Multidrug-resistant and heteroresistant Mycobacterium tuberculosis and associated gene mutations in Ethiopia

Molecular detection of rifampicin-resistant Mycobacterium tuberculosis by polymerase chain reaction in Ethiopia: a systematic review and meta-analysis

Introduction

Tuberculosis is a contagious bacterial disease caused by Mycobacterium tuberculosis. The emergence and spread of drug-resistant strains of M. tuberculosis in both developing and developed countries has made diagnosis, treatment, and control of tuberculosis more difficult. The PCR assay, which is a fast and sensitive technique and an alternative method for detecting multidrug-resistant tuberculosis, is used to determine rifampicin (RIF) resistance. There is no single figure in Ethiopia that represents rifampicin-resistant tuberculosis and that is why this study was conducted to overcome the inconsistency of the results of the previous studies.

Methods

Studies were researched from five major electronic databases. Studies which were cross-sectional in design, published, and written in English were included. The data were extracted using Microsoft Excel, and the data were managed and analyzed using Stata™ Version 17.0 statistical software. The Forest plot was used to check the presence of heterogeneity. The publication bias, meta-regression, and subgroup analysis were used to find out the source of heterogeneity. A random effect analysis model was used to pool the prevalence of RR TB from primary studies, and associated factors of RR among TB patients were identified using Meta regression. The presence of association was reported using OR with 95% CI.

Results

The overall pooled prevalence of tuberculosis was 14.9% (95% CI: 13.34, 16.46), of these approximately 7.48% (95% CI: 6.30, 8.66) showed rifampicin-resistant tuberculosis in Ethiopia. Among the computed variables, 2.05% living with HIV1.39 (95%CI: 1.13, 1.72) and having a history of TB treatment (95%CI: 1.34, 3.15) were identified as significant factors associated with RR TB in Ethiopia.

Conclusion

Drug-resistant TB is one of the prevalent emerging infectious diseases among TB patients, which affects approximately one out of every thirteen TB patients. Having TB-HIV coinfection and a history of prior TB treatment were identified as significant factors associated with RR TB. To prevent and control RR TB, patients should complete their follow-up course; the health professionals should educate the actions taken by the patients when they experience drug toxicity and side effects; and the Minister of Health should initiate telemedicine and recruit tracers to overcome TB patients' default and have good drug adherence and retention after initiation of the treatment.

Genotypic and phenotypic drug resistance patterns of Mycobacterium tuberculosis isolated from presumptive pulmonary tuberculosis patients in Ethiopia: A multicenter study

BACKGROUND

The emergence of drug-resistant tuberculosis (DR-TB) has been a major obstacle to global tuberculosis control programs, especially in developing countries, including Ethiopia. This study investigated drug resistance patterns and associated mutations of Mycobacterium tuberculosis Complex (MTBC) isolates from the Amhara, Gambella, and Benishangul-Gumuz regions of Ethiopia.

METHODS

A cross-sectional study was conducted using 128 MTBC isolates obtained from patients with presumptive tuberculosis (TB). Phenotypic (BACTEC MGIT 960) and genotypic (MTBDRplus and MTBDRsl assays) methods were used for drug susceptibility testing. Data were entered into Epi-info and analyzed using SPSS version 25. Frequencies and proportions were determined to describe drug resistance levels and associated mutations.

RESULTS

Of the 127 isolates recovered, 100 (78.7%) were susceptible to four first-line anti-TB drugs. Any drug resistance, polydrug resistance, and multi-drug resistance (MDR) were detected in 21.3% (27), 15.7% (20), and 15% (19) of the isolates, respectively, by phenotypic and/or genotypic methods. Mono-resistance was observed for Isoniazid (INH) (2, 1.6%) and Streptomycin (STR) (2, 1.6%). There were two genotypically discordant RIF-resistant cases and one INH-resistant case. One case of pre-extensively drug-resistant TB (pre-XDR-TB) and one case of extensively drug-resistant TB (XDR-TB) were identified. The most frequent gene mutations associated with INH and rifampicin (RIF) resistance were observed in the katG MUT1 (S315T1) (20, 76.9%) and rpoB (S531L) (10, 52.6%) genes, respectively. Two MDR-TB isolates were resistant to second-line drugs; one had a mutation in the gyrA MUT1 gene, and the other had missing gyrA WT1, gyrA WT3, and rrs WT1 genes without any mutation.

CONCLUSIONS

The detection of a significant proportion of DR-TB cases in this study suggests that DR-TB is a major public health problem in Ethiopia. Thus, we recommend the early detection and treatment of DR-TB and universal full first-line drug-susceptibility testing in routine system.

Analysis of Discordance between Genotypic and Phenotypic Assays for Rifampicin-Resistant Mycobacterium tuberculosis Isolated from Healthcare Facilities in Mthatha

The study sought to determine the rate of discordant results between genotypic and phenotypic tests for the diagnosis of drug-resistant tuberculosis (DR-TB). Sputum samples and cultured isolates from suspected DR-TB patients were, respectively, analyzed for Mycobacterium tuberculosis by Xpert^® MTB/RIF (Cepheid, Sunnyvale, CA, USA) and line probe assays (LPA) (Hain, Nehren, Germany). Discrepant rifampicin (RMP)-resistant results were confirmed using BACTEC MGIT960 (BD, New York, NY, USA). Of the 224 RMP-resistant results obtained by Xpert MTB/RIF, 5.4% were susceptible to RMP by LPA. MGIT960 showed a 75% agreement with LPA. The discrepancy was attributed to either heteroresistance or DNA contamination during LPA testing in 58.3% of cases. In 25% of the samples showing agreement in RMP resistance between Xpert MTB/RIF and MGIT960, the discrepancy was attributed to laboratory errors causing false RMP susceptible results with LPA. In 16.7% of the cases, the discrepancy was attributed to false RMP susceptible results with Xpert MTB/RIF. Out of the 224 isolates, susceptibility to isoniazid (INH) by LPA was performed in 73.7% RMP-resistant isolates, of which, 80.6% were resistant. All RMP-resistant isolates by Xpert MTB/RIF were confirmed in 98.5% by LPA if TB isolates were resistant to INH, but were only confirmed in 81.3% if TB isolates were susceptible to INH (p < 0.001). In conclusion, laboratory errors should be considered when investigating discordant results.

Drug Resistance in Tuberculous Lymphadenitis: Molecular Characterization

Background

Drug-resistant tuberculosis (TB) epidemic in high-TB-incidence countries, particularly Ethiopia, remains a significant challenge. As a result, we investigated the drug resistance, common gene mutation, and molecular characterization of mycobacterial isolates from patients with suspected tuberculous lymphadenitis (TBLN). Methodology. A cross-sectional study of 218 FNA samples from TBLN patients inoculated on Lowenstein-Jensen media was carried out. The culture isolates were identified as MTB by polymerase chain reaction (PCR) and the difference-9 (RD9) test region. In addition, the GenoType MTBDRplus assay tested the first and second-line MTB drugs, and the spoligotyping strain-dependent polymorphism test was determined.

Results

Among the 50 culture-positive isolates, 14% (7/50) had drug resistance caused by a gene mutation. Out of these, 4 (8%) isolates were mono-resistant to isoniazid drug, which is caused by a gene mutation in katG in the region of interrogated at codon 315 in the amino acid sequence of S315T1, and 3 (6%) isolates were resistant to both rifampicin and isoniazid drugs. The mutation was observed for katG (at codon 315 with a change in the sequence of amino acid S315T) and rpoB (at codon 530-533 with a change in the sequence of amino acid S531L (S450L)) genes. The most prevalent spoligotypes were orphan and SIT53 strains.

Conclusion

The predominance of INH mono-resistance poses a critical risk for the potential development of MDR-TB, as INH mono-resistance is a typical pathway to the occurrence of MDR-TB. The orphan and SIT53 (T) strains were the most common in the study area, and a drug-resistant strain caused by a common gene mutation could indicate the transmission of clonal-resistant strains in the community.

Heteroresistance to rifampicin & isoniazid in clinical samples of patients with presumptive drug-resistant tuberculosis in Central India

Background & objectives

A combination of resistant and susceptible Mycobacterium tuberculosis (MTB) isolated from clinical specimens is referred to as heteroresistance. Heteroresistance leads to difficulties in drug resistance testing and may adversely affect treatment outcomes. The present study estimated the proportion of heteroresistance among MTB in clinical samples of presumptive drug-resistant tuberculosis (TB) patients in Central India.

Methods

A retrospective analysis of data generated from line probe assay (LPA) at a tertiary care hospital in Central India between January 2013 and December 2018 was carried out. A heteroresistant MTB in a sample was indicated by the presence of both wild-type and mutant-type patterns on an LPA strip.

Results

Data analysis was carried out on interpretable 11,788 LPA results. Heteroresistance in MTB was detected in 637 (5.4%) samples. Of these, heteroresistance in MTB was detected in 413 (64.8%), 163 (25.5%) and 61 (9.5%) samples with respect to rpoB, katG and inhA genes, respectively.

Interpretation & conclusions

Heteroresistance is considered a preliminary step in the development of drug resistance. Delayed or suboptimal anti-tubercular therapy in patients with heteroresistance of MTB may elicit full clinical resistance and negatively impact the National TB Elimination Programme. Further studies are, however, needed to determine the impact of heteroresistance on treatment outcomes in individual patients.

Genotypic and phenotypic drug-resistance detection and prevalence of heteroresistance in patients with isoniazid- and multidrug-resistant tuberculosis in Ethiopia

Objective

To assess the agreement between genotypic and phenotypic methods for detecting drug resistance, and examine the prevalence of heteroresistance among isoniazid (INH)- and multidrug/rifampicin-resistant (MDR/RR) TB.

Method

In total, 127 Mycobacterium tuberculosis (Mtb) isolates, including 65 MDR/RR and 62 INH resistant, were used. First-line drug susceptibility testing (DST) was performed using the LJ method to determine the percentage of resistant bacteria. All drug-resistant isolates underwent testing with LPA. Heteroresistance was defined as simultaneous detection of wild-type and resistance-conferring mutations using LPA.

Result

The sensitivity of LPA (compared with LJ DST) was 96% for any INH-resistant TB and 94% for any RR TB. The prevalence of heteroresistance among the 123. Mtb isolates was 9.8%. The percentage of resistant bacteria ranged from 1% to 10% for heteroresistant TB. Rifampicin heteroresistance was detected in 1.6% of MDR TB patients. INH heteroresistance was detected in 1.6% and 16.7% of MDR and INH-resistant TB patients, respectively. The proportion of INH heteroresistance was significantly higher (p = 0.030) in persons living with HIV.

Conclusion

Some phenotypic drug resistances were not captured by LPA. The prevalence and percentage of resistant bacteria among heteroresistant TB highlight the importance of LPA for early detection of heteroresistant TB.

Antibiotic heteroresistance in Mycobacterium tuberculosis isolates: a systematic review and meta-analysis

BACKGROUND

Mycobacterium tuberculosis (MTB) is responsible for tuberculosis; that continues to be a public health threat across the globe. Furthermore, increasing heteroresistance (HR)-the presence of resistant and susceptible isolates among MTB strains- has been reported from around the world. This phenomenon can lead to full resistance development and treatment failure.

METHODS

We systematically searched the relevant studies in PubMed, Scopus, and Embase (Until October 21, 2020). The study outcomes revealed the weighted pooled prevalence of antibiotic HR in MTB isolates with subgroup analysis by year, quality of study, and heteroresistance detection method.

RESULTS

A total of 38 studies which had investigated MTB isolates were included in the meta-analysis. Geographically, the highest number of studies were reported from Asia (n  =  24), followed by Africa (n  =  5). Nineteen studies reported HR to isoniazid, with a weighted pooled prevalence of 5% (95% CI 0-12) among 11,761 MTB isolates. Also, there is no important trend for the subgroup analysis by the study period (2001-2014 vs 2015-2017 vs 2018-2020). HR to rifampin was reported in 17 studies, with a weighted pooled prevalence of 7% (95% CI 2-14) among 3782 MTB isolates. HR to fluoroquinolone and ethambutol were reported in 12 and 4 studies, respectively, with weighted pooled prevalence of 10% and 1% among 2153 and 1509 MTB isolates, correspondingly.

CONCLUSION

Based on our analysis, HR in MTB isolates with different frequency rate is present worldwide. Thus, the selection of appropriate and reliable methods for HR detection is crucial for TB eradication.

Prevalence of drug resistance-conferring mutations associated with isoniazid- and rifampicin-resistant Mycobacterium tuberculosis in Ethiopia: a systematic review and meta-analysis

OBJECTIVES

Globally, the incidence and mortality of tuberculosis (TB) are declining; however, low detection of drug-resistant disease threatens to reverse current progress toward global TB control. Multiple rapid molecular diagnostic tests have recently been developed to detect genetic mutations in Mycobacterium tuberculosis (Mtb) known to confer drug resistance. However, their utility depends on the frequency and distribution of resistance-associated mutations in the pathogen population. This review aimed to assess the prevalence of gene mutations associated with rifampicin (RIF)- and isoniazid (INH)-resistant Mtb in Ethiopia.

METHODS

We searched the literature in PubMed/MEDLINE, Web of Science, Scopus and Cochrane Library. Data analysis was conducted in Stata 11.

RESULTS

Totally, 909 (95.8%) of 949 INH-resistant Mtb isolates had detectable gene mutations: 95.8% in katG315 and 5.9% in the inhA promoter region. Meta-analysis resulted in an estimated pooled prevalence of katGMUT1(S315T1) of 89.2% (95% CI 81.94-96.43%) and a pooled prevalence of inhAMUT1(C15T) of 77.5% (95% CI 57.84-97.13%). Moreover, 769 (90.8%) of 847 RIF-resistant strains had detectable rpoB gene mutations. Meta-analysis resulted in a pooled prevalence of rpoBMUT3(S531L) of 74.2% (95% CI 66.39-82.00%).

CONCLUSION

RIF-resistant Mtb were widespread, particularly those harbouring rpoB(S531L) mutation. Similarly, INH-resistant Mtb with katG(S315T1) and inhA(C15T) mutations were common. Tracking S531L, S315T1 and C15T mutations among RIF- and INH-resistant isolates, respectively, would be diagnostically and epidemiologically valuable. Rapid diagnosis of RIF- and INH-resistant Mtb would expedite modification of TB treatment regimens, and proper timely infection control interventions could reduce the risk of development and transmission of multidrug-resistant TB.

Trends of Mycobacterium tuberculosis and rifampicin resistance in Adigrat General Hospital, Eastern zone of Tigrai, North Ethiopia

Background

Tuberculosis is an infectious disease usually caused by Mycobacterium tuberculosis bacteria. The global emergence of mono- or multidrug-resistant tuberculosis and extensively drug-resistant forms of tuberculosis pose a considerable challenge to tuberculosis control programs. There has been no reliable and organized data on trends and drug resistance of Mycobacterium tuberculosis in the study area. Therefore, this study aimed to determine the trends of Mycobacterium tuberculosis and rifampicin resistance in the Adigrat General Hospital, eastern Zone of Tigrai, North Ethiopia.

Methods

A hospital-based retrospective cross-sectional study was conducted at Adigrat General Hospital from January 2015 to 2018.Data was collected retrospectively from the GeneXpert™ TB registration book using a data extraction format. Data was entered into Epi-Info 3.1 and subsequently exported and analyzed using SPSS Version 20.The results were summarized using descriptive statistics, tables, and figures. Bivariate and multi-variant regression analysis was employed to measure the association between dependent and independent variables. P values < 0.05 were considered statistically significant.

Result

A total of 5944 Mycobacterium tuberculosis presumptive patients were included in the study. The majority of the study participants were male (58.1%) with participants’ median age of 40.0 (IQR 26–57) years, the majority were 30–44 years. The overall positive cases of Mycobacterium tuberculosis was 24.3% (1446) with a total of 132 (9.1%) found to be resistant to rifampicin. Of the total confirmed positive cases 8.7% (103/1188) and 11.2% (29/258) were rifampicin resistance of presumptive tuberculosis and presumptive drug resistance tuberculosis patients respectively. Age, the reason for diagnosis, site of presumptive tuberculosis, and/or being HIV infected showed significant association with our dependent variable; however, only age and being HIV infected were associated with rifampicin resistance.

Conclusion

In our study, the overall trends of Mycobacterium tuberculosis and rifampicin resistance were found to be high. Rifampicin resistance is more common in patients with HIV and presumptive drug resistance tuberculosis individuals. Therefore, maximizing early detection of drug-resistant and strengthening tuberculosis infection control activities are recommended to reduce the burden of this contagious and potentially deadly disease.

Characteristics of pulmonary multidrug-resistant tuberculosis patients in Tigray Region, Ethiopia: A cross-sectional study

BACKGROUND

Tuberculosis (TB) is among the top 10 causes of mortality and the first killer among infectious diseases worldwide. One of the factors fuelling the TB epidemic is the global rise of multidrug resistant TB (MDR-TB). The aim of this study was to determine the magnitude and factors associated with MDR-TB in the Tigray Region, Ethiopia.

METHOD

This study employed a facility-based cross-sectional study design, which was conducted between July 2018 and August 2019. The inclusion criteria for the study participants were GeneXpert-positive who were not under treatment for TB, PTB patients' ≥15 years of age and who provided written informed consent. A total of 300 participants were enrolled in the study, with a structured questionnaire used to collect data on clinical, sociodemographic and behavioral factors. Sputum samples were collected and processed for acid-fast bacilli staining, culture and drug susceptibility testing. Drug susceptibility testing was performed using a line probe assay. Logistic regression was used to analyze associations between outcome and predictor variables.

RESULTS

The overall proportion of MDR-TB was 16.7% (11.6% and 32.7% for new and previously treated patients, respectively). Of the total MDR-TB isolates, 5.3% were pre-XDR-TB. The proportion of MDR-TB/HIV co-infection was 21.1%. A previous history of TB treatment AOR 3.75; 95% CI (0.7-2.24), cigarette smoking AOR 6.09; CI (1.65-2.50) and patients who had an intermittent fever (AOR = 2.54, 95% CI = 1.21-5.4) were strongly associated with MDR-TB development.

CONCLUSIONS

The magnitude of MDR-TB observed among new and previously treated patients is very alarming, which calls for an urgent need for intervention. The high proportion of MDR-TB among newly diagnosed cases indicates ongoing transmission, which suggests the need for enhanced TB control program performance to interrupt transmission. The increased proportion of MDR-TB among previously treated cases indicates a need for better patient management to prevent the evolution of drug resistance. Assessing the TB control program performance gaps and an optimal implementation of the WHO recommended priority actions for the management of drug-resistant TB, is imperative to help reduce the current high MDR-TB burden in the study region.

Molecular detection of multidrug resistance pattern and associated gene mutations in M. tuberculosis isolates from newly diagnosed pulmonary tuberculosis patients in Addis Ababa, Ethiopia

INTRODUCTION

Multi-drug resistance is a major challenge in the control of tuberculosis. Despite newer modalities for diagnosis and treatment, people are still suffering from this disease. Understanding the common gene mutations conferring rifampicin and isoniazid resistance is crucial for the implementation of effective molecular tools at local and national levels. Hence, this study aimed to evaluate the molecular detection of rifampicin and isoniazid-resistant gene mutations in M.tuberculosis isolates in Addis Ababa, Ethiopia.

METHOD

Health Center-based cross-sectional study was conducted between January and September 2017 in Addis Ababa, Ethiopia. The collected sputum samples were processed for mycobacterial isolation and Region of difference 9 based polymerase chain reaction for species identification. To characterize the rifampicin and isoniazid-resistant M. tuberculosis isolates, a molecular genetic assay (GenoType MTBDRplus) was used; the assay is based on DNA-STRIP technology.

RESULT

Culture positivity was confirmed in 82.6% (190/230) of smear-positive newly diagnosed pulmonary tuberculosis cases enrolled in the study. From 190 isolates 93.2% were sensitive for both rifampicin and isoniazid, and 6.8% of the isolates were resistant to at least one of the tested anti-TB drugs. Gene mutations were observed in all studied multidrug resistance-associated gene loci (rpoB, katG, and inhA). Two isolates exhibited heteroresistance, a mutated, as well as wild type sequences, were detected in the respective strains. MDR-TB case was observed in 1.1% (2/190) of the cases. All the MDR-TB cases were positive for HIV and found to have a history of prior hospital admission.

CONCLUSION

In our finding a relatively high prevalence of any drug resistance was observed and the overall prevalence of multidrug-resistant tuberculosis was 1.1%.The majority of drug-resistant isolates demonstrated common mutations. Heteroresistant strains were detected, signaling the existence of an M.tuberculosis population with variable responses to anti-tuberculosis drugs or of mixed infections.

Emergence of Heteroresistance Mycobacterium Tuberculosis in Saudi Arabia

PURPOSE

Heteroresistant Mycobacterium tuberculosis (MTB) is defined as a group of drug-susceptible and resistant bacteria in a single clinical specimen from tuberculosis (TB) patients. Heteroresistance of MTB is considered a preliminary stage to full resistance. The present study aimed to determine the heteroresistance in Mycobacterium tuberculosis in Tabuk province, in the north of the Kingdom of Saudi Arabia.

METHOD

GenoType MTBDRplus assay was used to determine mutations associated with isoniazid and rifampicin resistance.

RESULTS

A total number of 46 confirmed M. tuberculosis positive sputum samples were scanned for heteroresistance. The present study revealed 3 (6.5%) heteroresistant mutations to either rpoB gene alone, 2 (4.4%) to rpoB and 1 (2.2%) to inhA genes.

CONCLUSION

The detection of heteroresistant mutations could guide the initiation of an appropriate regimen of treatment.

Efficacy Of Line Probe Assay In Detection Of Drug-Resistant Pulmonary Tuberculosis In Comparison With GeneXpert And Phenotypic Methods In Iran And Genetic Analysis Of Isolates By MIRU-VNTR

Background

Successful treatment of tuberculosis depends on early diagnosis and use of appropriate drug susceptibility testing in a timely manner. In the present study, LPA efficacy was assayed in detection and drug susceptibility testing of pulmonary tuberculosis in comparison to available methods in Iran and phylogenetic analyses of isolated cases carried out by MIRU-VNTR.

Methods

This study was conducted at the Tehran Regional Reference Laboratory for Tuberculosis. All sputum specimens were subjected to smear, culture, and drug susceptibility testing (DST), GeneXpert, and LPA. Finally, 15-locus-based MIRU-VNTR was used for molecular genotyping.

Results

From a total of 920 sputum specimens, 6.08% (n=56) were identified as MTBC by culture, 6.8% (n=63) by GeneXpert, and 6.5% (n=60) by LPA. Phenotype DST and LPA methods confirmed the resistance of 4 and 14 specimens to rifampin (RIF) and isoniazid (INH); two cases were considered as multidrug-resistant (MDR). Using GeneXpert, four cases were identified as RIF-resistant. Based on LPA results, inhA and katG mutations were detected in 100% and 21.4% of INH-resistant cases, respectively. All 56 culture positive Mycobacterium tuberculosis isolates were placed in 29 different clusters using MIRU-VNTR genotyping. Two MDR-TB, 2 RIF mono-resistant, and 12 INH mono-resistant cases were placed in different clusters.

Conclusion

LPA is an appropriate method for early detection and accurate diagnosis of TB and drug-resistant cases that makes it possible to distinguish INH mono-resistant cases from MDR cases in Iran.

Evaluation of the QuantaMatrix Multiplexed Assay Platform for Molecular Diagnosis of Multidrug- and Extensively Drug-Resistant Tuberculosis Using Clinical Strains Isolated in Myanmar

Background

Although the incidence of tuberculosis (TB) is decreasing, cases of multidrug-resistant (MDR) TB and extensively drug-resistant (XDR) TB continue to increase. As conventional phenotype drug susceptibility testing (pDST) takes six to eight weeks, molecular assays are widely used to determine drug resistance. we developed QuantaMatrix Multiplexed Assay Platform (QMAP) MDR/XDR assay (QuantaMatrix Inc., Seoul, Korea) that can simultaneously detect mutations related to both first- and second-line drug resistance (rifampin, isoniazid, ethambutol, fluoroquinolones, second-line injectable drugs, and streptomycin).

Methods

We used 190 clinical Mycobacterium tuberculosis (MTB) strains isolated from Myanmar, compared QMAP and pDST results, and determined concordance rates. Additionally, we performed sequence analyses for discordant results.

Results

QMAP results were 87.9% (167/190) concordant with pDST results. In the 23 isolates with discordant results, the QMAP and DNA sequencing results completely matched.

Conclusions

The QMAP MDR/XDR assay can detect all known DNA mutations associated with drug resistance for both MDR- and XDR-MTB strains. It can be used for molecular diagnosis of MDR- and XDR-TB to rapidly initiate appropriate anti-TB drug therapy.

Risk factors associated with multidrug-resistant tuberculosis (MDR-TB) in a tertiary armed force referral and teaching hospital, Ethiopia

Background

Ethiopia is one of the world health organization defined higher tuberculosis (TB) burden countries where the disease remains a massive public health threat. This study aimed to identify the prevalence and associated factors of multidrug-resistant tuberculosis (MDR-TB) using all armed force and civilian TB attendants in a tertiary level armed force hospital, where data for MDR-TB are previously unpublished.

Methods

Cross-sectional study was conducted from September 2014 to August 2015 in a tertiary level Armed Force Referral and Teaching Hospital (AFRTH), Ethiopia. Armed force members (n = 251) and civilians (n = 130) which has been undergone TB diagnosis at AFRTH were included. All the specimens collected were subjected to microscopic smear observation, culture growth and drug susceptibility testing. Data were analyzed using statistical package for social sciences following binary logistic regression and Chi-square. P-values < 0.05 were considered statistically significant.

Results

Among 381 TB patients, 355 (93.2%) new and 26 (6.8%) retreatment cases were identified. Culture and smear positive TB cases were identified in 297 (77.9%) and 252 (66.1%) patients, respectively. The overall prevalence of MDR-TB in AFRTH was found 1.8% (1.3% for armed force members and 0.5% for civilian patients) all of which were previously TB treated cases. The entire treatment success rates were 92.6% achieved highest in the armed force (active and pension) than the civilian patients. The failure and dead cases were also found 2.5 and 4.6%, respectively. Using bivariate analysis, category of attendants and TB contact history were strong predictors of MDR-TB in armed force and civilian patients. Moreover, human immunodeficiency virus (HIV) infection also identified a significant (OR = 14.6; 95% CI = 2.3–92.1; p = 0.004) predicting factor for MDR-TB in armed force members. However, sex, age and body mass index were not associated factor for MDR-TB.

Conclusions

In AFRTH, lower prevalence of MDR-TB was identified in armed force and civilian patients that were significantly associated with category of attendants, HIV infection and TB contact history. Considering armed force society as one segment of population significantly helps to plan a better MDR-TB control management, especially for countries classified as TB high burden country.

Performance of MTBDRplus assay in detecting multidrug resistant tuberculosis at hospital level

OBJECTIVE

Multidrug-resistant tuberculosis (MDR-TB) case finding progressively increased in Ethiopia mainly as a result of the utilization of World Health Organization (WHO)-endorsed rapid technologies including MTBDRplus assay. However, there is inadequate data on routine testing performance of the MTBDRplus assay. Consequently, the aim of the study was to assess the routine performance of the MTBDRplus assay in detecting MDR-TB at St. Peter's TB Specialized Hospital.

RESULTS

The sensitivity and specificity of MTBDRplus in detecting isoniazid (INH) resistance were 96.3 and 100%, respectively. While for rifampicin (RIF) 100% was recorded for both. Similarly, a sensitivity of 97.96% and a specificity of 100% was measured for detecting MDR-TB. Among 49 MTBDRplus RIF resistant isolates, 46 (93.9%) strains had rpoB mutation. S531L was the most common rpoB mutant (81.6% of RIF resistant cases). All MTBDRplus INH resistant isolates (n = 52) had S315T1 katG mutation.

Rifampicin-resistance pattern of Mycobacterium tuberculosis and associated factors among presumptive tuberculosis patients referred to Debre Markos Referral Hospital, Ethiopia: a cross-sectional study

BACKGROUND

Prevailing data on rifampicin-resistant M. tuberculosis is essential for early management of MDR-TB. Therefore, this study was conducted to determine the prevalence of rifampicin-resistant Mycobacterium tuberculosis and associated factors among presumptive TB cases in Debre Markos Referral Hospital, Ethiopia.

METHODS

A cross-sectional study was conducted from September 2014 to March 2015. Detection of M. tuberculosis and resistance to rifampicin was performed using Gene Xpert MTB/RIF assay. Data was collected using structured questionnaire by face to face interview. Logistic regression analysis was computed to determine the associated factors of rifampicin-resistant M. tuberculosis.

RESULTS

A total of 505 presumptive TB patients included in the study. The prevalence of M. tuberculosis confirmed cases was 117 (23.2%) (95% CI 19.7-27%). It was higher among males (27.9%) than females (17.9%) (AOR: 2.17; CI 1.35-3.49). Of the 117 M. tuberculosis confirmed cases, 12 (10.3%) (95% CI 6.0-17.1%) were resistant to rifampicin. Rifampicin-resistant M. tuberculosis was noticed in 7 previously treated TB patients (17.1%) and 5 treatment naive patients (6.7%) (AOR: 4.16; CI 1.04-16.63). The prevalence of rifampicin-resistant M. tuberculosis was 6 (9.8%) and 6 (11.3%) in pulmonary and extra-pulmonary infections, respectively. Of the 30, MTB/HIV co-infection, 3 (10%) were rifampicin-resistant M. tuberculosis.

CONCLUSION

Rifampicin-resistant M. tuberculosis is prevalent in both pulmonary and extra-pulmonary tuberculosis patients. Previous treatment with anti-TB drugs was significantly associated with rifampicin resistance. Therefore, the use of Gene Xpert should be scaled up across the country for rapid detection and management of drug resistant M. tuberculosis.

Detection of Isoniazid-, Fluoroquinolone-, Amikacin-, and Kanamycin-Resistant Tuberculosis in an Automated, Multiplexed 10-Color Assay Suitable for Point-of-Care Use

Extensively drug-resistant (XDR) tuberculosis (TB) cannot be easily or quickly diagnosed. We developed a rapid, automated assay for the detection of XDR-TB plus resistance to the drug isoniazid (INH) for point-of-care use. Using a simple filter-based cartridge with an integrated sample processing function, the assay identified a wide selection of wild-type and mutant sequences associated with XDR-TB directly from sputum. Four new large-Stokes-shift fluorophores were developed. When these four Stokes-shift fluorophores were combined with six conventional fluorophores, 10-color probe detection in a single PCR tube was enabled. A new three-phase, double-nested PCR approach allowed robust melting temperature analysis with enhanced limits of detection (LODs). Finally, newly designed sloppy molecular beacons identified many different mutations using a small number of probes. The assay correctly distinguished wild-type sequences from 32 commonly occurring mutant sequences tested in gyrA, gyrB, katG, and rrs genes and the promoters of inhA and eis genes responsible for resistance to INH, the fluoroquinolone (FQ) drugs, amikacin (AMK), and kanamycin (KAN). The LOD was 300 CFU of Mycobacterium tuberculosis in 1 ml sputum. The rate of detection of heteroresistance by the assay was equivalent to that by Sanger sequencing. In a blind study of 24 clinical sputum samples, resistance mutations were detected in all targets with 100% sensitivity, with the specificity being 93.7 to 100%. Compared to the results of phenotypic susceptibility testing, the sensitivity of the assay was 75% for FQs and 100% each for INH, AMK, and KAN and the specificity was 100% for INH and FQ and 94% for AMK and KAN. Our approach could enable testing for XDR-TB in point-of-care settings, potentially identifying highly drug-resistant TB more quickly and simply than currently available methods.

Drug resistance-conferring mutations in Mycobacterium tuberculosis from pulmonary tuberculosis patients in Southwest Ethiopia

OBJECTIVE/BACKGROUND

The nature and frequency of mutations in rifampicin (RIF) and isoniazid (INH) resistant Mycobacterium tuberculosis isolates vary considerably according to geographic locations. However, information regarding specific mutational patterns in Ethiopia remains limited.

METHODS

A cross-sectional prospective study was carried out among confirmed pulmonary tuberculosis cases in Southwest Ethiopia. Mutations associated with RIF and INH resistances were studied using GenoType MTBDRplus line probe assay in 112 M. tuberculosis isolates. Culture (MGIT960) and identification tests were performed at the Mycobacteriology Research Center of Jimma University, Jimma, Ethiopia.

RESULTS

Mutations conferring resistance to INH, RIF, and multidrug resistance were detected in 36.6% (41/112), 30.4% (34/112), and 27.7% (31/112) of M. tuberculosis isolates respectively. Among 34 RIF-resistant isolates, 82.4% (28/34) had rpoB gene mutations at S531L, 2.9% (1/34) at H526D, and 14.7% (5/34) had mutations only at wild type probes. Of 41 INH-resistant strains, 87.8% (36/41) had mutations in the katG gene at Ser315Thr1 and 9.8% (4/41) had mutations in the inhA gene at C15T. Mutations in inhA promoter region were strongly associated with INH monoresistance.

CONCLUSION

A high rate of drug resistance was commonly observed among failure cases. The most frequent gene mutations associated with the resistance to INH and RIF were observed in the codon 315 of the katG gene and codon 531 of the rpoB gene, respectively. Further studies on mutations in different geographic regions using DNA sequencing techniques are warranted to improve the kit by including more specific mutation probes in the kit.