Two-site comparison of broth microdilution and semisolid agar dilution methods for susceptibility testing of Cryptococcus neoformans in three media

Anaissie, Elias; Shawar, Ribhi; Paetznick, Victor L.; Ensign, Lisa G.; Witte, Z.; LaRocco, Mark

doi:10.1128/jcm.31.5.1370-1372.1993

Cited by 8 publications

(8 citation statements)

References 19 publications

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“…However, in our study, we found that this medium provided adequate growth of the 53 cryptococcal strains tested. This finding agrees with that reported by Anaisse et al (1), who found that RPMI 1640 is a suitable medium for testing cryptococci.…”

supporting

confidence: 93%

In vitro susceptibilities of clinical and environmental isolates of Cryptococcus neoformans to five antifungal drugs

Franzot

Hamdan

1996

Antimicrob Agents Chemother

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A total of 53 Cryptococcus neoformans strains, including clinical and environmental Brazilian isolates, were tested for their susceptibilities to amphotericin B, 5-flucytosine, ketoconazole, fluconazole, and itraconazole. The tests were performed according to the National Committee of Clinical Laboratory Standards recommendations (document M27-P). In general, there was a remarkable homogeneity of results for all strains, and comparable MICs were found for environmental and clinical isolates. This paper represents the first contribution in which susceptibility data for Brazilian C. neoformans isolates are provided.

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supporting

confidence: 93%

In vitro susceptibilities of clinical and environmental isolates of Cryptococcus neoformans to five antifungal drugs

Franzot

Hamdan

1996

Antimicrob Agents Chemother

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“…Although in vitro susceptibilities of different C. neoformans strains to amphotericin B, flucytosine, ketoconazole, fluconazole and itraconazole have been studied and the direct comparisons of MIC data between studies are complicated by variability in the test methods and the lack of standardization approaches. However, our results on the in vitro activities of amphotericin B, flucytosine, ketoconazole, fluconazole and itraconazole against C. neoformans are similar to those published earlier 7, 8, 18, 21 . Among the azoles, fluconazole showed lower activity than ketoconazole and itraconazole.…”

Section: Discussionsupporting

confidence: 89%

“…Among the azoles, fluconazole showed lower activity than ketoconazole and itraconazole. In fact, previous reports have already shown the low activity of fluconazole against C. neoformans isolates, even though the drug has proven to be more effective in vivo 4, 8, 18, 20, 24 . This might be due to its wide use as superior and available all over the world including Egypt.…”

Section: Discussionmentioning

confidence: 99%

“…Systemic infections with C. neoformans are frequently fatal for patients with imunocompromised cell‐mediated immune response 6, 7 . Despite the availability of newer antifungal drugs, therapeutic difficulties have been encountered during treatment of acute phases of cryptococcosis and lifelong therapy is necessary to suppress the infections 8, 9 …”

Section: Introductionmentioning

confidence: 99%

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In vitro susceptibility of Cryptococcus neoformans clinical isolates from Egypt to seven antifungal drugs

Abdel-Salam

2005

Mycoses

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The in vitro susceptibility of 29 clinical isolates of Cryptococcus neoformans to fluconazole, miconazole, itraconazole, ketoconazole, flucytosine, nystatin and amphotericin B was tested by broth and colorimetric microdilution methods. Most of the isolates showed uniform patterns of susceptibility to the used antifungal agents. Only three isolates exhibited resistance [fourfold or greater rise in the minimum inhibitory concentrations (MICs)] to the tested antifungal drugs. The MIC50 and MIC90 were 0.5-8 mg l(-1) for 5-flucytosine, 0.2-8.25 mg l(-1) for nystatin, 0.5-16 mg l(-1) for fluconazole and 0.2-12.5 mg l(-1) for miconazole. However, MIC50 and MIC90 were in narrow range for the clinical yeast isolates in both methods used and showed 0.5-1 mg l(-1) for amphotericin B and 0.016-0.25 mg l(-1) for both ketoconazole and itraconazole. The combination of fluconazole plus flucytosine showed greater synergistic and fungicidal activity compared with that of fluconazole plus amphotericin B or the use of individual drugs.

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“…RPMI 1640 medium is the standard medium used with the NCCLS M27-A method, and some workers have reported the suitability of RPMI 1640 medium for susceptibility testing of C. neoformans. Anaissie et al (2) found that RPMI 1640 medium gave more consistent results than Eagle's minimum essential medium or YNB when testing clinical isolates of C. neoformans in a microdilution format in broth, and a recent eightcenter collaborative study (3) showed that RPMI 1640 medium provided satisfactory growth for both C. albicans and C. neoformans. Likewise, Franzot and Hamdan (11) reported the ability of RPMI 1640 medium to support the growth of 53 cryptococcal isolates, and Gadea et al (13) found that supplementation of RPMI 1640 medium with 2% glucose provided enough growth of C. neoformans for the determination of MICs after 48 h of incubation.…”

Section: Discussionmentioning

confidence: 99%

Detection of Resistance to Amphotericin B among Cryptococcus neoformans Clinical Isolates: Performances of Three Different Media Assessed by Using E-Test and National Committee for Clinical Laboratory Standards M27-A Methodologies

Lozano-Chiu¹,

Paetznick²,

Ghannoum

et al. 1998

J Clin Microbiol

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Although reliable detection of resistance in vitro is critical to the overall performance of any susceptibility testing method, the recently released National Committee for Clinical Laboratory Standards M27-A methodology for susceptibility testing of yeasts discriminates poorly between resistant and susceptible isolates ofCandida spp. We have previously shown that both substitution of antibiotic medium 3 for RPMI 1640 medium in the microdilution variant of the M27-A method and use of the E-test agar diffusion methodology permit detection of amphotericin B-resistantCandida isolates. To determine the relevance of these observations to Cryptococcus neoformans, we have evaluated the performances of both the M27-A and the E-test methodologies with this yeast using three different media (RPMI 1640 medium, antibiotic medium 3, and yeast nitrogen base). As with Candida, we found that only antibiotic medium 3 permitted consistent detection of resistant isolates when testing was performed in broth by the M27-A method. When testing was performed by the E-test agar diffusion method, both RPMI 1640 medium and antibiotic medium 3 agar permitted ready detection of the resistant isolates. Reading of the results after 48 h of incubation was required for testing in broth by the M27-A method, while the MIC could be determined after either 48 or 72 h when the agar diffusion method was used.

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Two-site comparison of broth microdilution and semisolid agar dilution methods for susceptibility testing of Cryptococcus neoformans in three media

Cited by 8 publications

References 19 publications

In vitro susceptibilities of clinical and environmental isolates of Cryptococcus neoformans to five antifungal drugs

In vitro susceptibilities of clinical and environmental isolates of Cryptococcus neoformans to five antifungal drugs

In vitro susceptibility of Cryptococcus neoformans clinical isolates from Egypt to seven antifungal drugs

Detection of Resistance to Amphotericin B among Cryptococcus neoformans Clinical Isolates: Performances of Three Different Media Assessed by Using E-Test and National Committee for Clinical Laboratory Standards M27-A Methodologies

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