8%) were declared treatment failure, 12 (7.5%) were lost to follow-up and 27 (17.0%) died. The overall treatment success rate was 71.7%. Patients who were female (adjusted OR (AOR)=1.27, 95% CI: 1.18 to 1.39, p=0.023), younger (AOR=0.53, 95% CI: 0.19 to 2.11, p=0.012), had a higher level of education (AOR=1.12, 95% CI: 0.65 to 1.90, p=0.034), had a baseline body mass index of 18.5 kg/m² or above (AOR=1.57, 95% CI: 1.23 to 2.47, p=0.011) and those who did not have a history of TB (AOR=0.47, 95% CI: 0.10 to 0.75, p=0.028) were more likely to have successful MDR-TB treatment outcomes.

CONCLUSIONS

Favourable treatment outcomes for patients with MDR-TB can be achieved in a resource-limited country. Although the recommended WHO target of ≥75% was not met, the current result (71.7% treatment success rate) is still commendable considering all the challenges associated with TB treatment in Ghana.

Genetic Analysis of TB Susceptibility Variants in Ghana Reveals Candidate Protective Loci in SORBS2 and SCL11A1 Genes

Despite advancements made toward diagnostics, tuberculosis caused by Mycobacterium africanum (Maf) and Mycobacterium tuberculosis sensu stricto (Mtbss) remains a major public health issue. Human host factors are key players in tuberculosis (TB) outcomes and treatment. Research is required to probe the interplay between host and bacterial genomes. Here, we explored the association between selected human/host genomic variants and TB disease in Ghana. Paired host genotype datum and infecting bacterial isolate information were analyzed for associations using a multinomial logistic regression. Mycobacterium tuberculosis complex (MTBC) isolates were obtained from 191 TB patients and genotyped into different phylogenetic lineages by standard methods. Two hundred and thirty-five (235) nondisease participants were used as healthy controls. A selection of 29 SNPs from TB disease-associated genes with high frequency among African populations was assayed using a TaqMan® SNP Genotyping Assay and iPLEX Gold Sequenom Mass Genotyping Array. Using 26 high-quality SNPs across 326 case-control samples in an association analysis, we found a protective variant, rs955263, in the SORBS2 gene against both Maf and Mtb infections (P BH  = 0.05; OR = 0.33; 95% CI = 0.32-0.34). A relatively uncommon variant, rs17235409 in the SLC11A1 gene was observed with an even stronger protective effect against Mtb infection (MAF = 0.06; PBH = 0.04; OR = 0.05; 95% CI = 0.04-0.05). These findings suggest SLC11A1 and SORBS2 as a potential protective gene of substantial interest for TB, which is an important pathogen in West Africa, and highlight the need for in-depth host-pathogen studies in West Africa.

Analysis of Factors Influencing Multidrug-Resistant Tuberculosis and Validation of Whole-Genome Sequencing in Children with Drug-Resistant Tuberculosis

Objective

Pediatric tuberculosis (TB) is one of the top ten causes of death in children. Our study was to analyze influencing factors of multidrug-resistant tuberculosis (MDR-TB) and validation of whole-genome sequencing (WGS) used in children with drug-resistant TB (DR-TB).

Methods

All Mycobacterium tuberculosis (Mtb) strains were isolated from patients aged below 18 years old of Children’s Hospital of Chongqing Medical University, China. A total of 208 Mtb isolates were tested for eight anti-TB drugs with phenotypic drug susceptibility test (DST) and for genetic prediction of the susceptible profile with WGS. The patients corresponding to each strain were grouped according to drug resistance and genotype. Influencing factors of MDR-TB and DR-TB were analyzed.

Results

According to the phenotypic DST and WGS, 82.2% of Mtb strains were susceptible to all eight drugs, and 6.3% were MDR-TB. Using the phenotypic DSTs as the gold standard, the kappa value of WGS to predict isoniazid, rifampin, ethambutol, rifapentine, prothionamide, levofloxacin, moxifloxacin and amikacin was 0.84, 0.89, 0.59, 0.86, 0.89, 0.82, 0.88 and 1.00, respectively. There was significant difference in the distribution of severe TB, diagnosis, treatment and outcome between MDR and drug-susceptible group (P<0.05). The distribution of severe TB and treatment between DR and drug-susceptible group was statistically different (P<0.05). The results of binary logistic regression showed that Calmette–Guérin bacillus (BCG) vaccine is the protective factor for MDR-TB (OR=0.19), and MDR-TB is the risk factor for PTB and EPTB (OR=17.98).

Conclusion

The BCG vaccine is a protective factor for MDR-TB, and MDR-TB might not be confined to pulmonary infection, spreading to extrapulmonary organs in children. MDR-TB had more severe cases and a lower recovery rate than drug-susceptible TB. WGS could provide an accurate prediction of drug susceptibility test results for anti-TB drugs, which are needed for the diagnosis and precise treatment of TB in children.

Genotypic and phenotypic diversity of Mycobacterium tuberculosis complex genotypes prevalent in West Africa

Findings from previous comparative genomics studies of the Mycobacterium tuberculosis complex (MTBC) suggest genomic variation among the genotypes may have phenotypic implications. We investigated the diversity in the phenotypic profiles of the main prevalent MTBC genotypes in West Africa. Thirty-six whole genome sequenced drug susceptible MTBC isolates belonging to lineages 4, 5 and 6 were included in this study. The isolates were phenotypically characterized for urease activity, tween hydrolysis, Thiophen-2-Carboxylic Acid Hydrazide (TCH) susceptibility, nitric oxide production, and growth rate in both liquid (7H9) and solid media (7H11 and Löwenstein-Jensen (L-J)). Lineage 4 isolates showed the highest growth rate in both liquid (p = 0.0003) and on solid (L-J) media supplemented with glycerol (p<0.001) or pyruvate (p = 0.005). L6 isolates optimally utilized pyruvate compared to glycerol (p<0.001), whereas L5 isolates grew similarly on both media (p = 0.05). Lineage 4 isolates showed the lowest average time to positivity (TTP) (p = 0.01; Average TTP: L4 = 15days, L5 = 16.7days, L6 = 29.7days) and the highest logCFU/mL (p = 0.04; average logCFU/mL L4 = 5.9, L5 = 5.0, L6 = 4.4) on 7H11 supplemented with glycerol, but there was no significant difference in growth on 7H11 supplemented with pyruvate (p = 0.23). The highest release of nitrite was recorded for L5 isolates, followed by L4 and L6 isolates. However, the reverse was observed in the urease activity for the lineages. All isolates tested were resistant to TCH except for one L6 isolate. Comparative genomic analyses revealed several mutations that might explain the diverse phenotypic profiles of these isolates. Our findings showed significant phenotypic diversity among the MTBC lineages used for this study.

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.

Molecular epidemiology and drug susceptibility profiles of Mycobacterium tuberculosis complex isolates from Northern Ghana

OBJECTIVE

We conducted a cross-sectional study in the five administrative regions of Northern Ghana to determine the diversity of Mycobacterium tuberculosis complex (MTBC) sub/lineages and their susceptibility to isoniazid (INH) and rifampicin (RIF).

METHODS

Sputum specimens were collected and cultured from 566 pulmonary tuberculosis patients reporting to 17 health facilities from 2015 to 2019. Mycobacterial isolates obtained from solid cultures were confirmed as members of the MTBC by PCR amplification of IS6110 and rpoß and assigned lineages and sub-lineages using spoligotyping.

RESULTS

Of 294 mycobacterial isolates recovered, MTBC species identified were: M. tuberculosis sensu stricto (Mtbss) 241 (82.0%), M. africanum 41 (13.9%) and M. bovis four (1.4%) with eight (2.7%) unidentified. The human-adapted lineages (L) identified (N=279) were L1 (8/279, 2.9%), L2 (15/279, 5.4%), L3 (7/279, 2.5%), L4 (208/279, 74.5%), L5 (13/279, 4.7%) and L6 (28/279, 10.0%) with three unidentified lineages. Among the 208 L4, the dominant sub-lineages in the region were the Cameroon 120/208 (57.7%) and Ghana 50/208 (24.0%). We found 4.4% (13/294) and 0.7% (2/294) of the patients infected with MTBC isolates resistant to INH only and RIF only, respectively, with 2.4% (7/294) being infected with MDR strains. Whereas L6 was associated with the elderly, we identified that the Ghana sub-lineage of L4 was associated with both INH and MDR (p<0.05), making them important TB pathogens in Northern Ghana and a growing public health concern.

TB or not TB? Definitive determination of species within the Mycobacterium tuberculosis complex in unprocessed sputum from adults with presumed multidrug-resistant tuberculosis

Objectives

Differences among Mycobacterium tuberculosis complex (MTC) species may predict drug resistance or treatment success. Thus, we optimised and deployed the genotype MTBC assay (gMTBC) to identify MTC to the species level, and then performed comparative genotypic drug‐susceptibility testing to anti‐tuberculosis drugs from direct sputum of patients with presumed multidrug‐resistant tuberculosis (MDR‐TB) by the MTBDRplus/sl reference method.

Methods

Patients with positive Xpert^® MTB/RIF (Xpert) results were consented to provide early‐morning‐sputum for testing by the gMTBC and the reference MTBDRplus/sl. Chi‐square or Fisher’s exact test compared proportions. Modified Poisson regression modelled detection of MTC by gMTBC.

Results

Among 73 patients, 53 (73%) were male and had a mean age of 43 (95% CI; 40–45) years. In total, 34 (47%), 36 (49%) and 38 (55%) had positive gMTBC, culture and MTBDR respectively. Forty patients (55%) had low quantity MTC by Xpert, including 31 (78%) with a negative culture. gMTBC was more likely to be positive in patients with chest cavity 4.18 (1.31–13.32, P = 0.016), high‐quantity MTC by Xpert 3.03 (1.35–6.82, P = 0.007) and sputum smear positivity 1.93 (1.19–3.14, P = 0.008). The accuracy of gMTBC in detecting MTC was 95% (95% CI; 86–98; κ = 0.89) compared to MTBDRplus/sl. All M. tuberculosis/canettii identified by gMTB were susceptible to fluoroquinolone and aminoglycosides/capreomycin.

Conclusions

The concordance between the gMTBC assay and MTBDRplus/sl in detecting MTC was high but lagged behind the yield of Xpert MTB/RIF. All M. tuberculosis/canettii were susceptible to fluoroquinolones, a core drug in MDR‐TB treatment regimens.

The burden of drug resistance tuberculosis in Ghana; results of the First National Survey

Resistance to Tuberculosis drugs has become a major threat to the control of tuberculosis (TB) globally. We conducted the first nation-wide drug resistance survey to investigate the level and pattern of resistance to first-line TB drugs among newly and previously treated sputum smear-positive TB cases. We also evaluated associations between potential risk factors and TB drug resistance. Using the World Health Organization (WHO) guidelines on conducting national TB surveys, we selected study participants from 33 health facilities from across the country, grouped into 29 clusters, and included them into the survey. Between April 2016 and June 2017, a total of 927 patients (859 new and 68 previously treated) were enrolled in the survey. Mycobacterium tuberculosis complex (MTBC) isolates were successfully cultured from 598 (65.5%) patient samples and underwent DST, 550 from newly diagnosed and 48 from previously treated patients. The proportion of patients who showed resistance to any of the TB drugs tested was 25.2% (95% CI; 21.8–28.9). The most frequent resistance was to Streptomycin (STR) (12.3%), followed by Isoniazid (INH) (10.4%), with Rifampicin (RIF), showing the least resistance of 2.4%. Resistance to Isoniazid and Rifampicin (multi-drug resistance) was found in 19 (3.2%; 95% CI: 1.9–4.9) isolates. Prevalence of multidrug resistance was 7 (1.3%; 95% CI: 0.5–2.6) among newly diagnosed and 12 (25.0%; 95% CI: 13.6–39.6) among previously treated patients. At both univariate and multivariate analysis, MDR-TB was positively associated with previous history of TB treatment (OR = 5.09, 95% CI: 1.75–14.75, p = 0.003); (OR = 5.41, 95% CI: 1.69–17.30, p = 0.004). The higher levels of MDR-TB and overall resistance to any TB drug among previously treated patients raises concerns about adherence to treatment. This calls for strengthening existing TB programme measures to ensure a system for adequately testing and monitoring TB drug resistance.

Molecular epidemiology of Mycobacterium tuberculosis complex in the Volta Region of Ghana

CONTEXT

Available molecular epidemiological data from recent studies suggest significant genetic variation between the different lineages of Mycobacterium tuberculosis complex (MTBC) and the MTBC lineages might have adapted to different human populations.

AIM

This study sought to determine the population structure of clinical MTBC isolates from the Volta Region of Ghana.

METHODS

The MTBC isolates obtained from collected sputum samples were identified by PCR detecting of IS6110 and genotyped using spoligotyping. Non-tuberculous mycobacterial isolates were characterized by amplification of the heat shock protein 65 (hsp65) gene and sequencing. The drug susceptibility profiles of the MTBCs determined using GenoType MTBDRplus.

RESULTS

One hundred and seventeen (117, 93.6%) out of 125 mycobacterial positive isolates were characterized as members of the MTBC of which M. tuberculosis sensu stricto (MTBss) and M. africanum (MAF) were respectively 94 (80.3%) and 23 (19.7%). In all, 39 distinct spoligotype patterns were obtained; 26 for MTBss and 13 for MAF lineages. Spoligotyping identified 89 (76%) Lineage 4, 16 (13.6%) Lineage 5, 7 (6.0%) Lineage 6, 3 (2.6%) Lineage 2, 1(0.9%) Lineage 3 and 1 (0.9%) Lineage 1. Among the Lineage 4 isolates, 62/89 (69.7%) belonged to Cameroon sub-lineage, 13 (14.7%) Ghana, 8 (9.0%) Haarlem, 2 (2.2%) LAM, 1 (1.1%) Uganda I, 1 (1.1%) X and the remaining two (2.2%) were orphan. Significant localization of MAF was found within the Ho municipality (n = 13, 29.5%) compared to the more cosmopolitan Ketu-South/Aflao (n = 3, 8.3%) (p-value = 0.017). Eight (8) non-tuberculous mycobacteria were characterized as M. abscessus (7) and M. fortuitum (1).

CONCLUSION

We confirmed the importance of M. africanum lineages as a cause of TB in the Volta region of Ghana.

Genomic epidemiological analysis identifies high relapse among individuals with recurring tuberculosis and provides evidence of recent household-related transmission of tuberculosis in Ghana

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Unresolved previous infection as major cause of recurring tuberculosis (TB) in Ghana.

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Genomic epidemiology identifies high relapse among recurrent TB cases in Ghana.

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15-locus MIRU-VNTR typing is sufficient to predict the cause of TB recurrence.

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Evidence of recent household-related TB transmission in Ghana.

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Need for increased education by national TB control program.

Objective

To retrospectively investigate the cause of recurring tuberculosis (rcTB) among participants with pulmonary TB recruited from a prospective population-based study conducted between July 2012 and December 2015.

Methods

Mycobacterium tuberculosis complex isolates obtained from rcTB cases were characterized by standard mycobacterial genotyping tools, whole-genome sequencing, and phylogenetic analysis carried out to assess strain relatedness.

Results

The majority (58.3%, 21/36) of study participants with rcTB episodes had TB recurrence within 12 months post treatment. TB strains with isoniazid (INH) resistance were found in 19.4% (7/36) of participants at the primary episode, of which 29% (2/7) were also rifampicin-resistant. On TB recurrence, an INH-resistant strain was found in a larger proportion of participants, 27.8% (10/36), of which 40% (4/10) were MDR-TB strains. rcTB was attributed to relapse (same strain) in 75.0% (27/36) of participants and 25.0% (9/36) to re-infection.

Conclusion

Our findings indicate that previous unresolved infectiondue to inadequate treatment, may be the major cause of rcTB.

Phylogenomics of Mycobacterium africanum reveals a new lineage and a complex evolutionary history

Human tuberculosis (TB) is caused by members of the Mycobacterium tuberculosis complex (MTBC). The MTBC comprises several human-adapted lineages known as M. tuberculosis sensu stricto, as well as two lineages (L5 and L6) traditionally referred to as Mycobacterium africanum. Strains of L5 and L6 are largely limited to West Africa for reasons unknown, and little is known of their genomic diversity, phylogeography and evolution. Here, we analysed the genomes of 350 L5 and 320 L6 strains, isolated from patients from 21 African countries, plus 5 related genomes that had not been classified into any of the known MTBC lineages. Our population genomic and phylogeographical analyses showed that the unclassified genomes belonged to a new group that we propose to name MTBC lineage 9 (L9). While the most likely ancestral distribution of L9 was predicted to be East Africa, the most likely ancestral distribution for both L5 and L6 was the Eastern part of West Africa. Moreover, we found important differences between L5 and L6 strains with respect to their phylogeographical substructure and genetic diversity. Finally, we could not confirm the previous association of drug-resistance markers with lineage and sublineages. Instead, our results indicate that the association of drug resistance with lineage is most likely driven by sample bias or geography. In conclusion, our study sheds new light onto the genomic diversity and evolutionary history of M. africanum, and highlights the need to consider the particularities of each MTBC lineage for understanding the ecology and epidemiology of TB in Africa and globally.

Whole Genome Sequencing and Spatial Analysis Identifies Recent Tuberculosis Transmission Hotspots in Ghana

Whole genome sequencing (WGS) is progressively being used to investigate the transmission dynamics of Mycobacterium tuberculosis complex (MTBC). We used WGS analysis to resolve traditional genotype clusters and explored the spatial distribution of confirmed recent transmission clusters. Bacterial genomes from a total of 452 MTBC isolates belonging to large traditional clusters from a population-based study spanning July 2012 and December 2015 were obtained through short read next-generation sequencing using the illumina HiSeq2500 platform. We performed clustering and spatial analysis using specified R packages and ArcGIS. Of the 452 traditional genotype clustered genomes, 314 (69.5%) were confirmed clusters with a median cluster size of 7.5 genomes and an interquartile range of 4–12. Recent tuberculosis (TB) transmission was estimated as 24.7%. We confirmed the wide spread of a Cameroon sub-lineage clone with a cluster size of 78 genomes predominantly from the Ablekuma sub-district of Accra metropolis. More importantly, we identified a recent transmission cluster associated with isoniazid resistance belonging to the Ghana sub-lineage of lineage 4. WGS was useful in detecting unsuspected outbreaks; hence, we recommend its use not only as a research tool but as a surveillance tool to aid in providing the necessary guided steps to track, monitor, and control TB.

Molecular epidemiology of drug resistant Mycobacterium tuberculosis in Africa: a systematic review

Background

The burden of drug resistant tuberculosis in Africa is largely driven by the emergence and spread of multidrug resistant (MDR) and extensively drug resistant (XDR) Mycobacterium tuberculosis strains. MDR-TB is defined as resistance to isoniazid and rifampicin, while XDR-TB is defined as MDR-TB with added resistance to any of the second line injectable drugs and any fluoroquinolone.

The highest burden of drug resistant TB is seen in countries further experiencing an HIV epidemic. The molecular mechanisms of drug resistance as well as the evolution of drug resistant TB strains have been widely studied using various genotyping tools. The study aimed to analyse the drug resistant lineages in circulation and transmission dynamics of these lineages in Africa by describing outbreaks, nosocomial transmission and migration. Viewed as a whole, this can give a better insight into the transmission dynamics of drug resistant TB in Africa.

Methods

A systematic review was performed on peer reviewed original research extracted from PubMed reporting on the lineages associated with drug resistant TB from African countries, and their association with outbreaks, nosocomial transmission and migration. The search terms “Tuberculosis AND drug resistance AND Africa AND (spoligotyping OR molecular epidemiology OR IS6110 OR MIRU OR DNA fingerprinting OR RFLP OR VNTR OR WGS)” were used to identify relevant articles reporting the molecular epidemiology of drug resistant TB in Africa.

Results

Diverse genotypes are associated with drug resistant TB in Africa, with variations in strain predominance within the continent. Lineage 4 predominates across Africa demonstrating the ability of “modern strains” to adapt and spread easily. Most studies under review reported primary drug resistance as the predominant type of transmission. Drug resistant TB strains are associated with community and nosocomial outbreaks involving MDR- and XDR-TB strains. The under-use of molecular epidemiological tools is of concern, resulting in gaps in knowledge of the transmission dynamics of drug resistant TB on the continent.

Conclusions

Genetic diversity of M. tuberculosis strains has been demonstrated across Africa implying that diverse genotypes are driving the epidemiology of drug resistant TB across the continent.

Whole genome enrichment approach for rapid detection of Mycobacterium tuberculosis and drug resistance-associated mutations from direct sputum sequencing

Tuberculosis is the leading cause of death among infectious diseases worldwide. Detection of Mycobacterium tuberculosis (Mtb), using routine culture-based methods is time consuming resulting in delayed diagnosis and poor treatment outcomes. Currently available molecular tests provide faster diagnosis but are able to screen only limited hot-spot mutations. Whole genome sequencing from direct sputum offers a potential solution, however, due to the presence of other microbes and host DNA its use in diagnostic testing remains challenging. In this study, we present a targeted Mtb-enrichment assay for lineage-4 coupled with an improved analysis pipeline that uses 1657 bacterial taxa as background for reducing non-Mtb genome from sputum DNA. This method drastically improved the recovery of Mtb DNA from sputum (Mtb alignment increased from 3% to >65%) as compared to non-enrichment-based sequencing. We obtained >99% Mtb genome coverage as compared to 49% in non-enriched sputum sequencing. We were able to identify Mtb positive samples from controls with 100% accuracy using Mpt64 gene coverage. Our method not only achieved 100% sensitivity to resistance variants profiled by line probe assay (LPA), but also outperformed LPA in determining drug resistance based on phenotypic drug susceptibility tests for 6 anti-tuberculosis drugs (accuracy of 97.7% and 92.8% by enriched WGS and LPA, respectively).

Detection of drug resistant Mycobacterium tuberculosis by high-throughput sequencing of DNA isolated from acid fast bacilli smears

BACKGROUND

Drug susceptibility testing for Mycobacterium tuberculosis (MTB) is difficult to perform in resource-limited settings where Acid Fast Bacilli (AFB) smears are commonly used for disease diagnosis and monitoring. We developed a simple method for extraction of MTB DNA from AFB smears for sequencing-based detection of mutations associated with resistance to all first and several second-line anti-tuberculosis drugs.

METHODS

We isolated MTB DNA by boiling smear content in a Chelex solution, followed by column purification. We sequenced PCR-amplified segments of the rpoB, katG, embB, gyrA, gyrB, rpsL, and rrs genes, the inhA, eis, and pncA promoters and the entire pncA gene.

RESULTS

We tested our assay on 1,208 clinically obtained AFB smears from Ghana (n = 379), Kenya (n = 517), Uganda (n = 262), and Zambia (n = 50). Coverage depth varied by target and slide smear grade, ranging from 300X to 12000X on average. Coverage of ≥20X was obtained for all targets in 870 (72%) slides overall. Mono-resistance (5.9%), multi-drug resistance (1.8%), and poly-resistance (2.4%) mutation profiles were detected in 10% of slides overall, and in over 32% of retreatment and follow-up cases.

CONCLUSION

This rapid AFB smear DNA-based method for determining drug resistance may be useful for the diagnosis and surveillance of drug-resistant tuberculosis.

Identification and Characterization of Genetic Determinants of Isoniazid and Rifampicin Resistance in Mycobacterium tuberculosis in Southern India

Drug-resistant tuberculosis (TB), one of the leading causes of death worldwide, arises mainly from spontaneous mutations in the genome of Mycobacterium tuberculosis. There is an urgent need to understand the mechanisms by which the mutations confer resistance in order to identify new drug targets and to design new drugs. Previous studies have reported numerous mutations that confer resistance to anti-TB drugs, but there has been little systematic analysis to understand their genetic background and the potential impacts on the drug target stability and/or interactions. Here, we report the analysis of whole-genome sequence data for 98 clinical M. tuberculosis isolates from a city in southern India. The collection was screened for phenotypic resistance and sequenced to mine the genetic mutations conferring resistance to isoniazid and rifampicin. The most frequent mutation among isoniazid and rifampicin isolates was S315T in katG and S450L in rpoB respectively. The impacts of mutations on protein stability, protein-protein interactions and protein-ligand interactions were analysed using both statistical and machine-learning approaches. Drug-resistant mutations were predicted not only to target active sites in an orthosteric manner, but also to act through allosteric mechanisms arising from distant sites, sometimes at the protein-protein interface.

First genetic characterisation of multidrug-resistant Mycobacterium tuberculosis isolates from Algeria

OBJECTIVES

To characterise the genotypes of multidrug-resistant (MDR) Mycobacterium tuberculosis (MTB) isolated in Algeria, where there is a low MDR-MTB incidence rate.

METHODS

Ten MDR isolates and one resistant to isoniazid were investigated by PCR-Sanger sequencing for 10 loci involved in resistance. Amplicon-based next generation sequencing (NGS) of 15 loci was additionally performed on isolates harbouring novel mutations.

RESULTS

Sanger and amplicon-NGS provided the same results as with GenoType kits. Mutations known to be associated with resistance were described for most isolates: rpoB S531L in seven of 10 rifampicin-R MTB isolates, katG S315T in nine of 11 isoniazid-R, and promoter inhA c-15t in three of 11, embB M306V or M306I in two of two ethambutol-R, rpsL K43R in four of eight or rrs a514c associated with gidB L16R in streptomycin-R, gyrA A90V in the ofloxacin-R pre-XDR isolate. New and rare mutations were also described in rpoB (deletion 512-513-514), katG (S315R, M126I/ R496L), gidB (V124G, E92A, V139A, G37V), and gyrA (P8A). Mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) profiles were similar for three isolates (lineage Cameroon), indicating a possible clonal diffusion in epidemiologically unrelated patients.

CONCLUSIONS

Resistant MTB isolates in Algeria harbour resistance genotypes similar to other countries, but some rare patterns may result from selection and transmission processes inherent to the country.

Molecular epidemiology and whole genome sequencing analysis of clinical Mycobacterium bovis from Ghana

BACKGROUND

Bovine tuberculosis (bTB) caused by Mycobacterium bovis is a re-emerging problem in both livestock and humans. The association of some M. bovis strains with hyper-virulence, MDR-TB and disseminated disease makes it imperative to understand the biology of the pathogen.

METHODS

Mycobacterium bovis (15) among 1755 M. tuberculosis complex (MTBC) isolated between 2012 and 2014 were characterized and analyzed for associated patient demography and other risk factors. Five of the M. bovis isolates were whole-genome sequenced and comparatively analyzed against a global collection of published M. bovis genomes.

RESULTS

Mycobacterium bovis was isolated from 3/560(0.5%) females and 12/1195(1.0%) males with pulmonary TB. The average age of M. bovis infected cases was 46.8 years (7-72years). TB patients from the Northern region of Ghana (1.9%;4/212) had a higher rate of infection with M. bovis (OR = 2.7,p = 0.0968) compared to those from the Greater Accra region (0.7%;11/1543). Among TB patients with available HIV status, the odds of isolating M. bovis from HIV patients (2/119) was 3.3 higher relative to non-HIV patients (4/774). Direct contact with livestock or their unpasteurized products was significantly associated with bTB (p<0.0001, OR = 124.4,95% CI = 30.1-508.3). Two (13.3%) of the M. bovis isolates were INH resistant due to the S315T mutation in katG whereas one (6.7%) was RIF resistant with Q432P and I1491S mutations in rpoB. M. bovis from Ghana resolved as mono-phyletic branch among mostly M. bovis from Africa irrespective of the host and were closest to the root of the global M. bovis phylogeny. M. bovis-specific amino acid mutations were detected among MTBC core genes such as mce1A, mmpL1, pks6, phoT, pstB, glgP and Rv2955c. Additional mutations P6T in chaA, G187E in mgtC, T35A in Rv1979c, S387A in narK1, L400F in fas and A563T in eccA1 were restricted to the 5 clinical M. bovis from Ghana.

CONCLUSION

Our data indicate potential zoonotic transmission of bTB in Ghana and hence calls for intensified public education on bTB, especially among risk groups.

Unexpected Genomic and Phenotypic Diversity of Mycobacterium africanum Lineage 5 Affects Drug Resistance, Protein Secretion, and Immunogenicity

Mycobacterium africanum consists of Lineages L5 and L6 of the Mycobacterium tuberculosis complex (MTBC) and causes human tuberculosis in specific regions of Western Africa, but is generally not transmitted in other parts of the world. Since M. africanum is evolutionarily closely placed between the globally dispersed Mycobacterium tuberculosis and animal-adapted MTBC-members, these lineages provide valuable insight into M. tuberculosis evolution. Here, we have collected 15 M. africanum L5 strains isolated in France over 4 decades. Illumina sequencing and phylogenomic analysis revealed a previously underappreciated diversity within L5, which consists of distinct sublineages. L5 strains caused relatively high levels of extrapulmonary tuberculosis and included multi- and extensively drug-resistant isolates, especially in the newly defined sublineage L5.2. The specific L5 sublineages also exhibit distinct phenotypic characteristics related to in vitro growth, protein secretion and in vivo immunogenicity. In particular, we identified a PE_PGRS and PPE-MPTR secretion defect specific for sublineage L5.2, which was independent of PPE38. Furthermore, L5 isolates were able to efficiently secrete and induce immune responses against ESX-1 substrates contrary to previous predictions. These phenotypes of Type VII protein secretion and immunogenicity provide valuable information to better link genome sequences to phenotypic traits and thereby understand the evolution of the MTBC.

Reduced transmission of Mycobacterium africanum compared to Mycobacterium tuberculosis in urban West Africa

OBJECTIVE

Understanding transmission dynamics is useful for tuberculosis (TB) control. A population-based molecular epidemiological study was conducted to determine TB transmission in Ghana.

METHODS

Mycobacterium tuberculosis complex (MTBC) isolates obtained from prospectively sampled pulmonary TB patients between July 2012 and December 2015 were characterized using spoligotyping and standard 15-locus mycobacterial interspersed repetitive unit variable number tandem repeat (MIRU-VNTR) typing for transmission studies.

RESULTS

Out of 2309 MTBC isolates, 1082 (46.9%) unique cases were identified, with 1227 (53.1%) isolates belonging to one of 276 clusters. The recent TB transmission rate was estimated to be 41.2%. Whereas TB strains of lineage 4 belonging to M. tuberculosis showed a high recent transmission rate (44.9%), reduced recent transmission rates were found for lineages of Mycobacterium africanum (lineage 5, 31.8%; lineage 6, 24.7%).

CONCLUSIONS

The study findings indicate high recent TB transmission, suggesting the occurrence of unsuspected outbreaks in Ghana. The observed reduced transmission rate of M. africanum suggests other factor(s) (host/environmental) may be responsible for its continuous presence in West Africa.

Comparative genomics of Mycobacterium africanum Lineage 5 and Lineage 6 from Ghana suggests distinct ecological niches

Mycobacterium africanum (Maf) causes a substantial proportion of human tuberculosis in some countries of West Africa, but little is known on this pathogen. We compared the genomes of 253 Maf clinical isolates from Ghana, including N = 175 Lineage 5 (L5) and N = 78 Lineage 6 (L6). We found that the genomic diversity of L6 was higher than in L5 despite the smaller sample size. Regulatory proteins appeared to evolve neutrally in L5 but under purifying selection in L6. Even though over 90% of the human T cell epitopes were conserved in both lineages, L6 showed a higher ratio of non-synonymous to synonymous single nucleotide variation in these epitopes overall compared to L5. Of the 10% human T cell epitopes that were variable, most carried mutations that were lineage-specific. Our findings indicate that Maf L5 and L6 differ in some of their population genomic characteristics, possibly reflecting different selection pressures linked to distinct ecological niches.

Isolation and characterization of nontuberculous mycobacteria from patients with pulmonary tuberculosis in Ghana

OBJECTIVE/BACKGROUND

Nontuberculous mycobacterial (NTM) species are assuming public health importance in pulmonary diseases; they are increasingly being isolated, and importantly, most NTMs do not respond to routine tuberculosis (TB) drugs. This study aimed to identify NTMs isolated from pulmonary TB cases and also determine their susceptibility to streptomycin (STR), isoniazid (INH), and rifampicin (RIF).

METHODS

A total of 1755 mycobacterial isolates, obtained between August 2012 and July 2014, from 2036 smear-positive pulmonary cases were identified using polymerase chain reaction amplification of IS6110, and hsp65 gene sequencing analysis. Drug susceptibility testing (DST) was then performed for the identified NTMs against STR, INH, and RIF using microplate Alamar blue assay. The results were analyzed against patients' biodata for statistical associations.

RESULTS

Of the 1755 analyzed isolates, we identified 43 (2.5%) NTMs, which included 18 (41.9%) Mycobacterium intracellulare, 13 (30.2%) Mycobacterium avium subs. paratuberculosis, 5 (11.3%) Mycobacterium abscessus, 3 (7.0%) each of Mycobacterium mucogenicum and Mycobacterium colombiense, and 1 (2.3%) Mycobacterium simiae. Patients infected with NTMs (52.0%) were more likely to be human immunodeficiency virus-positive (P = 0.001, odds ratio = 6.6, 95% confidence interval = 2.7-16.2) than those infected with M. tuberculosis complex (5.8%). All the 43 (100%) NTMs were resistant to INH, whereas 32 (74%) and 19 (44%) were resistant to RIF and STR, respectively. Furthermore, 16 (37.2%) NTMs were resistant to all three drugs, 20 were resistant to INH and RIF, and 3 were resistant to STR and INH. All the M. abscessus isolates were resistant to all the three drugs, whereas all the M. avium isolates were resistant to INH and RIF, but only three were resistant to STR. Among the M. intracellulare isolates, 8, 18, and 15 isolates were resistant to STR, INH, and RIF, respectively.

CONCLUSION

The observed high-resistance level to INH and RIF supports the need for rapid species identification and DST of nonresponding TB cases before retreatment.

Whole genome sequencing for M/XDR tuberculosis surveillance and for resistance testing

Whole genome sequencing (WGS) can help to relate Mycobacterium tuberculosis genomes to one another to assess genetic relatedness and infer the likelihood of transmission between cases. The same sequence data are now increasingly being used to predict drug resistance and susceptibility. Controlling the spread of tuberculosis and providing patients with the correct treatment are central to the World Health Organization's target to 'End TB' by 2035, for which the global prevalence of drug-resistant tuberculosis remains one of the main obstacles to success. So far, WGS has been applied largely to drug-susceptible strains for the purposes of understanding transmission, leaving a number of analytical considerations before transferring what has been learnt from drug-susceptible disease to drug-resistant tuberculosis. We discuss these potential problems here, alongside some of the challenges to characterizing the Mycobacterium tuberculosis 'resistome'-the optimal knowledge-base required for WGS-based assays to successfully direct individualized treatment regimens through the prediction of drug resistance and susceptibility in the future.