scholarly journals A Multilaboratory, Multicountry Study To Determine Bedaquiline MIC Quality Control Ranges for Phenotypic Drug Susceptibility Testing

2016 ◽  
Vol 54 (12) ◽  
pp. 2956-2962 ◽  
Author(s):  
Koné Kaniga ◽  
Daniela M. Cirillo ◽  
Sven Hoffner ◽  
Nazir A. Ismail ◽  
Devinder Kaur ◽  
...  
Keyword(s):  
Quality Control ◽  
Reference Strain ◽  
Susceptibility Testing ◽  
Geometric Mean ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Broth Microdilution ◽  
Data Set ◽  
Content Type ◽  
Agar Dilution

The aim of this study was to establish standardized drug susceptibility testing (DST) methodologies and reference MIC quality control (QC) ranges for bedaquiline, a diarylquinoline antimycobacterial, used in the treatment of adults with multidrug-resistant tuberculosis. Two tier-2 QC reproducibility studies of bedaquiline DST were conducted in eight laboratories using Clinical Laboratory and Standards Institute (CLSI) guidelines. Agar dilution and broth microdilution methods were evaluated.Mycobacterium tuberculosisH37Rv was used as the QC reference strain. Bedaquiline MIC frequency, mode, and geometric mean were calculated. When resulting data occurred outside predefined CLSI criteria, the entire laboratory data set was excluded. For the agar dilution MIC, a 4-dilution QC range (0.015 to 0.12 μg/ml) centered around the geometric mean included 95.8% (7H10 agar dilution; 204/213 observations with one data set excluded) or 95.9% (7H11 agar dilution; 232/242) of bedaquiline MICs. For the 7H9 broth microdilution MIC, a 3-dilution QC range (0.015 to 0.06 μg/ml) centered around the mode included 98.1% (207/211, with one data set excluded) of bedaquiline MICs. Microbiological equivalence was demonstrated for bedaquiline MICs determined using 7H10 agar and 7H11 agar but not for bedaquiline MICs determined using 7H9 broth and 7H10 agar or 7H9 broth and 7H11 agar. Bedaquiline DST methodologies and MIC QC ranges against the H37RvM. tuberculosisreference strain have been established: 0.015 to 0.12 μg/ml for the 7H10 and 7H11 agar dilution MICs and 0.015 to 0.06 μg/ml for the 7H9 broth microdilution MIC. These methodologies and QC ranges will be submitted to CLSI and EUCAST to inform future research and provide guidance for routine clinical bedaquiline DST in laboratories worldwide.

scholarly journals A Multilaboratory, Multicountry Study To Determine MIC Quality Control Ranges for Phenotypic Drug Susceptibility Testing of Selected First-Line Antituberculosis Drugs, Second-Line Injectables, Fluoroquinolones, Clofazimine, and Linezolid

2016 ◽  
Vol 54 (12) ◽  
pp. 2963-2968 ◽  
Author(s):  
Koné Kaniga ◽  
Daniela M. Cirillo ◽  
Sven Hoffner ◽  
Nazir A. Ismail ◽  
Devinder Kaur ◽  
...  
Keyword(s):  
Quality Control ◽  
Reference Strain ◽  
Susceptibility Testing ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Second Line ◽  
Broth Microdilution ◽  
First Line ◽  
Antituberculosis Drugs ◽  
Content Type

Our objective was to establish reference MIC quality control (QC) ranges for drug susceptibility testing of antimycobacterials, including first-line agents, second-line injectables, fluoroquinolones, and World Health Organization category 5 drugs for multidrug-resistant tuberculosis using a 7H9 broth microdilution MIC method. A tier-2 reproducibility study was conducted in eight participating laboratories using Clinical Laboratory and Standards Institute (CLSI) guidelines. Three lots of custom-made frozen 96-well polystyrene microtiter plates were used and prepared with 2× prediluted drugs in 7H9 broth-oleic acid albumin dextrose catalase. The QC reference strain wasMycobacterium tuberculosisH37Rv. MIC frequency, mode, and geometric mean were calculated for each drug. QC ranges were derived based on predefined, strict CLSI criteria. Any data lying outside CLSI criteria resulted in exclusion of the entire laboratory data set. Data from one laboratory were excluded due to higher MIC values than other laboratories. QC ranges were established for 11 drugs: isoniazid (0.03 to 0.12 μg/ml), rifampin (0.03 to 0.25 μg/ml), ethambutol (0.25 to 2 μg/ml), levofloxacin (0.12 to 1 μg/ml), moxifloxacin (0.06 to 0.5 μg/ml), ofloxacin (0.25 to 2 μg/ml), amikacin (0.25 to 2 μg/ml), kanamycin (0.25 to 2 μg/ml), capreomycin (0.5 to 4 μg/ml), linezolid (0.25 to 2 μg/ml), and clofazimine (0.03 to 0.25 μg/ml). QC ranges could not be established for nicotinamide (pyrazinamide surrogate), prothionamide, or ethionamide, which were assay nonperformers. Using strict CLSI criteria, QC ranges against theM. tuberculosisH37Rv reference strain were established for the majority of commonly used antituberculosis drugs, with a convenient 7H9 broth microdilution MIC method suitable for use in resource-limited settings.

scholarly journals Antifungal Susceptibility Testing of Malassezia spp. with an Optimized Colorimetric Broth Microdilution Method

2017 ◽  
Vol 55 (6) ◽  
pp. 1883-1893 ◽  
Author(s):  
Cheryl Leong ◽  
Antonino Buttafuoco ◽  
Martin Glatz ◽  
Philipp P. Bosshard
Keyword(s):  
Susceptibility Testing ◽  
Skin Diseases ◽  
Antifungal Susceptibility ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Broth Microdilution ◽  
Content Type ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Colorimetric Indicator

ABSTRACTMalasseziais a genus of lipid-dependent yeasts. It is associated with common skin diseases such as pityriasis versicolor and atopic dermatitis and can cause systemic infections in immunocompromised individuals. Owing to the slow growth and lipid requirements of these fastidious yeasts, convenient and reliable antifungal drug susceptibility testing assays forMalasseziaspp. are not widely available. Therefore, we optimized a broth microdilution assay for the testing ofMalasseziathat is based on the CLSI and EUCAST assays forCandidaand other yeasts. The addition of ingredients such as lipids and esculin provided a broth medium formulation that enabled the growth of allMalasseziaspp. and could be read, with the colorimetric indicator resazurin, by visual and fluorescence readings. We tested the susceptibility of 52 strains of 13Malasseziaspecies to 11 commonly used antifungals. MIC values determined by visual readings were in good agreement with MIC values determined by fluorescence readings. The lowest MICs were found for the azoles itraconazole, posaconazole, and voriconazole, with MIC90values of 0.03 to 1.0 μg/ml, 0.06 to 0.5 μg/ml, and 0.03 to 2.0 μg/ml, respectively. AllMalasseziaspp. were resistant to echinocandins and griseofulvin. SomeMalasseziaspp. also showed high MIC values for ketoconazole, which is the most widely recommended topical antifungal to treatMalasseziaskin infections. In summary, our assay enables the fast and reliable susceptibility testing ofMalasseziaspp. with a large panel of different antifungals.

scholarly journals Impact of Variations in Test Method Parameters onIn VitroActivity of Surotomycin against Clostridium difficile and Surotomycin Quality Control Limits for Broth Microdilution and Agar Dilution Susceptibility Testing

2015 ◽  
Vol 54 (3) ◽  
pp. 749-753 ◽  
Author(s):  
Maria M. Traczewski ◽  
Jennifer Deane ◽  
Daniel Sahm ◽  
Steven D. Brown ◽  
Laurent Chesnel
Keyword(s):  
Quality Control ◽  
Clostridium Difficile ◽  
Calcium Concentration ◽  
Susceptibility Testing ◽  
Test Method ◽  
Test Parameter ◽  
Content Type ◽  
Parameter Variations ◽  
Agar Dilution ◽  
Control Limits

Test parameter variations were evaluated for their effects on surotomycin MICs. Calcium concentration was the only variable that influenced MICs; therefore, 50 μg/ml (standard for lipopeptide testing) is recommended. Quality control ranges forClostridium difficile(0.12 to 1 μg/ml) andEggerthella lenta(broth, 1 to 4 μg/ml; agar, 1 to 8 μg/ml) were approved by the Clinical and Laboratory Standards Institute based on these data.

scholarly journals Epidemiological cutoff values for a 96-well broth microdilution plate for high-throughput research antibiotic susceptibility testing of M. tuberculosis

2021 ◽  
Author(s):  
◽  
Philip W Fowler
Keyword(s):  
Genetic Variants ◽  
Susceptibility Testing ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Broth Microdilution ◽  
Wild Type ◽  
Genetic Sequencing ◽  
Indicator Tube ◽  
Cutoff Values ◽  
Type Population

AbstractDrug susceptibility testing of M. tuberculosis is rooted in a binary susceptible/resistant paradigm. There are considerable advantages in measuring the minimum inhibitory concentrations (MICs) of a panel of drugs for an isolate, including quantifying the magnitude of effect conferred by genetic variants and being able to identify isolates with elevated MICs that can still be treated with standard therapy. It is necessary, however, to measure the epidemiological cutoff values (ECOFF/ECVs) to permit comparison with qualitative data. Here we present ECOFF/ECVs for 13 anti-TB compounds, including bedaquiline and delamanid, derived from 20,637 clinical isolates collected by 14 laboratories based in 11 countries on five continents. Each isolate was incubated for 14 days on a dry 96-well broth microdilution plate and then read. Resistance to the majority of the drugs due to prior exposure is expected and the MIC distributions for many of the compounds are complex and therefore a phenotypically wild-type population could not be defined. Since a majority of samples also underwent genetic sequencing, we defined a genotypically wild-type population and measured the MIC of the 99th percentile by direct measurement and via fitting a Gaussian using interval regression. The proposed ECOFF/ECV values were then validated by comparing to the MIC distributions of high-confidence genetic variants that confer resistance and to qualitative drug susceptibility tests obtained via Mycobacterial Growth Indicator Tube and the Microscopic-Observation Drug-Susceptibility assay.

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 Comparison of the Sensititre YeastOne and CLSI M38-A2 Microdilution Methods in Determining the Activity of Amphotericin B, Itraconazole, Voriconazole, and Posaconazole against Aspergillus Species

2018 ◽  
Vol 56 (10) ◽  
Author(s):  
Hsuan-Chen Wang ◽  
Ming-I Hsieh ◽  
Pui-Ching Choi ◽  
Chi-Jung Wu
Keyword(s):  
Aspergillus Fumigatus ◽  
Amphotericin B ◽  
Antifungal Agents ◽  
Susceptibility Testing ◽  
Geometric Mean ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Aspergillus Species ◽  
Broth Microdilution ◽  
Content Type

ABSTRACT This study compared the YeastOne and reference CLSI M38-A2 broth microdilution methods for antifungal susceptibility testing of Aspergillus species. The MICs of antifungal agents were determined for 100 Aspergillus isolates, including 54 Aspergillus fumigatus (24 TR34/L98H isolates), 23 A. flavus, 13 A. terreus, and 10 A. niger isolates. The overall agreement (within 2 2-fold dilutions) between the two methods was 100%, 95%, 92%, and 90% for voriconazole, posaconazole, itraconazole, and amphotericin B, respectively. The voriconazole geometric mean (GM) MICs were nearly identical for all isolates using both methods, whereas the itraconazole and posaconazole GM MICs obtained using the YeastOne method were approximately 1 dilution lower than those obtained using the reference method. In contrast, the amphotericin B GM MIC obtained using the YeastOne method was 3.3-fold higher than that observed using the reference method. For the 24 A. fumigatus TR34/L98H isolates assayed, the categorical agreement (classified according to the CLSI epidemiological cutoff values) was 100%, 87.5%, and 83.3% for itraconazole, voriconazole, and posaconazole, respectively. For four A. niger isolates, the itraconazole MICs were >8 μg/ml using the M38-A2 method due to trailing growth, whereas the corresponding itraconazole MICs obtained using the YeastOne method were all ≤0.25 μg/ml without trailing growth. These data suggest that the YeastOne method can be used as an alternative for azole susceptibility testing of Aspergillus species and for detecting the A. fumigatus TR34/L98H isolates but that this method fails to detect A. niger isolates exhibiting trailing growth with itraconazole. Additionally, for isolates with azole MICs that approach or that are at susceptibility breakpoints or with high amphotericin B MICs detected using the YeastOne method, further MIC confirmation using the reference CLSI method is needed.

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 In VitroActivity of Fosfomycin against a Collection of Clinical Pseudomonas aeruginosa Isolates from 16 Spanish Hospitals: Establishing the Validity of Standard Broth Microdilution as Susceptibility Testing Method

2013 ◽  
Vol 57 (11) ◽  
pp. 5701-5703 ◽  
Author(s):  
María Díez-Aguilar ◽  
María-Isabel Morosini ◽  
Rosa del Campo ◽  
María García-Castillo ◽  
Javier Zamora ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Susceptibility Testing ◽  
Disk Diffusion ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Broth Microdilution ◽  
Content Type ◽  
Testing Method ◽  
Broth Microdilution Method ◽  
Agar Dilution

ABSTRACTThe broth microdilution method for fosfomycin andPseudomonas aeruginosawas assessed and compared with the approved agar dilution method in 206 genetically unrelatedP. aeruginosaclinical isolates. Essential agreement between the two methods was 84%, and categorical agreement was 89.3%. Additionally, Etest and disk diffusion assays were performed. Results validate broth microdilution as a reliable susceptibility testing method for fosfomycin againstP. aeruginosa. Conversely, unacceptable concordance was established between Etest and disk diffusion results with agar dilution results.

scholarly journals Pyrazinamide Is Active against Mycobacterium tuberculosis Cultures at Neutral pH and Low Temperature

2016 ◽  
Vol 60 (8) ◽  
pp. 4956-4960 ◽  
Author(s):  
Alice L. den Hertog ◽  
Sandra Menting ◽  
Richard Pfeltz ◽  
Matthew Warns ◽  
Salman H. Siddiqi ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Low Temperature ◽  
Susceptibility Testing ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Acidic Ph ◽  
Content Type ◽  
The Past ◽  
Neutral Ph

ABSTRACTFor the past decades, an acidic pH has been used to renderMycobacterium tuberculosissusceptible to pyrazinamide forin vitrotesting. Here, we show that at the standard breakpoint concentration and reduced culture temperatures, pyrazinamide (PZA) is active against tuberculosis (TB) at neutral pH. This finding should help unravel the mechanism of action of PZA and allow drug susceptibility testing (DST) methods to be optimized.

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