Evaluation of the Etest method for determining voriconazole susceptibilities of 312 clinical isolates of Candida species by using three different agar media

Performance of the Etest for voriconazole susceptibility testing of 312 isolates of Candida spp. was assessed against that of the National Committee for Clinical Laboratory Standards (NCCLS) microdilution broth method. The NCCLS method employed RPMI 1640 broth medium, and MICs were read after incubation for 48 h at 35 degrees C. Etest MICs were determined with RPMI agar containing 2% glucose (RPG), Casitone agar (CAS), and antibiotic medium 3 (AM3) agar and were read after incubation for 48 h at 35 degrees C. The Candida spp. isolates included C. albicans (n = 174), C. glabrata (n = 55), C. tropicalis (n = 31), C. parapsilosis (n = 39), C. krusei (n = 5), C. lusitaniae (n = 2), and C. guilliermondii (n = 6). The Etest results obtained using RPG correlated well with the reference MICs. Overall agreement ranged from 91% for C. glabrata to 100% for C. tropicalis, C. parapsilosis, C. guilliermondii, C. krusei, and C. lusitaniae. When CAS was used, agreement ranged from 80% for C. krusei to 100% for C. parapsilosis, C. guilliermondii, and C. lusitaniae. With AM3, agreement ranged from 58% for C. glabrata to 100% for C. lusitaniae and C. guilliermondii. The Etest method using RPG appears to be a useful method for determining voriconazole susceptibilities of Candida species.     

Evaluation of Etest Method for Determining Posaconazole MICs for 314 Clinical Isolates of Candida Species

The performance of the Etest for posaconazole (SCH 56592) susceptibility testing of 314 isolates of Candida spp. was assessed against the National Committee for Clinical Laboratory Standards (NCCLS) microdilution broth method. The NCCLS method employed RPMI 1640 broth medium, and MICs were read after incubation for 48 h at 35 degrees C. MICs were determined by Etest for all 314 isolates with RPMI agar containing 2% glucose (RPG agar) and were read after incubation for 48 h at 35 degrees C. The Candida isolates included C. albicans (n = 174), C. glabrata (n = 57), C. tropicalis (n = 31), C. parapsilosis (n = 39), C. krusei (n = 5), C. guilliermondii (n = 6), and C. lusitaniae (n = 2). The Etest results correlated well with reference MICs. Overall agreement was 95%, and agreements for individual species were as follows: C. krusei, 100%; C. albicans, 98%; C. tropicalis, 97%; C. glabrata, 93%; C. parapsilosis, 85%; C. guilliermondii, 83%; and C. lusitaniae, 50%. The problem of trailing end points was minimized with RPG agar, and good agreement with broth dilution MICs was obtained when discernible growth within an established ellipse was ignored. The Etest method using RPG agar appears to be a useful method for determining posaconazole susceptibilities of Candida species.     

Evaluation of Etest Method for Determining Caspofungin (MK-0991) Susceptibilities of 726 Clinical Isolates of Candida Species

The performance of the Etest for testing the susceptibilities to caspofungin (MK-0991) of 726 isolates of Candida spp. was assessed against the National Committee for Clinical Laboratory Standards (NCCLS) microdilution broth method. The NCCLS method employed RPMI 1640 broth medium, and MICs were read after incubation for 48 h at 35 degrees C. MICs were determined by Etest for all 726 isolates with RPMI agar containing 2% glucose (RPG) and were read after incubation for 48 h at 35 degrees C. The Candida isolates included Candida albicans (n = 486), Candida glabrata (n = 96), Candida tropicalis (n = 51), Candida parapsilosis (n = 47), Candida krusei (n = 11), Candida lusitaniae (n = 2), and Candida guilliermondii (n = 33). In addition, a subset of 314 isolates were also tested by Etest using Casitone agar (CAS) and antibiotic medium 3 agar (AM3). The Etest results obtained using RPG correlated well with reference MICs. Overall agreement was 94% with RPG, 82% with CAS, and 79% with AM3. When RPG was used, agreement ranged from 79% for C. parapsilosis to 100% for C. krusei, C. lusitaniae, and C. guilliermondii. When CAS was used, agreement ranged from 0% for C. lusitaniae to 100% for C. glabrata. With AM3, agreement ranged from 0% for C. lusitaniae to 100% for C. guilliermondii. All three media supported growth of each of the Candida species. Etest results were easy to read, with sharp zones of inhibition. In most instances (75%) where a discrepancy was observed between the Etest and the reference method, the Etest MIC was lower. The Etest method using RPG appears to be useful for determining caspofungin susceptibilities of Candida species.     

CHROMagar Candida medium for direct susceptibility testing of yeast from blood cultures

An evaluation was performed on 95 blood cultures positive for Candida spp. to determine the correlation of direct susceptibility testing of fluconazole versus both standardized disk diffusion and MIC methods. For direct testing, an aliquot taken from BD BACTEC Plus and/or BD BACTEC Lytic/10 bottles (Becton Dickinson [BD], Sparks, MD) positive by gram stain for yeast was subcultured to CHROMagar Candida (BD), and a 25-microg fluconazole disk (BD) was placed on the plate. The area of growth inhibition surrounding the disk was measured at 24 and 48 h. In addition, a subculture of the isolate was tested by a microdilution MIC using YeastOne (TREK Diagnostics Systems Inc., OH) and disk diffusion (NCCLS M44-A) using a standardized inoculum plated onto CHROMagar Candida as well as Mueller-Hinton agar to which 2% glucose and 0.5 microg/ml methylene blue dye was added (MH-GMB). The categorical interpretation derived from the MIC was used as the reference to which the disk diffusion results were compared. There were a total of 41 Candida albicans, 23 Candida glabrata, 20 Candida parapsilosis, 9 Candida tropicalis, and 1 each of Candida krusei and Candida lusitaniae tested. At 24 h there was full agreement among the methods for all C. albicans, C. tropicalis, C. lusitaniae, and C. krusei isolates. For the C. parapsilosis isolates at 24 h there was one very major discrepancy using the direct CHROMagar and one major error with the standardized MH-GMB. The majority of the errors were seen at 24 h with the C. glabrata isolates. Of the 23 C. glabrata isolates at 24 h by direct CHROMagar, there were 10 minor and 1 very major error; by MH-GMB there were 12 minor and 2 very major errors; and by standardized CHROMagar Candida there were 13 minor and 2 major errors. There were no very major errors with C. glabrata when all plates were read at 48 h. At 24 h by the direct and standardized CHROMagar the majority of C. glabrata isolates were more resistant, whereas by MH-GMB they were more susceptible than the reference MIC interpretation. In summary, subculturing yeast directly from blood cultures onto CHROMagar to which a fluconazole disk has been added may provide a presumptive identification at 24 h and, with the exception of C. glabrata, was able to predict the susceptibility to fluconazole with the majority of Candida isolates examined in this evaluation.     

Survey of amphotericin B susceptibility of Candida clinical isolates determined by Etest.

BACKGROUND AND PURPOSE: The minimal inhibitory concentrations (MICs) of amphotericin B (AmB) determined by the National Committee for Clinical Laboratory Standards (NCCLS; NCCLS document M27-A) broth dilution method are in a relatively narrow ranges and this may lead to underestimation of the AmB-resistant rate in clinical isolates. We evaluated in vitro susceptibility of clinical isolates of Candida spp. to AmB using Etest and determined the distribution of AmB MICs in different species. METHODS: We used the Etest (AB Biodisk, Solna, Sweden) to evaluate the MICs of Candida isolates randomly collected during 2001-2003 in a teaching hospital. RESULTS: Of the 572 isolates evaluated, Candida albicans (50.7%) was the most common species, followed by Candida tropicalis (23.9%), Candida parapsilosis (13.1%), Candida glabrata (9.4%), Candida krusei (1.9%), and Candida guilliermondii (0.9%). The majority of isolates were from blood (85%). The minimal concentrations of AmB required to inhibit 50%/90% of the isolates (MIC(50)/MIC(90)) were 0.19/0.38 microg/mL for C. krusei, 0.125/0.38 microg/mL for C. glabrata, 0.094/0.25 microg/mL for C. tropicalis, 0.032/0.19 microg/mL for C. albicans, 0.016/0.125 microg/mL for C. parapsilosis, and 0.023/0.032 microg/mL for C. guilliermondii. Only 1 blood isolate of C. glabrata was resistant to AmB (MIC > or =1 microg/mL) [0.17%]. 18.2% of isolates were less susceptible to AmB (MIC > or =0.19 microg/mL) with the highest rates for C. krusei (63.6%), followed by C. glabrata (37.0%), C. tropicalis (29.9%), C. albicans (11.0%), C. parapsilosis (5.3%), and C. guilliermondii (0%). More isolates collected from patients with hematologic malignancy were less susceptible to AmB than those collected from those with other diseases (30.5% vs 15.4%, p<0.05). CONCLUSION: This study demonstrated that AmB resistance remains rare at this hospital in Candida clinical isolates despite increasing use of this agent during the past 4 decades.     

Voriconazole and fluconazole susceptibility of Candida isolates

An adapted NCCLS M27-A method was used to evaluate the activity of voriconazole (VRC) and fluconazole (FLC) against 295 Candida isolates collected from 189 patients (including isolates from deep sites). Isolates included 186 C. albicans, 54 C. glabrata, 27 C. tropicalis, 14 C. parapsilosis, 6 C. krusei, 6 C. lusitaniae, 1 C. lypolytica and 1 C. sake. Forty-two isolates had reduced susceptibility to FLC (MIC >8 mg/L); 83.3% of these had VRC MICs < or =2 mg/L (9 of 11 C. albicans, 18 of 19 C glabrata, 6 of 6 C. krusei, 2 of 2 C. lusitaniae and 0 of 4 C. tropicalis), including 60% of isolates collected from deep-seated infections. These results suggested that in the era of azole resistance, VRC has a promising antifungal activity for serious infections with Candida spp., including most species with low susceptibility to FLC and uncommonly isolated species.     

Rapid identification of commonly encountered Candida species directly from blood culture bottles

We report a rapid-cycle, real-time PCR method for identifying six Candida spp. directly from BACTEC blood culture bottles. Target sequences in the noncoding internal transcribed spacer regions of the rRNA operon were simultaneously amplified and interrogated with fluorescent probes to identify Candida albicans, C. glabrata, C. parapsilosis, C. tropicalis, C. krusei, and C. lusitaniae; these account for 88% of the yeast species isolated from positive blood cultures in our laboratory. Any of the first four species can be identified in a single reaction using two fluorescent hybridization probe sets. The antifungal-resistant species C. krusei and C. lusitaniae are detected in a second reaction, also with two probe sets. The assay was validated with DNA extracted from BACTEC blood culture bottles positive for yeasts (n = 62) and was 100% concordant with culture identification based on biochemical and morphological features of C. albicans (n = 22), C. parapsilosis (n = 10), C. tropicalis (n = 1) C. glabrata (n = 22), C. krusei (n = 2), and C. lusitaniae (n = 1). No cross-reactivity was observed in blood culture samples growing yeasts other than the above-mentioned species (n = 4), in those growing bacteria (n = 12), or in the absence of microbial growth. Our assay allows rapid (相似文献   

Prevalence and antifungal susceptibility of 442 Candida isolates from blood and other normally sterile sites: results of a 2-year (1996 to 1998) multicenter surveillance study in Quebec, Canada

During a 2-year surveillance program (1996 to 1998) in Quebec, Canada, 442 strains of Candida species were isolated from 415 patients in 51 hospitals. The distribution of species was as follows: Candida albicans, 54%; C. glabrata, 15%; C. parapsilosis, 12%; C. tropicalis, 9%; C. lusitaniae, 3%; C. krusei, 3%; and Candida spp., 3%. These data, compared to those of a 1985 survey, indicate variations in species distribution, with the proportions of C. glabrata and C. parapsilosis increasing by 9 and 4%, respectively, and those of C. albicans and C. tropicalis decreasing by 10 and 7%, respectively. However, these differences are statistically significant for C. glabrata and C. tropicalis only. MICs of amphotericin B were > or =4 microg/ml for 3% of isolates, all of which were non-C. albicans species. Three percent of C. albicans isolates were resistant to flucytosine (> or =32 microg/ml). Resistance to itraconazole (> or =1 microg/ml) and fluconazole (> or =64 microg/ml) was observed, respectively, in 1 and 1% of C. albicans, 14 and 9% of C. glabrata, 5 and 0% of C. tropicalis, and 0% of C. parapsilosis and C. lusitaniae isolates. Clinical data were obtained for 343 patients. The overall crude mortality rate was 38%, reflecting the multiple serious underlying illnesses found in these patients. Bloodstream infections were documented for 249 patients (73%). Overall, systemic triazoles had been administered to 10% of patients before the onset of candidiasis. The frequency of isolation of non-C. albicans species was significantly higher in this group of patients. Overall, only two C. albicans isolates were found to be resistant to fluconazole. These were obtained from an AIDS patient and a leukemia patient, both of whom had a history of previous exposure to fluconazole. At present, it appears that resistance to fluconazole in Quebec is rare and is restricted to patients with prior prolonged azole treatment.     

Echinocandin susceptibility testing of Candida isolates collected during a 1-year period in Sweden

The susceptibilities of Candida isolates to the echinocandins anidulafungin, caspofungin, and micafungin were determined by using the recently revised CLSI breakpoints and Etest on 238 clinical bloodstream Candida isolates collected between September 2005 and August 2006. The isolates represent approximately 95% of all non-albicans Candida bloodstream infections and one-third of Candida albicans bloodstream infections during this 1-year period in Sweden. The collection included 81 C. albicans, 81 C. glabrata, 36 C. parapsilosis, 14 C. dubliniensis, 8 C. tropicalis, 8 C. lusitaniae, 5 C. krusei, 2 C. guilliermondii and 2 C. inconspicua isolates as well as 1 C. pelliculosa isolate. The MICs were largely consistent with the global epidemiology of bloodstream Candida isolates. All C. albicans and C. glabrata isolates were susceptible to all 3 echinocandins (MIC ≤ 0.016 μg/ml in all instances). Resistance (MIC ≥ 8 μg/ml) to anidulafungin alone was observed for 4 (11.1%) C. parapsilosis isolates and for 1/2 C. guilliermondii isolates. Intermediate susceptibility to caspofungin alone was observed for 2/5 C. krusei isolates. One of the eight C. tropicalis isolates was classified as being intermediately susceptible to micafungin (MIC, 0.5 μg/ml) and as being resistant to anidulafungin and caspofungin (MIC ≥ 1 μg/ml). This isolate harbored a heterozygous FKS1 hot spot mutation (S80P) known to confer echinocandin resistance. This first study to apply the revised CLSI breakpoints for Etest endpoints showed that the breakpoints worked successfully in detecting an isolate with a hot spot mutation. Acquired echinocandin resistance is rare in Sweden. Echinocandin MICs against C. parapsilosis and C. guilliermondii were lowest for micafungin.     

Antifungal susceptibilities of Candida species causing vulvovaginitis and epidemiology of recurrent cases

There are limited data regarding the antifungal susceptibility of yeast causing vulvovaginal candidiasis, since cultures are rarely performed. Susceptibility testing was performed on vaginal yeast isolates collected from January 1998 to March 2001 from 429 patients with suspected vulvovaginal candidiasis. The charts of 84 patients with multiple positive cultures were reviewed. The 593 yeast isolates were Candida albicans (n = 420), Candida glabrata (n = 112), Candida parapsilosis (n = 30), Candida krusei (n = 12), Saccharomyces cerevisiae ( n = 9), Candida tropicalis (n = 8), Candida lusitaniae (n = 1), and Trichosporon sp. (n = 1). Multiple species suggesting mixed infection were isolated from 27 cultures. Resistance to fluconazole and flucytosine was observed infrequently (3.7% and 3.0%); 16.2% of isolates were resistant to itraconazole (MIC > or = 1 microg/ml). The four imidazoles (econazole, clotrimazole, miconazole, and ketoconazole) were active: 94.3 to 98.5% were susceptible at < or =1 microg/ml. Among different species, elevated fluconazole MICs (> or = 16 microg/ml) were only observed in C. glabrata (15.2% resistant [R], 51.8% susceptible-dose dependent [S-DD]), C. parapsilosis (3.3% S-DD), S. cerevisiae (11.1% S-DD), and C. krusei (50% S-DD, 41.7% R, considered intrinsically fluconazole resistant). Resistance to itraconazole was observed among C. glabrata (74.1%), C. krusei (58.3%), S. cerevisiae (55.6%), and C. parapsilosis (3.4%). Among 84 patients with recurrent episodes, non-albicans species were more common (42% versus 20%). A > or = 4-fold rise in fluconazole MIC was observed in only one patient with C. parapsilosis. These results support the use of azoles for empirical therapy of uncomplicated candidal vulvovaginitis. Recurrent episodes are more often caused by non-albicans species, for which azole agents are less likely to be effective.     

Comparative evaluation of macrodilution and alamar colorimetric microdilution broth methods for antifungal susceptibility testing of yeast isolates.

A comparative evaluation of the macrodilution method and the Alamar colorimetric method for the susceptibility testing of amphotericin B, fluconazole, and flucytosine was conducted with 134 pathogenic yeasts. The clinical isolates included 28 Candida albicans, 17 Candida tropicalis, 15 Candida parapsilosis, 12 Candida krusei, 10 Candida lusitaniae, 9 Candida guilliermondii, 18 Torulopsis glabrata, and 25 Cryptococcus neoformans isolates. The macrodilution method was performed and interpreted according to the recommendations of the National Committee for Clinical Laboratory Standards (document M27-P), and the Alamar colorimetric method was performed according to the manufacturer's instructions. For the Alamar colorimetric method, MICs were determined at 24 and 48 h of incubation for Candida species and T. glabrata and at 48 and 72 h of incubation for C. neoformans. The overall agreement within +/- 1 dilution for Candida species and T. glabrata against the three antifungal agents was generally good, with the values for amphotericin B, fluconazole, and flucytosine being 85.3, 77.9, and 86.2%, respectively, at the 24-h readings and 69.3, 65.2, and 97.2%, respectively, at the 48-h readings. Most disagreement was noted with fluconazole against C. tropicalis and T. glabrata. Our studies indicate that determination of MICs at 24 h by the Alamar colorimetric method is a valid alternate method for testing amphotericin B, fluconazole, and flucytosine against Candida species but not for testing fluconazole against C. tropicalis and T. glabrata. For flucytosine, much better agreement can be demonstrated against Candida species and T. glabrata at the 48-h readings by the Alamar method.(ABSTRACT TRUNCATED AT 250 WORDS)     

In vitro susceptibilities of Candida spp. to caspofungin: four years of global surveillance

Caspofungin is being used increasingly as therapy for invasive candidiasis. Prospective sentinel surveillance for emergence of in vitro resistance to caspofungin among invasive Candida spp. isolates is indicated. We determined the in vitro activity of caspofungin against 8,197 invasive (bloodstream or sterile-site) unique patient isolates of Candida collected from 91 medical centers worldwide from 1 January 2001 to 31 December 2004. We performed antifungal susceptibility testing according to the Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) M27-A2 method and used a 24-h prominent inhibition endpoint for determination of the MIC. Of 8,197 invasive Candida spp. isolates, species distribution was as follows: 54% Candida albicans, 14% C. glabrata, 14% C. parapsilosis, 11% C. tropicalis, 3% C. krusei, and 4% other Candida spp. Overall, caspofungin was very active against Candida (MIC50/MIC90, 0.03/0.25 microg/ml; 98.2% were inhibited at a MIC of < or = 0.5 microg/ml and 99.7% were inhibited at a MIC of < or = 1 microg/ml). Results by species (expressed as MIC50/MIC90 and the percentage inhibited at < or = 1 microg/ml) were as follows: C. albicans, 0.03/0.06, 99.9; C. glabrata, 0.03/0.06, 99.9; C. parapsilosis, 0.5/0.5, 99.0; C. tropicalis, 0.03/0.06, 99.7; C. krusei, 0.12/0.5, 99.0; and C. guilliermondii, 0.5/1, 94.4. Of the 25 isolates with caspofungin MICs of >1 microg/ml, 12 isolates were C. parapsilosis, 6 isolates were C. guilliermondii, 2 isolates were C. rugosa, and 1 isolate each was C. albicans, C. glabrata, C. krusei, C. lusitaniae, and C. tropicalis. There was no significant change in caspofungin activity over the 4-year study period. Likewise, there was no difference in activity by geographic region. Caspofungin has excellent in vitro activity against invasive clinical isolates of Candida from centers worldwide. Our prospective sentinel surveillance reveals no evidence of emerging caspofungin resistance among invasive clinical isolates of Candida.     

Effect of amphotericin B alone or in combination with rifampicin or clarithromycin against Candida species biofilms

Effectiveness of amphotericin B alone or in combination with rifampicin or clarithromycin on the killing of Candida species biofilms was investigated in vitro. Amphotericin B was assayed at 0.005 to 10 mg/ml. Rifampin and clarithromycin were assayed at 10 mg/ml. We studied 7 Candida albicans, 3 Candida parapsilosis, 3 Candida glabrata, 3 Candida krusei and 2 Candida tropicalis strains. Biofilms were developed in 96-well, flat-bottomed microtiter plates for 48 hours. A synergistic effect between amphotericin B and clarithromycin was demonstrated against 66.6% of C. parapsilosis, 66.6% of C. glabrata, and 42.8% of C. albicans biofilms. A synergistic effect between amphotericin B and rifampin was demonstrated against 66.6% of C. parapsilosis, 42.8% of C. albicans, and 33.3% of C. glabrata biofilms. No synergistic effect was observed against C. krusei or C. tropicalis biofilms with any of the combinations. Rifampin or clarithromycin alone did not exert any effect on Candida species biofilms. Rifampin or clarithromycin combinations with amphotericin B might be of interest in the treatment of Candida biofilm-related infections.     

Wild-type MIC distributions and epidemiological cutoff values for posaconazole and voriconazole and Candida spp. as determined by 24-hour CLSI broth microdilution

We tested 16,191 strains of Candida against posaconazole and voriconazole, using the CLSI M27-A3 broth microdilution (BMD) method (24-h incubation), in order to define wild-type (WT) populations and epidemiological cutoff values (ECVs). From 2001 to 2009, 8,619 isolates of Candida albicans, 2,415 isolates of C. glabrata, 2,278 isolates of C. parapsilosis, 1,895 isolates of C. tropicalis, 508 isolates of C. krusei, 205 isolates of C. lusitaniae, 177 isolates of C. guilliermondii, and 93 isolates of C. kefyr were obtained from over 100 centers worldwide. The modal MICs (μg/ml) for posaconazole and voriconazole, respectively, were as follows: for C. albicans, 0.016 and 0.007; for C. glabrata, 0.5 and 0.06; for C. parapsilosis, 0.06 and 0.007; for C. tropicalis, 0.03 and 0.015; for C. krusei, 0.25 and 0.12; for C. lusitaniae, 0.03 and 0.007; for C. guilliermondii, 0.12 and 0.03; and for C. kefyr, 0.06 and 0.007. The ECVs (μg/ml [% of isolates that had MICs equal to or less than the ECV]) for posaconazole and voriconazole, respectively, were as follows: 0.06 (98.5) and 0.03 (98.9) for C. albicans, 2 (96.2) and 0.5 (90.4%) for C. glabrata, 0.25 (99.3) and 0.12 (97.9) for C. parapsilosis, 0.12 (97.6) and 0.06 (97.2) for C. tropicalis, 0.5 (99.8) and 0.5 (99.4) for C. krusei, 0.12 (95.6) and 0.03 (96.6) for C. lusitaniae, 0.5 (98.9) and 0.25 (98.3) for C. guilliermondii, and 0.25 (100.0) and 0.015 (100.0) for C. kefyr. In the absence of clinical breakpoints (CBPs) for posaconazole, these WT distributions and ECVs will be useful in surveillance for emergence of reduced susceptibility to posaconazole among Candida spp. Whereas a CBP for susceptibility of ≤ 1 μg/ml has been established for voriconazole and all species of Candida, it is notable that ECVs for this agent range from 10- to >100-fold lower than the CBP, depending on the species of Candida. The CBP is inadequate in detecting the emergence of voriconazole resistance among most Candida species encountered clinically. The CBPs for voriconazole should be reassessed, with consideration for development of species-specific CBPs.     

Activities of fluconazole and voriconazole against 1,586 recent clinical isolates of Candida species determined by Broth microdilution,disk diffusion,and Etest methods: report from the ARTEMIS Global Antifungal Susceptibility Program, 2001

The ARTEMIS Global Antifungal Susceptibility Program (ARTEMIS Program) was initiated in 2001 to provide focused surveillance of the activities of fluconazole and voriconazole against Candida spp. isolated from blood and other normally sterile sites. A total of 1,586 episodes of infection were detected at 61 international study sites. Overall, 57.7% of the infections were due to Candida albicans, followed by C. glabrata (14.8%), C. parapsilosis (12.5%), C. tropicalis (9.4%), C. krusei (2.7%), and C. lusitaniae (1.5%). Isolates of C. albicans, C. parapsilosis, and C. tropicalis were all highly susceptible to fluconazole (for 99% of the isolates the MICs were 相似文献   

Fluconazole and voriconazole multidisk testing of Candida species for disk test calibration and MIC estimation

Fluconazole and voriconazole MICs were determined for 114 clinical Candida isolates, including isolates of Candida albicans, Candida glabrata, Candida krusei, Candida lusitaniae, Candida parapsilosis, and Candida tropicalis. All strains were susceptible to voriconazole, and most strains were also susceptible to fluconazole, with the exception of C. glabrata and C. krusei, the latter being fully fluconazole resistant. Single-strain regression analysis (SRA) was applied to 54 strains, including American Type Culture Collection reference strains. The regression lines obtained were markedly different for the different Candida species. Using an MIC limit of susceptibility to fluconazole of < or =8 microg/ml, according to NCCLS standards, the zone breakpoint for susceptibility for the 25-microg fluconazole disk was calculated to be > or =18 mm for C. albicans and > or =22 mm for C. glabrata and C. krusei. SRA results for voriconazole were used to estimate an optimal disk content according to rational criteria. A 5-microg disk content of voriconazole gave measurable zones for a tentative resistance limit of 4 microg/ml, whereas a 2.5-microg disk gave zones at the same MIC level for only three of the species. A novel SRA modification, multidisk testing, was also applied to the two major species, C. albicans and C. glabrata, and the MIC estimates were compared with the true MICs for the isolates. There was a significant correlation between the two measurements. Our results show that disk diffusion methods might be useful for azole testing of Candida isolates. The method can be calibrated using SRA. Multidisk testing gives direct estimations of the MICs for the isolates.     

Distribution and antifungal susceptibility of Candida species causing nosocomial candiduria

The aim of the study was to investigate the distribution of Candida species isolated from urine specimens of hospitalized patients in Akdeniz University Hospital, Antalya, Turkey, as well as their susceptibilities to antifungal agents. A total of 100 patients who had nosocomial candiduria between March 2003 and May 2004 at the facility were included in the study. Organisms were identified by conventional methods and the use of API ID 32C strips. Susceptibilities of the isolates to amphotericin B were determined by Etest, whereas the minimum inhibitory concentration (MIC) values of these same strains to fluconazole, voriconazole and caspofungin were assessed using the broth microdilution method. The most common species recovered was C. albicans 44% of all yeasts, followed by C. tropicalis (20%), C. glabrata (18%), C. krusei (6%), C. famata (5%), C. parapsilosis (4%), C. kefyr (2%) and C. guilliermondii (1%). A total of nine (9%) of the isolates, including five C. krusei and four C. glabrata isolates were susceptible dose-dependent (SDD) to fluconazole. In constrast, only two C. glabrata and one C. krusei isolates were resistant to this antifungal. The voriconazole MICs for all Candida isolates were ≤0.5 μg/ml, except for one C. glabrata isolate with a MIC value of 2 μg/ml. Among all isolates, 94% were susceptible to amphotericin B with MIC values of <1 μg/ml and all isolates were susceptible to caspofungin with MIC values of ≤0.5 μg/ml. Future studies are needed to define better treatment regimens for those patients who have fluconazole-resistant Candida urinary tract infections.     

Comparison of two microdilution methods for testing susceptibility of Candida spp. to voriconazole

The growing number of fungal infections, coupled with emerging resistance to classical antifungal agents, has led to the development of new agents, among them voriconazole. Susceptibility to voriconazole was tested by using two microdilution techniques: the reference method described in National Committee for Clinical Laboratory Standards document M27-A2 and a colorimetric method, Sensititre YeastOne. A total of 272 Candida isolates (132 of Candida albicans, 62 of C. parapsilosis, 33 of Candida glabrata, 21 of C. krusei, 15 of C. tropicalis, and 9 of C. lusitaniae) and two control strains (C. parapsilosis ATCC 22019 and C. krusei ATCC 6258) were tested. There was a high rate of agreement between the two methods used (97 to 100%).     

Correlation between microdilution, E-test, and disk diffusion methods for antifungal susceptibility testing of posaconazole against Candida spp

Agar-based antifungal susceptibility testing is an attractive alternative to the microdilution method. We examined the correlation between the microdilution, E-test, and disk diffusion methods for posaconazole against Candida spp. A total of 270 bloodstream isolates of Candida spp. with a broad range of posaconazole MICs were tested using the CLSI M27-A2 method for microdilution, as well as the M-44A method and E-test methods for agar-based testing on Mueller-Hinton agar supplemented with 2% glucose and 0.5 microg of methylene blue. MICs and inhibitory zone diameters at the prominent growth reduction endpoint were recorded at 24 and 48 h. The Candida isolates included Candida albicans (n = 124), C. parapsilosis (n = 44), C. tropicalis (n = 41), C. glabrata (n = 36), C. krusei (n = 20), C. lusitaniae (n = 3), and C. dubliniensis (n = 2). The overall concordance (i.e., the percentage of isolates within two dilutions) between the E-test and microdilution was 64.8% at 24 h and 82.6% at 48 h. When we considered an arbitrary breakpoint of < or = 1 microg/ml, the agreement between the E-test and microdilution methods was 87.8% at 24 h and 93.0% at 48 h. The correlation of MICs with disk diffusion zone diameters was better for the E-test than the microdilution method. Zone correlation for diameters produced by the disks of two manufacturers was high, with a Pearson test value of 0.941 at 24 h. The E-test and microdilution MICs show good concordance and interpretative agreement. The disk diffusion zone diameters are highly reproducible and correlate well with both the E-test and the microdilution method, making agar-based methods a viable alternative to microdilution for posaconazole susceptibility testing.     

Susceptibility profile of 200 bloodstream isolates of Candida spp. collected from Brazilian tertiary care hospitals.

We evaluated the antifungal susceptibility profile of 200 recent bloodstream isolates of Candida spp. sequentially obtained from patients admitted to five tertiary care hospitals in Brazil. Isolates were identified by classical methods and the antifungal susceptibility profile was determined by the NCCLS microbroth assay method. Candida albicans was the most frequent species (41.5%); followed by C. tropicalis (24%) and C. parapsilosis (20.5%). The frequency of C. glabrata and C. krusei was low (nine and two isolates, respectively). Only three strains were resistant to fluconazole (two C. krusei and one C. glabrata) and only one was resistant to itraconazole (the same C. glabrata strain that was resistant to fluconazole). Two strains were considered susceptible dose-dependent (SDD) to fluconazole and 13 isolates (6.5%) were SDD to itraconazole. Overall, the MIC50 value of non-C. albicans isolates for fluconazole was two dilutions higher than that of C. albicans isolates, and for itraconazole was one dilution higher. Resistance to amphotericin B (MIC > or = 2 microg ml(-1)) was observed in 2.5% of isolates (two strains of C. albicans, two of C. parapsilosis and one of C. krusei). This study showed that episodes of candidemia in Brazilian public hospitals are represented mainly by fluconazole-susceptible non-C. albicans species. This finding is probably related to the low use of fluconazole in these hospitals.