Species distribution and fluconazole susceptibility of Candida clinical isolates in a medical center in 2002.

Fluconazole disk-diffusion susceptibility was evaluated in 230 blood isolates and 344 non-blood clinical isolates of Candida spp. collected in 2002 at National Taiwan University Hospital. Up to 93.5% of blood isolates were susceptible to fluconazole, 3% were susceptible dose-dependent, and 3.5% were resistant. The minimum inhibitory concentrations at which 50% of tested isolates were inhibited (MIC50) of fluconazole against Candida blood isolates were highest for Candida glabrata (5 microg/mL), followed by Candida tropicalis (2.4 microg/mL), Candida albicans (2.4 microg/mL), and Candida parapsilosis (0.41 microg/mL). C. glabrata had less fluconazole-susceptible strains (76.7%) than C. albicans (98.2%), C. tropicalis (98%) and C. parapsilosis (93.8%) [p<0.05]. The proportions of fluconazole resistance in the non-blood isolates of C. albicans, C. glabrata and C. parapsilosis were similar to those of the blood isolates. However, the proportions of fluconazole resistance in the non-blood isolates of C. tropicalis surpassed those of the blood isolates (14.7% vs 2%, p<0.05). Comparison of species distribution of Candida blood isolates obtained in 2002 to those in 1981-2000 demonstrated that C. albicans remained the leading pathogen, and the proportion of C. albicans in blood isolates was lowest in 1996 (38%) and did not change significantly thereafter. However, the proportion of C. tropicalis increased from 14% during 1981-1993 to 22-23% during 1996-2002. Overall, the MIC50, MIC90 and the proportion of Candida blood isolates with fluconazole resistance remained stable during 1994-2002.     

Biofilm production by isolates of Candida species recovered from nonneutropenic patients: comparison of bloodstream isolates with isolates from other sources

Biofilm production has been implicated as a potential virulence factor of some Candida species responsible for catheter-related fungemia in patients receiving parenteral nutrition. We therefore compared clinical bloodstream isolates representing seven different Candida species to each other and to those from other anatomical sites for the capacity to form biofilms in glucose-containing medium. Potential associations between the capacity to form biofilms and the clinical characteristics of fungemia were also analyzed. Isolates included the following from nonneutropenic patients: 101 bloodstream isolates (35 C. parapsilosis, 30 C. albicans, 18 C. tropicalis, 8 C. glabrata, and 10 other Candida species isolates) and 259 clinical isolates from other body sites (116 C. albicans, 53 C. glabrata, 43 C. tropicalis, 17 C. parapsilosis, and 30 other Candida species isolates). Organisms were grown in Sabouraud dextrose broth (SDB) containing a final concentration of 8% glucose to induce biofilm formation, as published previously. Biofilm production was determined by both visual and spectrophotometric methods. In this medium, biofilm production by C. albicans isolates was significantly less frequent (8%) than that by non-C. albicans Candida species (61%; P < 0.0001). The overall proportion of non-C. albicans Candida species isolates from the blood that produced biofilms was significantly higher than that of non-C. albicans Candida isolates obtained from other sites (79% versus 52%; P = 0.0001). Bloodstream isolates of C. parapsilosis alone were significantly more likely to be biofilm positive than were C. parapsilosis isolates from other sites (86% versus 47%; P = 0.0032). Non-C. albicans Candida species, including C. parapsilosis, were more likely to be biofilm positive if isolates were derived from patients whose candidemia was central venous catheter (CVC) related (95%; P < 0.0001) and was associated with the use of total parenteral nutrition (TPN) (94%; P < 0.005). These data suggest that the capacity of Candida species isolates to produce biofilms in vitro in glucose-containing SDB may be a reflection of the pathogenic potential of these isolates to cause CVC-related fungemia in patients receiving TPN.     

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.     

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.     

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.     

International surveillance of bloodstream infections due to Candida species: frequency of occurrence and in vitro susceptibilities to fluconazole, ravuconazole, and voriconazole of isolates collected from 1997 through 1999 in the SENTRY antimicrobial surveillance program

A surveillance program (SENTRY) of bloodstream infections (BSI) in the United States, Canada, Latin America, and Europe from 1997 through 1999 detected 1,184 episodes of candidemia in 71 medical centers (32 in the United States, 23 in Europe, 9 in Latin America, and 7 in Canada). Overall, 55% of the yeast BSIs were due to Candida albicans, followed by Candida glabrata and Candida parapsilosis (15%), Candida tropicalis (9%), and miscellaneous Candida spp. (6%). In the United States, 45% of candidemias were due to non-C. albicans species. C. glabrata (21%) was the most common non-C. albicans species in the United States, and the proportion of non-C. albicans BSIs was highest in Latin America (55%). C. albicans accounted for 60% of BSI in Canada and 58% in Europe. C. parapsilosis was the most common non-C. albicans species in Latin America (25%), Canada (16%), and Europe (17%). Isolates of C. albicans, C. parapsilosis, and C. tropicalis were all highly susceptible to fluconazole (97 to 100% at < or =8 microg/ml). Likewise, 97 to 100% of these species were inhibited by < or =1 microg/ml of ravuconazole (concentration at which 50% were inhibited [MIC(50)], 0.007 to 0.03 microg/ml) or voriconazole (MIC(50), 0.007 to 0.06 microg/ml). Both ravuconazole and voriconazole were significantly more active than fluconazole against C. glabrata (MIC(90)s of 0.5 to 1.0 microg/ml versus 16 to 32 microg/ml, respectively). A trend of increased susceptibility of C. glabrata to fluconazole was noted over the three-year period. The percentage of C. glabrata isolates susceptible to fluconazole increased from 48% in 1997 to 84% in 1999, and MIC(50)s decreased from 16 to 4 microg/ml. A similar trend was documented in both the Americas (57 to 84% susceptible) and Europe (22 to 80% susceptible). Some geographic differences in susceptibility to triazole were observed with Canadian isolates generally more susceptible than isolates from the United States and Europe. These observations suggest susceptibility patterns and trends among yeast isolates from BSI and raise additional questions that can be answered only by continued surveillance and clinical investigations of the type reported here (SENTRY Program).     

Candida glabrata,an emerging fungal pathogen,exhibits superior relative cell surface hydrophobicity and adhesion to denture acrylic surfaces compared with Candida albicans

Oral candidosis is a common opportunistic infection in debilitated individuals and Candida glabrata is the second most frequently isolated species from this condition, after Candida albicans. Candidal adherence to various biological or non-biological surfaces is considered a prerequisite for colonization, and pathogenesis of candidal infections, and their relative cell surface hydrophobicity (CSH) is likely to be a possible contributory force involved in this process. Whereas a large body of data on the latter features of C. albicans is available, there is surprisingly little information on C. glabrata. As a comprehensive database on the relative adhesion and CSH of Candida spp. is instructive and useful, we investigated in vitro the latter attributes of 34 oral isolates of C. glabrata and 15 isolates of C albicans. There were remarkable intraspecies differences in both the CSH and the adhesive ability of C. glabrata strains (p < 0.001). Compared with C. albicans, C glabrata demonstrated a four-fold greater CSH value (30.63 +/- 11.20% vs 7.23+/-3.56%, p < 0.0001) and a two-fold greater tendency to adhere to denture acrylic surfaces (75.18 +/- 39.96 vs 30.36+/-9.21, p < 0.0001). A significant positive correlation between CSH and adhesion was also noted for both C. glabrata (r=0.674, p < 0.0001) and C. albicans ( r = 0.636, p < 0.05). When the effect of different incubation conditions on the relative CSH and adherence of C. glabrata was examined, CSH and the adherence to acrylic surfaces of four of six C. glabrata isolates were significantly affected by a reduction of the culture temperature (from 37 degrees C to 25 degrees C). A positive relationship also emerged when the temperature-induced variations in the adherence values were correlated with their relative CSH. These data provide hitherto unavailable archival information on important pathogenic attributes of the two most common oral Candida species that may help explain their predominance in this milieu.     

Use of epidemiological cutoff values to examine 9-year trends in susceptibility of Candida species to anidulafungin, caspofungin, and micafungin

The CLSI clinical breakpoint (CBP) for echinocandin susceptibility (S; MICs of ≤ 2 μg/ml) may classify isolates with acquired resistance (R) mutations as susceptible. Epidemiological cutoff values (ECVs) have been established to distinguish wild-type (WT) Candida strains from those that may exhibit R mutations. The CLSI-developed ECVs for anidulafungin, caspofungin, and micafungin were applied to 15,269 isolates of Candida spp. collected from over 100 centers worldwide between 2001 and 2009 to determine the frequency of non-WT strains of each species. The collection included 8,378 isolates of Candida albicans, 2,352 isolates of C. glabrata, 2,195 isolates of C. parapsilosis, 1,841 isolates of C. tropicalis, and 503 isolates of C. krusei. The mean percentages of non-WT isolates per year for anidulafungin, caspofungin, and micafungin, respectively, were as follows: for C. albicans, 0.3, 0.1, and 2.1; for C. glabrata, 0.8, 1.3, and 1.6; for C. parapsilosis, 0.0, 1.5, and 0.5; for C. tropicalis, 0.9, 0.7, and 0.9; and for C. krusei, 0.5, 6.4, and 3.5. We noted increases in the percentage of non-WT isolates, from 0.5% (2001) to 3.1% (2009) for caspofungin and C. parapsilosis, from 0.4% (2004) to 1.8% (2009) for anidulafungin and C. glabrata, from 2.4% (2004) to 5.7% (2009) for micafungin and C. krusei, and from 0.0% (2004) to 3.1% (2009) for micafungin and C. parapsilosis. No trends were noted for any species and drug when we used the CBP. Echinocandin CBPs are insensitive for detecting emerging R. Although uncommon, decreased S among Candida isolates was observed for each of the echinocandins and varied by species. Using ECVs is important in determining R trends among echinocandins and Candida.     

Comparison of restriction enzyme analysis versus pulsed-field gradient gel electrophoresis as a typing system for Torulopsis glabrata and Candida species other than C. albicans.

Candida species have recently emerged as important nosocomial pathogens. Because of the lack of a reliable system for detecting differences within the same species, little is known about the epidemiology of infection with Candida species. We describe a typing system for Torulopsis glabrata and the non-C. albicans Candida species that uses contour-clamped homogeneous electric field electrophoresis (CHEF), a version of pulsed-field gradient gel electrophoresis, and compared it with restriction enzyme analysis (REA) of genomic DNA. One hundred seventeen clinical isolates from 40 patients were evaluated. CHEF and REA were performed on each of the isolates, and the results of the two procedures were compared. The REA procedure revealed 8 different types of Candida lusitaniae, 20 of Torulopsis glabrata, 5 of Candida tropicalis, 3 of Candida parapsilosis, and 7 of Candida kefyr, whereas the CHEF method revealed 14 different types of C. lusitaniae, 16 of T. glabrata, 10 of C. tropicalis, 10 of C. parapsilosis, and 7 of C. kefyr. The CHEF technique yielded unique patterns of electrophoretic karyotypes that could be used to distinguish intraspecies variations. When compared with REA, CHEF demonstrated greater sensitivity in recognizing subtle strain-to-strain variations in most isolates and will be a useful epidemiologic tool for studying non-C. albicans Candida species and T. glabrata.     

Molecular genotyping of Candida species with special respect to Candida (Torulopsis) glabrata strains by arbitrarily primed PCR

A set of 46 epidemiologically related or unrelated Candida (Torulopsis) glabrata isolates from four different medical centres in Germany and Hungary, and the type strain of this species, were genetically typed by arbitrarily primed PCR (AP-PCR). The resulting band patterns of C. glabrata strains were compared with those of other species of the genus Candida including C. albicans, C. guilliermondii, C. kefyr, C. parapsilosis, C. tropicalis and C. krusei. After preliminary trials of various reaction parameters and control experiments to test the reproducibility of this method, it was found that consistently reproducible amplification patterns were obtained only when rigorously optimised and standardised reaction conditions were employed. Discriminatory abilities were studied with 29 generated 10-mer oligonucleotides of different G+C content. Typing of clinical isolates with the optimised AP-PCR protocol was then performed with the primer 50-1, with a G+C content of 50%. Sufficiently discriminatory polymorphisms were observed among the band patterns of the Candida species included. The gel electrophoresis patterns of each species showed an adequate similarity. Variations in minor bands were characteristic for comparison at the isolate level. Only three AP-PCR genotypes were identified among the clinical isolates of C. glabrata tested. Two of these genotypes were closely related and appeared to be widespread within German and Hungarian isolates. The third genotype of C. glabrata showed a distinct band pattern. With optimised, validated and standardised assay conditions, the feasibility, sensitivity and rapidity of AP-PCR may offer a discriminatory method for genotyping of yeasts in epidemiological studies, as well as in the control of nosocomial infections.     

Oligonucleotide fingerprinting of isolates of Candida species other than C. albicans and of atypical Candida species from human immunodeficiency virus-positive and AIDS patients.

Oligonucleotide fingerprinting of genomic DNA from oral isolates of four different Candida species other than C. albicans and atypical chlamydospore-positive isolates from human immunodeficiency virus (HIV)-positive individuals and AIDS patients was investigated as a means for differentiating between isolates within individual species. Oligonucleotides composed of simple repetitive sequence motifs, including (GACA)4, (GATA)4, (GGAT)4, (GTG)5, and (GT)8, all yielded fingerprints suitable for strain segregation of 8 C. tropicalis isolates, 12 Torulopsis (Candida) glabrata isolates, 8 atypical Candida isolates, and, except for (GATA)4, 2 C. krusei probe in turn and so generate several distinct DNA fingerprints of the same DNA sample. However, none of the probes yielded fingerprints suitable for strain segregation with three C. parapsilosis isolates. The (GATA)4 probe was also used to detect restriction fragment length polymorphisms among a genetically closely related group of atypical Candida isolates on primary isolation from an additional HIV-infected patient. These chlamydospore-positive atypical Candida isolates were sucrose positive, were of C. albicans serotype A, hybridized weakly with the C. albicans-specific mid-repeat sequence probe 27A, and yielded fingerprint profiles by random polymorphic DNA analysis that were distinct from those derived from C. albicans isolates. The C. stellatoidea ex-type strain NCPF 3108 was indistinguishable from the atypical Candida isolates in all these tests and also yielded an identical carbohydrate and nitrogen source assimilation profile by using the ID 32C yeast identification system.     

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.     

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.     

Geographic variations in species distribution and echinocandin and azole antifungal resistance rates among Candida bloodstream infection isolates: report from the SENTRY Antimicrobial Surveillance Program (2008 to 2009)

Antifungal testing results from the SENTRY Antimicrobial Surveillance Program (2008 to 2009) were analyzed for regional variations of invasive Candida species infections. Among 2,085 cases from the Asian-Pacific (APAC) (51 cases), Latin American (LAM) (348 cases), European (EU) (750 cases), and North American (NAM) (936 cases) regions, Candida albicans predominated (48.4%), followed by C. glabrata (18.0%), C. parapsilosis (17.2%), C. tropicalis (10.5%), and C. krusei (1.9%). Resistance to echinocandins (anidulafungin [2.4%] and micafungin [1.9%]) and azoles (3.5 to 5.6%) was most prevalent among C. glabrata isolates, as determined using recently established CLSI breakpoint criteria. C. glabrata isolates were more common in NAM (23.5%), and C. albicans isolates were more common in APAC (56.9%), with C. parapsilosis (25.6%) and C. tropicalis (17.0%) being more prominent in LAM. Emerging resistance patterns among C. glabrata cases in NAM require focused surveillance.     

Persistence of pigment production by yeast isolates grown on CHROMagar Candida medium

We evaluated the persistence of pigmentation in yeast isolates grown on the chromogenic medium CHROMagar Candida over 7 days. Candida, Cryptococcus, and Trichosporon isolates were inoculated alone or mixed onto duplicate sets of plates and incubated at 30 and 35 degrees C. Candida albicans and Candida krusei were readily identified throughout the reading period, but Candida glabrata was difficult to differentiate from other species until the 3- or 4-day time point. Candida tropicalis produced colonies similar to those of rare Cryptococcus and Trichosporon species, and mixed cultures were often difficult to identify as such.     

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.     

Trends in antifungal susceptibility among Candida sp. Urinary isolates from 1994 and 1998

Antifungal susceptibilities were determined from 80 urinary isolates of Candida species collected in 1994 and 1998. Our findings demonstrate increasing geometric means of fluconazole MICs and fluconazole resistance in Candida albicans and Candida tropicalis (those for Candida glabrata were unchanged) within the 4-year span. Amphotericin B and voriconazole MICs remained constant.     

Epidemiology of candidemia: 3-year results from the emerging infections and the epidemiology of Iowa organisms study

Bloodstream infections due to Candida species cause significant morbidity and mortality. Surveillance for candidemia is necessary to detect trends in species distribution and antifungal resistance. We performed prospective surveillance for candidemia at 16 hospitals in the State of Iowa from 1 July 1998 through 30 June 2001. Using U.S. Census Bureau and Iowa Hospital Association data to estimate a population denominator, we calculated the annual incidence of candidemia in Iowa to be 6.0 per 100,000 of population. Candida albicans was the most common species detected, but 43% of candidemias were due to species other than C. albicans. Overall, only 3% of Candida species were resistant to fluconazole. However, Candida glabrata was the most commonly isolated species other than C. albicans and demonstrated some resistance to azoles (fluconazole MIC at which 90% of the isolates tested are inhibited, 32 microg/ml; 10% resistant, 10% susceptible dose dependent). C. glabrata was more commonly isolated from older patients (P = 0.02) and caused over 25% of candidemias among persons 65 years of age or older. The investigational triazoles posaconazole, ravuconazole, and voriconazole had excellent in vitro activity overall against Candida species. C. albicans is the most important cause of candidemia and remains highly susceptible to available antifungal agents. However, C. glabrata has emerged as an important and potentially antifungal resistant cause of candidemia, particularly among the elderly.     

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.     

Incidence of bloodstream infections due to Candida species and in vitro susceptibilities of isolates collected from 1998 to 2000 in a population-based active surveillance program

To determine the incidence of Candida bloodstream infections (BSI) and antifungal drug resistance, population-based active laboratory surveillance was conducted from October 1998 through September 2000 in two areas of the United States (Baltimore, Md., and the state of Connecticut; combined population, 4.7 million). A total of 1,143 cases were detected, for an average adjusted annual incidence of 10 per 100,000 population or 1.5 per 10,000 hospital days. In 28% of patients, Candida BSI developed prior to or on the day of admission; only 36% of patients were in an intensive care unit at the time of diagnosis. No fewer than 78% of patients had a central catheter in place at the time of diagnosis, and 50% had undergone surgery within the previous 3 months. Candida albicans comprised 45% of the isolates, followed by C. glabrata (24%), C. parapsilosis (13%), and C. tropicalis (12%). Only 1.2% of C. albicans isolates were resistant to fluconazole (MIC, > or = 64 microg/ml), compared to 7% of C. glabrata isolates and 6% of C. tropicalis isolates. Only 0.9% of C. albicans isolates were resistant to itraconazole (MIC, > or = 1 micro g/ml), compared to 19.5% of C. glabrata isolates and 6% of C. tropicalis isolates. Only 4.3% of C. albicans isolates were resistant to flucytosine (MIC, > or = 32 microg/ml), compared to < 1% of C. parapsilosis and C. tropicalis isolates and no C. glabrata isolates. As determined by E-test, the MICs of amphotericin B were > or = 0.38 microg/ml for 10% of Candida isolates, > or =1 microg/ml for 1.7% of isolates, and > or = 2 microg/ml for 0.4% of isolates. Our findings highlight changes in the epidemiology of Candida BSI in the 1990s and provide a basis upon which to conduct further studies of selected high-risk subpopulations.