Mycobacterium tuberculosis drug resistance, Ghana

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.

Molecular epidemiology and multidrug resistance of Mycobacterium tuberculosis complex from pulmonary tuberculosis patients in the Eastern region of Ghana

Background

Tuberculosis (TB) and drug-resistant TB (DR-TB) continue to persist as a serious public health challenges in Ghana. Although several research has evaluated the drug resistance of Mycobacterium tuberculosis complex (MTBc) strains across the country, there is a paucity of data on its magnitude as well as the various lineages circulating in the Eastern region of Ghana.

Objective

This study therefore evaluated the distribution of the various lineages of MTBc in the Eastern region of the country and the associated drug resistance.

Materials and methods

One hundred and forty-three (143) patients with pulmonary TB attending the Eastern Regional Hospital, Koforidua/Ghana were included in the study. The BACTEC MGIT 960 tube media was used for both sputum culture and drug susceptibility of streptomycin (STR), isoniazid (INH), rifampicin (RIF) and Ethambutol (ETH). Isolates were initially typed using IS6110, followed by large sequence polymorphisms analysis and spoligotyping.

Results

The majority [108 (75.5%)] of the 143 patients were male gender and the 45-54 years [46 (32.2%)] age range had the highest frequency. Forty-one (28.7%) of the 143 isolates were IS6110 negative. Of the 102 spoligotyped isolates, the main sub-lineages included 45 (44.1%) Cameroon and 23 (22.5%) Ghana. SITs 61 and 53 represented the major cluster with 22/102 (21.6%) and 13/102 (12.7%) isolates respectively, while 59/65 (90.8%) isolates belonged to Lineage 4 with 27/65 (41.5%) LAM10_CAM. MDR-TB occurred in 26/79 (32.9%) isolates, and was not associated with neither gender [20/58 (34.5%) male vs 6/21 (28.6%) female, OR = 1.31; 95%CI, 0.44-3.92; p = 0.624)] nor age. No association was found between MDR-TB and the major sub-lineages [8/25 (32%) Cameroon (OR = 0.94; 95%CI, 0.34-2.59; p = 0.920) and 5/11 (45.5%) Ghana (OR = 1.87; 95%CI, 0.51-6.80; p = 0.489)], or previously treated [8/23 (34.8%), OR = 0.89; 95%CI, 0.32-2.48; p = 0.823)] patients.

Conclusion

Despite the serious threat posed by MDR in the study area, no sub-lineage was shown to be associated with drug resistance. Nonetheless, a sustained surveillance of drug resistance pattern is advocated. A lower proportion of M. africanum was observed in the Eastern region of Ghana and will require further evaluation.

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.

A multi-phenotype genome-wide association study of clades causing tuberculosis in a Ghanaian- and South African cohort

Despite decades of research and advancements in diagnostics and treatment, tuberculosis remains a major public health concern. New computational methods are needed to interrogate the intersection of host- and bacterial genomes. Paired host genotype datum and infecting bacterial isolate information were analysed for associations using a multinomial logistic regression framework implemented in SNPTest. A cohort of 853 admixed South African participants and a Ghanaian cohort of 1359 participants were included. Two directly genotyped variants, namely rs529920 and rs41472447, were identified in the Ghanaian cohort as being statistically significantly associated with risk for infection with strains of different members of the MTBC. Thus, a multinomial logistic regression using paired host-pathogen data may prove valuable for investigating the complex relationships driving infectious disease.

Evaluation of timeliness of treatment initiation among smear positive pulmonary tuberculosis patients in Brong Ahafo Region, Ghana, 2015

Background

We evaluated timeliness and factors influencing treatment initiation (TI) among smear positive pulmonary tuberculosis (PTB+) patients in Brong Ahafo Region (BAR), Ghana.

Design and Setting

We conducted a cross-sectional study in health facilities (HF) in six districts in BAR, from November 2014 to May 2015. Newly diagnosed smear positive PTB patients were selected randomly proportionate to size of facility cases. Timeliness of symptoms, diagnosis, TI and factors for delay were assessed using structured questionnaire. Patient delay was defined as presentation to a health care provider after 21 days of the onset of TBrelated symptoms and TI delay as therapy initiated after 30-days of onset of TB-related symptoms. We determined median patient timeliness, HF, and TI timeliness. We identified factors associated with TI delay using logistic regression.

Results

There were a total of 237 PTB+ patients; median patient timeliness of 30 days (IQR:14, 60). The median health facility timeliness was 8 days (IQR:4, 10); and the median TI timeliness was 36 days (IQR:25, 69). Majority (58.7%) of patients delayed in seeking treatment. TI delay was associated with: unemployment [aOR=7.4, 95%CI(1.9-28.8)], fear of losing job [aOR=3.4, 95%CI(1.3-8.5)], traditional healer as first port of call [aOR=10.6, 95%CI(13.0-66.8)], and initially being treated for HIV [aOR=4.9, 95%CI(1.6-14.8)].

Conclusion

There were delays in treatment initiation and patient treatment seeking timeliness. One-third of patients would prefer traditional healers/self-treatment/drug store as an option. A concerted effort by stakeholders is needed to improve behaviour change communication on good health seeking behaviour for persons living with TB to reduce delays in seeking treatment.

Funding

The study was funded by the authors.

Community-based active tuberculosis case finding using a symptom-based screening tool in the Volta Region, Ghana

BACKGROUND

Early tuberculosis case detection is important for early commencement of treatment to improve treatment outcomes and also to prevent community spread of the disease. However, there is a paucity of data in Ghana on the efficiency of the symptom-based screening tool (SBS tool) to detect Mycobacterium tuberculosis in the communities. Therefore, this study assessed the usefulness of the SBS tool for community-based active case finding in the Volta Region of Ghana.

METHODS AND MATERIALS

This cross-sectional study used house-to-house and durbar screening approaches for active tuberculosis (TB) case searching from six communities, three each from the Ketu South (high TB risk) and Akatsi North (low TB risk) districts in the Volta Region of Ghana. Random eligible participants were screened with the SBS tool to identify presumptive TB cases. One sputum sample was collected from each person with presumptive TB for detection of M. tuberculosis by the GeneXpert real-time technique.

RESULTS

A total of 1,025 people were screened from a population of 40,462, from which 332 (32.4%) were presumed to have M. tuberculosis infection. Of the 332 presumptive TB cases, 63.9% were obtained through house-to-house screening, while 36.1% were obtained through community durbar screening. Six M. tuberculosis-positive cases (with one rifampicin resistance) were detected by house-to-house screening but not from community durbar samples, yielding an overall prevalence of 15 per 100,000 population. Among TB symptoms screened and analysed, association existed only between night sweat and TB case detection (χ² = 3.9, P = 0.049).

CONCLUSION

Although cumbersome and capital intensive, community-based active case searching through house-to-house screening using the SBS tool proved effective in detecting M. tuberculosis in the communities.

Antibiotic resistance patterns in human, animal, food and environmental isolates in Ghana: a review

Many articles have been published on resistant microorganisms isolated from humans, animals, foods and the environment in Ghana. However, there are no reviews that summarize the information on the isolates and antibiotics tested so far in the country. This literature review was completed through “PubMed” and “Google Scholar” searches. We included publications from the period 1975-2015 with a laboratory-based methodology to determine antibiotic resistance of strains isolated in Ghana. In total, 60 articles were included in the analysis with 10% of the articles carrying out nationwide research on antibiotic resistance. The regions of Ghana with the highest published articles were Greater Accra (40%), Ashanti (21.7%) and Northern Region (10%). Most of the studies (86.7%) were related to isolates collected from human samples followed by environmental (5%), animal (3%) and food samples (2%). Ten different bacteria genera were observed in the studies. The most common was Escherichia coli, followed by Staphylococcus spp., Mycobacterium spp. and Streptococcus spp. The highest mean resistance rate was encountered in Escherichia coli (62.2%) followed by Klebsiella spp. (60.4%) and Pseudomonas spp. (52.1%). High resistance rates have been found in Ghana, however, the data are skewed and some regions of the country have been neglected. There is a need for higher quality research to establish and monitor resistance patterns in Upper West, Brong-Ahafo, Volta and Eastern Regions of Ghana.

Microscopic Observation Drug Susceptibility (MODS) Assay: A Convenient Method for Determining Antibiogram of Clinical Isolates of Mycobacterium tuberculosis in Ghana

(1) Background: Present methods for drug susceptibility tests (DST) rely on culture methods that are sophisticated and relatively faster, or a slow and cheaper option. These methods frustrate disease control; therefore, there is a need for methods that incorporate key functions of microscopy and culture, with reduced cost burden and sophistry. Thus, the purpose of this study was to identify which, among the most commonly used (in Ghana) methods, can conveniently be used at health centers located in rural areas for effective DST determination of Mycobacterium tuberculosis (MTB). (2) Methods: Mycobacterium tuberculosis isolates were tested for their susceptibility to streptomycin, isoniazid, rifampicin, ethambutol (SIRE), and pyrazinamide by microscopic observation drug susceptibility (MODS) and BACTEC MGIT 960 methods. Evaluations were based on shorter turnaround periods, rapidity, ease of use, cost, etc. A comparative analysis was statistically expressed as kappa values. (3) Results: Endpoints for drug susceptibilities by MODS averaged 13 days (7–32), whilst that for BACTEC MGIT 960 was 10 days with a further 12 days to detect resistance. Therefore, a turnaround period of 22 days was needed for DST by BACTEC MGIT 960, compared to 13 days for MODS. There were differences in correlation levels between the two methods, as determined by their kappa values. (4) Conclusion: The MODS assay was found to be less costly, more user-friendly, and still able to be conveniently used at health centers located in rural areas known to be endemic for TB, particularly in Ghana.

Plasma Levels of Cytokines (IL-10, IFN-γ and TNF-α) in Multidrug Resistant Tuberculosis and Drug Responsive Tuberculosis Patients in Ghana

The emergence of multidrug-resistant tuberculosis (MDR–TB) and more recently, extensively drug-resistant (XDR) TB has intensified the need for studies aimed at identifying factors associated with TB drug resistance. This study determined the differences in plasma concentrations of pro-inflammatory (IFN-γ and TNF-α) and anti-inflammatory (IL-10) cytokines in MDR-TB and drug-susceptible (DS) TB patients, in addition to some socio-economic factors. Plasma levels of IL-10, IFN-γ and TNF-α were measured in 83 participants (comprising 49 MDR-TB and 34 DS-TB patients) using sandwich ELISA. Levels of the three cytokines were elevated in MDR-TB patients compared to DS-TB patients. The mean level of IL-10 (7.8 ± 3.61 ρg/mL) measured in MDR-TB cases was relatively higher than those of TNF-α and IFN-γ, and statistically significant (p = 0.0022) when compared to the level of IL-10 (4.8 ± 4.94 ρg/mL) in the DS-TB cases. There were statistically significant associations between MDR-TB and factors such as education level (X² = 9.895, p = 0.043), employment status (X² = 19.404, p = 0.001) and alcoholism (X² = 3.971, p = 0.046). This study adds to the knowledge that IFN-γ, TNF-α and IL-10 play a role in the host response to Mycobacterium tuberculosis (MTB). Alcohol intake can be considered as an important MDR-TB risk factor.

A cross-sectional study of tuberculosis drug resistance among previously treated patients in a tertiary hospital in Accra, Ghana: public health implications of standardized regimens

Background

Mycobacterium tuberculosis drug resistance is a major challenge to the use of standardized regimens for tuberculosis (TB) therapy, especially among previously treated patients. We aimed to investigate the frequency and pattern of drug resistance among previously treated patients with smear-positive pulmonary tuberculosis at the Korle-Bu Teaching Hospital Chest Clinic, Accra.

Methods

This was a cross-sectional survey of mycobacterial isolates from previously treated patients referred to the Chest Clinic Laboratory between October 2010 and October 2013. The Bactec MGIT 960 system for mycobactrerial culture and drug sensitivity testing (DST) was used for sputum culture of AFB smear-positive patients with relapse, treatment failure, failure of smear conversion, or default. Descriptive statistics were used to summarize patient characteristics, and frequency and patterns of drug resistance.

Results

A total of 112 isolates were studied out of 155 from previously treated patients. Twenty contaminated (12.9%) and 23 non-viable isolates (14.8%) were excluded. Of the 112 studied isolates, 53 (47.3%) were pan-sensitive to all first-line drugs tested Any resistance (mono and poly resistance) to isoniazid was found in 44 isolates (39.3%) and any resistance to streptomycin in 43 (38.4%). Thirty-one (27.7%) were MDR-TB. Eleven (35.5%) out of 31 MDR-TB isolates were pre-XDR. MDR-TB isolates were more likely than non-MDR isolates to have streptomycin and ethambutol resistance.

Conclusions

The main findings of this study were the high prevalence of MDR-TB and streptomycin resistance among previously treated TB patients, as well as a high prevalence of pre-XDR-TB among the MDR-TB patients, which suggest that first-line and second-line DST is essential to aid the design of effective regimens for these groups of patients in Ghana.

Second-line anti-tuberculosis drug resistance testing in Ghana identifies the first extensively drug-resistant tuberculosis case

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.

An Evaluation of Treatment Outcomes in a Cohort of Clients on the DOTS Strategy, 2012-2016

We present, for the first time, an evaluation of treatment outcomes in a cohort at a TB referral centre in the Central Region of Ghana. Of the 213 clients placed on DOTS, 59.2% (126/213) were sputum smear-positive. An overall cure rate of 90.2% (51.6% cured + 37.6% completed) and a death rate of 8.5% (18/213) were estimated. Of the number of clients who died, 5.7% (12/213) were males (χ² = 2.891, p = 0.699; LR = 3.004, p = 0.699). Deaths were only recorded among clients who were > 19 years old (χ² = 40.319, p = 0.099; LR = 41.244, p = 0.083). Also, 0.9% (2/213) was lost to follow-up, while 1.4% (3/213) had treatment failure. In total, 13.6% (7.0%, 15/213 males, and 6.6%, 14/213 females) of clients who were placed on DOTS were HIV seropositive. Ages of 40–49 years had the highest number, 13/213 (6.1%), infected with HIV, though the difference among the remaining age groups was not statistically significant (χ² = 9.621, p = 0.142). Furthermore, 7.0% (15/213) had TB/HIV coinfection. Out of them, 9 were cured and 5 died at home, while 1 had treatment failure. Tuberculosis/HIV infection prevention advocacy and interventions that address sociodemographic determinants of unfavourable treatment outcomes are urgently required to augment national efforts towards control.

Genotyping and drug susceptibility testing of mycobacterial isolates from population-based tuberculosis prevalence survey in Ghana

Background

Mycobacterium tuberculosis complex (MTBC) and Non-tuberculosis Mycobacterium (NTM) infections differ clinically, making rapid identification and drug susceptibility testing (DST) very critical for infection control and drug therapy. This study aims to use World Health Organization (WHO) approved line probe assay (LPA) to differentiate mycobacterial isolates obtained from tuberculosis (TB) prevalence survey in Ghana and to determine their drug resistance patterns.

Methods

A retrospective study was conducted whereby a total of 361 mycobacterial isolates were differentiated and their drug resistance patterns determined using GenoType Mycobacterium Assays: MTBC and CM/AS for differentiating MTBC and NTM as well MTBDRplus and NTM-DR for DST of MTBC and NTM respectively.

Results

Out of 361 isolates, 165 (45.7%) MTBC and 120 (33.2%) NTM (made up of 14 different species) were identified to the species levels whiles 76 (21.1%) could not be completely identified. The MTBC comprised 161 (97.6%) Mycobacterium tuberculosis and 4 (2.4%) Mycobacterium africanum. Isoniazid and rifampicin monoresistant MTBC isolates were 18/165 (10.9%) and 2/165(1.2%) respectively whiles 11/165 (6.7%) were resistant to both drugs. Majority 42/120 (35%) of NTM were M. fortuitum. DST of 28 M. avium complex and 8 M. abscessus complex species revealed that all were susceptible to macrolides (clarithromycin, azithromycin) and aminoglycosides (kanamycin, amikacin, and gentamicin).

Conclusion

Our research signifies an important contribution to TB control in terms of knowledge of the types of mycobacterium species circulating and their drug resistance patterns in Ghana.

Electronic supplementary material

The online version of this article (10.1186/s12879-017-2853-3) contains supplementary material, which is available to authorized users.

Trends in prevalence of multi drug resistant tuberculosis in sub-Saharan Africa: A systematic review and meta-analysis

Background

Multidrug resistant tuberculosis (MDR-TB), is an emerging public health problem in sub-Saharan Africa (SSA). This study aims to determine the trends in prevalence of MDR-TB among new TB cases in sub-Saharan Africa over two decades.

Methods

We searched electronic data bases and accessed all prevalence studies of MDR-TB within SSA between 2007 and 2017. We determined pooled prevalence estimates using random effects models and determined trends using meta-regression.

Results

Results: We identified 915 studies satisfying inclusion criteria. Cumulatively, studies reported on MDR-TB culture of 34,652 persons. The pooled prevalence of MDR-TB in new cases was 2.1% (95% CI; 1.7–2.5%). There was a non-significant decline in prevalence by 0.12% per year.

Conclusion

We found a low prevalence estimate of MDR-TB, and a slight temporal decline over the study period. There is a need for continuous MDR-TB surveillance among patients with TB.

Pharmacogenomics Implications of Using Herbal Medicinal Plants on African Populations in Health Transition

The most accessible points of call for most African populations with respect to primary health care are traditional health systems that include spiritual, religious, and herbal medicine. This review focusses only on the use of herbal medicines. Most African people accept herbal medicines as generally safe with no serious adverse effects. However, the overlap between conventional medicine and herbal medicine is a reality among countries in health systems transition. Patients often simultaneously seek treatment from both conventional and traditional health systems for the same condition. Commonly encountered conditions/diseases include malaria, HIV/AIDS, hypertension, tuberculosis, and bleeding disorders. It is therefore imperative to understand the modes of interaction between different drugs from conventional and traditional health care systems when used in treatment combinations. Both conventional and traditional drug entities are metabolized by the same enzyme systems in the human body, resulting in both pharmacokinetics and pharmacodynamics interactions, whose properties remain unknown/unquantified. Thus, it is important that profiles of interaction between different herbal and conventional medicines be evaluated. This review evaluates herbal and conventional drugs in a few African countries and their potential interaction at the pharmacogenomics level.

Variation and risk factors of drug resistant tuberculosis in sub-Saharan Africa: a systematic review and meta-analysis

Background

Prevalence of multidrug resistant tuberculosis (MDR-TB), defined as in vitro resistance to both rifampicin and isoniazid with or without resistance to other TB drugs, in sub-Saharan Africa (SSA) is reportedly low compared to other regions. These estimates are based on data reported to the World Health Organization (WHO) on drug resistance surveys, which may suffer from a reporting bias. We set out to evaluate the variation in prevalence of drug resistant tuberculosis (DR-TB) and its determinants across SSA countries among new and previously treated TB patients.

Methods

The aim was to perform a systematic review and meta-analysis of DR-TB prevalence and associated risk factors in SSA. PubMed, EMBASE, Cochrane and bibliographies of DR-TB studies were searched. Surveys at national or sub-national level, with reported DR-TB prevalence (or sufficient data to calculate a prevalence) to isoniazid (INH), rifampicin (RMP), ethambutol (EMB), and streptomycin (SM) conducted in SSA excluding the Republic of South Africa, published between 2003 and 2013 with no language restriction were considered. Two authors searched and reviewed the studies for eligibility and extracted the data in pre-defined forms. Forest plots of all prevalence estimates by resistance outcome were performed. Summary estimates were calculated using random effects models, when appropriate. Associations between any DR-TB and MDR-TB with potential risk factors were examined through subgroup analyses stratified by new and previously treated patients.

Results

A total of 726 studies were identified, of which 27 articles fulfilled the inclusion criteria. Studies reported drug susceptibility testing (DST) results for a total of 13,465 new and 1,776 previously treated TB patients. Pooled estimate of any DR-TB prevalence among the new cases was 12.6% (95% CI 10.6-15.0) while for MDR-TB this was 1.5% (95% CI 1.0-2.3). Among previously treated patients, these were 27.2% (95% CI 21.4-33.8) and 10.3% (95% CI 5.8-17.4%), respectively. DR-TB (any and MDR-TB) did not vary significantly with respect to study characteristics.

Conclusions

The reported prevalence of DR-TB in SSA is low compared to WHO estimates. MDR-TB in this region does not seem to be driven by the high HIV prevalence rates.

High Frequency of First-Line Anti-Tuberculosis Drug Resistance among Persons with Chronic Pulmonary Tuberculosis at a Teaching Hospital Chest Clinic

INTRODUCTION

The burden of MDR-TB is unknown in areas that do not have drug susceptibility testing (DST), but its frequency is expected to be higher in previously treated cases. Where DST is not available the WHO recommended standardized retreatment (Category II) regimen is given to previously treated TB patients

OBJECTIVE

To evaluate the frequency and pattern of drug resistance of Mycobacterium tuberculosis isolated from patients with chronic smear positive pulmonary tuberculosis.

METHOD

We conducted a retrospective review of mycobacterial cultures and drug susceptibility testing (DST) performed on sputum samples collected, between January 2005 and September 2006, from 40 patients with pulmonary TB who had failed at least one standard retreatment regimen. Clinical data was extracted from patients' case notes.

RESULTS

M. tuberculosis was recovered from 28 (70%) of the 40 patients. Of the 28 culture positive cases, 10 (36%) had resistance to at least rifampicin and isoniazid (multi-drug resistant TB), 22 (79%) isolates had resistance to streptomycin and 13 (46%) to ethambutol. Of the patients with a positive culture, only one (3.6%) had a fully susceptible organism. Of the 10 patients with MDR TB, 7 had received two or more retreatment courses.

CONCLUSION

The frequency of drug resistant TB was high among patients who failed at least one course of category II therapy. Effective combination regimens based on DST is necessary in patients who remain smear positive on the standardized retreatment regimen.

Variant G57E of mannose binding lectin associated with protection against tuberculosis caused by Mycobacterium africanum but not by M. tuberculosis

Structural variants of the Mannose Binding Lectin (MBL) cause quantitative and qualitative functional deficiencies, which are associated with various patterns of susceptibility to infectious diseases and other disorders. We determined genetic MBL variants in 2010 Ghanaian patients with pulmonary tuberculosis (TB) and 2346 controls and characterized the mycobacterial isolates of the patients. Assuming a recessive mode of inheritance, we found a protective association between TB and the MBL2 G57E variant (odds ratio 0.60, confidence interval 0.4–0.9, P 0.008) and the corresponding LYQC haplotype (P_corrected 0.007) which applied, however, only to TB caused by M. africanum but not to TB caused by M. tuberculosis. In vitro, M. africanum isolates bound recombinant human MBL more efficiently than did isolates of M. tuberculosis. We conclude that MBL binding may facilitate the uptake of M. africanum by macrophages, thereby promoting infection and that selection by TB may have favoured the spread of functional MBL deficiencies in regions endemic for M. africanum.

Unequal distribution of resistance-conferring mutations among Mycobacterium tuberculosis and Mycobacterium africanum strains from Ghana

Isoniazid (INH) and rifampicin (RMP) resistance in Mycobacterium tuberculosis complex (MTC) isolates are mainly based on mutations in a limited number of genes. However, mutation frequencies vary in different mycobacterial populations. In this work, we analyzed the distribution of resistance-associated mutations in M. tuberculosis and M. africanum strains from Ghana, West Africa. The distribution of mutations in katG, fabG1-inhA, ahpC, and rpoB was determined by DNA sequencing in 217 INH-resistant (INH(r)) and 45 multidrug-resistant (MDR) MTC strains isolated in Ghana from 2001 to 2004. A total of 247 out of 262 strains investigated (94.3%) carried a mutation in katG (72.5%), fabG1-inhA (25.1%), or ahpC (6.5%), respectively. M. tuberculosis strains mainly had katG 315 mutations (80.1%), whereas this proportion was significantly lower in M. africanum West-African 1 (WA1) strains (43.1%; p<0.05). In contrast, WA1 strains showed more mutations in the fabG1-inhA region (39.2%, p<0.05) compared to M. tuberculosis strains (20.9%). In 44 of 45 MDR strains (97.8%) mutations in the 81-bp core region of the rpoB gene could be verified. Additionally, DNA sequencing revealed that 5 RMP-susceptible strains also showed mutations in the rpoB hotspot region. In conclusion, although principally the same genes were affected in INH(r)M. tuberculosis and M. africanum strains, disequilibrium in the distribution of mutations conferring resistance was verified that might influence the efficiency of molecular tests for determination of resistance.

IL10 haplotype associated with tuberculin skin test response but not with pulmonary TB

Evidence from genetic association and twin studies indicates that susceptibility to tuberculosis (TB) is under genetic control. One gene implicated in susceptibility to TB is that encoding interleukin-10 (IL10). In a group of 2010 Ghanaian patients with pulmonary TB and 2346 healthy controls exposed to Mycobacterium tuberculosis, among them 129 individuals lacking a tuberculin skin test (PPD) response, we genotyped four IL10 promoter variants at positions -2849 , -1082 , -819 , and -592 and reconstructed the haplotypes. The IL10 low-producer haplotype -2849A/-1082A/-819C/-592C, compared to the high-producer haplotype -2849G/-1082G/-819C/-592C, occurred less frequent among PPD-negative controls than among cases (OR 2.15, CI 1.3-3.6) and PPD-positive controls (OR 2.09, CI 1.2-3.5). Lower IL-10 plasma levels in homozygous -2849A/-1082A/-819C/-592C carriers, compared to homozygous -2849G/-1082G/-819C/-592C carriers, were confirmed by a IL-10 ELISA (p = 0.016). Although we did not observe differences between the TB patients and all controls, our results provide evidence that a group of individuals exposed to M. tuberculosis transmission is genetically distinct from healthy PPD positives and TB cases. In these PPD-negative individuals, higher IL-10 production appears to reflect IL-10-dependent suppression of adaptive immune responses and sustained long-term specific anergy.

MCP-1 promoter variant -362C associated with protection from pulmonary tuberculosis in Ghana, West Africa

Current endeavour focuses on human genetic factors that contribute to susceptibility to or protection from tuberculosis (TB). Monocytes are crucial in containing Mycobacterium tuberculosis infection, and the monocyte chemoattractant protein-1 (MCP-1) cytokine plays a role in their recruitment to the site of infection. The G allele of the MCP-1 promoter polymorphism at position -2581 relative to the ATG transcription start codon has been described to be associated in Mexican and Korean TB patients with increased susceptibility to TB. We genotyped this and additional MCP-1 variants in sample collections comprising more than 2000 cases with pulmonary TB and more than 2300 healthy controls and 332 affected nuclear families from Ghana, West Africa, and more than 1400 TB patients and more than 1500 controls from Russia. In striking contrast to previous reports, MCP-1 -2581G was significantly associated with resistance to TB in cases versus controls [odds ratio (OR) 0.81, corrected P-value (P(corr)) = 0.0012] and nuclear families (OR 0.72, P(corr) = 0.04) and not with disease susceptibility, whereas in the Russian sample no evidence of association was found (P = 0.86). Our and other results do not support an association of MCP-1 -2581 with TB. In the Ghanaian population, eight additional MCP-1 polymorphisms were genotyped. MCP-1 -362C was associated with resistance to TB in the case-control collection (OR 0.83, P(corr) = 0.00017) and in the affected families (OR 0.7, P(corr) = 0.004). Linkage disequilibrium (LD) and logistic regression analyses indicate that, in Ghanaians, the effect results exclusively from the MCP-1 -362 variant, whereas the effect of -2581 may in part be explained by its LD with -362.

Pulmonary tuberculosis: virulence of Mycobacterium africanum and relevance in HIV co-infection

Although Mycobacterium africanum is being isolated in a significant proportion of cases of pulmonary tuberculosis in West Africa, its pathogenic potential remains a matter of discussion. Recent reports leave the question of whether M. africanum causes more severe pathology than M. tuberculosis or resembles opportunistic pathogens and might gain importance in the course of the HIV pandemic. Patients with pulmonary tuberculosis associated with M. africanum (n=556) and M. tuberculosis (n=1350) were studied in Ghana, West Africa, and compared regarding self-reported signs and symptoms, chest radiography, HIV status, mycobacterial drug resistance and mycobacterial clustering as determined by spoligotyping and IS6110 fingerprints. The rate of M. africanum infections was similar in HIV-positive (27%) and HIV-negative (30%) patients. M. africanum clustered less than M. tuberculosis (21% vs 79%; OR, 0.38; 95% CI, 0.3-0.5; p<0.001) corresponding to its lower prevalence (29% vs 70%). Clinically and radiographically, no significant differences were found except that M. africanum caused lower-lobe disease less frequently than M. tuberculosis (OR, 0.39; 95% CI, 0.2-0.7; Pc=0.01), whereby this association applied to HIV-negative patients only. No difference in virulence, as assessed by the severity of radiological presentation, was found when the two M. africanum subtypes West African 1 and West African 2 were compared. In the population studied, M. africanum closely resembled M. tuberculosis in pathology and cannot be considered an opportunistic pathogen.

Tuberculosis transmission in a high incidence area: a retrospective molecular epidemiological study of Mycobacterium tuberculosis in Casablanca, Morocco

Like in most developing countries, tuberculosis represents a major public health problem in Morocco. This paper describes the first study combining molecular and conventional epidemiology of tuberculosis in Casablanca, the economic capital of this country. Molecular fingerprinting of the genomic DNA recovered from cultures of sputum of 150 patients was performed by MIRU-VNTR. This molecular marker revealed that 53.1% of the total cases were clustered. These cases were classified into 23 clusters ranging in size from 2 to 13 patients, suggesting a rate of 37% of recent transmission in the sample under study. In a multivariate analysis, there were no independent predictors of clustering. However, the clinical form was associated with drug resistance (odds ratio=9.9; P value=0.0006). The phylogenetic analysis showed that the heterogeneity found in this population includes also the members from a same patient family, and that the 2 major families distributed in Casablanca were the Latin-American-Mediterranean (LAM) and Haarlem families. All the results of this work allow to understand better the tuberculosis transmission in Casablanca, and suggest that different clones of M. tuberculosis seem to circulate in this city, and that the reactivation of latent infections would be mainly responsible for the endemic situation of this disease. These findings indicate also that the transmission of TB in Morocco is not optimally controlled, and that efforts for control strategies should be sustained in all developing countries where the incidence of TB is high and still raising.

Proposal for standardization of optimized mycobacterial interspersed repetitive unit-variable-number tandem repeat typing of Mycobacterium tuberculosis

Molecular typing based on 12 loci containing variable numbers of tandem repeats of mycobacterial interspersed repetitive units (MIRU-VNTRs) has been adopted in combination with spoligotyping as the basis for large-scale, high-throughput genotyping of Mycobacterium tuberculosis. However, even the combination of these two methods is still less discriminatory than IS6110 fingerprinting. Here, we define an optimized set of MIRU-VNTR loci with a significantly higher discriminatory power. The resolution and the stability/robustness of 29 loci were analyzed, using a total of 824 tubercle bacillus isolates, including representatives of the main lineages identified worldwide so far. Five loci were excluded for lack of robustness and/or stability in serial isolates or isolates from epidemiologically linked patients. The use of the 24 remaining loci increased the number of types by 40%--and by 23% in combination with spoligotyping--among isolates from cosmopolitan origins, compared to those obtained with the original set of 12 loci. Consequently, the clustering rate was decreased by fourfold--by threefold in combination with spoligotyping--under the same conditions. A discriminatory subset of 15 loci with the highest evolutionary rates was then defined that concentrated 96% of the total resolution obtained with the full 24-locus set. Its predictive value for evaluating M. tuberculosis transmission was found to be equal to that of IS6110 restriction fragment length polymorphism typing, as shown in a companion population-based study. This 15-locus system is therefore proposed as the new standard for routine epidemiological discrimination of M. tuberculosis isolates and the 24-locus system as a high-resolution tool for phylogenetic studies.