P1973 Comparison of RPMI and AM3 medium for in vitro susceptibility testing of caspofungin against Candida spp. by EUCAST broth microdilution method

The antifungal activities of fluconazole, itraconazole, ketoconazole, terbinafine and griseofulvin were tested by broth microdilution technique, against 60 dermatophytes isolated from nail or skin specimens from Goiania city patients, Brazil. In this study, the microtiter plates were incubated at 28 ºC allowing a reading of the minimal inhibitory concentration (MIC) after four days of incubation for Trichophyton mentagrophytes and five days for T. rubrum and Microsporum canis. Most of the dermatophytes had uniform patterns of susceptibility to the antifungal agents tested. Low MIC values as 0.03 µg/mL were found for 33.3%, 31.6% and 15% of isolates for itraconazole, ketoconazole and terbinafine, respectively.

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

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.04381-14 ◽

2015 ◽

Vol 59 (6) ◽

pp. 3675-3682 ◽

Cited By ~ 4

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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Evaluation of Amphotericin B Interpretive Breakpoints for Candida Bloodstream Isolates by Correlation with Therapeutic Outcome

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.50.4.1287-1292.2006 ◽

2006 ◽

Vol 50 (4) ◽

pp. 1287-1292 ◽

Cited By ~ 86

Author(s):

Benjamin J. Park ◽

Beth A. Arthington-Skaggs ◽

Rana A. Hajjeh ◽

Naureen Iqbal ◽

Meral A. Ciblak ◽

...

Keyword(s):

Amphotericin B ◽

Susceptibility Testing ◽

Clinical Laboratory ◽

National Committee ◽

Restricted Range ◽

Broth Microdilution ◽

Therapeutic Success ◽

In Vitro Susceptibility ◽

In Vitro Susceptibility Testing

ABSTRACT One hundred seven Candida bloodstream isolates (51 C. albicans, 24 C. glabrata, 13 C. parapsilosis, 13 C. tropicalis, 2 C. dubliniensis, 2 C. krusei, and 2 C. lusitaniae strains) from patients treated with amphotericin B alone underwent in vitro susceptibility testing against amphotericin B using five different methods. Fifty-four isolates were from patients who failed treatment, defined as death 7 to 14 days after the incident candidemia episode, having persistent fever of ≥5 days' duration after the date of the incident candidemia, or the recurrence of fever after two consecutive afebrile days while on antifungal treatment. MICs were determined by using the Clinical Laboratory Standards Institute (formally National Committee for Clinical Laboratory Standards) broth microdilution procedure with two media and by using Etest. Minimum fungicidal concentrations (MFCs) were also measured in two media. Broth microdilution tests with RPMI 1640 medium generated a restricted range of MICs (0.125 to 1 μg/ml); the corresponding MFC values ranged from 0.5 to 4 μg/ml. Broth microdilution tests with antibiotic medium 3 produced a broader distribution of MIC and MFC results (0.015 to 0.25 μg/ml and 0.06 to 2 μg/ml, respectively). Etest produced the widest distribution of MICs (0.094 to 2 μg/ml). However, none of the test formats studied generated results that significantly correlated with therapeutic success or failure.

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Comparison of disc diffusion, E-Test and a modified CLSI broth microdilution method for in vitro susceptibility testing of itraconazole, posaconazole and voriconazole against Madurella mycetomatis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00433-21 ◽

2021 ◽

Author(s):

Bertrand Nyuykonge ◽

Lukas van Amelsvoort ◽

Kimberly Eadie ◽

Ahmed H. Fahal ◽

Annelies Verbon ◽

...

Keyword(s):

Low Income ◽

Susceptibility Testing ◽

Fungal Infections ◽

Disc Diffusion ◽

Broth Microdilution ◽

In Vitro Susceptibility ◽

Bead Beating ◽

Broth Microdilution Method ◽

Madurella Mycetomatis

For many fungal infections, in vitro susceptibility testing is used to predict if an isolate is resistant or susceptible to the antifungal agent used to treat the fungal infection. For Madurella mycetomatis , the main causative agent of mycetoma, in vitro susceptibility testing currently is not performed on a routine basis. The current in vitro susceptibility testing method is labor intensive and sonication must be done to generate a hyphal inoculum. For endpoint visualization, expensive viability dyes are needed. Here we investigated if the currently used in vitro susceptibility method could be adapted to make it amendable for use in a routine setting which can be used in low income countries, where mycetoma is endemic. First, we developed a methodology in which hyphal fragments can be generated without the need for sonication, by comparing different bead beating methodologies. Next, in vitro susceptibility was assessed using standard broth microdilution assays as well as disc diffusion, E-testing and VIPcheck™ methodologies. We demonstrate that after a hyphal suspension is generated by glass bead beating, disc diffusion, E-testing and VIPcheck™ can be used to determine susceptibility towards itraconazole, posaconazole and voriconazole of Madurella mycetomatis . The MICs found with the E-test were comparable to those obtained with our modified CLSI-based broth microdilution in vitro susceptibility assay for itraconazole and posaconazole. Furthermore, we found an inverse relationship between the zone of inhibition and MIC obtained with E-test and the modified CLSI broth microdilution technique.

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New sulfone and sulfanyl derivatives with antifungal activity

Medycyna Doświadczalna i Mikrobiologia ◽

10.32394/mdm.70.2.7 ◽

2018 ◽

pp. 175-184

Author(s):

Małgorzata Gizińska ◽

Marzena Połaska ◽

Zbigniew Ochal ◽

Monika Staniszewska

Keyword(s):

Antifungal Agents ◽

Fungal Infections ◽

In Vitro Susceptibility ◽

Microdilution Method ◽

Alternative Approach ◽

Broth Microdilution Method ◽

Fungal Morphogenesis ◽

In Vitro Susceptibility Testing ◽

Base Structure

Introduction: Increasing occurrence of fungal infections raises the need to develop novel antifungal agents. In this context, an inhibition of morphological switch may provide an alternative approach to find compounds with a potential to control the Candida albicans infections. Methods: A series of 17 sulfone and sulfanyl derivatives was synthesized and evaluated for activity against the C. albicans wild type (SC5314, ATCC) and SAP-deficient mutant strains using the broth microdilution method M27-A3. Afterwards, phase-contrast microscopy was applied to evaluate the inhibition of fungal morphogenesis under the influence of randomly selected active compounds: 1, 5 and 6. Results: By in vitro susceptibility testing of C. albicans, we identified the effective antifungal agents displaying moderate-to-good activity. Newly synthesized sulfanyl and sulfone derivatives strongly inhibited the C. albicans morphogenetic transition under the hyphae inducing conditions. Conclusions: The leading compound 6 has the potential to be used as a base structure in antifungal drug development, however further structural optimalization and toxicity studies are required.

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Emerging MDR-Mycobacterium avium subsp. avium in house-reared domestic birds as the first report in Egypt

BMC Microbiology ◽

10.1186/s12866-021-02287-y ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Abdelazeem M. Algammal ◽

Hany R. Hashem ◽

Amenah S. Al-otaibi ◽

Khyreyah J. Alfifi ◽

Esraa M. El-dawody ◽

...

Keyword(s):

Mycobacterium Avium ◽

Susceptibility Testing ◽

Broth Microdilution ◽

First Report ◽

Microdilution Method ◽

Broth Microdilution Method ◽

Domestic Birds ◽

In Vitro Antibacterial Activity ◽

Genetic Detection

Abstract Background Avian tuberculosis is a chronic and zoonotic disease that affects a wide variety of birds, mammals, and humans. This study aimed to estimate the frequency of Mycobacterium avium subsp. avium in some domestic birds based on molecular diagnosis, antibiogram profile, and PCR-based detection of inhA, rpoB, rpsL, and otrB antibiotic resistance-related genes. Methods A total of 120 fecal samples were collected from small flocks of house-reared domestic birds at Ismailia Governorate, Egypt. The collected samples were processed and subjected to the bacteriological examination. The antimicrobial susceptibility testing of the recovered isolates was performed using the broth microdilution method for the detection of minimum inhibitory concentrations (MICs). The genetic detection of the IS901confirmatory gene, inhA, rpoB, rpsL, and otrB genes was carried out using PCR. Results The frequency of M. avium subsp. avium was 4.1% (5/120); 10% (4/40) in ducks, and 2.5% (1/10) in geese. The identification of the recovered isolates was confirmed using PCR, where all the tested isolates were positive for IS901confirmatory gene. The results of the broth microdilution method revealed that most of the recovered isolates exhibited multidrug resistance (MDR) to isoniazid, rifampicin, streptomycin, oxytetracycline, and doxycycline, and harbored the inhA, rpoB, rpsL, and otrB genes. Conclusion In brief, to the best of our knowledge this is the first report that emphasized the emergence of avian tuberculosis in house-reared domestic birds in Egypt. The emergence of MDR- M. avium subsp. avium is considered a public health threat. Emerging MDR-M. avium subsp. avium in domestic birds are commonly harbored the IS901, inhA, rpoB, rpsL, and otrB genes. Azithromycin and clofazimine revealed a promising in-vitro antibacterial activity against M. avium subsp. avium.

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In vitro Susceptibility Testing of Clinical Zygomyceteous Species isolated in Cairo, Egypt against Ten Antifungal Agents by Broth Microdilution, Disk Diffusion and E-test Methods

Egyptian Journal of Botany ◽

10.21608/ejbo.2016.386 ◽

2016 ◽

Vol 56 (1) ◽

pp. 255-267

Keyword(s):

Antifungal Agents ◽

Susceptibility Testing ◽

Test Methods ◽

Disk Diffusion ◽

Broth Microdilution ◽

In Vitro Susceptibility ◽

In Vitro Susceptibility Testing

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Revised Reference Broth Microdilution Method for Testing Telavancin: Effect on MIC Results and Correlation with Other Testing Methodologies

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03172-14 ◽

2014 ◽

Vol 58 (9) ◽

pp. 5547-5551 ◽

Cited By ~ 34

Author(s):

David J. Farrell ◽

Rodrigo E. Mendes ◽

Paul R. Rhomberg ◽

Ronald N. Jones

Keyword(s):

Susceptibility Testing ◽

Previous Method ◽

Broth Microdilution ◽

Content Type ◽

Testing Method ◽

Microdilution Method ◽

Drug Potency ◽

Broth Microdilution Method ◽

Plastic Surfaces

ABSTRACTThe reference broth microdilution (BMD) antimicrobial susceptibility testing method for telavancin was revised to include dimethyl sulfoxide (DMSO) as a solvent and diluent for frozen-form panel preparation, following the CLSI recommendations for water-insoluble agents. Polysorbate 80 (P-80) was also added to the test medium to minimize proven drug losses associated with binding to plastic surfaces. Four hundred sixty-two Gram-positive isolates, including a challenge set of organisms with reduced susceptibilities to comparator agents, were selected and tested using the revised method for telavancin, and the MIC results were compared with those tested by the previously established method and several Sensititre dry-form BMD panel formulations. The revised method provided MIC results 2- to 8-fold lower than the previous method when tested against staphylococci and enterococci, resulting in MIC50values of 0.03 to 0.06 μg/ml for staphylococci and 0.03 and 0.12 μg/ml forEnterococcus faeciumandEnterococcus faecalis, respectively. Less-significant MIC decreases (1 to 2 log2dilution steps) were observed when testing streptococci in broth supplemented with blood, which showed similar MIC50values for both methods. However,Streptococcus pneumoniaehad MIC50results of 0.008 and 0.03 μg/ml when tested by the revised and previous methods, respectively. Highest essential agreement rates (≥94.0%) were noted for one candidate dry-form panel formulation compared to the revised test. The revised BMD method provides lower MIC results for telavancin, especially when tested against staphylococci and enterococci. This is secondary to the use of DMSO for panel production and the presence of P-80, which ensure the proper telavancin testing concentration and result in a more accurate MIC determination. Moreover, earlier studies where the previous method was applied underestimated thein vitrodrug potency.

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