Research Articles

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A research article reports the results of original research, assesses its contribution to the body of knowledge in a given area, and is published in a peer-reviewed scholarly journal. The faculty publications through published and on-going articles/researches are captured in this community

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    The Relevance of Genomic Epidemiology for Control of Tuberculosis in West Africa
    (Frontiers, 2021) Asare, P.; Asante-Poku, A.; Osei-Wusu, S.; Otchere, I.D.; Yeboah-Manu, D.
    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 tocmonitor 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.
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    Synthesis and Initial Testing of Novel Antimalarial and Antitubercular Isonicotinohydrazides
    (Elsevier B.V., 2022) Amewu, R. K.; Ade, C.F.; Otchere, I.D.; Morgan, P.; Yeboah-Manu, D.
    Malaria and tuberculosis (TB) though curable and preventable, remain serious public health problems globally, with devastating consequences. Co-infection of these two deadly diseases worsens the situation and particularly makes treatment very difficult. The current mainstay for malaria treatment is gradually losing their potency due to the development of resistance. Macobacterium tuberculosis (MTB) has developed Multi-drug Resistance (MDR) and Extensive Drug Resistance (XDR) to current antitubercular drugs due to patient incompliance resulting from long treatment regimen. A small library of isonicotinohydrazide were synthesised by incorporating 1,2,4,5- tetraoxane and hydrazine moieties. Evaluation of the compounds gave antimalarial activities in the range 0.060 ± 0.033–0.491 ± 0.012 μM against 3D7 strain of Plasmodium falciparum. We assessed antimycobacterial activity of selected compounds against the standard Mycobacterium tuberculosis reference strain H37Rv and M. aurum (a non-tuberculous mycobacteria) using the microplate Alamar blue (MABA) assay and found four compounds to be very potent against H37Rv but largely inactive against Macobacterium aurum. We followed up to estimate the minimum inhibitory concentrations of these active compounds and tested them against clinical M. tuberculosis strains resistant to isoniazid (INH) and rifampicin (RIF). The MICs of the active compounds against H37Rv were between 0.003 and 0.5 mg/mL however, they were largely inactive against drug resistant clinical strains except for the INH mono-resistant resistant strain which was very active with compounds 5 and 8 possessing MICs of 0.125 mg/mL.
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    Relevance of genomic diversity of Mycobacterium tuberculosis complex in Africa
    (Elsevier, 2022) Osei-Wusu, S.; Otchere, I.D.; Asare, P.; Ntoumi, F.; Zumla, A.; Asante-Poku, A.; Yeboah-Manu, D.
    Background: The diversity in the lineages of Mycobacterium tuberculosis complex (MTBC) was initially considered insignificant. However, comparative genomics analysis of MTBC have found genomic variation among the genotypes with potential phenotypic implications. Objective: Therefore, this viewpoint seeks to discuss the impact of the identified genotypic diversity on the physiology of MTBC and the potential implications on TB control. Results: Studies conducted in West Africa and other parts of Africa have unravelled the implications of the genomic diversity on phenotypes such as disease outcome, transmission dynamics and host immune response. The understanding of the phenotypic diversity among the different lineages of MTBC may be an important key to the fight against TB. Conclusion: The relevance of these differences has been observed in the design of new control tools such as diagnostics and anti-TB drugs/vaccines. This only points to the fact that the diversity in MTBC cannot be ignored in future studies especially clinical trials for new vaccines and new anti-TB drugs.
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    Genetic Analysis of TB Susceptibility Variants in Ghana Reveals Candidate Protective Loci in SORBS2 and SCL11A1 Genes
    (Frontier, 2022) Asante-Poku, A.; Morgan, P.; Osei-Wusu, S.; Aboagye, S.Y.; Asare, P.; Otchere, I.D.; Adadey, S.W.; Mnika, K.; Esoh, K.; Mawuta, K.H.; Arthur, N.; Forson, A.; Mazandu, G.K.; Wonkam, A.; Yeboah-Manu, D.
    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 (PBH = 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.
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    Molecular epidemiology of Mycobacterium tuberculosis complex in the Volta Region of Ghana
    (PlOS ONE, 2021) Ameke, S.; Asare, P.; Aboagye, S.Y.; Otchere, I.D.; Osei-Wusu, S.; Yeboah-Manu, D.; Asante-Poku, A.
    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 spoligo type 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). We confirmed the importance of M. africanum lineages as a cause of TB in the Volta region of Ghana.
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    Genotypic and phenotypic diversity of Mycobacterium tuberculosis complex genotypes prevalent in West Africa
    (PLOS ONE, 2021) Osei-Wusu, S.; Otchere, I.D.; Morgan, P.; Musah, A.B.; Siam, I.M.; Asandem, D.; Afum, T.; Asare, P.; Asante-Poku, A.; Kusi, K.A.; Gagneux, S.; Yeboah-Manu, D.
    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 Lo¨wenstein–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.
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    Whole Genome Sequencing and Spatial Analysis Identifies Recent Tuberculosis Transmission Hotspots in Ghana
    (Frontiers in Medicine, 2020-05-19) Asare, P.; Otchere, I.D.; Bedeley, E.; Brites, D.; Loiseau, C.; Baddoo, N.A.; Asante-Poku, A.; Osei-Wusu, S.; Prah, D.A.; Borrell, S.; Reinhard, M.; Forson, A.; Koram, K.A.; Gagneux, S.; Yeboah-Manu, D.
    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.
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    Second-line anti-tuberculosis drug resistance testing in Ghana identifies the first extensively drug-resistant tuberculosis case
    (Infection and Drug Resistance, 2018-02) Osei-Wusu, S.; Omari, M.A.; Asante-Poku, A.; Otchere, I.D.; Asare, P.; Forson, A.; Otu, J.; Antonio, M.; Yeboah-Manu, D.
    Background Drug resistance surveillance is crucial for tuberculosis (TB) control. Therefore, our goal was to determine the prevalence of second-line anti-TB drug resistance among diverse primary drug-resistant Mycobacterium tuberculosis complex (MTBC) isolates in Ghana. Materials and methods One hundred and seventeen MTBC isolates with varying first-line drug resistance were analyzed. Additional resistance to second-line anti-TB drugs (streptomycin [STR], amikacin [AMK] and moxifloxacin [MOX]) was profiled using the Etest and GenoType MTBDRsl version 2.0. Genes associated with resistance to AMK and MOX (gyrA, gyrB, eis, rrs, tap, whiB7 and tlyA) were then analyzed for mutation. Results Thirty-seven (31.9%) isolates had minimum inhibitory concentration (MIC) values ≥2 µg/mL against STR while 12 (10.3%) isolates had MIC values ≥1 µg/mL for AMK. Only one multidrug-resistant (MDR) isolate (Isolate ID: TB/Nm 919) had an MIC value of ≥0.125 µg/mL for MOX (MIC = 3 µg/mL). This isolate also had the highest MIC value for AMK (MIC = 16 µg/mL) and was confirmed as resistant to AMK and MOX by the line probe assay GenoType MTBDRsl version 2.0. Mutations associated with the resistance were: gyrA (G88C) and rrs (A514C and A1401G). Conclusion Our findings suggest the need to include routine second-line anti-TB drug susceptibility testing of MDR/rifampicin-resistant isolates in our diagnostic algorithm.
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    Low sensitivity of the MPT64 identification test to detect lineage 5 of the Mycobacterium tuberculosis complex
    (Journal of Medical Microbiology, 2018-11) N’Dira Sanoussi, C.; de Jong, B.C.; Odoun, M.; Arekpa, K.; Ligali, M.A.; Bodi, O.; Harris, S.; Ofori-Anyinam, B.; Yeboah-Manu, D.; Otchere, I.D.; Asante-Poku, A.et.al.
    Purpose: Differentiation of the Mycobacterium tuberculosis complex (MTBc) from non-tuberculous mycobacteria (NTM) is important for tuberculosis diagnosis and is a prerequisite for reliable phenotypic drug-resistance testing. We evaluated the performance of the rapid MPT64 antigen identification test for the detection of Mycobacterium africanum lineage 5 (MAF L5). Methodology: Smear-positive tuberculosis patients' sputa were included prospectively. Culture was performed on Löwenstein-Jensen medium and, when positive, the MPT64 test and the classical para-nitro benzoic acid susceptibility and heat-labile catalase (PNB/catalase) identification tests were performed. The MPT64 test was repeated 14 days after an initially negative first testing. Direct spoligotyping was performed for MTBc lineage determination. Results: In total, 333 isolates were tested for all of the methods. Three hundred and twenty-two (96.7 %) were pure MTBc, by agreement between spoligotyping and PNB/catalase, and 11 were NTM or a mixture of MTBc/NTM. The MPT64 test conducted on day zero of culture-positivity correctly identified most of the pure MTBc isolates (93.2 %, 300/322), but it failed to detect 24 % of the L5 isolates (18/75) versus 2 % (4/202) of the L4 ones [OR=15.6 (5.3-45.8), P<0.0001], with improved sensitivity for L5 detection on repeat testing after 14 days. The L5-wide non-synonymous single-nucleotide polymorphism in the mpt64 gene may explain the poor performance of the MPT64 test for L5. Conclusion: The MPT64 test has a lower sensitivity for detecting L5 isolates of the MTBc, and can be considered as a first-screening test that should be confirmed by another identification method when it produces negative results in countries with L5. Given the microbiological bias in both the isolation and identification of MAF lineages, diagnostics with high sensitivity for direct testing on clinical material are preferable.
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    Isolation of nontuberculous mycobacteria from the environment of ghanian communities where buruli ulcer is endemic
    (American Society for Microbiology, 2016) Aboagye, S.Y.; Danso, E.; Ampah, K.A.; Nakobu, Z.; Asare, P.; Otchere, I.D.; Röltgen, K.; Yirenya-Tawiah, D.; Yeboah-Manu, D.
    This study aimed to isolate nontuberculous mycobacterial species from environmental samples obtained from some selected communities in Ghana. To optimize decontamination, spiked environmental samples were used to evaluate four decontamination solutions and supplemented media, after which the best decontamination solution and media were used for the actual analysis. The isolates obtained were identified on the basis of specific genetic sequences, including heat shock protein 65, IS2404, IS2606, rpoB, and the ketoreductase gene, as needed. Among the methods evaluated, decontamination with 1MNaOH followed by 5% oxalic acid gave the highest rate of recovery of mycobacteria (50.0%) and the lowest rate of contamination (15.6%). The cultivation medium that supported the highest rate of recovery of mycobacteria was polymyxin B-amphotericin B-nalidixic acidtrimethoprim- azlocillin-supplemented medium (34.4%), followed by isoniazid-supplemented medium (28.1%). Among the 139 samples cultivated in the main analysis, 58 (41.7%) yielded mycobacterial growth, 70 (50.4%) had no growth, and 11 (7.9%) had all inoculated tubes contaminated. A total of 25 different mycobacterial species were identified. Fifteen species (60%) were slowly growing (e.g., Mycobacterium ulcerans, Mycobacterium avium, Mycobacterium mantenii, and Mycobacterium malmoense), and 10 (40%) were rapidly growing (e.g., Mycobacterium chelonae, Mycobacterium fortuitum, and Mycobacterium abscessus). The occurrence of mycobacterial species in the various environmental samples analyzed was as follows: soil, 16 species (43.2%); vegetation, 14 species (38.0%); water, 3 species (8.0%); moss, 2 species (5.4%); snail, 1 species (2.7%); fungi, 1 species (2.7%). This study is the first to report on the isolation of M. ulcerans and other medically relevant nontuberculous mycobacteria from different environmental sources in Ghana. © 2016, American Society for Microbiology.