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Sevtap Arikan

Publications and source records attributed to Sevtap Arikan.

16 recordsLinked to original sources
PubMed2005

Incubation at room temperature may be an independent factor that induces chlamydospore production in Candida dubliniensis.

Production of chlamydospores is one of the phenotypic features used to differentiate Candida albicans and Candida dubliniensis. C. albicans produces few chlamydospores on only cornmeal/rice-Tween agar at room temperature, whereas C. dubliniensis produces abundant chlamydospores at this temperature both on cornmeal agar and some other commonly used media. We tried to determine whether the room temperature is the main factor that induces chlamydospore production of C. dubliniensis, regardless of the medium used. For this purpose, 100 C. albicans and 24 C. dubliniensis isolates were tested for chlamydospore production at room temperature and at 37 degrees C on some routinely used media, including eosin-methylene blue agar (EMB), nutrient agar (NA), nutrient broth (NB), and also on an investigational medium, phenol red agar (PR). At 37 degrees C, none of the isolates produced chlamydospores on any of the tested media. At 26 degrees C, all C. dubliniensis isolates produced abundant chlamydospores and pseudohyphae after 24-48 h on all tested media. At this incubation temperature, all C. albicans isolates failed to produce chlamydospores and pseudohyphae on EMB, NA, and NB, whereas 2 of the C. albicans isolates produced a few chlamydospores on PR. We also observed that all C. dubliniensis isolates tested on EMB and PR produced rough colonies with a hyphal fringe around the colonies, whereas none of the C. albicans isolates showed this property. In conclusion, incubation at 26 degrees C may play the key role for production of abundant chlamydospores and pseudohyphae by C. dubliniensis. Comprehensive molecular studies are needed to clarify the genetic basis of this observation. Using EMB and PR may be an inexpensive, a time-saving, and a simple way of presumptive identification of C. dubliniensis based on chlamydospore formation and colony morphology.

Agar↗
PubMed2005

In vitro activity of caspofungin compared to amphotericin B, fluconazole, and itraconazole against Candida strains isolated in a Turkish University Hospital.

We investigated the in vitro activity of caspofungin compared to amphotericin B, fluconazole, and itraconazole against clinical strains of Candida spp. (n =239). Antifungal susceptibility tests were done in accordance with NCCLS M27-A2 microdilution method and the results were read after 24 and 48 h. In general, 24 h MIC readings were similar to those at 48 h for most isolates and all antifungal agents. Caspofungin was active against all species tested. Caspofungin MICs of Candida parapsilosis were slightly higher than those for other Candida spp. Caspofungin MIC (microg/ml) ranges at 24 h for C. albicans, C. glabrata, C tropicalis, C. parapsilosis, C kefyr, C krusei, C. lusitaniae, C. norvegensis, C. guilliermondii and C. lipolytica were 0.06-2, 0.125-2, 0.125-2, 1-4, 0.125-2, 1-2, 0.5-2, 0.5-1, 0.5-2 and 1-2, respectively. Eagle (paradoxical) effect was observed in 31 and 8% of the isolates at highest concentrations of caspofungin and itraconazole, respectively. The activity of caspofungin against fluconazole- and/or itraconazole-resistant isolates was similar to that detected for the susceptible ones. We conclude that caspofungin appears as a promising antifungal agent with enhanced activity against Candida, including the azole-resistant strains.

Amphotericin B↗
PubMed2005

[In vitro activity of ketoconazole, itraconazole and terbinafine against Malassezia strains isolated from neonates].

Malassezia, a yeast-like fungus found in normal skin flora is known to be associated with various skin diseases and systemic infections. There is yet no standardized in vitro susceptibility testing method and minimum inhibitory concentration (MIC) breakpoints for Malassezia species. In this study, we investigated the in vitro activity of ketoconazole, itraconazole and terbinafine against 30 Malassezia strains (22 Malassezia furfur/dermatis, 8 M. japonica) isolated from cheek and/or scalp swabs and/or cephalic pustules of 21 neonates. The isolates were identified to species level on the basis of growth on Sabouraud dextrose agar, assimilation of Tween compounds and catalase reaction. The antifungal susceptibility tests were performed by agar dilution method using modified Dixon agar (MDA) and the agar dilution plates were incubated at 32 degrees C. For the isolates which exhibited sufficient growth, MICs were read at 48 hours, for the remaining slow-growing isolates, MIC readings were done on 7th day. For all drugs tested, the lowest concentration that provided complete inhibition of growth visually was interpreted as the MIC (microg/ml) value. Itraconazole was the most active drug in vitro against Malassezia species, followed by ketoconazole and terbinafine in rank order. In vitro activity of terbinafine was poor for half of the Malassezia strains tested. Variations in activity against individual Malassezia strains were detected for ketoconazole and terbinafine, while in vitro activity of itraconazole was similar for all strains tested. In order to validate the clinical significance of these results, further in vitro and in vivo correlation studies are needed.

Antifungal Agents↗
PubMed2004

Deep dermatophytosis caused by Trichophyton rubrum with concomitant disseminated nocardiosis in a renal transplant recipient.

Deep dermatophytosis and nocardiosis are uncommon infections. This article describes a patient who was immunosuppressed with deep dermatophytosis caused by Trichophyton rubrum and concurrent disseminated nocardiosis. The infections occurred 16 years after the patient underwent renal transplantation, and may have been related to tacrolimus therapy.

Dermatomycoses↗
PubMed2004

[Evaluation of the Tween 80 opacity test for detection of the lipolytic activity of various Candida species and its utility in differentiation of C. albicans and C. dubliniensis].

In this study a total of 253 strains belonging to 10 different species of Candida were examined for their lipolytic activity by using the Tween-80 opacity test. Hundred and seventy-four of 182 C. albicans, all of 21 C. tropicalis, 1 C. rugosa and 2 of 5 C. famata strains produced halo on Tween 80 medium and around the inoculum after 10 days of incubation pointing out the positive lipolytic (esterase) activity. Seven of 8 negative C. albicans strains were isolated from hemocultures of patients with different malignancies. Remaining strains of Candida species; C. glabrata (12), C. dubliniensis (6), C. kefyr (8), C. guillermondii (5) and C. spherica (3) did not produce the halo. Tween 80 medium may be useful for the presumptive identification of some Candida species but regarding our results further large scale studies are necessary to establish the role of the medium in differentiating particularly the two similar species, C. albicans and C. dubliniensis.

Candida↗
PubMed2003

Comparison of two methods and three end points in determination of in vitro activity of micafungin against Aspergillus spp.

We investigated the in vitro activity of micafungin against clinical Aspergillus isolates (n = 37) (Aspergillusfumigatus [n = 21], Aspergillusflavus [n = 14], and Aspergillus niger [n = 2]) by using NCCLS M38A microdilution and an investigational disk diffusion assay. Microdilution assay results were evaluated by using the end points of a MIC-2 (measured in micrograms per milliliter) and minimum effective concentration (MEC, measured in micrograms per milliliter; the lowest concentration of micafungin that produces short and aberrant hyphal branchings microscopically). Disk diffusion results were interpreted by measuring the zone(s) of inhibition (ZOI, measured in millimeters). Micafungin proved to be similarly active against all Aspergillus species tested. At 24 h, MIC-2s and MECs were identical. At 48 h, however, MIC-2s increased unpredictably, leading to the loss of a consistent correlation between the two end points. MECs and ZOI remained consistent and correlated at both reading times, suggesting their use as relevant end points in susceptibility testing of micafungin against Aspergillus: All Aspergillus isolates yielded intrazonal growth on disk diffusion agar plates. The intrazonal colonies contained short, aberrant hyphal branchings microscopically. The in vivo significance of these findings remains to be further investigated.

Antifungal Agents↗
PubMed2003

[Identification of Candida dubliniensis strains using heat tolerance tests, morphological characteristics and molecular methods].

Described in 1995, Candida dubliniensis is a novel Candida species closely related to Candida albicans due primarily to its ability to produce germ tube and chlamydospores. Given these phenotypic similarities between the two species, C. dubliniensis cannot be readily distinguished from Candida albicans by routine laboratory work-up. We explored the frequency of isolation of C. dubliniensis among 213 strains previously defined as C. albicans based on their ability to produce germ tube. The test isolates were initially examined for their morphological features on cornmeal tween 80 agar, inability to grow at 45 degrees C, and the biochemical assimilation profile (ID 32C system, bioMerieux, France). Among all, 2 (0.9%) of the isolates were identified as C. dubliniensis based on the production of numerous chlamydospores in chains on cornmeal tween 80 agar and the lack of growth at 45 degrees C. The assimilation profile of these isolates was found to be in accordance with this identification. In an effort to confirm the identification, polymerase chain reaction (PCR) studies were carried out by using the C. dubliniensis specific primer set, DUBF and DUBR. Both of the isolates yielded C. dubliniensis-specific 288 base pair amplification products, confirming the previous identification obtained with the initial screening tests. The isolates were found to be susceptible to fluconazole and itraconazole, and generated amphotericin B minimal inhibitory concentrations of 0.5-1 microgram/ml by NCCLS M27-A2 microdilution method. These data suggest that the isolation rate of C. dubliniensis among our clinical isolates is low. The morphological features on cornmeal tween 80 agar and the lack of ability to grow at 45 degrees C appear as reliable, cheap, and practical screening tests in initial identification of C. dubliniensis among germ tube-producing Candida strains.

Antifungal Agents↗
PubMed2002

Comparison of NCCLS microdilution method and Etest in antifungal susceptibility testing of clinical Trichosporon asahii isolates.

We investigated the in vitro activity of amphotericin B, fluconazole, and itraconazole against clinical Trichosporon asahii isolates (n = 43) by NCCLS M27A reference microdilution method and explored the correlation between Etest and NCCLS reference method. Microdilution MIC ranges following 48 h of incubation were 1-8, 0.25-16, and 0.06-4 microg/ml for amphotericin B, fluconazole, and itraconazole, respectively. The corresponding Etest MIC ranges were determined as 0.125- > 8, 0.25- > 64, and 0.03-8 microg/ml. Of interest, Etest tended to produce lower amphotericin B MICs and widen the MIC range compared to microdilution. The influence of Etest on fluconazole and itraconazole MICs was in contrary with that observed for amphotericin B. Etest MICs of fluconazole and itraconazole tended to be higher than microdilution MICs. The wider range of amphotericin B MICs obtained by using Etest methodology may facilitate discrimination of isolates with reduced susceptibility to amphotericin B. However, clinical significance of these findings remain yet unknown and determination of MIC breakpoint values is required.

Amphotericin B↗
PubMed2002

Prevalence of dermatomycoses in Mal de Meleda patients: a field study.

Mal de Meleda is a rare autosomal recessive form of palmoplantar keratoderma characterized by hyperkeratosis of the palms and soles. The presence of yeast and dermatophytes was investigated in 29 mal de Meleda patients from Koprucay canyon, Turkey, a newer geographical focus, and was found in 62.0% and 20.7% of cases, respectively. Antifungal resistance of isolates was not detected.

Adult↗
PubMed2002

In vitro synergy of caspofungin and amphotericin B against Aspergillus and Fusarium spp.

We investigated the in vitro interaction of caspofungin and amphotericin B for clinical isolates of Aspergillus and FUSARIUM: Synergy tests were performed using the checkerboard method and following the NCCLS M38-P guidelines in Antibiotic Medium 3 broth supplemented to 2% glucose. Antagonism was not observed for any of the isolates tested. Caspofungin and amphotericin B were synergistic or synergistic to additive for at least half of the isolates.

Amphotericin B↗
PubMed2002

Comparative evaluation of disk diffusion with microdilution assay in susceptibility testing of caspofungin against Aspergillus and Fusarium isolates.

We compared the disk diffusion and broth microdilution methods for susceptibility testing of caspofungin against Aspergillus (n = 78) and Fusarium (n = 22) isolates. Microdilution testing followed the NCCLS M-38P guidelines but was performed in antibiotic medium 3 supplemented to 2% glucose (AM3). Disk diffusion assays were performed on AM3 agar plates with a 2- micro g caspofungin disk. By both methods, caspofungin showed favorable activity against Aspergillus isolates and no activity against Fusarium isolates. In the disk-based format, intrazonal growth that was not influenced by the drug concentration gradient was consistently observed for all of the Aspergillus isolates tested.

Anti-Bacterial Agents↗
PubMed2002

In vitro activity of nystatin compared with those of liposomal nystatin, amphotericin B, and fluconazole against clinical Candida isolates.

We investigated the in vitro activity of nystatin and liposomal nystatin against 103 Candida isolates to determine the effect of both time and medium on MICs. We also compared the nystatin MICs with those of amphotericin B and fluconazole. Testing was performed in accordance with the National Committee for Clinical Laboratory Standards M27-A microdilution methodology with RPMI 1640, RPMI 1640 supplemented with glucose to 2% (RPMI-2), and antibiotic medium 3 supplemented with glucose to 2% (AM3). While nystatin MICs were similar to or slightly lower than liposomal nystatin MICs in RPMI 1640 and RPMI-2, they were markedly higher than liposomal nystatin MICs in AM3. Use of AM3 and determination of the MIC after 24 h of incubation provided a slightly wider range of liposomal nystatin MICs (0.06 to >16 microg/ml). Under these conditions, the MICs at which 90% of isolates were inhibited of nystatin and liposomal nystatin were 2 and 1 microg/ml, respectively. Nystatin and liposomal nystatin in general showed good activity against all Candida spp. tested. Although the MICs of nystatin and liposomal nystatin tended to rise in parallel with the amphotericin B MICs, nystatin and liposomal nystatin MICs of 1 to 2 and 0.5 to 1 microg/ml, respectively, were obtained for seven and six, respectively, of nine isolates for which amphotericin B MICs were >or=0.25 microg/ml. No correlation between fluconazole and nystatin or liposomal nystatin MICs was observed. As amphotericin B MICs of >or=0.25 microg/ml correlate with in vitro resistance, these results suggest that liposomal nystatin might have activity against some amphotericin B-resistant isolates. In vivo testing in animal models is required for clarification of this issue.

Amphotericin B↗
PubMed2002

New agents for the treatment of systemic fungal infections--current status.

Systemic antifungal chemotherapy is enjoying its most dynamic era. More antifungal agents are under development than ever before, including agents in entirely new classes. Major goals of current investigations are to identify compounds with a wide spectrum of activity, minimal toxicity and a high degree of target specificity. The antifungal drugs in development include new azoles {voriconazole, posaconazole (formerly SCH-56592), ravuconazole (formerly BMS-207147)}, lipid formulations of amphotericin B, a lipid formulation of nystatin, echinocandins {anidulafungin (formerly, LY-303366, VER-002), caspofungin (formerly MK-991), micafungin (formerly FK-463)}, antifungal peptides other than echinocandins, and sordarin derivatives. This discussion reviews the currently available antifungal agents and summarises the developmental issues that surround these new systemic antifungal drugs.

Journal Article↗
PubMed2002

Ravuconazole Eisai/Bristol-Myers Squibb.

Eisai and Bristol-Myers Squibb (BMS) are developing the triazole, ravuconazole, as a potential treatment for fungal infection [187888]. Eisai selected the compound for further development on the basis of its good safety profile and well-balanced antifungal activity [187888]. Ravuconazole has a broader antifungal spectrum than fluconazole and itraconazole, particularly against strains of Candida krusei and Cryptococcus neoformans [271854], [342757], [370312]. By June 1999, the compound was undergoing phase II trials [327113]. In November 2001, it was reported that BMS was seeking a co-development partner for the compound [430011]. In October 2001, analysts at ABN Amro predicted sales of US $50 million in 2003 [444020].

Administration, Oral↗
PubMed2002

Lipid-based antifungal agents: a concise overview.

The development of lipid formulations of antifungal drugs has been a remarkable progress in the systemic antifungal arena. The lipid-based amphotericin B formulations; amphotericin B lipid complex (ABLC), amphotericin B colloidal dispersion (ABCD), and liposomal amphotericin B (L-AMB) have been in clinical use since the 1990s. They are significantly less nephrotoxic than the parent compound and can be safely used at higher doses. The primary cost of these formulations is significantly high and the extent of data related to their head-to-head comparison remains limited. The lipid formulation of nystatin, liposomal nystatin, is another lipid-based polyene under development. Available data concerning the in vitro activity, pharmacokinetic profile, in vivo efficacy, and safety of these formulations are summarized in this overview.

Amphotericin B↗