Antifungal susceptibility of Candida spp. isolated from pediatric patients: a survey of 4 children's hospitals

Candida species are the most common cause of fungal infections in hospitalized patients. Recent studies have reported a relative reduction in the rates of infection caused by Candida albicans and a shift toward non-albicans Candida spp. Data on the distribution and susceptibility of Candida spp. from children's hospitals are limited. Clinical isolates of Candida were collected from 4 US children's hospitals in 2003. Broth dilution MICs for amphotericin B, fluconazole, voriconazole, caspofungin, posaconazole, and ravuconazole were performed according to National Committee for Clinical Laboratory Standards-approved methodology. A total of 179 clinical isolates were identified and included. Of 179, 77 (43%) were C. albicans. Candida parapsilosis isolates were the second most frequently identified (57/175, 32%), followed by Candida glabrata, Candida tropicalis, and Candida lusitaniae (approximately 8% each). Caspofungin was the most active agent in vitro against all Candida spp. Fluconazole resistance was seen among C. glabrata, C. tropicalis, and Candida krusei isolates. Newer azoles had improved activity against fluconazole-resistant isolates of Candida. Among isolates of C. parapsilosis, nearly 20% were resistant to amphotericin B. The current study highlights the emergence of C. parapsilosis as a distinct pediatric pathogen with clinical and therapeutic implications. Furthermore, our current susceptibility data include newer antifungal agents that appear to be quite active in vitro and may provide new therapeutic options for the treatment of serious yeast infections in children.     

Association of fluconazole area under the concentration-time curve/MIC and dose/MIC ratios with mortality in nonneutropenic patients with candidemia

The present study tested in vitro susceptibility of Candida bloodstream isolates to fluconazole to determine if the ratio of the fluconazole area under the concentration-time curve (AUC) or weight-normalized daily dose (dose(wn)) to MIC correlated with mortality. Fluconazole susceptibility and outcome data were determined for 77 patients with a positive Candida blood culture between 2002 and 2005. The most commonly isolated Candida species were C. albicans (64%), C. glabrata (14%), C. parapsilosis (8%), C. tropicalis (6%), and C. lusitaniae (4%). Only two isolates were classified as fluconazole resistant by the CLSI M27-A2 method. Fluconazole MICs were highest against C. glabrata relative to other Candida species. Overall the crude mortality assessed at hospital discharge was 19.4% (n = 15). Mortality rates by species were as follows: C. albicans, 16.3%; C. glabrata, 36.4%; C. parapsilosis, 0%; C. tropicalis, 0%; C. lusitaniae, 33.3%. A mortality rate of 50% was noted among patients infected with nonsusceptible isolates (MIC > or = 16 microg/ml) compared to 18% for patients infected with susceptible (MIC < or = 8 microg/ml) isolates (P = 0.17). The fluconazole dose(wn)/MIC (24-h) values were significantly higher for the 62 survivors (13.3 +/- 10.5 [mean +/- standard deviation]) compared to the 15 nonsurvivors (7.0 +/- 8.0) (P = 0.03). The fluconazole AUC/MIC (24 h) values also trended higher for survivors (775 +/- 739) compared to nonsurvivors (589 +/- 715) (P = 0.09). These data support the dose-dependent properties of fluconazole. Underdosing fluconazole against less-susceptible Candida isolates has the potential to increase the risk of mortality associated with candidemia.     

Susceptibilities to amphotericin B and fluconazole of Candida species in TSARY 2002

Susceptibilities to amphotericin B and fluconazole of 909 Candida species collected during the Taiwan Surveillance of Antimicrobial Resistance of Yeasts (TSARY) in 2002 were determined by the broth microdilution method. There were 395 (43.5%) Candida albicans, 244 (26.8%) C. tropicalis, 187 (20.6%) C. glabrata, 63 (6.9%) C. parapsilosis, 9 (1%) C. krusei, and 11 (1.2%) others. Among them, 23 (2.5%) isolates were resistant to amphotericin B. They consisted of 10 C. glabrata, 6 C. krusei, 3 C. albicans, 1 C. tropicalis, 1 C. parapsilosis, and 2 others. The resistance rate to amphotericin B has increased compared with that of TSARY 1999 (2.5% versus 0.5%). There were 7 C. krusei, 5 C. albicans, 3 C. glabrata, and 2 others isolates resistant to fluconazole. The resistance rate to fluconazole has decreased from 8.4% in 1999 to 1.9% in 2002. A pattern of coresistance to both amphotericin B and fluconazole was observed.     

改良纸片扩散法检测172株酵母菌对氟康唑的敏感性

目的 研究氟康唑对172株酵母菌的体外抗菌活性。方法 酵母菌收集自2004年4月至2004年10月从住院患者采集的标本。采用NCCLS建议的改良纸片扩散法敏感试验，并以标准菌株做质量控制。结果 白念珠菌最常见，有110株，占64．0％；光滑念珠菌31株，占18．0％；热带念珠菌20株，占11．6％；克柔念珠菌3株，占1．8％；其他8株，占4．6％。白念珠菌、光滑念珠菌、热带念珠菌和克柔念珠菌对氟康唑的敏感率为92．3％～100％。结论 氟康唑对白念珠菌、光滑念珠菌、热带念珠菌和克柔念珠菌有较好的抗菌活性。     

Susceptibilities to amphotericin B and fluconazole of Candida species in Taiwan Surveillance of Antimicrobial Resistance of Yeasts 2006

Susceptibilities to amphotericin B and fluconazole of 964 Candida isolates collected in Taiwan Surveillance of Antimicrobial Resistance of Yeasts in 2006 were determined. There were 419 (43.5%) Candida albicans, 246 (25.5%) Candida tropicalis, 211 (21.9%) Candida glabrata, 62 (6.4%) Candida parapsilosis, 14 (1.5%) Candida krusei, and 12 (1.2%) others. Interestingly, 16 of the 17 amphotericin B-resistant isolates were non-albicans Candida species. The resistant rate to amphotericin B has decreased from 2.5% in 2002 to 1.8% in 2006. On the other hand, there were 132 C. tropicalis, 14 C. krusei, 10 C. albicans, and 9 C. glabrata isolates that had MICs to fluconazole > or =64 microg/mL. The prevalence of isolates with such high MICs was significantly higher than that in 2002 (17.1% versus 1.9%). Our results further indicate that most of the isolates with MICs to fluconazole > or =64 microg/mL exhibited the "trailing" phenomenon.     

Prospective Study of Candida Species in Patients at a Comprehensive Cancer Center

Since most nosocomial systemic yeast infections arise from the endogenous flora of the patient, we prospectively evaluated the species stratification and antifungal susceptibility profile of Candida spp. associated with heavy colonization and systemic infection in patients at Memorial Sloan-Kettering Cancer Center in New York. A total of 349 Candida isolates were obtained from 223 patients during the later half of 1998. Cancer was the most common underlying disease, occurring in 91% of the patients, including 61.8% with organ and 23.7% with hematological malignancies; 4.4% of the patients had AIDS. Candida albicans was the predominant species (67.3%); among 114 non-albicans Candida spp., C. glabrata (45.6%) was the most frequent, followed by C. tropicalis (18.4%), C. parapsilosis (16.6%), and C. krusei (9.6%). The overall resistance to triazole-based agents among all yeast isolates was 9.4 and 10.8% for fluconazole and itraconazole, respectively. A total of 5% of C. albicans strains were resistant to triazole antifungals, whereas 30.8 and 46.2% of C. glabrata strains were resistant to fluconazole (MIC > or = 64 microg/ml) and itraconazole (MIC > or = 1 microg/ml), respectively. A significant association was observed between prior treatment with triazole and isolation of fluconazole-resistant C. albicans (P = 0.005, OR 36), although this relationship was not seen in C. glabrata isolates (P = 0.4). This study reinforces the importance of periodic, prospective surveillance of clinical fungal isolates to determine appropriate prophylactic, empiric, and preemptive antifungal therapy for the highly susceptible patient population.     

Commercial systems for fluconazole susceptibility testing of yeasts: comparison with the broth microdilution method

Fluconazole susceptibility was tested in 100 clinical yeast isolates (65 Candida albicans, 13 C. glabrata, 8 C. tropicalis, 7 C. parapsilosis, 3 Saccharomyces cerevisiae, 1 each of C. krusei, C. lusitaniae, Cryptococcus neoformans, Rhodotorula glutinis) and two control strains (Candida krusei ATCC 6258, C. parapsilosis ATCC 22019) using broth microdilution (reference method), disk diffusion, Etest strips, Sensititre YeastOne, Candifast, Integral System Yeasts. Using M27-A breakpoints, isolates were classified as susceptible (81%), susceptible-dose dependent or Resistant with broth dilution. Rates of concordance with the reference method were good for Sensititre YeastOne, Etest and disc-diffusion (81.2%-94.7%) but very low for the Candifast (3.1%) and Integral System (16.6%), which classified most susceptible isolates as resistant. Lack of standardisation (inoculum, medium composition) and non-objective interpretation schemes may be the cause of their poor performance. Sensititre YeastOne, Etest and disc-diffusion are potentially useful for fluconazole antifungal susceptibility testing of yeasts in clinical laboratories.     

Distribution and antifungal susceptibility of Candida species causing candidemia from 1996 to 1999

Susceptibilities to amphotericin B and fluconazole of 383 Candida species isolated from blood were determined. Candida albicans was the most common species (55.6%), followed by Candida parapsilosis (17.5%), Candida tropicalis (16.5%), Candida glabrata (5.2%), Candida guilliermondii (2.3%), and others (2.9%). All but three isolates, Candida ciferrii, C. tropicalis, and C. glabrata, one each, were susceptible to amphotericin B. A total of 367 (95.8%) and 15 (4.2%) isolates were susceptible and susceptible-dose dependent to fluconazole, respectively. Only one isolate, a C. glabrata, was resistant to fluconazole. Few patients (13%) having prior fluconazole treatments may explain the low rate of resistance to fluconazole in this study.     

In Vitro Activity of 5-Fluorocytosine Against Candida and Torulopsis Species

One hundred yeasts were studied. Tests included detailed identification and determination of 24- and 48-hr minimal inhibitory concentrations and minimal fungicidal concentrations of 5-fluorocytosine (5-FC). Final identifications included 57 isolates of Candida albicans, 15 isolates of C. tropicalis, 13 isolates of C. parapsilosis, 7 isolates of Torulopsis glabrata, 3 isolates of C. guilliermondii, 2 isolates each of C. stellatoidea and Cryptococcus neoformans, and 1 isolate of Candida krusei. Twenty-three original identifications were in error; these involved mostly C. albicans, C. tropicalis, C. parapsilosis, and T. glabrata. Inhibitory end point readings based on 24 hr of incubation were misleading. Whereas 79 of 91 isolates of Candida appeared to be inhibited at 24 hr by 12.5 mug or less of 5-FC/ml, only 52 were inhibited at 48 hr; whereas only 12 isolates appeared to be resistant to 100 mug/ml after 24 hr, 37 were resistant after 48 hr. Susceptibility varied amount the different species. C. tropicalis was the most susceptible, with 10 of 15 isolates (66.7%) being inhibited by 12.5 mug or less/ml and 7 (46.7%) being killed by 100 mug or less/ml. C. albicans was similarily susceptible; 33 of 57 isolates (57.9%) were inhibited by 12.5 mug or less/ml and 25 (43.9%) were killed by 100 mug or less/ml. C. parapsilosis was quite resistant, as only 4 of 13 isolates (30.8%) were inhibited by 12.5 mug or less/ml and 3 (23.1%) were killed by 100 mug or less/ml.     

Comparison of in vivo activity of fluconazole with that of amphotericin B against Candida tropicalis, Candida glabrata, and Candida krusei.

Fluconazole (UK-49,858) is a new oral bis-triazole antifungal agent with demonstrated activity against Candida albicans. Because of the increasing importance of infections due to other species of Candida, we studied the efficacy of fluconazole in a rat model of established systemic candidiasis, using clinical isolates of C. tropicalis, C. glabrata, and C. Krusei. In normal rats, oral fluconazole at both 20 and 80 mg/kg per day for 7 days reduced both kidney and liver titers of C. tropicalis and C. glabrata compared with those in control animals and was only slightly inferior to amphotericin B. Both fluconazole and amphotericin B were ineffective in reducing kidney titers of C. krusei, but amphotericin B was more effective than fluconazole in reducing liver titers. Fluconazole showed no increased efficacy at the higher dose of 80 mg/kg per day compared with 20 mg/kg per day in any experiment. These results suggest that oral fluconazole may be useful in the treatment of established disseminated candidiasis caused by species other than C. albicans. Further in vivo studies are needed, however, to define minimum effective doses and length of therapy and to test additional Candida isolates.     

National surveillance of species distribution in blood isolates of Candida species in Japan and their susceptibility to six antifungal agents including voriconazole and micafungin

OBJECTIVES: The aim of this study was to evaluate species distribution and antifungal susceptibility of Candida blood isolates in Japan. METHODS: In a 1 year surveillance programme, 535 Candida blood isolates were collected. Identification of species was followed by examination with the broth microdilution method, as described in NCCLS M27-A2, of antifungal susceptibility to six agents, including voriconazole and micafungin, with readings after 24 and 48 h of incubation. RESULTS: The overall species distribution was: 41% Candida albicans, 23% Candida parapsilosis, 18% Candida glabrata, 12% Candida tropicalis and 2% Candida krusei. The concentrations of fluconazole necessary to inhibit 90% of the isolates (MIC(90)) at 24/48 h were 0.25/1 mg/L for C. albicans, 0.5/2 mg/L for C. parapsilosis, 4/32 mg/L for C. glabrata and 4/>128 mg/L for C. tropicalis. Percentages of fluconazole resistance were 1.8% for C. albicans, 0.8% for C. parapsilosis, 5.2% for C. glabrata and 3.2% for C. tropicalis, taking the tendency of trailing growth of C. tropicalis into account. MIC(90) of voriconazole was 0.5 mg/L, although 35% of isolates less susceptible (>/=16 mg/L) to fluconazole showed resistance (>/=2 mg/L). Micafungin was very active against all species (MIC(90), 0.03 mg/L) except for C. parapsilosis (MIC(90), 2 mg/L). CONCLUSIONS: These data suggest that, in Japan, the species distribution of Candida bloodstream infections and the fluconazole resistance rate are similar to those reported previously in North America and Europe. Voriconazole and micafungin appear to have strong in vitro activity against Candida blood isolates, although continuing surveillance and further clinical research are needed.     

Stable susceptibility of Candida blood isolates to fluconazole despite increasing use during the past 10 years

The prevalence of drug-resistant bacterial pathogens is very high in Taiwan. Accordingly, there was great concern that the introduction of fluconazole would result in rapid emergence of drug-resistant yeasts. Thus, we recommended in 1991 that fluconazole be used for treatment only. To explore the impact of this policy fluconazole susceptibility of Candida species blood culture isolates and outcome of patients with nosocomial candidaemia were monitored prospectively at National Taiwan University Hospital during 1994-2000. The MICs of fluconazole were determined by the disc diffusion method. There were 1095 episodes of nosocomial candidaemia during 1994-2000. Candida albicans was the most common species (50.4%), followed by Candida tropicalis (20.5%), Candida parapsilosis (14.2%) and Candida glabrata (12.0%). There were 0-2 isolates of Candida krusei per year. The incidence of nosocomial candidaemia and the proportion of C. glabrata peaked in 1996 and decreased thereafter. Fluconazole susceptibility was determined for 552 Candida blood isolates. Only 0.7% of blood isolates were resistant to fluconazole. Fluconazole susceptibility was 94.0% in 1994-1995 and 97.9% in 1999-2000 (P = 0.06). Attributable mortality for patients with nosocomial candidaemia was 43.2% in 1994-1995 and was 25% in 2000 (P = 0.005). Despite an increase in the incidence of nosocomial fungal infection and increased consumption of fluconazole from 1994 to 2000, there was no significant change in the susceptibility to fluconazole for bloodstream isolates of Candida species. These findings appear to be attributed to several factors. These include low prevalence of C. krusei and C. glabrata, changing patterns of use of antifungal drugs and broad-spectrum antibiotics, and efforts to improve the rational use of antifungal agents at our hospital.     

In vitro susceptibility of 245 yeast isolates to amphotericin B, 5-fluorocytosine, ketoconazole, fluconazole and itraconazole.

The in vitro activity of amphotericin B, 5-fluorocytosine, ketoconazole, fluconazole and itraconazole was tested against 245 yeast strains isolated from clinical specimens (68 Candida albicans, 74 Candida tropicalis, 43 Candida krusei, 28 Candida glabrata, 19 Candida parapsilosis, 8 Candida lusitaniae and 5 Candida guilliermondii). An agar dilution method was employed to carry out testing. Minimal inhibitory concentrations to restrain 90% of isolate growth (MIC90) ranged from 0.12 to 2 mg/l for amphotericin B and for 5-fluorocytosine, from 0.03 to 8 mg/l for ketoconazole, from 0.05 to 50 mg/l for itraconazole and from 0.1 to > 100 mg/l for fluconazole. Among the azole derivatives, the most active was ketoconazole, followed by itraconazole. Only 1 strain of C. albicans was resistant to amphotericin B (MIC > 4 mg/l). Both C. tropicalis and C. krusei responded poorly to fluconazole and the former to itraconazole as well. The species most susceptible to the antifungal agents tested was C. glabrata and the most resistant were C. tropicalis and C. krusei.     

Trends in frequency and in vitro susceptibilities to antifungal agents,including voriconazole and anidulafungin,of Candida bloodstream isolates. Results from a six-year study (1996-2001)

The frequency of isolation and antifungal susceptibility patterns to established and two new antifungal agents were determined for 218 Candida spp isolates causing bloodstream infection from 1996 to 2001. Overall, 41.7% of the candidemias were due to C. albicans, followed by C. parapsilosis (22%), C. tropicalis (16.1%), C. glabrata (11.9%), C. krusei (6%) and miscellaneous Candida spp (2.3%). Isolates of C. albicans C. parapsilosis and C. tropicalis (80% of isolates) were highly susceptible to fluconazole (94 to 100% at /= 32 microg/ml).     

In vitro fluconazole susceptibility of 1565 clinical isolates of Candida species evaluated by the disk diffusion method performed using NCCLS M44-A guidelines

We determined the in vitro activity of fluconazole against 1565 clinical Candida spp. isolates collected from different specimens of non-AIDS outpatients and inpatients in 3 different regions of Italy. Susceptibility testing was performed by agar disk diffusion using the NCCLS document M44-A guidelines. Candida albicans was the most frequently isolated yeast (68%) followed by C. glabrata (15%), C. tropicalis (5%), C. parapsilosis (5%), and C. krusei (5%). Other yeasts represented 4% of all isolates. Of the 1565 isolates tested, 1449 (92.6%) were susceptible (S) to fluconazole, 43 (2.7%) were susceptible dose-dependent (S-DD) and 73 (4.7%) were resistant (R). Almost all (98.2%) of the C. albicans isolates were classified as S or S-DD. Despite its widespread use, fluconazole displayed good activity against the isolates we tested, and the disk diffusion method was confirmed as a reliable approach to the evaluation of in vitro susceptibility of yeasts to this antimycotic agent.     

Real-time antifungal susceptibility screening aids management of invasive yeast infections in immunocompromised patients

We examined the utility of a semi-solid agar antifungal susceptibility screening (SAAS) test in real-time management of eight immunocompromised patients with invasive yeast infections. Tests of amphotericin B and fluconazole concentrations of 0.5 and 2 mg/L and 1, 8 and 40 mg/L, respectively, were performed on Candida albicans (two), Candida tropicalis (two), Candida krusei (one), Candida glabrata (one) and Trichosporon species (spp.) (two). All but the Trichosporon spp. and C. glabrata isolates were resistant to fluconazole at > or = 40 mg/L, and patients were successfully managed accordingly. Real-time antifungal susceptibility screening can assist in clinical management of invasive yeast infections.     

Trends in species distribution and susceptibility to fluconazole among blood stream isolates of Candida species in the United States

National surveillance of blood stream infections (BSI) attributable to Candida spp. has been limited to date. Recent studies have suggested in increase in the proportion of BSI attributable to non-Candida albicans species and have also raised concerns regarding the emergence of antifungal resistance among Candida spp. The increased utilization of broad-spectrum antifungal agents and the recognition of Candida spp. as prominent pathogens with the potential for developing antifungal resistance, emphasize the need for ongoing surveillance of antifungal susceptibility patterns. In this investigation trends in species distribution and susceptibility to fluconazole among BSI isolates of Candida spp. referred to our laboratory by United States hospitals were evaluated over the 7-year period from 1992 to 1998. A total of 1579 BSI isolates from more than 50 medical centers were processed. Overall, C. albicans accounted for 52% of isolates followed by C. glabrata (18%), C. parapsilosis (15%), C. tropicalis (11%), and C. krusei (2%). The proportion of BSI isolates that were C. albicans ranged from 45% in 1992 to 60% in 1998. Among the non-C. albicans isolates, C. glabrata succeeded C. parapsilosis as the most common species beginning in 1995. Overall, the susceptibility of all Candida species (C. albicans plus all other species) to fluconazole remained stable (MIC90, 16 micrograms/mL). The fluconazole MIC90 for C. albicans was 0.5-2.0 micrograms/ml for all years studied except 1995 (8.0 micrograms/mL) and was 1.0 microgram/mL overall. The present study suggests a continued prominent role of C. albicans as a cause of BSI, and a constant level of susceptibility of Candida BSI isolates to fluconazole over 7 years. These data should serve as a baseline for future surveillance efforts for anti-fungal agents tested against yeast BSI isolates.     

In vitro activities of ravuconazole and four other antifungal agents against fluconazole-resistant or -susceptible clinical yeast isolates

The activities of ravuconazole and four other antifungal agents were tested against a collection of 1,796 clinical yeast isolates, including fluconazole-susceptible and -resistant strains. Ravuconazole was active against the majority of fluconazole-resistant isolates; but for 102 of 562 (18%) resistant isolates, mainly Candida tropicalis, Candida glabrata, and Cryptococcus neoformans, ravuconazole MICs were > or =1 microg/ml.     

Correlation of posaconazole minimum fungicidal concentration and time kill test against nine Candida species

OBJECTIVES: We evaluated the in vitro activity of posaconazole against nine Candida species using minimum fungicidal concentration (MFC) measurements and time-kill methods. METHODS: MFCs of posaconazole were determined for 209 clinical isolates (32 Candida albicans, 30 Candida glabrata, 21 Candida tropicalis, 29 Candida krusei, 28 Candida parapsilosis sensu stricto, 50 Candida inconspicua, 13 Candida kefyr, 3 Candida lusitaniae and 3 Candida guilliermondii) and 7 ATCC Candida strains. The following strains were tested in time-kill studies: 3 strains each of C. glabrata, C. kefyr, C. guilliermondii and C. lusitaniae; 2 C. tropicalis; 4 C. albicans; 4 C. inconspicua; 9 C. krusei; 12 C. parapsilosis; and 7 ATCC strains. RESULTS: Posaconazole was fungicidal in both MFC and time-kill experiments (at 2 mg/L within 48 h in time-kill assays) against each C. krusei, C. inconspicua and C. lusitaniae strain and was fungistatic against each C. albicans, C. glabrata, C. tropicalis and C. guilliermondii strain. For the C. parapsilosis strains, posaconazole MFCs were 相似文献   

Minimum fungicidal concentrations of amphotericin B for bloodstream Candida species

Minimum fungicidal concentrations (MFCs) of amphotericin B were obtained for 165 bloodstream isolates (104 Candida parapsilosis, 14 C.glabrata, 13 C.tropicalis, 15 C.krusei, and 19 C.albicans) and 36 C.dubliniensis from oropharyngeal infections. Minimum inhibitory concentrations (MICs) were determined by the M27-A microdilution method. MFCs (> or =99.9% killing) were obtained following MIC determination (inoculum size, 10(4) CFU/ml) by seeding the entire volume of all clear wells. The best fungicidal activity was for C. albicans, (MFC90 1 microg/ml) and the lowest for C.parapsilosis, C.tropicalis and C.glabrata (MFC90 16 microg/ml). Although MFCs were > or =16x MIC for some isolates, including C. glabrata, the overall MFCs were > or =2x MICs. However, major differences between MICs and MFCs were observed for C.parapsilosis and C.dubliniensis (3.8% and 8.9%, respectively, were tolerant: MFC > or =32MIC). MFCs for C.tropicalis and C. glabrata were > or =2 microg/ml. By this more stringent method we found substantial differences from those previously reported between amphotericin B MIC and MFCs for Candida spp.