scholarly journals Evaluation of Diagnostics Colistin MIC-Strip Test for Colistin Susceptibility Testing

ANKEM Dergisi ◽  
2021 ◽  
Author(s):  
Gülşen Altınkanat Gelmez ◽  
Elvan Sayın ◽  
Ufuk Hasdemir ◽  
Güner Söyletir
Keyword(s):  
Error Rate ◽  
Susceptibility Testing ◽  
Antimicrobial Treatment ◽  
Error Rates ◽  
Multi Drug Resistance ◽  
Routine Laboratory ◽  
Broth Microdilution ◽  
Major Error ◽  
Broth Microdilution Method ◽  
Strip Test

Due to the limited number of antimicrobials to be used in the treatment of infections caused by Gram-negative microorganisms with multi-drug resistance recently, old antibiotics such as colistin have started to be preferred frequently. However, some problems are encountered in antibiotic susceptibility tests (disk diffusion, gradient test, automated systems) which are frequently used in the routine laboratory due to the cationic nature of colistin. For this reason, only the broth microdilution test is recommended by European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) for the detection of colistin susceptibility. Since broth microdilution tests are time consuming and inconvenient, tests that can provide fast and reliable colistin susceptibility result is needed in routine laboratories. In this study, it was aimed to evaluate the performance of the commercially produced Diagnostics MIC-COL test (Diagnostics I.n.c, Galanta, Slovakia) for the detection of colistin susceptibility in Klebsiella pneumoniae and Acinetobacter baumannii strains. The strains of K.pneumoniae (n = 22) and A.baumannii (n = 28) isolated from various clinical specimens between 2016 and 2019 in our routine laboratory were included in the study. Colistin minimum inhibitory concentrations (MIC) of the strains were studied with both the reference broth microdilution method and the commercially produced Diagnostics Colistin MIC-COL test. The essential agreement, categorical agreement, major error, and very major error rates of the test were calculated by comparing the obtained results. The essential agreement of the Diagnostics Colistin MIC-Strip test was determined as 84 %, categorical agreement as 98 %, and major error rate as 3.8 %, while no very major error was detected. İt is very important to guide antimicrobial treatment with rapid and reliable detection of colistin susceptibility. The commercial test used in our study is easy to use and not time-consuming. Also, due to its strip from, each isolate can be studied separately. Because of the major error rate being above the expected values, it will be useful to re-evaluate these rates with further studies to be conducted with a larger number of strains with different resistance levels.

scholarly journals Multicenter Evaluation of Ceftazidime-Avibactam Susceptibility Testing of Enterobacterales and Pseudomonas aeruginosa on the VITEK® 2 System

2020 ◽  
Author(s):  
Romney Humphries ◽  
Shelley Campeau ◽  
Thomas E. Davis ◽  
Kristin J. Nagaro ◽  
Vincent J. LaBombardi ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Error Rate ◽  
Susceptibility Testing ◽  
Reference Method ◽  
Error Rates ◽  
Performance Criteria ◽  
Test Results ◽  
Major Error ◽  
Overall Performance ◽  
Vitek 2

In this multisite study, VITEK® 2 AST-Gram-Negative Ceftazidime-Avibactam (CZA) test results for 1073 isolates (866 Enterobacterales and 207 Pseudomonas aeruginosa) were compared to the Clinical & Laboratory Standards Institute (CLSI) broth microdilution (BMD) reference method. The results were analyzed for essential agreement (EA), category agreement (CA), major error rates, and very major error rates following FDA/ISO performance criteria using the FDA-recognized CLSI/EUCAST breakpoints (S ≤8/4 μg/ml and R ≥16/4 μg/ml). The overall EA was 94.5% (1014/1073) and CA was 98.7% (1059/1073). No very major errors were reported. The major error rate was 1.4% (14/998). Out of 14 major errors, 9 were within EA. Based on the EA and lack of an intermediate category for CZA, the adjusted major error rate for FDA criteria was 0.5% (5/998). The performance for ISO criteria after error resolutions included EA 94.5% (1014/1073), CA 98.9% (1061/1073), major error 1.2% (12/998), and no very major error. Vitek 2 met the ISO and FDA criteria of ≥95% reproducibility and ≥95% quality control (QC) results within acceptable ranges for QC organisms. Vitek 2 overall performance for Enterobacterales and P. aeruginosa met or exceeded the FDA and ISO performance criteria and thus is a reliable alternative to BMD reference method for routine CZA susceptibility testing.

scholarly journals Evaluating the performance characteristics of different antimicrobial susceptibility testing methodologies for testing susceptibility of gram-negative bacteria to tigecycline

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Sima Babaei ◽  
Mehri Haeili
Keyword(s):  
Susceptibility Testing ◽  
Error Rates ◽  
Multi Drug Resistance ◽  
Gram Negative Bacteria ◽  
Dependent Manner ◽  
Major Error ◽  
Gram Negative ◽  
Minor Error ◽  
Mueller Hinton ◽  
Testing Susceptibility

Abstract Background The current emergence of multi-drug resistance among nosocomial pathogens has led to increased use of last-resort agents including Tigecycline (TGC). Availability of reliable methods for testing TGC susceptibility is crucial to accurately predict clinical outcomes. We evaluated the influence of different methodologies and type of media on TGC susceptibility of different gram-negative bacteria of clinical origin. Methods The TGC susceptibility of 84 clinical isolates of Klebsiella pneumoniae (n = 29), Escherichia coli (n = 30), and Acinetobacter baumannii (n = 25) was tested by broth microdilution (BMD), Etest, agar dilution (AD) and disk diffusion (DD) methods using Mueller Hinton agar from Difco and Mueller Hinton broth (MHB) from two different manufacturers (Difco and Condalab). FDA TGC susceptibility breakpoints issued for Enterobacteriaceae were used for interpretation of the results. Results MICs determined by BMD using MHB from two suppliers showed a good correlation with overall essential agreement (EA) and categorical agreement (CA) being 100% and 95% respectively. However, a twofold rise in BMD-Condalab MICs which was detected in 50% of the isolates, resulted in changes in susceptibility categories of few isolates with MICs close to susceptibility breakpoints leading to an overall minor error (MI) rate of 4.7%. Among the tested methods, Etest showed the best correlation with BMD, being characterized with the lowest error rates (only 1% MI) and highest overall EA (100%) and CA (98.8%) for all subsets of isolates. AD yielded the lowest overall agreement (EA 77%, CA 81%) with BMD in a species dependent manner, with the highest apparent discordance being found among the A. baumannii isolates. While the performance of DD for determination of TGC susceptibility among Enterobacteriaceae was excellent, (CA:100% with no errors), the CA was lower (84%) when it was used for A. baumannii where an unacceptably high minor-error rate was noted (16%). No major error or very major error was detected for any of the tested methods. Conclusions Etest can be reliably used for TGC susceptibility testing in the three groups of studied bacteria. For the isolates with close-to-breakpoint MICs, testing susceptibility using the reference method is recommended.

scholarly journals Colistin and Polymyxin B Susceptibility Testing for Carbapenem-Resistant and mcr -Positive Enterobacteriaceae: Comparison of Sensititre, MicroScan, Vitek 2, and Etest with Broth Microdilution

2017 ◽  
Vol 55 (9) ◽  
pp. 2609-2616 ◽  
Author(s):  
Ka Lip Chew ◽  
My-Van La ◽  
Raymond T. P. Lin ◽  
Jeanette W. P. Teo
Keyword(s):  
Susceptibility Testing ◽  
Polymyxin B ◽  
Error Rates ◽  
Test Results ◽  
Broth Microdilution ◽  
Major Error ◽  
Testing Methods ◽  
Content Type ◽  
Carbapenem Resistant ◽  
Vitek 2

ABSTRACT Colistin and polymyxin B remain part of the last line of antibiotics for multidrug-resistant Gram-negative bacteria, such as carbapenem-resistant Enterobacteriaceae . Current joint EUCAST-CLSI recommendations are for broth microdilution (BMD) to be performed for MIC testing of colistin. Commercial susceptibility testing methods were evaluated and compared against the reference BMD, using a susceptibility breakpoint of ≤2 mg/liter for both colistin and polymyxin B. Seventy-six Enterobacteriaceae were included, of which 21 were mcr-1 positive (18 Escherichia coli isolates, 2 Klebsiella pneumoniae isolates, and 1 Enterobacter aerogenes isolate). Rates of essential agreement (EA) of colistin test results between BMD and Vitek 2, Sensititre, and Etest were 93.4%, 89.5%, and 75.0%, respectively. Rates of EA of polymyxin B test results between BMD and Vitek 2, Sensititre, and Etest were 96.1%, 96.1%, and 48.7%, respectively. A positive MIC correlation with a categorical agreement of >90% was achieved for Sensititre (colistin Spearman's ρ = 0.863, and polymyxin B Spearman's ρ = 0.877) and Vitek 2 (polymyxin B [only] Spearman's ρ = 0.8917). Although a positive MIC correlation (Spearman's ρ = 0.873) with the reference method was achieved for colistin testing with Vitek 2, categorical agreement was <90%, with very major error rates of 36%. Correlation with the Etest MIC was lower, with very major error rates of 12% (colistin) and 26.1% (polymyxin B). MicroScan (colistin) categorical agreement was 88.2%, with a very major error rate of 4%. Colistin MICs for 15 of the 21 mcr-1 -positive isolates were >2 mg/liter, and polymyxin MICs for 17 of them were >2 mg/liter by broth microdilution. The use of a lower breakpoint of ≤1 mg/liter further improves detection of mcr-1 for all testing methods. However, further data on the correlation between MICs and clinical outcome are required to determine the most suitable breakpoint to guide clinical management.

scholarly journals Comparison of Agar Dilution, Disk Diffusion, MicroScan, and Vitek Antimicrobial Susceptibility Testing Methods to Broth Microdilution for Detection of Fluoroquinolone-Resistant Isolates of the FamilyEnterobacteriaceae

1999 ◽  
Vol 37 (3) ◽  
pp. 544-547 ◽  
Author(s):  
Christine D. Steward ◽  
Sheila A. Stocker ◽  
Jana M. Swenson ◽  
Caroline M. O’Hara ◽  
Jonathan R. Edwards ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Error Rates ◽  
Disk Diffusion ◽  
Fluoroquinolone Resistance ◽  
Broth Microdilution ◽  
Major Error ◽  
Testing Methods ◽  
Minor Error ◽  
Agar Dilution

Fluoroquinolone resistance appears to be increasing in many species of bacteria, particularly in those causing nosocomial infections. However, the accuracy of some antimicrobial susceptibility testing methods for detecting fluoroquinolone resistance remains uncertain. Therefore, we compared the accuracy of the results of agar dilution, disk diffusion, MicroScan Walk Away Neg Combo 15 conventional panels, and Vitek GNS-F7 cards to the accuracy of the results of the broth microdilution reference method for detection of ciprofloxacin and ofloxacin resistance in 195 clinical isolates of the familyEnterobacteriaceae collected from six U.S. hospitals for a national surveillance project (Project ICARE [Intensive Care Antimicrobial Resistance Epidemiology]). For ciprofloxacin, very major error rates were 0% (disk diffusion and MicroScan), 0.9% (agar dilution), and 2.7% (Vitek), while major error rates ranged from 0% (agar dilution) to 3.7% (MicroScan and Vitek). Minor error rates ranged from 12.3% (agar dilution) to 20.5% (MicroScan). For ofloxacin, no very major errors were observed, and major errors were noted only with MicroScan (3.7% major error rate). Minor error rates ranged from 8.2% (agar dilution) to 18.5% (Vitek). Minor errors for all methods were substantially reduced when results with MICs within ±1 dilution of the broth microdilution reference MIC were excluded from analysis. However, the high number of minor errors by all test systems remains a concern.

scholarly journals Detection of Colistin Resistance in Carbapenem Resistant Enterobacteriaceae by Reference Broth Microdilution and Comparative Evaluation of Three Other Methods

2021 ◽  
Author(s):  
Punyatoya Kar ◽  
Bijayini Behera ◽  
Srujana Mohanty ◽  
Jayanti Jena ◽  
Ashoka Mahapatra
Keyword(s):  
Susceptibility Testing ◽  
Good Alternative ◽  
Broth Microdilution ◽  
Major Error ◽  
Colistin Resistance ◽  
Carbapenem Resistant ◽  
Agar Dilution ◽  
Moderate Sensitivity ◽  
Phenotypic Methods ◽  
User Friendly

Abstract Objective Challenges in susceptibility testing of colistin along with increase in the prevalence of colistin-resistant carbapenemase-producing Enterobacteriaceae (CRE) pathogens needs addressal. Evaluation of user-friendly methods is necessary as an alternative to broth microdilution (BMD), the reference susceptibility testing method, for routine implementation in diagnostic clinical microbiology laboratories. Genotypic detection of the plasmid-mediated colistin resistance is also needed for infection control purposes. Materials and Methods Colistin susceptibility of 200 nonduplicate clinical CRE isolates from December 2017 to June 2019 was determined by BMD, agar dilution (AD), E test, and rapid polymyxin NP test and interpreted as per the European Committee on Antimicrobial Susceptibility Testing. The results of AD, E test, and NP test were compared with that of BMD, considering minimal inhibitory concentration (MIC) ≤ 2 µg/mL as susceptible and > 2 µg/mL as resistant. Presence of any plasmid-mediated colistin resistance (mcr-1 and 2) was evaluated in 27 colistin-resistant CRE isolates by polymerase chain reaction. Statistical Analysis Performance of different phenotypic methods was analyzed by comparing MIC results of AD and E test with that of reference BMD method. Agreement between BMD and the other two methods was expressed in terms of categorical agreement and essential agreement. Errors were expressed as very major error (VME: false-susceptible) and major error (ME: false-resistance) by AD/E test. VME and ME of 3% disagreement were considered unacceptable. Results Colistin resistance was found in 27 (13.5%) isolates by BMD method. The VME rates of both AD (11%) and E test (37%) could not meet the Clinical and Laboratory Standards Institute recommendation (< 3% VME rate is acceptable) as alternative tests to the reference BMD. Colistin NP test showed sensitivity and specificity of 85% and 98%, respectively. The percentage discordant result in NP test was highest in Enterobacter spp. (17%). None of the 27 colistin resistant isolates showed presence of mcr-1 and mcr-2 genes. Conclusion High VME rate in AD and E tests precludes their use as alternatives to BMD for colistin susceptibility testing. NP test with moderate sensitivity but excellent specificity can be a good alternative for testing colistin susceptibility in CRE isolates, except in Enterobacter spp. Absence of mcr-1 and mcr-2 gene necessitates the exploration of other mechanisms of colistin resistance.

scholarly journals Agreement Assessment of Tigecycline Susceptibilities Determined by the Disk Diffusion and Broth Microdilution Methods among Commonly Encountered Resistant Bacterial Isolates: Results from the TigecyclineIn VitroSurveillance in Taiwan (TIST) Study, 2008 to 2010

2011 ◽  
Vol 56 (3) ◽  
pp. 1414-1417 ◽  
Author(s):  
Jien-Wei Liu ◽  
Wen-Chien Ko ◽  
Cheng-Hua Huang ◽  
Chun-Hsing Liao ◽  
Chin-Te Lu ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Total Error ◽  
Error Rates ◽  
Resistant Bacteria ◽  
Drug Resistant ◽  
Broth Microdilution ◽  
Content Type ◽  
E Coli ◽  
Drug Resistant Bacteria

ABSTRACTThe TigecyclineIn VitroSurveillance in Taiwan (TIST) study, initiated in 2006, is a nationwide surveillance program designed to longitudinally monitor thein vitroactivity of tigecycline against commonly encountered drug-resistant bacteria. This study compared thein vitroactivity of tigecycline against 3,014 isolates of clinically important drug-resistant bacteria using the standard broth microdilution and disk diffusion methods. Species studied included methicillin-resistantStaphylococcus aureus(MRSA;n= 759), vancomycin-resistantEnterococcus faecium(VRE;n= 191), extended-spectrum β-lactamase (ESBL)-producingEscherichia coli(n= 602), ESBL-producingKlebsiella pneumoniae(n= 736), andAcinetobacter baumannii(n= 726) that had been collected from patients treated between 2008 and 2010 at 20 hospitals in Taiwan. MICs and inhibition zone diameters were interpreted according to the currently recommended U.S. Food and Drug Administration (FDA) criteria and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. The MIC90values of tigecycline against MRSA, VRE, ESBL-producingE. coli, ESBL-producingK. pneumoniae, andA. baumanniiwere 0.5, 0.125, 0.5, 2, and 8 μg/ml, respectively. The total error rates between the two methods using the FDA criteria were high: 38.4% for ESBL-producingK. pneumoniaeand 33.8% forA. baumannii. Using the EUCAST criteria, the total error rate was also high (54.6%) forA. baumanniiisolates. The total error rates between these two methods were <5% for MRSA, VRE, and ESBL-producingE. coli. For routine susceptibility testing of ESBL-producingK. pneumoniaeandA. baumanniiagainst tigecycline, the broth microdilution method should be used because of the poor correlation of results between these two methods.

Two Novel Mutations Associated with Polymyxin-B Resistance in a Pandemic Lineage of Uropathogenic Escherichia coli of the Sequence Type 69

Chemotherapy ◽  
2021 ◽  
pp. 1-7
Author(s):  
Carla Adriana dos Santos ◽  
Rodrigo Tavanelli Hernandes ◽  
Marcos Paulo Vieira Cunha ◽  
Filipe Onishi Nagamori ◽  
Claudia Regina Gonçalves ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Susceptibility Testing ◽  
Polymyxin B ◽  
Antimicrobial Treatment ◽  
Sequence Type ◽  
Broth Microdilution ◽  
Economic Costs ◽  
Novel Mutations ◽  
E Coli ◽  
Total Inhibition

<b><i>Background:</i></b> Uropathogenic <i>Escherichia coli</i> (UPEC) are frequent pathogens worldwide, impacting on the morbidity and economic costs associated with antimicrobial treatment. <b><i>Objectives:</i></b> We report two novel mutations associated with polymyxin-B resistance in an UPEC isolate collected in 2019. <b><i>Methods:</i></b> Isolate was submitted to antimicrobial susceptibility testing including broth microdilution for polymyxin B. Whole genome was sequenced and analyzed. <b><i>Results:</i></b> Polymyxin-B total inhibition occurred at 16 mg/L (resistant). UPEC isolate was assigned to the phylogroup D, serotype O117:H4, and Sequence Type 69. <i>mcr</i> genes were not detected, but two novel mutations in the <i>pmrA/basS</i> (A80S) and <i>pmrB/</i>basR (D149N) genes were identified. <b><i>Conclusions:</i></b> The occurrence of non-<i>mcr</i> polymyxin resistance in <i>E. coli</i> from extraintestinal infections underscores the need of a continuous surveillance of this evolving pathogen.

Susceptibility of Filamentous Fungi to Voriconazole in Malaysia Tested by Sensititre YeastOne and CLSI Microdilution Methods

2021 ◽  
Author(s):  
Xue Ting Tan ◽  
Stephanie Jane Ginsapu ◽  
Fairuz binti Amran ◽  
Salina binti Mohamed Sukur ◽  
Surianti binti Shukor
Keyword(s):  
Filamentous Fungi ◽  
Susceptibility Testing ◽  
Rhizopus Oryzae ◽  
Antifungal Susceptibility ◽  
Sporothrix Schenckii ◽  
Rank Test ◽  
Broth Microdilution ◽  
Syncephalastrum Racemosum ◽  
Microdilution Method ◽  
Broth Microdilution Method

Abstract Background: Voriconazole is a trizaole antifungal to treat fungal infection. In this study, the susceptibility pattern of voriconazole against filamentous fungi was studied using Sensititre® YeastOne and Clinical & Laboratory Standards Institute (CLSI) M38 broth microdilution method. Methods: The suspected cultures of Aspergillus niger, A. flavus, A. fumigatus, A. versicolor, A. sydowii, A. calidoutus, A. creber, A. ochraceopetaliformis, A. tamarii, Fusarium solani, F. longipes, F. falciferus, F. keratoplasticum, Rhizopus oryzae, R. delemar, R. arrhizus, Mucor sp., Poitrasia circinans, Syncephalastrum racemosum and Sporothrix schenckii were received from hospitals. Their identification had been confirmed in our lab and susceptibility tests were performed using Sensititre® YeastOne and CLSI M38 broth microdilution method. The significant differences between two methods were calculated using Wilcoxon Sign Rank test.Results: Mean of the minimum inhibitory concentrations (MIC) for Aspergillus spp. and Fusarium were within 0.25 μg/mL-2.00 μg/mL by two methods except A. calidoutus, F. solani and F. keratoplasticum. Moreover, mean of MIC for S. schenkii were around 3.00 μg/mL by two methods. In contrast, mean of MIC for Rhizopus spp., Mucor sp., P. circinans and S. racemosum were ≥6.00 μg/mL by two methods. Generally, the MIC obtained by Sensititre YeastOne was one two-fold increase or decrease compared with the results obtained by CLSI method. The overall agreement between Sensititre YeastOne and CLSI methods to test susceptibility testing of voricaonazole was more than 70% except A. sydowii. The significant differences between two methods were significant when tested on A. niger, A. flavus, A. fumigatus, A. versicolor, A. sydowii, F. solani and S. schenkii. Conclusions: In conclusion, Sensititre YeastOne method appears to be an alternative procedure for antifungal susceptibility testing for some Malaysian moulds.

scholarly journals Flow Cytometry Antifungal Susceptibility Testing of Pathogenic Yeasts other than Candida albicans and Comparison with the NCCLS Broth Microdilution Test

2000 ◽  
Vol 44 (10) ◽  
pp. 2752-2758 ◽  
Author(s):  
Rama Ramani ◽  
Vishnu Chaturvedi
Keyword(s):  
Flow Cytometry ◽  
Candida Albicans ◽  
Amphotericin B ◽  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Antifungal Susceptibility Testing ◽  
Broth Microdilution ◽  
Nitrogen Base ◽  
Microdilution Method ◽  
Broth Microdilution Method

ABSTRACT Candida species other than Candida albicansfrequently cause nosocomial infections in immunocompromised patients. Some of these pathogens have either variable susceptibility patterns or intrinsic resistance against common azoles. The availability of a rapid and reproducible susceptibility-testing method is likely to help in the selection of an appropriate regimen for therapy. A flow cytometry (FC) method was used in the present study for susceptibility testing ofCandida glabrata, Candida guilliermondii,Candida krusei, Candida lusitaniae,Candida parapsilosis, Candida tropicalis, andCryptococcus neoformans based on accumulation of the DNA binding dye propidium iodide (PI). The results were compared with MIC results obtained for amphotericin B and fluconazole using the NCCLS broth microdilution method (M27-A). For FC, the yeast inoculum was prepared spectrophotometrically, the drugs were diluted in either RPMI 1640 or yeast nitrogen base containing 1% dextrose, and yeast samples and drug dilutions were incubated with amphotericin B and fluconazole, respectively, for 4 to 6 h. Sodium deoxycholate and PI were added at the end of incubation, and fluorescence was measured with a FACScan flow cytometer (Becton Dickinson). The lowest drug concentration that showed a 50% increase in mean channel fluorescence compared to that of the growth control was designated the MIC. All tests were repeated once. The MICs obtained by FC for all yeast isolates except C. lusitaniae were in very good agreement (within 1 dilution) of the results of the NCCLS broth microdilution method. Paired ttest values were not statistically significant (P = 0.377 for amphotericin B; P = 0.383 for fluconazole). Exceptionally, C. lusitaniae isolates showed higher MICs (2 dilutions or more) than in the corresponding NCCLS broth microdilution method for amphotericin B. Overall, FC antifungal susceptibility testing provided rapid, reproducible results that were statistically comparable to those obtained with the NCCLS method.

scholarly journals Evaluation of a Modified EUCAST Fragmented-Mycelium Inoculum Method forIn VitroSusceptibility Testing of Dermatophytes and the Activity of Novel Antifungal Agents

2015 ◽  
Vol 59 (6) ◽  
pp. 3675-3682 ◽  
Author(s):  
B. Risslegger ◽  
C. Lass-Flörl ◽  
G. Blum ◽  
M. Lackner
Keyword(s):  
Antifungal Agents ◽  
Susceptibility Testing ◽  
Preparation Method ◽  
Antifungal Susceptibility ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Inoculum Preparation ◽  
Minimal Effective Concentration

ABSTRACTFor antifungal susceptibility testing of nonsporulating or poorly sporulating dermatophytes, a fragmented-mycelium inoculum preparation method was established and compared to broth microdilution testing according to CLSI and EUCAST guidelines. Moreover, thein vitroactivity of new antifungal agents against dermatophytes was evaluated. Agreement between the mycelial inoculum method and the CLSI broth microdilution method was high (93% to 100%). Echinocandins (minimal effective concentration [MEC], ≤0.5 mg/liter) and posaconazole (MIC, ≤3.00 mg/liter) showed good activity against all tested dermatophytes.

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