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Agar Diffusion

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Katherine A Hammer – One of the best experts on this subject based on the ideXlab platform.

A Wang – One of the best experts on this subject based on the ideXlab platform.

  • multicenter evaluation of a new disk Agar Diffusion method for susceptibility testing of filamentous fungi with voriconazole posaconazole itraconazole amphotericin b and caspofungin
    Journal of Clinical Microbiology, 2007
    Co-Authors: A Espinelingroff, Beth A Arthingtonskaggs, Naureen Iqbal, David Ellis, M A Pfaller, S A Messer, Michael G Rinaldi, Annette W Fothergill, D L Gibbs, A Wang
    Abstract:

    The purpose of this study was to correlate inhibition zone diameters, in millimeters (Agar Diffusion disk method), with the broth dilution MICs or minimum effective concentrations (MECs) (CLSI M38-A method) of five antifungal agents to identify optimal testing guidelines for disk mold testing. The following disk Diffusion testing parameters were evaluated for 555 isolates of the molds Absidia corymbifera, Aspergillus sp. (five species), Alternaria sp., Bipolaris spicifera, Fusarium sp. (three species), Mucor sp. (two species), Paecilomyces lilacinus, Rhizopus sp. (two species), and Scedosporium sp. (two species): (i) two media (supplemented Mueller-Hinton Agar [2% dextrose and 0.5 μg/ml methylene blue] and plain Mueller-Hinton [MH] Agar), (ii) three incubation times (16 to 24, 48, and 72 h), and (iii) seven disks (amphotericin B and itraconazole 10-μg disks, voriconazole 1- and 10-μg disks, two sources of caspofungin 5-μg disks [BBL and Oxoid], and posaconazole 5-μg disks). MH Agar supported better growth of all of the species tested (24 to 48 h). The reproducibility of zone diameters and their correlation with either MICs or MECs (caspofungin) were superior on MH Agar (91 to 100% versus 82 to 100%; R, 0.71 to 0.93 versus 0.53 to 0.96 for four of the five agents). Based on these results, the optimal testing conditions for mold disk Diffusion testing were (i) plain MH Agar; (ii) incubation times of 16 to 24 h (zygomycetes), 24 h (Aspergillus fumigatus, A. flavus, and A. niger), and 48 h (other species); and (iii) the posaconazole 5-μg disk, voriconazole 1-μg disk, itraconazole 10-μg disk (for all except zygomycetes), BBL caspofungin 5-μg disk, and amphotericin B 10-μg (zygomycetes only).

  • multicenter evaluation of a new disk Agar Diffusion method for susceptibility testing of filamentous fungi with voriconazole posaconazole itraconazole amphotericin b and caspofungin
    Journal of Clinical Microbiology, 2007
    Co-Authors: A Espinelingroff, David Ellis, Michael G Rinaldi, Annette W Fothergill, D L Gibbs, Eth A Arthingtonskaggs, Nauree Iqbal, M A Pfalle, S A Messe, A Wang
    Abstract:

    The Clinical and Laboratory Standards Institute (CLSI; formerly the NCCLS) Subcommittee on Antifungal Susceptibility Tests has developed reproducible procedures for antifungal susceptibility testing of molds by the broth microdilution method (M38-A document) (3). An Agar Diffusion method has been developed for yeasts by disk Diffusion methodology (CLSI M44-A document for fluconazole and voriconazole) (2, 4, 6). Reference guidelines are not available for mold disk Diffusion testing. However, although infections caused by molds are not as common as yeast infections, an increased incidence of systemic infections caused by Aspergillus and more recently the zygomycetes and other species (Aspergillus, Fusarium, and Scedosporium) has been documented (16). Therefore, there is a need for an easier and more economical standard method to test the susceptibility of mold isolates to available antifungal agents. The overall objective of this study was to identify standard testing guidelines for disk testing of molds (i) by determining the correlation between zone diameters in millimeters by a disk Diffusion method that were read at each of three incubation times with broth microdilution reference MICs (CLSI M38-A method) or MECs (minimum effective concentrations, caspofungin) (3), (ii) by determining the reproducibility of replicate zone diameters obtained on 3 different days and under different testing conditions by the disk Diffusion method, and (iii) by determining the performance of the disk Diffusion method in identifying resistant isolates. This study evaluated the following 18 mold species (555 isolates): Absidia corymbifera, Aspergillus sp. (five species), Alternaria sp., Bipolaris spicifera, Fusarium sp. (three species), Mucor sp. (two species), Paecilomyces lilacinus, Rhizopus sp. (two species), and Scedosporium sp. (two species). Because MIC or MEC breakpoints are not available for mold testing, isolates were grouped as susceptible (MIC or MEC, ≤1 μg/ml), intermediate (MIC or MEC, 2 μg/ml) and resistant (MIC or MEC, ≥4 μg/ml) to determine the performance of the disk Diffusion method for identifying resistant isolates. These categorical breakpoints were chosen to enable this determination; supporting clinical data are not available. These breakpoints have not been approved by the CLSI, the FDA, or the pharmaceutical companies.

K L Boorn – One of the best experts on this subject based on the ideXlab platform.

  • antimicrobial activity of honey from the stingless bee trigona carbonaria determined by Agar Diffusion Agar dilution broth microdilution and time kill methodology
    Journal of Applied Microbiology, 2010
    Co-Authors: K L Boorn, Y Y Khor, E Sweetman, Tim A Heard, Katherine A Hammer
    Abstract:

    AIMS: The aim of this study was to determine the spectrum of antimicrobial activity of 11 samples of stingless bee honey compared to medicinal, table and artificial honeys. METHODS AND RESULTS: Activity was assessed by Agar Diffusion, Agar dilution, broth microdilution and time-kill viability assays. By Agar dilution, minimum inhibitory concentration (MIC) ranges were 4% to >10% (w/v) for Gram-positive bacteria, 6% to >16% (w/v) for Gram-negative bacteria and 6% to >10% (w/v) for Candida spp. By broth microdilution, all organisms with the exception of Candida albicans and Candida glabrata were inhibited at 3 log for Pseudomonas aeruginosa and <1 log for C. albicans. Similar treatment with each control honey resulted in decreases of <1 log for all organisms. CONCLUSIONS: Stingless bee honey has broad-spectrum antibacterial activity although activity against Candida was limited. Stingless bee honey samples varied in activity and the basis for this remains to be determined. SIGNIFICANCE AND IMPACT OF THE STUDY: Stingless bee honey had similar activity to medicinal honey and may therefore have a role as a medicinal agent.

  • antimicrobial activity of honey from the stingless bee trigona carbonaria determined by Agar Diffusion Agar dilution broth microdilution and time kill methodology
    Journal of Applied Microbiology, 2010
    Co-Authors: K L Boorn, Y Y Khor, E Sweetman, Tim A Heard, F Tan, Katherine A Hammer
    Abstract:

    Aims:  The aim of this study was to determine the spectrum of antimicrobial activity of 11 samples of stingless bee honey compared to medicinal, table and artificial honeys. Methods and Results:  Activity was assessed by Agar Diffusion, Agar dilution, broth microdilution and time-kill viability assays. By Agar dilution, minimum inhibitory concentration (MIC) ranges were 4% to >10% (w/v) for Gram-positive bacteria, 6% to >16% (w/v) for Gram-negative bacteria and 6% to >10% (w/v) for Candida spp. By broth microdilution, all organisms with the exception of Candida albicans and Candida glabrata were inhibited at ≤32% (w/v). Geometric MIC (w/v) means for stingless bee honeys ranged from 7·1% to 16·0% and were 11·7% for medicinal honey and 26·5% for table honey. Treatment of organisms with 20% (w/v) stingless bee honey for 60 min resulted in decreases of 1–3 log for Staphylococcus aureus, >3 log for Pseudomonas aeruginosa and <1 log for C. albicans. Similar treatment with each control honey resulted in decreases of <1 log for all organisms. Conclusions:  Stingless bee honey has broad-spectrum antibacterial activity although activity against Candida was limited. Stingless bee honey samples varied in activity and the basis for this remains to be determined. Significance and Impact of the Study:  Stingless bee honey had similar activity to medicinal honey and may therefore have a role as a medicinal agent.

A Espinelingroff – One of the best experts on this subject based on the ideXlab platform.

  • multicenter evaluation of a new disk Agar Diffusion method for susceptibility testing of filamentous fungi with voriconazole posaconazole itraconazole amphotericin b and caspofungin
    Journal of Clinical Microbiology, 2007
    Co-Authors: A Espinelingroff, Beth A Arthingtonskaggs, Naureen Iqbal, David Ellis, M A Pfaller, S A Messer, Michael G Rinaldi, Annette W Fothergill, D L Gibbs, A Wang
    Abstract:

    The purpose of this study was to correlate inhibition zone diameters, in millimeters (Agar Diffusion disk method), with the broth dilution MICs or minimum effective concentrations (MECs) (CLSI M38-A method) of five antifungal agents to identify optimal testing guidelines for disk mold testing. The following disk Diffusion testing parameters were evaluated for 555 isolates of the molds Absidia corymbifera, Aspergillus sp. (five species), Alternaria sp., Bipolaris spicifera, Fusarium sp. (three species), Mucor sp. (two species), Paecilomyces lilacinus, Rhizopus sp. (two species), and Scedosporium sp. (two species): (i) two media (supplemented Mueller-Hinton Agar [2% dextrose and 0.5 μg/ml methylene blue] and plain Mueller-Hinton [MH] Agar), (ii) three incubation times (16 to 24, 48, and 72 h), and (iii) seven disks (amphotericin B and itraconazole 10-μg disks, voriconazole 1- and 10-μg disks, two sources of caspofungin 5-μg disks [BBL and Oxoid], and posaconazole 5-μg disks). MH Agar supported better growth of all of the species tested (24 to 48 h). The reproducibility of zone diameters and their correlation with either MICs or MECs (caspofungin) were superior on MH Agar (91 to 100% versus 82 to 100%; R, 0.71 to 0.93 versus 0.53 to 0.96 for four of the five agents). Based on these results, the optimal testing conditions for mold disk Diffusion testing were (i) plain MH Agar; (ii) incubation times of 16 to 24 h (zygomycetes), 24 h (Aspergillus fumigatus, A. flavus, and A. niger), and 48 h (other species); and (iii) the posaconazole 5-μg disk, voriconazole 1-μg disk, itraconazole 10-μg disk (for all except zygomycetes), BBL caspofungin 5-μg disk, and amphotericin B 10-μg (zygomycetes only).

  • multicenter evaluation of a new disk Agar Diffusion method for susceptibility testing of filamentous fungi with voriconazole posaconazole itraconazole amphotericin b and caspofungin
    Journal of Clinical Microbiology, 2007
    Co-Authors: A Espinelingroff, David Ellis, Michael G Rinaldi, Annette W Fothergill, D L Gibbs, Eth A Arthingtonskaggs, Nauree Iqbal, M A Pfalle, S A Messe, A Wang
    Abstract:

    The Clinical and Laboratory Standards Institute (CLSI; formerly the NCCLS) Subcommittee on Antifungal Susceptibility Tests has developed reproducible procedures for antifungal susceptibility testing of molds by the broth microdilution method (M38-A document) (3). An Agar Diffusion method has been developed for yeasts by disk Diffusion methodology (CLSI M44-A document for fluconazole and voriconazole) (2, 4, 6). Reference guidelines are not available for mold disk Diffusion testing. However, although infections caused by molds are not as common as yeast infections, an increased incidence of systemic infections caused by Aspergillus and more recently the zygomycetes and other species (Aspergillus, Fusarium, and Scedosporium) has been documented (16). Therefore, there is a need for an easier and more economical standard method to test the susceptibility of mold isolates to available antifungal agents. The overall objective of this study was to identify standard testing guidelines for disk testing of molds (i) by determining the correlation between zone diameters in millimeters by a disk Diffusion method that were read at each of three incubation times with broth microdilution reference MICs (CLSI M38-A method) or MECs (minimum effective concentrations, caspofungin) (3), (ii) by determining the reproducibility of replicate zone diameters obtained on 3 different days and under different testing conditions by the disk Diffusion method, and (iii) by determining the performance of the disk Diffusion method in identifying resistant isolates. This study evaluated the following 18 mold species (555 isolates): Absidia corymbifera, Aspergillus sp. (five species), Alternaria sp., Bipolaris spicifera, Fusarium sp. (three species), Mucor sp. (two species), Paecilomyces lilacinus, Rhizopus sp. (two species), and Scedosporium sp. (two species). Because MIC or MEC breakpoints are not available for mold testing, isolates were grouped as susceptible (MIC or MEC, ≤1 μg/ml), intermediate (MIC or MEC, 2 μg/ml) and resistant (MIC or MEC, ≥4 μg/ml) to determine the performance of the disk Diffusion method for identifying resistant isolates. These categorical breakpoints were chosen to enable this determination; supporting clinical data are not available. These breakpoints have not been approved by the CLSI, the FDA, or the pharmaceutical companies.

Tim A Heard – One of the best experts on this subject based on the ideXlab platform.

  • antimicrobial activity of honey from the stingless bee trigona carbonaria determined by Agar Diffusion Agar dilution broth microdilution and time kill methodology
    Journal of Applied Microbiology, 2010
    Co-Authors: K L Boorn, Y Y Khor, E Sweetman, Tim A Heard, Katherine A Hammer
    Abstract:

    AIMS: The aim of this study was to determine the spectrum of antimicrobial activity of 11 samples of stingless bee honey compared to medicinal, table and artificial honeys. METHODS AND RESULTS: Activity was assessed by Agar Diffusion, Agar dilution, broth microdilution and time-kill viability assays. By Agar dilution, minimum inhibitory concentration (MIC) ranges were 4% to >10% (w/v) for Gram-positive bacteria, 6% to >16% (w/v) for Gram-negative bacteria and 6% to >10% (w/v) for Candida spp. By broth microdilution, all organisms with the exception of Candida albicans and Candida glabrata were inhibited at 3 log for Pseudomonas aeruginosa and <1 log for C. albicans. Similar treatment with each control honey resulted in decreases of <1 log for all organisms. CONCLUSIONS: Stingless bee honey has broad-spectrum antibacterial activity although activity against Candida was limited. Stingless bee honey samples varied in activity and the basis for this remains to be determined. SIGNIFICANCE AND IMPACT OF THE STUDY: Stingless bee honey had similar activity to medicinal honey and may therefore have a role as a medicinal agent.

  • antimicrobial activity of honey from the stingless bee trigona carbonaria determined by Agar Diffusion Agar dilution broth microdilution and time kill methodology
    Journal of Applied Microbiology, 2010
    Co-Authors: K L Boorn, Y Y Khor, E Sweetman, Tim A Heard, F Tan, Katherine A Hammer
    Abstract:

    Aims:  The aim of this study was to determine the spectrum of antimicrobial activity of 11 samples of stingless bee honey compared to medicinal, table and artificial honeys. Methods and Results:  Activity was assessed by Agar Diffusion, Agar dilution, broth microdilution and time-kill viability assays. By Agar dilution, minimum inhibitory concentration (MIC) ranges were 4% to >10% (w/v) for Gram-positive bacteria, 6% to >16% (w/v) for Gram-negative bacteria and 6% to >10% (w/v) for Candida spp. By broth microdilution, all organisms with the exception of Candida albicans and Candida glabrata were inhibited at ≤32% (w/v). Geometric MIC (w/v) means for stingless bee honeys ranged from 7·1% to 16·0% and were 11·7% for medicinal honey and 26·5% for table honey. Treatment of organisms with 20% (w/v) stingless bee honey for 60 min resulted in decreases of 1–3 log for Staphylococcus aureus, >3 log for Pseudomonas aeruginosa and <1 log for C. albicans. Similar treatment with each control honey resulted in decreases of <1 log for all organisms. Conclusions:  Stingless bee honey has broad-spectrum antibacterial activity although activity against Candida was limited. Stingless bee honey samples varied in activity and the basis for this remains to be determined. Significance and Impact of the Study:  Stingless bee honey had similar activity to medicinal honey and may therefore have a role as a medicinal agent.