scholarly journals MIC of Delamanid (OPC-67683) against Mycobacterium tuberculosis Clinical Isolates and a Proposed Critical Concentration

2016 ◽  
Vol 60 (6) ◽  
pp. 3316-3322 ◽  
Author(s):  
Kelly Stinson ◽  
Natalia Kurepina ◽  
Amour Venter ◽  
Mamoru Fujiwara ◽  
Masanori Kawasaki ◽  
...  
Keyword(s):  
South Africa ◽  
Pathogenic Bacteria ◽  
Critical Concentration ◽  
Drug Susceptibility Testing ◽  
Clinical Isolates ◽  
Pharmacokinetic Data ◽  
Phase 2 ◽  
The European Union ◽  
Two Phase ◽  
Mdr Tb

The increasing global burden of multidrug-resistant tuberculosis (MDR-TB) requires reliable drug susceptibility testing that accurately characterizes susceptibility and resistance of pathogenic bacteria to effectively treat patients with this deadly disease. Delamanid is an anti-TB agent first approved in the European Union in 2014 for the treatment of pulmonary MDR-TB in adults. Using the agar proportion method, delamanid MIC was determined for 460 isolates: 316 from patients enrolled in a phase 2 global clinical trial, 76 from two phase 2 early bactericidal activity trials conducted in South Africa, and 68 isolates obtained outside clinical trials (45 from Japanese patients and 23 from South African patients). With the exception of two isolates, MICs ranged from 0.001 to 0.05 μg/ml, resulting in an MIC50of 0.004 μg/ml and an MIC90of 0.012 μg/ml. Various degrees of resistance to other anti-TB drugs did not affect the distribution of MICs, nor did origin of isolates from regions/countries other than South Africa. A critical concentration/breakpoint of 0.2 μg/ml can be used to define susceptible and resistant isolates based on the distribution of MICs and available pharmacokinetic data. Thus, clinical isolates from delamanid-naive patients with tuberculosis have a very low MIC for delamanid and baseline resistance is rare, demonstrating the potential potency of delamanid and supporting its use in an optimized background treatment regimen for MDR-TB.

scholarly journals Multicenter Noninferiority Evaluation of Hain GenoType MTBDRplusVersion 2 and Nipro NTM+MDRTB Line Probe Assays for Detection of Rifampin and Isoniazid Resistance

2016 ◽  
Vol 54 (6) ◽  
pp. 1624-1630 ◽  
Author(s):  
Ruvandhi R. Nathavitharana ◽  
Doris Hillemann ◽  
Samuel G. Schumacher ◽  
Birte Schlueter ◽  
Nazir Ismail ◽  
...  
Keyword(s):  
Sensitivity And Specificity ◽  
Phase 1 ◽  
Drug Susceptibility ◽  
Multidrug Resistant ◽  
Drug Susceptibility Testing ◽  
Phase 2 ◽  
Reference Standard ◽  
Two Phase ◽  
Mdr Tb ◽  
Resistance Detection

Less than 30% of multidrug-resistant tuberculosis (MDR-TB) patients are currently diagnosed, due to laboratory constraints. Molecular diagnostics enable rapid and simplified diagnosis. Newer-version line probe assays have not been evaluated against the WHO-endorsed Hain GenoType MTBDRplus(referred to as Hain version 1 [V1]) for the rapid detection of rifampin (RIF) and isoniazid (INH) resistance. A two-phase noninferiority study was conducted in two supranational reference laboratories to allow head-to-head comparisons of two new tests, Hain Genotype MTBDRplusversion 2 (referred to as Hain version 2 [V2]) and Nipro NTM+MDRTB detection kit 2 (referred to as Nipro), to Hain V1. In phase 1, the results for 379 test strains were compared to a composite reference standard that used phenotypic drug susceptibility testing (DST) and targeted sequencing. In phase 2, the results for 644 sputum samples were compared to a phenotypic DST reference standard alone. Using a challenging set of strains in phase 1, the values for sensitivity and specificity for Hain V1, Hain V2, and Nipro, respectively, were 90.3%/98.5%, 90.3%/98.5%, and 92.0%/98.5% for RIF resistance detection and 89.1%/99.4%, 89.1%/99.4%, and 89.6%/100.0% for INH resistance detection. Testing of sputa in phase 2 yielded values for sensitivity and specificity of 97.1%/97.1%, 98.2%/97.8%, and 96.5%/97.5% for RIF and 94.4%/96.4%, 95.4%/98.8%, and 94.9%/97.6% for INH. Overall, the rates of indeterminate results were low, but there was a higher rate of indeterminate results with Nipro than with Hain V1 and V2 in samples with low smear grades. Noninferiority of Hain V2 and Nipro to Hain V1 was demonstrated for RIF and INH resistance detection in isolates and sputum specimens. These results serve as evidence for WHO policy recommendations on the use of line probe assays, including the Hain V2 and Nipro assays, for MDR-TB detection.

scholarly journals Rifampicin mono-resistant tuberculosis is not the same as multidrug-resistant tuberculosis: a descriptive study from Khayelitsha, South Africa

2021 ◽  
Author(s):  
Zubeida Salaam-Dreyer ◽  
Elizabeth M Streicher ◽  
Frederick A Sirgel ◽  
Fabrizio Menardo ◽  
Sonia Borrell Farnov ◽  
...  
Keyword(s):  
South Africa ◽  
Critical Concentration ◽  
Drug Susceptibility ◽  
Multidrug Resistant ◽  
Drug Susceptibility Testing ◽  
Potential Contribution ◽  
Resistant Tuberculosis ◽  
Mdr Tb ◽  
Potential Benefits ◽  
High Level

Rifampicin mono-resistant TB (RMR-TB) constitutes 38% of all rifampicin-resistant TB (RR-TB) in South Africa and is increasing. We aimed to compare RMR-TB with multidrug-resistant TB (MDR-TB) within a high TB, RR-TB and HIV burden setting. Patient-level clinical data and stored RR-TB isolates from 2008-2017 with available whole genome sequencing (WGS) data were used to describe risk factors associated with RMR-TB and to compare rifampicin-resistance (RR) conferring mutations between RMR-TB and MDR-TB. A subset of isolates with particular RR-conferring mutations were subjected to semi-quantitative rifampicin phenotypic drug susceptibility testing. Among 2,041 routinely diagnosed RR-TB patients, 463 (22.7%) had RMR-TB. HIV-positive individuals (adjusted Odds Ratio 1.4, 95% CI 1.1-1.9) and diagnosis between 2013-2017 versus 2008-2012 (aOR 1.3, 1.1-1.7) were associated with RMR-TB. Among 1,119 (54.8%) patients with available WGS data showing RR-TB, significant differences in the distribution of rpoB RR-conferring mutations between RMR-TB and MDR-TB isolates were observed. Mutations associated with high-level RR were more commonly found among MDR-TB isolates (811/889, 90.2% versus 162/230, 70.4% among RMR-TB, p<0.01). In particular, the rpoB L430P mutation, conferring low-level RR, was identified in 32/230 (13.9%) RMR-TB versus 10/889 (1.1%) in MDR-TB (p<0.01). Among 10 isolates with an rpoB L430P mutation, 7 were phenotypically susceptible using the critical concentration of 0.5 ug/ml (range 0.125-1 ug/ml). The majority (215/230, 93.5%) of RMR-TB isolates showed susceptibility to all other TB drugs, highlighting the potential benefits of WGS for simplified treatment. These data suggest that the evolution of RMR-TB differs from MDR-TB with a potential contribution from HIV infection.

scholarly journals Rifampicin mono-resistant tuberculosis is not the same as multidrug-resistant tuberculosis: a descriptive study from Khayelitsha, South Africa

2021 ◽  
Author(s):  
Zubeida Salaam-Dreyer ◽  
Elizabeth M. Streicher ◽  
Frederick A. Sirgel ◽  
Fabrizio Menardo ◽  
Sonia Borrell ◽  
...  
Keyword(s):  
South Africa ◽  
Critical Concentration ◽  
Drug Susceptibility ◽  
Multidrug Resistant ◽  
Drug Susceptibility Testing ◽  
Rifampicin Resistance ◽  
Potential Contribution ◽  
Resistant Tuberculosis ◽  
Mdr Tb ◽  
High Level

Rifampicin mono-resistant TB (RMR-TB, rifampicin resistance and isoniazid susceptibility) constitutes 38% of all rifampicin-resistant TB (RR-TB) in South Africa and is increasing. We aimed to compare RMR-TB with multidrug-resistant TB (MDR-TB) within a high TB, RR-TB and HIV burden setting. Patient-level clinical data and stored RR-TB isolates from 2008-2017 with available whole genome sequencing (WGS) data were used to describe risk factors associated with RMR-TB and to compare rifampicin-resistance (RR) conferring mutations between RMR-TB and MDR-TB. A subset of isolates with particular RR-conferring mutations were subjected to semi-quantitative rifampicin phenotypic drug susceptibility testing. Among 2,041 routinely diagnosed RR-TB patients, 463 (22.7%) had RMR-TB. HIV-positive individuals (adjusted Odds Ratio 1.4, 95% CI 1.1-1.9) and diagnosis between 2013-2017 versus 2008-2012 (aOR 1.3, 1.1-1.7) were associated with RMR-TB. Among 1,119 (54.8%) patients with available WGS data showing RR-TB, significant differences in the distribution of rpoB RR-conferring mutations between RMR-TB and MDR-TB isolates were observed. Mutations associated with high-level RR were more commonly found among MDR-TB isolates (811/889, 90.2% versus 162/230, 70.4% among RMR-TB, p<0.0001). In particular, the rpoB L430P mutation, conferring low-level RR, was identified in 32/230 (13.9%) RMR-TB versus 10/889 (1.1%) in MDR-TB (p<0.0001). Among 10 isolates with an rpoB L430P mutation, 7 were phenotypically susceptible using the critical concentration of 0.5 μg/ml (range 0.125-1 μg/ml). The majority (215/230, 93.5%) of RMR-TB isolates showed susceptibility to all other TB drugs, highlighting the potential benefits of WGS for simplified treatment. These data suggest that the evolution of RMR-TB differs from MDR-TB with a potential contribution from HIV infection.

scholarly journals Disparities in Capreomycin Resistance Levels Associated with therrsA1401G Mutation in Clinical Isolates of Mycobacterium tuberculosis

2014 ◽  
Vol 59 (1) ◽  
pp. 444-449 ◽  
Author(s):  
Analise Z. Reeves ◽  
Patricia J. Campbell ◽  
Melisa J. Willby ◽  
James E. Posey
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Strong Predictor ◽  
Critical Concentration ◽  
Drug Susceptibility ◽  
Multidrug Resistant ◽  
Drug Susceptibility Testing ◽  
Clinical Isolates ◽  
Cross Resistance ◽  
Second Line ◽  
Content Type

ABSTRACTAs the prevalence of multidrug-resistant and extensively drug-resistant tuberculosis strains continues to rise, so does the need to develop accurate and rapid molecular tests to complement time-consuming growth-based drug susceptibility testing. Performance of molecular methods relies on the association of specific mutations with phenotypic drug resistance and while considerable progress has been made for resistance detection of first-line antituberculosis drugs, rapid detection of resistance for second-line drugs lags behind. TherrsA1401G allele is considered a strong predictor of cross-resistance between the three second-line injectable drugs, capreomycin (CAP), kanamycin, and amikacin. However, discordance is often observed between therrsA1401G mutation and CAP resistance, with up to 40% ofrrsA1401G mutants being classified as CAP susceptible. We measured the MICs to CAP in 53 clinical isolates harboring therrsA1401G mutation and found that the CAP MICs ranged from 8 μg/ml to 40 μg/ml. These results were drastically different from engineered A1401G mutants generated in isogenicMycobacterium tuberculosis, which exclusively exhibited high-level CAP MICs of 40 μg/ml. These data support the results of prior studies, which suggest that the critical concentration of CAP (10 μg/ml) used to determine resistance by indirect agar proportion may be too high to detect all CAP-resistant strains and suggest that a larger percentage of resistant isolates could be identified by lowering the critical concentration. These data also suggest that differences in resistance levels among clinical isolates are possibly due to second site or compensatory mutations located elsewhere in the genome.

scholarly journals Mycobacterium Tuberculosis Strain Lineage in Mixed Tribal Population Across India and Andaman Nicobar Island

2021 ◽  
Author(s):  
Azger Dusthackeer V. N. ◽  
Azger Dusthackeer V. N. ◽  
Ashok Kumar ◽  
Kannappan Kannappan Sucharitha ◽  
S. Shivakumar ◽  
...  
Keyword(s):  
Small Sample Size ◽  
Drug Susceptibility ◽  
Multidrug Resistant ◽  
Drug Susceptibility Testing ◽  
Small Sample ◽  
Clinical Isolates ◽  
Nicobar Island ◽  
Tribal Population ◽  
Indian States ◽  
Mdr Tb

Abstract In India, the tribal population constitutes almost 8.6% of the nation’s total population. This study attempts to provide information pertaining to the TB strain diversity, its public health implications, and distribution among the tribal population in 10 Indian states and Andaman & Nicobar (A&N) Island. Clinical isolates were received from 66 villages (10 states and island). A total of 78 M. tuberculosis clinical isolates were received from 10 different states and A&N Island. Among these, 16 different strains were observed. The major M. tuberculosis strains spoligotype belong to the Beijing, CAS1_DELHI, and EAI5 family followed by EAI1_SOM, EAI6_BGD1, LAM3, LAM6, LAM9, T1, T2, U strains. Drug-susceptibility testing (DST) results showed almost 15.4% of clinical isolates found to be resistant to isoniazid (INH) or rifampicin (RMP) + INH. Predominant multidrug-resistant tuberculosis (MDR-TB) isolates seem to be Beijing strain. Beijing, CAS1_DELHI, EAI3_IND, and EAI5 were the principal strains infecting mixed tribal populations across India. Despite the small sample size, this study has demonstrated higher diversity among the TB strains with significant MDR-TB findings. Prevalence of Beijing MDR-TB strains in Central, Southern, Eastern India and A&N Island indicates the transmission of the TB strains.

scholarly journals Reevaluation of the Critical Concentration for Drug Susceptibility Testing of Mycobacterium tuberculosis against Pyrazinamide Using Wild-Type MIC Distributions andpncAGene Sequencing

2011 ◽  
Vol 56 (3) ◽  
pp. 1253-1257 ◽  
Author(s):  
J. Werngren ◽  
E. Sturegård ◽  
P. Juréen ◽  
K. Ängeby ◽  
S. Hoffner ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Critical Concentration ◽  
Gene Mutations ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Clinical Isolates ◽  
Wild Type ◽  
First Line ◽  
Content Type ◽  
Resistant Strains

ABSTRACTPyrazinamide (PZA) is a potent first-line agent for the treatment of tuberculosis (TB) with activity also against a significant part of drug-resistantMycobacterium tuberculosisstrains. Since PZA is active only at acid pH, testing for susceptibility to PZA is difficult and insufficiently reproducible. The recommended critical concentration for PZA susceptibility (MIC, 100 mg/liter) used in the Bactec systems (460 and MGIT 960) has not been critically evaluated against wild-type MIC distributions in clinical isolates ofMycobacterium tuberculosis. Using the Bactec MGIT 960 system, we determined the PZA MICs for 46 clinicalM. tuberculosisisolates and compared the results topncAsequencing and previously obtained Bactec 460 data. For consecutive clinical isolates (n= 15), the epidemiological wild-type cutoff (ECOFF) for PZA was 64 mg/liter (MIC distribution range, ≤8 to 64 mg/liter), and nopncAgene mutations were detected. In strains resistant in both Bactec systems (n= 18), the PZA MICs ranged from 256 to ≥1,024 mg/liter. The discordances betweenpncAsequencing, susceptibility results in Bactec 460, and MIC determinations in Bactec MGIT 960 were mainly observed in strains with MICs close to or at the ECOFF. We conclude that in general, wild-type and resistant strains were clearly separated and correlated topncAmutations, although some isolates with MICs close to the ECOFF cause reproducibility problems within and between methods. To solve this issue, we suggest that isolates with MICs of ≤64 mg/liter be classified susceptible, that an intermediary category be introduced at 128 mg/liter, and that strains with MICs of >128 mg/liter be classified resistant.

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

2021 ◽  
Author(s):  
Azar Dokht Khosravi ◽  
Mohammad Reza Tabandeh ◽  
Fatemeh Shahi ◽  
Shokrollah Salmanzadeh
Keyword(s):  
Drug Susceptibility ◽  
Multidrug Resistant ◽  
Drug Susceptibility Testing ◽  
Clinical Isolates ◽  
Drug Resistant ◽  
Microdilution Method ◽  
Linezolid Resistance ◽  
Main Challenge ◽  
Broth Microdilution Method ◽  
Mdr Tb

AbstractThe 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.

scholarly journals Rifampicin and rifabutin resistance in 1000 Mycobacterium tuberculosis clinical isolates

2018 ◽  
Author(s):  
Maha R Farhat ◽  
Jaimie Sixsmith ◽  
Roger Calderon ◽  
Nathan Hicks ◽  
Sarah Fortune ◽  
...  
Keyword(s):  
Inhibitory Concentration ◽  
Critical Concentration ◽  
Treatment Options ◽  
Laboratory Strain ◽  
Clinical Isolates ◽  
Cross Resistance ◽  
P Value ◽  
Resistant Tuberculosis ◽  
Mdr Tb ◽  
Loss Of Susceptibility

SynopsisDrug resistant tuberculosis (TB) remains a public health challenge with limited treatment options and high associated mortality. Rifamycins are among the most potent anti-TB drugs, and the loss of susceptibility to these agents, a hallmark of MDR TB, is considered a substantial therapeutic challenge. Rifamycins are known to target the RpoB subunit of RNA polymerase; however, our understanding of how rifamycin resistance is genetically encoded remains incomplete. Here we investigated rpoB genetic diversity and cross resistance between the two rifamycin drugs rifampicin (RIF) and rifabutin (RFB). We performed whole genome sequencing of 1005 MTB clinical isolates and measured minimum inhibitory concentration (MIC) to both agents on 7H10 agar using the indirect proportion method. Of the 1005 isolates, 767 were RIF resistant, and of these, 211 (27%) were sensitive to RFB at the critical concentration of 0.5ug/ml; 101/211 isolates had the rpoB mutation D435V (E.coli D516V). Isolates with discrepant resistance (RIF R and RFB S) 16.9 times more likely to harbor a D435V mutation as those resistant to both agents (OR 95% CI 10.5-27.9, P-value <10-40). To further understand this discrepancy, we generated both D435V and S450L (E.coli S531L) rpoB mutants in a laboratory strain and measured their antibiotic susceptibility using the alamar blue reduction assay. Compared with wildtype, D435V increased the 50% inhibitory concentration (IC50) to both RIF and RFB, however in both cases to a lesser degree than the S450L mutation. The observation that the rpoB D435V mutation produces an increase in the IC50 for both drugs contrasts with findings from previous smaller studies that suggested that isolates with D435V mutation remain RFB susceptible despite being RIF resistant. Our finding thus suggests that the recommended critical testing concentration for RFB should be revised.

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