scholarly journals Fluconazole Susceptibility Testing of Cryptococcus neoformans: Comparison of Two Broth Microdilution Methods and Clinical Correlates among Isolates from Ugandan AIDS Patients

1998 ◽  
Vol 36 (10) ◽  
pp. 2874-2876 ◽  
Author(s):  
C. J. Jessup ◽  
M. A. Pfaller ◽  
S. A. Messer ◽  
J. Zhang ◽  
M. Tumberland ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Clinical Laboratory ◽  
Reference Method ◽  
National Committee ◽  
Yeast Nitrogen Base ◽  
Broth Microdilution ◽  
Aids Patients ◽  
In Vitro Susceptibility ◽  
Nitrogen Base ◽  
Broth Microdilution Method

We compared the yeast nitrogen base (YNB) broth microdilution method with the National Committee for Clinical Laboratory Standards (NCCLS) M27-A microdilution reference method for measuring the in vitro susceptibility of Cryptococcus neoformans isolates to fluconazole. A total of 149 isolates of C. neoformans var.neoformans from Ugandan AIDS patients was tested by both methods. An overall agreement of 88% between the two microdilution methods was observed. All isolates grew well in both RPMI 1640 and YNB media, and MICs could be read after 48 h of incubation by both methods. The range of fluconazole MICs obtained with the YNB method was broader than that obtained with the NCCLS method. The extended range of MICs provided by the YNB method may be of clinical value, as it appears that the clinical outcome may be better among patients infected with strains inhibited by lower concentrations of fluconazole as determined by the YNB method. The YNB method appears to be a viable option for testing C. neoformans against fluconazole.

scholarly journals Comparison of Three Methods for Testing Azole Susceptibilities of Candida albicans Strains Isolated Sequentially from Oral Cavities of AIDS Patients

1998 ◽  
Vol 36 (6) ◽  
pp. 1578-1583 ◽  
Author(s):  
Anna Maria Tortorano ◽  
Maria Anna Viviani ◽  
Francesco Barchiesi ◽  
Daniela Arzeni ◽  
Anna Lisa Rigoni ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Clinical Laboratory ◽  
Reference Method ◽  
National Committee ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Aids Patients ◽  
Testing Procedures ◽  
Broth Microdilution Method ◽  
Mean Differences

Three susceptibility testing procedures were compared to determine fluconazole, itraconazole, and ketoconazole MICs against 47Candida albicans strains isolated sequentially from the oral cavities of five AIDS patients undergoing azole therapy. They included the broth microdilution method (BM), performed according to the National Committee for Clinical Laboratory Standards’ tentative standard, the agar dilution method (AD), and the Etest; the latter two tests were performed both in Casitone agar (AD-Cas and Etest-Cas) and in RPMI (AD-RPMI and Etest-RPMI). Twenty-four- and 48-h MICs obtained by AD and Etest were compared with 48-h MICs obtained by BM. The MICs of all the azoles determined by BM were usually lower than those obtained by the other methods, mainly due to different reading criteria. In order to assess the most appropriate way of evaluating the agreement of MICs obtained by different methods with those produced by the proposed reference method (BM), we used the mean differences calculated according to Bland and Altman’s method. Comparison of fluconazole MICs obtained by BM and AD-Cas yielded a mean difference of 3, and the percentages of agreement within ±2 dilutions were 98 and 100% at 24 and 48 h, respectively. For ketoconazole and itraconazole MICs, lower mean differences were noted, and agreement ranged from 96 to 100%. Agreement between the AD-RPMI and BM results was poor for all azoles, and an increase in MICs was always observed between the 1st- and 2nd-day readings. Similarly, Etest-Cas gave better agreement with BM than did Etest-RPMI for all the azoles. BM, AD-Cas, and Etest-Cas each demonstrated a progressive increase in fluconazole MICs against strains isolated sequentially from a given patient, in accordance with the decreased clinical response to fluconazole.

scholarly journals Influence of Shaking on Antifungal Susceptibility Testing of Cryptococcus neoformans: a Comparison of the NCCLS Standard M27A Medium, Buffered Yeast Nitrogen Base, and RPMI–2% Glucose

2000 ◽  
Vol 44 (2) ◽  
pp. 400-404 ◽  
Author(s):  
Juan L. Rodríguez-Tudela ◽  
Francisco Martín-Díez ◽  
Manuel Cuenca-Estrella ◽  
Laura Rodero ◽  
Yolanda Carpintero ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Clinical Laboratory ◽  
Culture Media ◽  
Antifungal Susceptibility ◽  
Optimal Growth ◽  
Inoculum Size ◽  
National Committee ◽  
Yeast Nitrogen Base ◽  
Nitrogen Base ◽  
Antifungal Susceptibility Test

ABSTRACT Cryptococcus neoformans is a nonfermentative yeast that requires oxygen for growth. The shaking of culture media achieves good oxygenation, promoting the growth of cryptococci. In this study, three test media (RPMI 1640, RPMI 1640–2% glucose, and buffered yeast nitrogen base [BYNB]) recommended in the National Committee for Clinical Laboratory Standards M27A standard were examined. Growth abilities and minimum inhibitory concentrations (MICs) in microplates incubated at 35°C for 48 h were determined. The results indicated that shaking and an inoculum size of 105 CFU/ml yielded optimal growth of this yeast. Compared to RPMI 1640, supplementation of RPMI 1640 with 2% glucose did not significantly improve growth of C. neoformans and resulted in an 8.7-h delay of exponential growth. Cryptococcal growth in RPMI 1640 at 24 h was notably better than that in RPMI–2% glucose, although by 48 h the growths were comparable. The MIC range of amphotericin B observed for the C. neoformans strains grown in RPMI 1640 with or without glucose was too narrow to allow the separation of susceptible and resistant strains based on clinical outcome. The widest ranges of MICs of flucytosine and fluconazole were obtained with BYNB. This work demonstrates the need for a new antifungal susceptibility test for C. neoformans.

Use of spectrophotometric reading for in vitro antifungal susceptibility testing ofAspergillusspp.

1999 ◽  
Vol 45 (10) ◽  
pp. 871-874 ◽  
Author(s):  
Eric Dannaoui ◽  
Florence Persat ◽  
Marie-France Monier ◽  
Elisabeth Borel ◽  
Marie-Antoinette Piens ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Antifungal Susceptibility Testing ◽  
Aspergillus Species ◽  
National Committee ◽  
Broth Microdilution Method

A comparative study of visual and spectrophotometric MIC endpoint determinations for antifungal susceptibility testing of Aspergillus species was performed. A broth microdilution method adapted from the National Committee for Clinical Laboratory Standards (NCCLS) was used for susceptibility testing of 180 clinical isolates of Aspergillus species against amphotericin B and itraconazole. MICs were determined visually and spectrophotometrically at 490 nm after 24, 48, and 72h of incubation, and MIC pairs were compared. The agreement between the two methods was 99% for amphotericin B and ranged from 95 to 98% for itraconazole. It is concluded that spectrophotometric MIC endpoint determination is a valuable alternative to the visual reference method for susceptibility testing of Aspergillus species.Key words: antifungal, susceptibility testing, Aspergillus, spectrophotometric reading.

scholarly journals In Vitro Activities of the New Antifungal Triazole SCH 56592 against Common and Emerging Yeast Pathogens

2000 ◽  
Vol 44 (1) ◽  
pp. 226-229 ◽  
Author(s):  
Francesco Barchiesi ◽  
Daniela Arzeni ◽  
Annette W. Fothergill ◽  
Luigi Falconi Di Francesco ◽  
Francesca Caselli ◽  
...  
Keyword(s):  
Clinical Laboratory ◽  
Clinical Development ◽  
National Committee ◽  
In Vitro Activity ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Vitro Data ◽  
In Vitro Data

ABSTRACT A broth microdilution method performed in accordance with the National Committee for Clinical Laboratory Standards guidelines was used to compare the in vitro activity of the new antifungal triazole SCH 56592 (SCH) to that of fluconazole (FLC), itraconazole (ITC), and ketoconazole (KETO) against 257 clinical yeast isolates. They included 220 isolates belonging to 12 different species of Candida, 15 isolates each of Cryptococcus neoformans andSaccharomyces cerevisiae, and seven isolates ofRhodotorula rubra. The MICs of SCH at which 50% (MIC50) and 90% (MIC90) of the isolates were inhibited were 0.06 and 2.0 μg/ml, respectively. In general, SCH was considerably more active than FLC (MIC50 and MIC90 of 1.0 and 64 μg/ml, respectively) and slightly more active than either ITC (MIC50 and MIC90 of 0.25 and 2.0 μg/ml, respectively) and KETO (MIC50 and MIC90 of 0.125 and 4.0 μg/ml, respectively). Our in vitro data suggest that SCH has significant potential for clinical development.

scholarly journals Effect of Metronidazole on the Growth of Vaginal Lactobacilliin vitro

2001 ◽  
Vol 9 (1) ◽  
pp. 41-45 ◽  
Author(s):  
Jose A. Simoes ◽  
Alla A. Aroutcheva ◽  
Susan Shott ◽  
Sebastian Faro
Keyword(s):  
Adverse Effect ◽  
Hydrogen Peroxide ◽  
Antimicrobial Agent ◽  
Clinical Laboratory ◽  
National Committee ◽  
Broth Microdilution ◽  
High Concentration ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
The Ideal

Objective:To determine whether metronidazole has an adverse effect on the growth ofLactobacillus.Methods:Hydrogen peroxide- and bacteriocin-producing strains ofLactobacilluswere used as test strains. Concentrations of metronidazole used ranged from 128 to 7000 μg/ml. Susceptibility to metronidazole was conducted by the broth microdilution method recommended by the National Committee for Clinical Laboratory Standards.Results:Growth ofLactobacilluswas partially inhibited at concentrations between 1000 and 4000 μg/ml (p= 0.014). Concentrations ≥ 5000 μg/ml completely inhibited growth ofLactobacillus. Concentrations between 128 and 256 μg/ml stimulated growth ofLactobacillus(p= 0.025 and 0.005, respectively). Concentrations of metronidazole between 64 and 128 μg/ml or ≥ 512 μg/ml did not have an inhibitory or a stimulatory effect on the growth ofLactobacilluscompared to the control.Conclusions:High concentration of metronidazole, i.e. between 1000 and 4000 μg/ml, partially inhibited the growth ofLactobacillus. Concentrations ≥ 5000 μg/ml completely suppressed the growth ofLactobacillus. Concentrations between ≥ 128 and ≤ 256 μg/ml stimulated the growth ofLactobacillus. Further investigation to determine the ideal concentration of metronidazole is needed in order to use the antimicrobial agent effectively in the treatment of bacterial vaginosis.

scholarly journals Evaluation of a Scanner-Assisted Colorimetric MIC Method for Susceptibility Testing of Gram-Negative Fermentative Bacteria

2004 ◽  
Vol 70 (4) ◽  
pp. 2398-2403 ◽  
Author(s):  
Mokhlasur Rahman ◽  
Inger Kühn ◽  
Motiur Rahman ◽  
Barbro Olsson-Liljequist ◽  
Roland Möllby
Keyword(s):  
Bacterial Growth ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
National Committee ◽  
Broth Microdilution ◽  
Gram Negative ◽  
Microdilution Method ◽  
Epidemiological Surveys ◽  
Fermentative Bacteria ◽  
Broth Microdilution Method

ABSTRACT We describe the ScanMIC method, a colorimetric MIC method for susceptibility testing of gram-negative fermentative bacteria. The method is a slight modification of the National Committee for Clinical Laboratory Standards (NCCLS) recommended broth microdilution method that uses a redox indicator 2,3,5-triphenyltetrazolium chloride (TTC) to enhance the estimate of bacterial growth inhibition in a microplate and a flatbed scanner to capture the microplate image. In-house software was developed to transform the microplate image into numerical values based on the amount of bacterial growth and to generate the MICs automatically. The choice of indicator was based on its low toxicity and ease of reading by scanner. We compared the ScanMIC method to the NCCLS recommended broth microdilution method with 197 coliform strains against seven antibacterial agents. The interpretative categorical agreement was obtained in 92.4% of the assays, and the agreement for MIC differences (within ±1 log2 dilution) was obtained in 96% for ScanMIC versus broth microdilution and 97% for a two-step incubation colorimetric broth microdilution versus the broth microdilution method. The method was found to be labor-saving, not to require any initial investment, and to show reliable results. Thus, the ScanMIC method could be useful for epidemiological surveys that include susceptibility testing of bacteria.

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

2006 ◽  
Vol 50 (4) ◽  
pp. 1287-1292 ◽  
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.

scholarly journals Methods for Improved Detection of Oxacillin Resistance in Coagulase-Negative Staphylococci: Results of a Multicenter Study

1999 ◽  
Vol 37 (12) ◽  
pp. 4051-4058 ◽  
Author(s):  
Fred C. Tenover ◽  
Ronald N. Jones ◽  
Jana M. Swenson ◽  
Barbara Zimmer ◽  
Sigrid McAllister ◽  
...  
Keyword(s):  
Clinical Laboratory ◽  
Reference Method ◽  
Disk Diffusion ◽  
National Committee ◽  
Broth Microdilution ◽  
Pcr Assay ◽  
Coagulase Negative Staphylococci ◽  
Oxacillin Resistance ◽  
Disk Diffusion Testing ◽  
Single Disk

A multilaboratory study was undertaken to determine the accuracy of the current National Committee for Clinical Laboratory Standards (NCCLS) oxacillin breakpoints for broth microdilution and disk diffusion testing of coagulase-negative staphylococci (CoNS) by using a PCR assay for mecA as the reference method. Fifty well-characterized strains of CoNS were tested for oxacillin susceptibility by the NCCLS broth microdilution and disk diffusion procedures in 11 laboratories. In addition, organisms were inoculated onto a pair of commercially prepared oxacillin agar screen plates containing 6 μg of oxacillin per ml and 4% NaCl. The results of this study and of several other published reports suggest that, in order to reliably detect the presence of resistance mediated bymecA, the oxacillin MIC breakpoint for defining resistance in CoNS should be lowered from ≥4 to ≥0.5 μg/ml and the breakpoint for susceptibility should be lowered from ≤2 to ≤0.25 μg/ml. In addition, a single disk diffusion breakpoint of ≤17 mm for resistance and ≥18 mm for susceptibility is suggested. Due to the poor sensitivity of the oxacillin agar screen plate for predicting resistance in this study, this test can no longer be recommended for use with CoNS. The proposed interpretive criteria for testing CoNS have been adopted by the NCCLS.

scholarly journals Evaluation of the Dade MicroScan MICroSTREP Antimicrobial Susceptibility Testing Panel with Selected Streptococcus pneumoniae Challenge Strains and Recent Clinical Isolates

1998 ◽  
Vol 36 (3) ◽  
pp. 788-791 ◽  
Author(s):  
J. H. Jorgensen ◽  
M. L. McElmeel ◽  
S. A. Crawford
Keyword(s):  
Streptococcus Pneumoniae ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Reference Panel ◽  
Clinical Isolates ◽  
National Committee ◽  
Broth Microdilution ◽  
Drug Concentrations ◽  
Broth Microdilution Method

The MicroScan MICroSTREP panel is a recently marketed frozen broth microdilution panel for susceptibility testing of various streptococci, including Streptococcus pneumoniae. The panel contains 10 antimicrobial agents in cation-adjusted Mueller-Hinton broth supplemented with 3% lysed horse blood, similar in concept to the National Committee for Clinical Laboratory Standards (NCCLS) reference broth microdilution method for testing streptococci. A group of 210 isolates of S. pneumoniae were selected to include isolates with previously documented resistance to agents incorporated in the MICroSTREP panel, as well as recent invasive clinical isolates. All isolates were tested simultaneously with the MICroSTREP panel and an NCCLS reference panel whose drug concentrations were prepared to coincide with those of the MICroSTREP panel. Of the 210 isolates, 5 failed to grow in the MICroSTREP panel; 3 of those also did not grow in the reference panel. Essential agreement of MICs determined by the two methods (test MIC ± one dilution of the reference MIC) was 99.6% overall and ranged from 98.0% with chloramphenicol to 100% with penicillin, ceftriaxone, erythromycin, tetracycline, and vancomycin. There were no very major or major interpretive category errors resulting from the MICroSTREP panel tests. Minor interpretive category errors ranged from 12.2% with cefotaxime and 9.8% with ceftriaxone (due mainly to clustering of MICs for the selected strains near the breakpoints) to 0% with chloramphenicol and vancomycin. These results indicate that the MicroScan MICroSTREP frozen panels provide susceptibility results with pneumococci that are essentially equivalent to results derived by the NCCLS reference broth microdilution procedure.

scholarly journals In Vitro Activity of the New Triazole Voriconazole (UK-109,496) against Opportunistic Filamentous and Dimorphic Fungi and Common and Emerging Yeast Pathogens

1998 ◽  
Vol 36 (1) ◽  
pp. 198-202 ◽  
Author(s):  
Ana Espinel-Ingroff
Keyword(s):  
Amphotericin B ◽  
Clinical Laboratory ◽  
Wide Spectrum ◽  
Sporothrix Schenckii ◽  
National Committee ◽  
Broth Microdilution ◽  
Pseudallescheria Boydii ◽  
Broth Microdilution Method ◽  
Better Than

The in vitro antifungal activity of a new triazole derivative, voriconazole, was compared with those of itraconazole and amphotericin B against 67 isolates of Aspergillus flavus,Aspergillus fumigatus, Bipolaris spp.,Fusarium oxysporum, Fusarium solani,Pseudallescheria boydii, Rhizopus arrhizus,Blastomyces dermatitidis, Histoplasma capsulatum, and Sporothrix schenckii. The in vitro activities of voriconazole were also compared with those of amphotericin B, fluconazole, and itraconazole against 189 isolates of emerging and common yeast pathogens of Blastoschizomyces capitatus, Candida (13 species), Cryptococcus neoformans, Hansenula anomala, Rhodotorula rubra, Saccharomyces cerevisiae, Sporobolomyces salmonicolor, and Trichosporon beigelii. MICs were determined according to a procedure under evaluation by the National Committee for Clinical Laboratory Standards (NCCLS) for broth microdilution testing of filamentous fungi and by the NCCLS M27-A broth microdilution method for yeasts. The in vitro activities of voriconazole were similar to or better than those of itraconazole and amphotericin B against Aspergillus spp.,Fusarium spp., and P. boydii as well as againstB. dermatitidis and H. capsulatum. The activities of voriconazole were also comparable to or better than those of amphotericin B, fluconazole, and itraconazole against most species of yeasts tested. Exceptions were certain isolates of R. rubra and S. salmonicolor. These results suggest that voriconazole has a wide spectrum of activity in vitro; its effectiveness in the treatment of human mycoses is under evaluation in clinical trials.

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