Antimycobacterial activity of linezolid against multidrug-resistant and extensively drug-resistant strains of Mycobacterium tuberculosis in Iran

Mycobacterium tuberculosis Drug Resistance in Ethiopia: An Updated Systematic Review and Meta-Analysis

Background: Tuberculosis (TB) remains a significant global public health issue, despite advances in diagnostic technologies, substantial global efforts, and the availability of effective chemotherapies. Mycobacterium tuberculosis, a species of pathogenic bacteria resistant to currently available anti-TB drugs, is on the rise, threatening national and international TB-control efforts. This systematic review and meta-analysis aims to estimate the pooled prevalence of drug-resistant TB (DR-TB) in Ethiopia. Materialsand Methods: A systematic literature search was undertaken using PubMed/MEDLINE, HINARI, the Web of Science, ScienceDirect electronic databases, and Google Scholar (1 January 2011 to 30 November 2020). After cleaning and sorting the records, the data were analyzed using STATA 11. The study outcomes revealed the weighted pooled prevalence of any anti-tuberculosis drug resistance, any isoniazid (INH) and rifampicin (RIF) resistance, monoresistance to INH and RIF, and multidrug-resistant TB (MDR-TB) in newly diagnosed and previously treated patients with TB. Results: A total of 24 studies with 18,908 patients with TB were included in the final analysis. The weighted pooled prevalence of any anti-TB drug resistance was 14.25% (95% confidence interval (CI): 7.05–21.44%)), whereas the pooled prevalence of any INH and RIF resistance was found in 15.62% (95%CI: 6.77–24.47%) and 9.75% (95%CI: 4.69–14.82%) of patients with TB, respectively. The pooled prevalence for INH and RIF-monoresistance was 6.23% (95%CI: 4.44–8.02%) and 2.33% (95%CI: 1.00–3.66%), respectively. MDR-TB was detected in 2.64% (95%CI: 1.46–3.82%) of newly diagnosed cases and 11.54% (95%CI: 2.12–20.96%) of retreated patients with TB, while the overall pooled prevalence of MDR-TB was 10.78% (95%CI: 4.74–16.83%). Conclusions: In Ethiopia, anti-tuberculosis drug resistance is widespread. The estimated pooled prevalence of INH and RIF-monoresistance rates were significantly higher in this review than in previous reports. Moreover, MDR-TB in newly diagnosed cases remained strong. Thus, early detection of TB cases, drug-resistance testing, proper and timely treatment, and diligent follow-up of TB patients all contribute to the improvement of DR-TB management and prevention. Besides this, we urge that a robust, routine laboratory-based drug-resistance surveillance system be implemented in the country.

Population pharmacokinetics and target attainment analysis of linezolid in multidrug-resistant tuberculosis patients

AIM

This study investigates the pharmacokinetic/pharmacodynamic (PK/PD) target attainment of linezolid in patients infected with multidrug-resistant (MDR) tuberculosis (TB).

METHODS

A pharmacometric model was developed including 244 timed linezolid concentration samples from 39 patients employing NONMEM 7.4. The probability of target attainment (PTA, PK/PD target: unbound (f) area-under-the-concentration-time-curve (AUC)/minimal inhibitory concentration (MIC) of 119) as well as a region-specific cumulative fraction of response (CFR) were estimated for different dosing regimens.

RESULTS

A one-compartment model with linear elimination with a clearance (CL) of 7.69 L/h (interindividual variability 34.1%), a volume of distribution (Vd) of 45.2 L and an absorption constant (KA) of 0.679 h^-1 (interoccasion variability 143.7%) allometric scaled by weight best described the PK of linezolid. The PTA at an MIC of 0.5 mg/L was 55% or 97% if patients receiving 300 or 600 mg twice daily, respectively. CFRs varied greatly among populations and geographic regions. A desirable global CFR of ≥90% was achieved if linezolid was administered at a dose of 600 mg twice daily but not at a dose of 300 mg twice daily.

CONCLUSION

This study showed that a dose of 300 mg twice daily of linezolid might not be sufficient to treat MDR-TB patients from a PK/PD perspective. Thus, it might be recommendable to start with a higher dose of 600 mg twice daily to ensure PK/PD target attainment. Hereby, therapeutic drug monitoring and MIC determination should be performed to control PK/PD target attainment as linezolid shows high variability in its PK in the TB population.

Linezolid resistance among multidrug-resistant Mycobacterium tuberculosis clinical isolates in Iran

The management of multidrug-resistant (MDR) and extensively drug-resistant tuberculosis (XDR-TB) presents a main challenge and the drug options for treating these infections are very limited. Linezolid (LNZ) has recently been approved for the treatment of MDR and XDR-TB. But, there are narrow data on genotypic and phenotypic LNZ resistance in clinical isolates. So, we aimed to determine the prevalence of LNZ resistance and to identify the mutations associated with LNZ resistance among clinical MDR-TB isolates. The minimum inhibitory concentration (MIC) values of LNZ for 22 MDR-TB isolates were determined by broth microdilution method. All MDR-TB isolates were sequenced in the rrl and rplC genes conferring LNZ resistance. LNZ resistance was found in 3 (13.6%) of 22 MDR-TB isolates. The MICs of LNZ were 8 μg/mL for two isolates and 16 μg/mL for one isolate. The 421 (A/G) and 449 (T/A) mutations in rplC gene were detected in one of the LNZ-resistant isolates. There was no mutation in rrl gene. The results reveal that the prevalence of LNZ-resistant isolates is 13.6% among MDR-TB isolates and drug susceptibility testing (DST) against LNZ is useful in the management of complicated and drug-resistant cases. However, further studies could identify other possible genetic mechanism of resistance in TB.

Antibacterial Components of Levisticum officinale Koch against Multidrug-resistant Mycobacterium tuberculosis

Background: A bioassay-guided fractionation technique was used to evaluate the active constituents of the perennial plant L. officinale W.D.J. Koch (Apiaceae) against multidrug resistant (MDR) Mycobacterium tuberculosis. Methods: Column chromatography was used to isolation of compounds from L. officinale and spectroscopic methods including 1D and 2D NMR (Nuclear magnetic resonance) and HRMS (high resolution mass spectrometry) were used to identification of the isolated compounds. Also, to evaluate antibacterial activity, minimum inhibitory concentration (MIC) was carried out by broth micro-dilution method. Finally, molecular docking (MD) was performed using the Schrödinger package to evaluate interactions between the active compounds and InhA protein. Results: Phytochemical analysis of the ethyl acetate extract of the plant roots led to isolation of bergapten (1), isogosferol (2), oxypeucedanin (3), oxypeucedanin hydrate (4), imperatorin (5), ferulic acid (6) and falcarindiol (7). Falcarindiol and oxypeucedanin indicated a moderate activity on MDR M. tuberculosis with MIC values of = 32 and 64 μg/mL, respectively. Antibacterial activity of falcarindiol was also observed against S. aureus and methicillin-resistant S. aureus strains with the MIC values of 7.8 and 15.6 μg/mL, respectively. The results of docking analysis showed a good affinity of oxypeucedanin (3) and falcarindiol (7) to InhA enzyme with docking score values of -7.764 and -7.703 kcal/mol, respectively. Conclusion: Finally, 7 compounds were isolated from L. officinale that compounds 2-6 report for the first time from this plant. On the basis of the molecular docking (MD) study, oxypeucedanin (3) and falcarindiol (7) as active compounds against M. tuberculosis may be proposed as potential inhibitors of 2-trans-enoyl-ACP reductase (InhA), a key enzyme involved in the biosynthesis of the mycobacterial cell wall. Moreover, antibacterial activity of falcarindiol against methicillin-resistant S. aureus (MRSA) was remarkable.

Whole Genome Sequencing Results Associated with Minimum Inhibitory Concentrations of 14 Anti-Tuberculosis Drugs among Rifampicin-Resistant Isolates of Mycobacterium Tuberculosis from Iran

Accurate and timely detection of drug resistance can minimize the risk of further resistance development and lead to effective treatment. The aim of this study was to determine the resistance to first/second-line anti-tuberculosis drugs in rifampicin/multidrug-resistant Mycobacterium tuberculosis (RR/MDR-MTB) isolates. Molecular epidemiology of strains was determined using whole genome sequencing (WGS)-based genotyping. A total of 35 RR/MDR-MTB isolates were subjected to drug susceptibility testing against first/second-line drugs using 7H9 Middlebrook in broth microdilution method. Illumina technology was used for paired-end WGS applying a Maxwell 16 Cell DNA Purification kit and the NextSeq platform. Data analysis and single nucleotide polymorphism calling were performed using MTBseq pipeline. The genome-based resistance to each drug among the resistant phenotypes was as follows: rifampicin (97.1%), isoniazid (96.6%), ethambutol (100%), levofloxacin (83.3%), moxifloxacin (83.3%), amikacin (100%), kanamycin (100%), capreomycin (100%), prothionamide (100%), D-cycloserine (11.1%), clofazimine (20%), bedaquiline (0.0%), and delamanid (44.4%). There was no linezolid-resistant phenotype, and a bedaquiline-resistant strain was wild type for related genes. The Beijing, Euro-American, and Delhi-CAS were the most populated lineage/sublineages. Drug resistance-associated mutations were mostly linked to minimum inhibitory concentration results. However, the role of well-known drug-resistant genes for D-cycloserine, clofazimine, bedaquiline, and delamanid was found to be more controversial.

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.

Expression analysis of 10 efflux pump genes in multidrug-resistant and extensively drug-resistant Mycobacterium tuberculosis clinical isolates

OBJECTIVES

Active extrusion of antituberculosis drugs via efflux pumps (EPs) has been suggested as contributing to drug resistance in Mycobacterium tuberculosis. This study was conducted to determine the role of 10 drug efflux transporters in the development of drug resistance in a series of clinical M. tuberculosis isolates.

METHODS

A total of 31 clinical M. tuberculosis isolates without drug exposure [21 multi/extensively drug-resistant (M/XDR-TB) and 10 drug-susceptible isolates] were studied. The expression profile of 10 EP genes, including efpA, mmr, stp, drrA, drrB, mmpL7, Rv1250, Rv1634, Rv2994 and Rv1258c, was investigated against the H37Rv standard strain by quantitative reverse transcription PCR (RT-qPCR).

RESULTS

Among the 21M/XDR-TB isolates, 10 showed significantly increased levels of gene expression (>4-fold) for at least one of the studied EPs. Moreover, of the isolates with overexpressed genes, three and seven lacked genetic alterations in the surveyed regions of the rpoB+katG+inhA and katG+inhA genes, respectively. Whilst no elevation was observed in the expression of mmr, Rv1250, Rv1634 and Rv1258c genes in any of the isolates, drrA, stp and drrB were found to be the most commonly overexpressed, being overexpressed in seven, five and three isolates, respectively. Decreased minimum inhibitory concentrations (MICs) of rifampicin, but not isoniazid, were observed in the presence of the efflux pump inhibitor carbonyl cyanide 3-chlorophenylhydrazone (CCCP).

CONCLUSION

Overexpression of EP genes can contribute to the emergence of a MDR phenotype in M. tuberculosis. Inhibition of EPs may provide a promising strategy for improving tuberculosis treatment outcomes in patients infected with M/XDR-TB isolates.

Resistance of Mycobacterium tuberculosis strains to Rifampicin: A systematic review and meta-analysis

Introduction

Antitubercular drug resistance strain is a horrifying barrier to effective TB treatment and prevention. The present study aimed to determine the prevalence and geographical distribution of rifampicin-resistance M. tuberculosis (MTB) strains.

Methods

We searched two electronic databases, PubMed and EMBASE, until 26 March 2017 and updated our search on 27 April 2018 and accessed all prevalence studies of MTB strain and their drug susceptibility patterns to rifampicin. The pooled prevalence estimate was determined using random effects model.

Results

We identified 23 studies satisfying the inclusion criteria. The proportion of rifampicin resistance strains was diverged depending on the type of strains, country and Regions. The pooled estimate of rifampicin-resistance strains of MTB for the included studies was 4% (95% CI: 3–5%). In subgroup analysis based on World Health Organization (WHO) Regions, the pooled estimate of rifampicin-resistance strains of MTB was 11% (95% CI: 9–13%) with the Western Pacific Region 24%, Europian Region 10%, South-East Asian Region 6%, African Region 3% and Region of American 1%. Beijing family was the most dominant strain resistance to rifampicin with pooled prevalence of 14% (95% CI: 10–18%). The pooled prevalence of other families, i.e. EAI, T, CAS, MANU, Haarlem, LAM and Ural, was ≤2% for each.

Conclusion

High burden of rifampicin resistance MTB strains was identified in the Western Pacific Region. Of these, Beijing family was predominantly resistance to rifampicin in Western Pacific Region and South-East Asian Region and also spread to European Region and Region of American.

Prevalence of Beijing and Haarlem genotypes among multidrug-resistant Mycobacterium tuberculosis in Iran: Systematic review and meta-analysis

Antimicrobial drug resistance creates major problems in the control of tuberculosis (TB). Beijing and Haarlem genotypes of Mycobacterium tuberculosis are the prevalent genotypes responsible for multidrug resistant (MDR) TB worldwide. The aim of this study was to conduct a systematic review using meta-analysis to indicate the prevalence of Beijing and Haarlem genotypes among MDR-TB cases in Iran. Data sources of current study were 311 original articles (2006-2016) that were searched in several databases including Medline, Scopus, Embase, Cochrane library, and Iranian databases. Sixteen articles were selected for the prevalence of Beijing and Haarlem families among MDR-TB strains. Data were evaluated using meta-analysis and random effects models with the Meta-Analysis Software package Version 2.2 (Biostat, Englewood, NJ). Final investigation indicated 856 MDR samples in the 16 articles. Overall, the prevalence of Beijing and Haarlem genotypes among MDR-TB isolates in Iran was estimated to be 19.3% (95% CI, 13.1-27.5) and 18.7% (95% CI, 11.9-28.3) respectively. The studies conducted in northern Iran showing a significant association between Haarlem genotype and MDR is of particular concern. Certain refugee migration flows make this genotype of particular epidemiological and clinical concern because of its potential ability to endanger TB control programs in Iran.

Molecular characterization of Mycobacterium tuberculosis isolates from Tehran, Iran by restriction fragment length polymorphism analysis and spoligotyping

INTRODUCTION Characterization of Mycobacterium tuberculosis (MTB) isolates by DNA fingerprinting has contributed to tuberculosis (TB) control. The aim of this study was to determine the genetic diversity of MTB isolates from Tehran province in Iran. METHODS MTB isolates from 60 Iranian and 10 Afghan TB patients were fingerprinted by standard IS6110-restriction fragment length polymorphism (RFLP) analysis and spoligotyping. RESULTS The copy number of IS6110 ranged from 10-24 per isolate. The isolates were classified into 22 clusters showing ≥ 80% similarity by RFLP analysis. Fourteen multidrug-resistant (MDR) isolates were grouped into 4 IS6110-RFLP clusters, with 10 isolates [71% (95% CI: 45-89%)] in 1 cluster, suggesting a possible epidemiological linkage. Eighteen Iranian isolates showed ≥ 80% similarity with Afghan isolates. There were no strains with identical fingerprints. Spoligotyping of 70 isolates produced 23 distinct patterns. Sixty (85.7%) isolates were grouped into 13 clusters, while the remaining 10 isolates (14.2%) were not clustered. Ural (formerly Haarlem4) (n = 22, 31.4%) was the most common family followed by Central Asian strain (CAS) (n = 18, 25.7%) and T (n = 9, 12.8%) families. Only 1strain was characterized as having the Beijing genotype. Among 60 Iranian and 10 Afghan MTB isolates, 25% (95% CI: 16-37) and 70% (95% CI: 39-89) were categorized as Ural lineage, respectively. CONCLUSIONS A higher prevalence of Ural family MTB isolates among Afghan patients than among Iranian patients suggests the possible transmission of this lineage following the immigration of Afghans to Iran.

Mycobacterium tuberculosis Beijing Genotype in Western Iran: Distribution and Drug Resistance

INTRODUCTION

Mycobacterium tuberculosis Beijing genotype is gaining importance all over the world because this genotype is highly prevalent in several areas and is also frequently associated with drug resistance.

AIM

To identify and determine the frequency of Beijing genotype and mix infection with Beijing and non-Beijing in west of Iran and analyse the association between Beijing genotype and drug resistance.

MATERIALS AND METHODS

This cross-sectional study was conducted on 146 Tuberculosis (TB) samples collected at the TB reference laboratory in Kermanshah west of Iran from January 2014 to February 2015, Mycobacterium tuberculosis isolates from sputum samples, detected by microcopy, biochemical tests and solid culture were included and then the confirmed samples with Cepheid Xpert MTB/RIF assay were subjected to drug susceptibility tests for rifampicin, isoniazid, ethambutol using proportional method. The prevalence rate of Beijing and non-Beijing genotype was determined by Multiplex- Polymerase Chain Reaction (PCR).

RESULT

A total of 15/146 (10%) isolates were diagnosed as Beijing genotypes and the remaining 131/146(90%) isolates were non-Beijing genotypes by Multiplex PCR method. Among the 15 Beijing cases, 14 samples have shown mix infection indicating the presence of both Beijing and non-Beijing strains in samples. Three isolates from all cases were drug resistant. Interestingly all drug resistance isolates were from Beijing genotype which shows strong association between drug resistance and Beijing genotype. Also this genotype was more prevalent in younger age-group people (p=0.035).

CONCLUSION

Frequency of Beijing genotype in west of Iran is more than other sites of Iran but less than Asia. According to our result, mix infections with Beijing and non-Beijing, had the most prevalence therefore we should be concerned more about mix infections. Multiplex-PCR method is feasible, trustworthy and can distinguish mix infections. It is suggested to perform spoligotyping in addition to multiplex PCR method to discriminate mix infections.

Evaluation of the Immunogenicity of Diphtheria Toxoid Conjugated to Salmonella Typhimurium-Derived OPS in a Mouse Model: A Potential Vaccine Candidate Against Salmonellosis

Background

Salmonella enterica serovar Typhimurium (S. Typhimurium) causes gastroenteritis in humans and paratyphoid disease in some animals. Given the emergence of antibiotic resistance, vaccines are more effective than chemotherapy in disease control.

Objectives

The aim of this experimental study was to evaluate the immunogenicity of diphtheria toxoid (DT) conjugated with S. Typhimurium -derived OPS (O side chain isolation) in mice to determine its potential as a vaccine candidate against salmonellosis.

Materials and Methods

Lipopolysaccharide (LPS) was extracted from the bacterial strain. After isolation of the O side chain of LPS, detoxification, and conjugation of the detoxified OPS samples with DT, pyrogenicity, toxicity, and sterility tests were performed. To vaccination, four groups of female Balb/c mice were used in an immunization test. Antibody responses were measured by the ELISA method. Challenging processes were performed to analyze the efficacy of the OPS-DT compound.

Results

Two weeks after the first vaccination dose, there was no significant difference in the antibody titers of the OPS and OPS-DT groups. However, after the second and third doses, the antibody titers of the OPS-DT group increased significantly compared with those of the control groups (P < 0.001). The induction of anti-OPS antibodies was as follows: OPS-DT>OPS. The most anti-OPS IgG antibody was IgG1. Challenging procedure showed successful protective characteristics in clinical examinations.

Conclusions

The results indicated that DT increased anti-OPS antibodies against the OPS-DT compound. The antibody response to OPS-DT was greater than that to OPS alone. We conclude that OPS-DT is an appropriate and acceptable vaccine candidate against salmonellosis.

Isoniazid-resistant tuberculosis in Iran: A systematic review

Isoniazid (INH) is one of the most potent anti-tuberculosis (TB) agents. INH resistance is an obstacle to the treatment of TB disease and the National TB control Program (NTP). We aimed to determine the true prevalence of INH-resistant TB in Iran. Several databases including Embase, Medline, Cochrane library and Iranian databases were searched to identify studies addressing INH-resistant tuberculosis in Iran. We identified 156 articles, of which 129 records were excluded based on their titles and abstracts. In a secondary screening, we assessed the eligibility of 27 full-text articles of which, 6 did not report usage data. Finally, 21 studies published from different regions of Iran from March 1999 until July 2015 were included in this study. Comprehensive meta-analysis (V2.2, Biostat) software was used to analyze the data. The meta-analysis showed that 12.8% (95% CI 9.4-15.8; I(2) = 87.8; P < 0.001 test for heterogeneity) of new TB cases and 40.1% (95% CI 28.5-53.0; I(2) = 88.2; P < 0.001 test for heterogeneity) of previously treated cases were resistant to INH. High prevalence of INH resistance among TB patients has been reported in many health-care settings, suggesting that better management of such cases, use of effective treatment regimens and establishing advanced diagnostic facilities are needed to avoid further emergence of INH-resistant TB.