scholarly journals Susceptibility Testing of Extensively Drug-Resistant and Pre-Extensively Drug-Resistant Mycobacterium tuberculosis against Levofloxacin, Linezolid, and Amoxicillin-Clavulanate

2013 ◽  
Vol 57 (6) ◽  
pp. 2522-2525 ◽  
Author(s):  
Imran Ahmed ◽  
Kauser Jabeen ◽  
Raunaq Inayat ◽  
Rumina Hasan
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Susceptibility Testing ◽  
Critical Concentration ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Fluoroquinolone Resistance ◽  
Drug Resistant ◽  
Content Type ◽  
Extensively Drug Resistant ◽  
Amoxicillin Clavulanate

ABSTRACTPakistan is a high-burden country for tuberculosis (TB). The emergence and increasing incidence of extensively drug-resistant (XDR) TB has been reported in Pakistan. Similarly, the prevalence of multidrug-resistant TB infections with fluoroquinolone resistance (pre-XDR) is also increasing. To treat these infections, local drug susceptibility patterns of alternate antituberculosis agents, including levofloxacin (LVX), linezolid (LZD), and amoxicillin-clavulanate (AMC), is urgently needed. The aim of this study was to determine the susceptibility frequencies of drug-resistant (DR)Mycobacterium tuberculosisagainst LVX, LZD, and AMC. All susceptibilities were determined on Middlebrook 7H10 agar. A critical concentration was used for LVX (1 μg/ml), whereas MICs were determined for LZD and AMC.M. tuberculosisH37Rv was used as a control strain. A total of 102M. tuberculosisisolates (XDR,n= 59; pre-XDR,n= 43) were tested. Resistance to LVX was observed in 91.2% (93/102). Using an MIC value of 0.5 μg/ml as a cutoff, resistance to LZD (MIC ≥ 1 μg/ml) was noted in 5.9% (6/102). Although the sensitivity breakpoints are not established for AMC, the MIC values were high (>16 μg/ml) in 97.1% (99/102). Our results demonstrate that LZD may be effective for the treatment of XDR and pre-XDR cases from Pakistan. High resistance rates against LVX in our study suggest the use of this drug with caution for DR-TB cases from this area. Drug susceptibility testing against LVX and AMC may be helpful in complicated and difficult-to-manage cases.

scholarly journals Sensititre MycoTB Plate Compared to Bactec MGIT 960 for First- and Second-Line Antituberculosis Drug Susceptibility Testing in Tanzania: a Call To Operationalize MICs

2015 ◽  
Vol 59 (11) ◽  
pp. 7104-7108 ◽  
Author(s):  
Scott K. Heysell ◽  
Suporn Pholwat ◽  
Stellah G. Mpagama ◽  
Saumu J. Pazia ◽  
Happy Kumburu ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Acquired Resistance ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Drug Resistant ◽  
Second Line ◽  
Drug Resistant Tuberculosis ◽  
Content Type ◽  
Resistant Tuberculosis ◽  
Extensively Drug Resistant

ABSTRACTMIC testing forMycobacterium tuberculosisis now commercially available. Drug susceptibility testing by the MycoTB MIC plate has not been directly compared to that by the Bactec MGIT 960. We describe a case of extensively drug-resistant tuberculosis (XDR-TB) in Tanzania where initial MIC testing may have prevented acquired resistance. From testing on archived isolates, the accuracy with the MycoTB plate was >90% for important first- and second-line drugs compared to that with the MGIT 960, and clinically useful quantitative interpretation was also provided.

scholarly journals Sensititre MYCOTB MIC Plate for Testing Mycobacterium tuberculosis Susceptibility to First- and Second-Line Drugs

2013 ◽  
Vol 58 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Jongseok Lee ◽  
Derek T. Armstrong ◽  
Willy Ssengooba ◽  
Jeong-ae Park ◽  
Yeuni Yu ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Susceptibility Testing ◽  
Critical Concentration ◽  
Microtiter Plate ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Second Line ◽  
Content Type ◽  
The Republic ◽  
Phenotypic Methods

ABSTRACTForMycobacterium tuberculosis, phenotypic methods for drug susceptibility testing of second-line drugs are poorly standardized and technically challenging. The Sensititre MYCOTB MIC plate (MYCOTB) is a microtiter plate containing lyophilized antibiotics and configured for determination of MICs to first- and second-line antituberculosis drugs. To evaluate the performance of MYCOTB forM. tuberculosisdrug susceptibility testing using the Middlebrook 7H10 agar proportion method (APM) as the comparator, we conducted a two-site study using archivedM. tuberculosisisolates from Uganda and the Republic of Korea. Thawed isolates were subcultured, and dilutions were inoculated into MYCOTB wells and onto 7H10 agar. MYCOTB results were read at days 7, 10, 14, and 21; APM results were read at 21 days. A total of 222 isolates provided results on both platforms. By APM, 106/222 (47.7%) of isolates were resistant to at least isoniazid and rifampin. Agreement between MYCOTB and APM with respect to susceptibility or resistance was ≥92% for 7 of 12 drugs when a strict definition was used and ≥96% for 10 of 12 drugs when agreement was defined by allowing a ± one-well range of dilutions around the APM critical concentration. For ethambutol, agreement was 80% to 81%. For moxifloxacin, agreement was 83% to 85%; incorporating existing DNA sequencing information for discrepant analysis raised agreement to 91% to 96%. For MYCOTB, the median time to plate interpretation was 10 days and interreader agreement was ≥95% for all drugs. MYCOTB provided reliable results forM. tuberculosissusceptibility testing of first- and second-line drugs except ethambutol, and results were available sooner than those determined by APM.

scholarly journals How To Optimally Combine Genotypic and Phenotypic Drug Susceptibility Testing Methods for Pyrazinamide

2020 ◽  
Vol 64 (9) ◽  
Author(s):  
Claudio U. Köser ◽  
Daniela M. Cirillo ◽  
Paolo Miotto
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Current Practice ◽  
Susceptibility Testing ◽  
Critical Concentration ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Resistance Mutations ◽  
Testing Methods ◽  
Content Type

ABSTRACT False-susceptible phenotypic drug-susceptibility testing (DST) results for pyrazinamide due to mutations with MICs close to the critical concentration (CC) confound the classification of pncA resistance mutations, leading to an underestimate of the specificity of genotypic DST. This could be minimized by basing treatment decisions on well-understood mutations and by adopting an area of technical uncertainty for phenotypic DST rather than only testing the CC, as is current practice for the Mycobacterium tuberculosis complex.

scholarly journals Rapid Drug Susceptibility Testing of Drug-Resistant Mycobacterium tuberculosis Isolates Directly from Clinical Samples by Use of Amplicon Sequencing: a Proof-of-Concept Study

2016 ◽  
Vol 54 (8) ◽  
pp. 2058-2067 ◽  
Author(s):  
Rebecca E. Colman ◽  
Julia Anderson ◽  
Darrin Lemmer ◽  
Erik Lehmkuhl ◽  
Sophia B. Georghiou ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Susceptibility Testing ◽  
Amplicon Sequencing ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Health Concern ◽  
Clinical Samples ◽  
Drug Resistant ◽  
Content Type

Increasingly complex drug-resistant tuberculosis (DR-TB) is a major global health concern and one of the primary reasons why TB is now the leading infectious cause of death worldwide. Rapid characterization of a DR-TB patient's complete drug resistance profile would facilitate individualized treatment in place of empirical treatment, improve treatment outcomes, prevent amplification of resistance, and reduce the transmission of DR-TB. The use of targeted next-generation sequencing (NGS) to obtain drug resistance profiles directly from patient sputum samples has the potential to enable comprehensive evidence-based treatment plans to be implemented quickly, rather than in weeks to months, which is currently needed for phenotypic drug susceptibility testing (DST) results. In this pilot study, we evaluated the performance of amplicon sequencing ofMycobacterium tuberculosisDNA from patient sputum samples using a tabletop NGS technology and automated data analysis to provide a rapid DST solution (the Next Gen-RDST assay). One hundred sixty-six out of 176 (94.3%) sputum samples from the Republic of Moldova yielded complete Next Gen-RDST assay profiles for 7 drugs of interest. We found a high level of concordance of our Next Gen-RDST assay results with phenotypic DST (97.0%) and pyrosequencing (97.8%) results from the same clinical samples. Our Next Gen-RDST assay was also able to estimate the proportion of resistant-to-wild-type alleles down to mixtures of ≤1%, which demonstrates the ability to detect very low levels of resistant variants not detected by pyrosequencing and possibly below the threshold for phenotypic growth methods. The assay as described here could be used as a clinical or surveillance tool.

scholarly journals Evaluation of Pyrosequencing for Detecting Extensively Drug-Resistant Mycobacterium tuberculosis among Clinical Isolates from Four High-Burden Countries

2014 ◽  
Vol 59 (1) ◽  
pp. 414-420 ◽  
Author(s):  
Kanchan Ajbani ◽  
Shou-Yean Grace Lin ◽  
Camilla Rodrigues ◽  
Duylinh Nguyen ◽  
Francine Arroyo ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
The Philippines ◽  
Drug Susceptibility Testing ◽  
Clinical Isolates ◽  
Drug Resistant ◽  
Second Line ◽  
Additional Advantage ◽  
Content Type ◽  
Extensively Drug Resistant

ABSTRACTReliable molecular diagnostics, which detect specific mutations associated with drug resistance, are promising technologies for the rapid identification and monitoring of drug resistance inMycobacterium tuberculosisisolates. Pyrosequencing (PSQ) has the ability to detect mutations associated with first- and second-line anti-tuberculosis (TB) drugs, with the additional advantage of being rapidly adaptable for the identification of new mutations. The aim of this project was to evaluate the performance of PSQ in predicting phenotypic drug resistance in multidrug- and extensively drug-resistant tuberculosis (M/XDR-TB) clinical isolates from India, South Africa, Moldova, and the Philippines. A total of 187 archived isolates were run through a PSQ assay in order to identifyM. tuberculosis(via the IS6110marker), and to detect mutations associated with M/XDR-TB within small stretches of nucleotides in selected loci. The molecular targets includedkatG, theinhApromoter and theahpC-oxyRintergenic region for isoniazid (INH) resistance; therpoBcore region for rifampin (RIF) resistance;gyrAfor fluoroquinolone (FQ) resistance; andrrsfor amikacin (AMK), capreomycin (CAP), and kanamycin (KAN) resistance. PSQ data were compared to phenotypic mycobacterial growth indicator tube (MGIT) 960 drug susceptibility testing results for performance analysis. The PSQ assay illustrated good sensitivity for the detection of resistance to INH (94%), RIF (96%), FQ (93%), AMK (84%), CAP (88%), and KAN (68%). The specificities of the assay were 96% for INH, 100% for RIF, FQ, AMK, and KAN, and 97% for CAP. PSQ is a highly efficient diagnostic tool that reveals specific nucleotide changes associated with resistance to the first- and second-line anti-TB drug medications. This methodology has the potential to be linked to mutation-specific clinical interpretation algorithms for rapid treatment decisions.

scholarly journals Evaluation of the Abbott RealTi m e MTB and RealTi m e MTB INH/RIF Assays for Direct Detection of Mycobacterium tuberculosis Complex and Resistance Markers in Respiratory and Extrapulmonary Specimens

2016 ◽  
Vol 54 (12) ◽  
pp. 3022-3027 ◽  
Author(s):  
Sabine Hofmann-Thiel ◽  
Nikolay Molodtsov ◽  
Uladzimir Antonenka ◽  
Harald Hoffmann
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Susceptibility Testing ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Nucleic Acid Amplification ◽  
Content Type ◽  
Clinical Specimens ◽  
Different Types ◽  
Resistance Markers ◽  
Smear Negative

The Abbott RealTi m e MTB (RT MTB) assay is a new automated nucleic acid amplification test for the detection of Mycobacterium tuberculosis complex (MTBC) in clinical specimens. In combination with the RealTi m e MTB INH/RIF (RT MTB INH/RIF) resistance assay, which can be applied to RT MTB-positive specimens as an add-on assay, the tests also indicate the genetic markers of resistance to isoniazid (INH) and rifampin (RIF). We aimed to evaluate the diagnostic sensitivity and specificity of RT MTB using different types of respiratory and extrapulmonary specimens and to compare performance characteristics directly with those of the FluoroType MTB assay. The resistance results obtained by RT MTB INH/RIF were compared to those from the GenoType MTBDR plus and from phenotypic drug susceptibility testing. A total of 715 clinical specimens were analyzed. Compared to culture, the overall sensitivity of RT MTB was 92.1%; the sensitivity rates for smear-positive and smear-negative samples were 100% and 76.2%, respectively. The sensitivities of smear-negative specimens were almost identical for respiratory (76.3%) and extrapulmonary (76%) specimens. Specificity rates were 100% and 95.8% for culture-negative specimens and those that grew nontuberculous mycobacteria, respectively. RT MTB INH/RIF was applied to 233 RT MTB-positive samples and identified resistance markers in 7.7% of samples. Agreement with phenotypic and genotypic drug susceptibility testing was 99.5%. In conclusion, RT MTB and RT MTB INH/RIF allow for the rapid and accurate diagnosis of tuberculosis (TB) in different types of specimens and reliably indicate resistance markers. The strengths of this system are the comparably high sensitivity with paucibacillary specimens, its ability to detect INH and RIF resistance, and its high-throughput capacities.

scholarly journals In Vitro Activity and MIC of Sitafloxacin against Multidrug-Resistant and Extensively Drug-Resistant Mycobacterium tuberculosis Isolated in Thailand

2017 ◽  
Vol 62 (1) ◽  
Author(s):  
Manoon Leechawengwongs ◽  
Therdsak Prammananan ◽  
Sarinya Jaitrong ◽  
Pamaree Billamas ◽  
Nampueng Makhao ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Critical Concentration ◽  
Multidrug Resistant ◽  
Quinolone Resistance ◽  
Drug Resistant ◽  
Content Type ◽  
Extensively Drug Resistant ◽  
Resistant Strains ◽  
Drug Resistant Strains

ABSTRACT New fluoroquinolones (FQs) have been shown to be more active against drug-resistant Mycobacterium tuberculosis strains than early FQs, such as ofloxacin. Sitafloxacin (STFX) is a new fluoroquinolone with in vitro activity against a broad range of bacteria, including M. tuberculosis. This study aimed to determine the in vitro activity of STFX against all groups of drug-resistant strains, including multidrug-resistant M. tuberculosis (MDR M. tuberculosis), MDR M. tuberculosis with quinolone resistance (pre-XDR), and extensively drug-resistant (XDR) strains. A total of 374 drug-resistant M. tuberculosis strains were tested for drug susceptibility by the conventional proportion method, and 95 strains were randomly submitted for MIC determination using the microplate alamarBlue assay (MABA). The results revealed that all the drug-resistant strains were susceptible to STFX at a critical concentration of 2 μg/ml. Determination of the MIC90s of the strains showed different MIC levels; MDR M. tuberculosis strains had a MIC90 of 0.0625 μg/ml, whereas pre-XDR and XDR M. tuberculosis strains had identical MIC90s of 0.5 μg/ml. Common mutations within the quinolone resistance-determining region (QRDR) of gyrA and/or gyrB did not confer resistance to STFX, except that double mutations of GyrA at Ala90Val and Asp94Ala were found in strains with a MIC of 1.0 μg/ml. The results indicated that STFX had potent in vitro activity against all the groups of drug-resistant M. tuberculosis strains and should be considered a new repurposed drug for treatment of multidrug-resistant and extensively drug-resistant TB.

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.

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