Significant differences in drug susceptibility among species in the Candida parapsilosis group

Candida parapsilosis family has 3 proposed species: C. parapsilosis sensu stricto, Candida orthopsilosis, and Candida metapsilosis. C. parapsilosis sensu stricto had significantly higher caspofungin (CAS) and anidulafungin MICs than C. orthopsilosis or C. metapsilosis; C. metapsilosis was least susceptible to fluconazole. C. parapsilosis sensu stricto more frequently displayed (37%) paradoxical growth in CAS (P < or = 0.02). These species susceptibility differences could affect therapeutic choices.     

Prospective multicenter study of the epidemiology, molecular identification, and antifungal susceptibility of Candida parapsilosis, Candida orthopsilosis, and Candida metapsilosis isolated from patients with candidemia

A 13-month prospective multicenter study including 44 hospitals was carried out to evaluate the epidemiology of Candida parapsilosis complex candidemia in Spain. Susceptibility to amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole, posaconazole, anidulafungin, caspofungin, and micafungin was tested by the microdilution colorimetric method. A total of 364 C. parapsilosis complex isolates were identified by molecular methods: C. parapsilosis (90.7%), Candida orthopsilosis (8.2%), and Candida metapsilosis (1.1%). Most candidemias (C. parapsilosis, 76.4%; C. orthopsilosis, 70.0%; C. metapsilosis, 100%) were observed in adults. No C. orthopsilosis or C. metapsilosis candidemias occurred in neonates. C. parapsilosis was most frequent in adult intensive care unit (28.8%), surgery (20.9%), and internal medicine (19.7%) departments; and C. orthopsilosis was most frequent in hematology (28.6%), pediatrics (12.0%), and neonatology (11.5%) departments. The geographic distribution of C. orthopsilosis and C. metapsilosis was not uniform. According to CLSI clinical breakpoints, all C. orthopsilosis and C. metapsilosis isolates were susceptible to the nine agents tested. Resistance (MICs > 1 mg/liter) was observed only in C. parapsilosis: amphotericin B, posaconazole, itraconazole, and caspofungin (0.3% each), anidulafungin (1.9%), and micafungin (2.5%). Applying the new species-specific fluconazole and echinocandin breakpoints, the rates of resistance to fluconazole for C. parapsilosis and C. orthopsilosis increased to 4.8% and 0.3%, respectively; conversely, for C. parapsilosis they shifted from 1.9 to 0.6% (anidulafungin) and from 2.5 to 0.6% (micafungin). Our study confirms the different prevalence of C. parapsilosis complex candidemia among age groups: neither C. orthopsilosis nor C. metapsilosis was isolated from neonates; interestingly, C. metapsilosis was isolated only from adults and the elderly. The disparity in antifungal susceptibility among species could be important for therapy.     

Molecular characterization of Italian Candida parapsilosis isolates reveals the cryptic presence of the newly described species Candida orthopsilosis in blood cultures from newborns

The authors report the molecular characterization of Candida parapsilosis isolates recovered from the blood and venous central catheter tips of patients admitted to different care units of the Polyclinic Hospital, University of Messina, Italy. Among 97 presumed C. parapsilosis isolates examined, 94 were identified as C. parapsilosis sensu stricto and the remaining 3 isolates were found to belong to the cryptic species Candida orthopsilosis which was recovered only from blood cultures of neonates (<30 days old) born prematurely. No C. metapsilosis was found in this study. This study emphasizes the role of C. parapsilosis as an important nosocomial pathogen, and it also describes, for the first time, the occurrence of C. orthopsilosis in newborns.     

PCR-RFLP在VVC相关念珠菌菌种鉴定中的应用

目的:用限制性片段长度多态性聚合酶链反应(polymerase chain reaction-restriction fragment length polymorphism,PCR-RFLP)技术快速准确鉴定外阴阴道念珠菌病(VVC)相关念珠菌菌种,并对科玛嘉显色培养法、Vitek 2 YST鉴定卡和PCR-RFLP 3种方法鉴定念珠菌菌种的效果进行方法学评价。方法:收集贵阳市妇幼保健院VVC患者感染的念珠菌菌种100株,用十六烷基三甲基溴化铵法(cetyltrimethylammonium bromide,CTAB)法提取念珠菌DNA,PCR扩增念珠菌DNA的ITS片段并进行测序分析确定念珠菌菌种;分别采用科玛嘉显色培养法、Vitek 2 YST鉴定卡和PCR-RFLP 3种方法对其进行鉴定,以测序结果为“金标准”,比较3种方法鉴定念珠菌菌种的正确率。结果:科玛嘉显色培养法中5株葡萄牙念珠菌与2株酿酒念珠菌显色错误,均显淡紫色;Vitek 2 YST鉴定卡中,1株白念珠菌与2株热带念珠菌鉴定不出,Cyberlindnera fabianii、Candida orthopsilosis与Candida metapsilosis鉴定错误;PCR-RFLP采用内切酶MspⅠ可成功鉴定念珠菌中除Candida metapsilosis、Candida orthopsilosis与近平滑念珠菌之外的其他菌种,进一步采用内切酶ApaⅠ与NcoⅠ可将Candida metapsilosis、Candida Orthopsilosis与近平滑念珠菌三者鉴别开。科玛嘉显色培养法对白念珠菌、克柔念珠菌、热带念珠菌等3种念珠菌鉴定正确率100%,对光滑念珠菌的鉴定正确率为73.1%;Vitek 2 YST鉴定卡可鉴定常见念珠菌且正确率较高,不能鉴定Cyberlindnera fabianii、Candida orthopsilosis与Candida metapsilosis等非常见念珠菌;PCR-RFLP技术可快速准确鉴定所有念珠菌菌种。结论:PCR-RFLP技术为早期准确鉴定临床念珠菌感染提供了新的选择,具有很好的应用前景。     

Effect of 50% human serum on the killing activity of micafungin against eight Candida species using time-kill methodology

Micafungin activity was determined against 24 wild-type clinical isolates and 5 American Type Culture Collection strains belonging to 8 Candida species in RPMI-1640 with and without 50% serum using broth microdilution and time-kill methodology. MIC values increased from 4- to 128-folds in 50% serum for all Candida species. Micafungin was not fungicidal against C. albicans, C. tropicalis, and against 2 of 3 C. metapsilosis at ≥0.25, 1, and 1 μg/mL, respectively, after 48 h with 50% serum, showing good fungistatic activity. Fungicidal activity at ≥2, 4, and 32 μg/mL was noticed against C. glabrata, C. inconspicua, and C. krusei isolates, respectively. Micafungin at 8-32 μg/mL showed fungistatic activity against C. parapsilosis and C. orthopsilosis. Serum decreased the in vitro activity of micafungin. With serum binding of echinocandins taken into account, safely fungistatic or fungicidal concentrations seem to require elevated doses against some Candida species, including C. parapsilosis, C. orthopsilosis, and C. krusei.     

A naturally occurring proline-to-alanine amino acid change in Fks1p in Candida parapsilosis, Candida orthopsilosis, and Candida metapsilosis accounts for reduced echinocandin susceptibility

Candida parapsilosis has emerged as a common cause of invasive fungal infection, especially in Latin America and in the neonatal setting. C. parapsilosis is part of a closely related group of organisms that includes the species Candida orthopsilosis and Candida metapsilosis. All three species show elevated MICs for the new echinocandin class drugs caspofungin, micafungin, and anidulafungin relative to other Candida species. Despite potential impacts on therapy, the mechanism behind this reduced echinocandin susceptibility has not been determined. In this report, we investigated the role of a naturally occurring Pro-to-Ala substitution at amino acid position 660 (P660A), immediately distal to the highly conserved hot spot 1 region of Fks1p, in the reduced-echinocandin-susceptibility phenotype. Kinetic inhibition studies demonstrated that glucan synthase from the C. parapsilosis group was 1 to 2 logs less sensitive to echinocandin drugs than the reference enzyme from C. albicans. Furthermore, clinical isolates of C. albicans and C. glabrata which harbor mutations at this equivalent position also showed comparable 2-log decreases in target enzyme sensitivity, which correlated with increased MICs. These mutations also resulted in 2.4- to 18.8-fold-reduced V(max) values relative to those for the wild-type enzyme, consistent with kinetic parameters obtained for C. parapsilosis group enzymes. Finally, the importance of the P660A substitution for intrinsic resistance was confirmed by engineering an equivalent P647A mutation into Fks1p of Saccharomyces cerevisiae. The mutant glucan synthase displayed characteristic 2-log decreases in sensitivity to the echinocandin drugs. Overall, these data firmly indicate that a naturally occurring P660A substitution in Fks1p from the C. parapsilosis group accounts for the reduced susceptibility phenotype.     

Paradoxical growth effect of caspofungin observed on biofilms and planktonic cells of five different Candida species

The paradoxical growth (PG) of Candida sp. biofilms in the presence of high caspofungin (CAS) concentrations was previously unknown. We sought to characterize the PG at supra-MICs of CAS among clinical Candida sp. isolates grown as biofilms in 96-well polystyrene microtiter plates. The MICs of CAS were determined for 30 clinical Candida sp. isolates (4 Candida albicans, 6 C. tropicalis, 7 C. parapsilosis, 8 C. orthopsilosis, and 5 C. metapsilosis isolates) when they were grown as planktonic cells and biofilms and were defined as the lowest drug concentrations that resulted in a prominent decrease in growth and a 50% reduction in metabolic activity, respectively. PG was defined as a resurgence of growth (>50% of that in the drug-free growth control well) at drug concentrations above the MIC. With the exception of C. tropicalis, all isolates displayed PG more frequently when they were grown as biofilms than when they grown as planktonic cells. PG was undetectable among C. metapsilosis isolates in planktonic cell MIC tests but was present in 100% of the isolates in biofilm MIC tests. The drug concentration and the number of drug dilutions supporting PG were higher for biofilms than for planktonic cells. Microscopic changes in cell morphology were observed among both planktonic and biofilm cells with PG. Specifically, the accumulation of enlarged, globose cells was associated with PG, and we hypothesize that CAS-induced changes in the cell wall composition may be the explanation.     

Effect of nikkomycin Z and 50% human serum on the killing activity of high-concentration caspofungin against Candida species using time-kill methodology

Caspofungin and nikkomycin Z (NIK) efficacy alone and in combination were tested against seven Candida species showing or not showing paradoxical growth (PG) against caspofungin in time-kill test in RPMI-1640. Selected isolates against caspofungin and NIK were also tested in 50% serum. PG was always eliminated by NIK as well as by serum. In the serum, 1 and 16 μg/ml caspofungin yielded 0.14-4.0 and 0.34-4.0 log CFU decreases from the starting inocula for C. albicans, C. glabrata, C. tropicalis, and C. dubliniensis, respectively. CFU decrease (0.10-2.08 log) at 16 μg/ml, but not at lower caspofungin concentration was noted against C. parapsilosis, C. orthopsilosis, and C. metapsilosis. One C. parapsilosis isolate was not inhibited even by 16 μg/ml caspofungin. Caspofungin against C. albicans, C. glabrata, C. tropicalis, and C. dubliniensis maintained its activity in serum at even 1 μg/ml concentration. PG seems to an in vitro phenomenon, without clinical relevance.     

Effect of usnic acid on Candida orthopsilosis and C. parapsilosis

The activity of usnic acid against Candida orthopsilosis and Candida parapsilosis on planktonic and biofilm conditions was investigated by using a broth microdilution and microplate methods. Potent in vitro activities against different Candida species were obtained. The metabolic activity of sessile cells of C. parapsilosis complex was reduced by 80% at four times the 80% inhibitory concentration. The in vitro studies support further efforts to determine whether usnic acid can be used clinically to cure patients with Candida infections.     

Changes in cell wall synthesis and ultrastructure during paradoxical growth effect of caspofungin on four different Candida species

Paradoxical growth (PG) has been described for echinocandins and is characterized by cell growth at drug concentrations above the MIC. In this study, two isolates each of Candida albicans, C. tropicalis, C. orthopsilosis, and C. parapsilosis, all of which displaying PG in response to caspofungin, were subjected to MIC, minimal fungicidal concentration (MFC), and time-kill curve assays to evaluate the levels of PG. Cell wall components and ultrastructural modifications of the PG cells were also investigated. The results showed that when cell growth and survival were evaluated by MFC or time-kill curve assays, high concentrations of caspofungin did not show fungicidal activity against PG cells. Furthermore, for C. parapsilosis and C. orthopsilosis, time-kill curves were more discriminatory than MFCs in detecting the PG effect. The four different Candida species studied demonstrated similar alterations in cell wall components and ultrastructure associated with PG. In PG cells, β-1,3-glucan content decreased from 2.7- to 7.8-fold, whereas chitin content increased from 4.0- to 6.6-fold. An electron microscopy study of the PG cells revealed morphological alterations, clumping of cells, enlarged cells, the absence of filamentation, abnormal septa, and accumulation of chitin in the cell wall. Also, PG cells basically exhibited a single dark high-density layer in the cell wall, indicating the loss of the β-1,3-glucan layer. Our results present novel details about the ultrastructural alterations that occur in C. albicans, C. parapsilosis, C. orthopsilosis, and C. tropicalis during PG and show that chitin is the major component of the cell walls of PG cells. Stimulation of chitin synthesis may represent a rescue mechanism against caspofungin activity.     

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.     

获得性免疫缺陷综合征患者白假丝酵母分离株基因型及耐药性分析

目的研究获得性免疫缺陷综合征(AIDS)患者白假丝酵母分离株的基因型及耐药性。方法对分离自上海市公共卫生中心AIDS住院患者的40株白假丝酵母,应用微卫星核心序列引物M13进行聚合酶链反应(PCR)指纹分型。用微量稀释法分析白假丝酵母抗真菌药物敏感性。结果PCR指纹分型将所有白假丝酵母分离株分为A、B、C、D 4种基因型,其中A型14株(35.0%),B型16株(40.0%),C型9株(22.5%),D型1株(2.5%)。白假丝酵母对抗真菌药物的耐药率为:两性霉素B 2.5%,氟康唑22.5%,伊曲康唑15.0%,氟胞嘧啶20.0%,;不同基因型白假丝酵母菌株间耐药性差异无统计学意义。结论上海市AIDS住院患者分离的白假丝酵母主要由3种克隆组成,但无明显优势流行株。     

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.     

Candida albicans and Candida glabrata clinical isolates exhibiting reduced echinocandin susceptibility

A recognized hotspot for mutations conferring reduced echinocandin susceptibility (RES) is residue S645 of Candida albicans Gsc1(Fks1). We report that the mutation F641Y is associated with RES in a C. albicans isolate. The analogous Fks2 residue is mutated F to V in a Candida glabrata RES isolate; the introduction of this mutation into susceptible C. glabrata confirmed its role in RES. Y641-equivalent Fks residues were identified in intrinsically RES Fusarium species and Candida guilliermondii.     

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.     

143株念珠菌菌种分布及对5种抗真菌药物的敏感性分析

目的分析临床标本中念珠菌属的菌种分布及对常用抗真菌药物的敏感性,为临床合理用药提供依据。方法总结分析昆明市延安医院2005—2009年念珠菌属的菌种分布及其对5种常用抗真菌药物的敏感性。药敏试验采用ATB-Fungus-3微量稀释法。结果在2005—2009年分离的共143株念珠菌中,白念珠菌占39.2%(56/143),非白念珠菌占60.8%(87/143),非白念珠菌中,以光滑念珠菌24.5%(35/143)、热带念珠菌7.7%(11/143)和近平滑念珠菌5.6%(8/143)较为常见。143株念珠菌对氟胞嘧啶、两性霉素B、氟康唑、伊曲康唑和伏立康唑的总敏感率分别为86.0%、100%、90.9%、69.9%和93.5%,56株白念珠菌对上述5种抗真菌药的敏感率分别为91.1%、100%、96.4%、82.1%和96.3%,87株非白念珠菌的敏感率分别为82.8%、100%、87.4%、62.1%和92.0%。结论白念珠菌仍是目前念珠菌感染较常见的菌种,但非白念珠菌已显著增加;白念珠菌对常用抗真菌药仍有较高的敏感性,非白念珠菌的耐药性则高于白念珠菌。临床在治疗念珠菌感染时应结合菌种鉴定及药敏试验结果合理选择抗真菌药物。     

Comparison of three methods for in vitro susceptibility testing of Candida species with flucytosine

Optimal methods for susceptibility testing of Candida spp. with flucytosine have not been determined. Breakpoints were recommended in 1984, but never validated. In this study, we compared the 1984 recommended macrodilution broth method (using an 80% endpoint) with a modification of the more recent NCCLS-recommended microdilution broth method with three endpoints-spectrophotometric 50% and 80% and a no growth endpoint determined by eye. NCCLS and British Society for Medical Mycology (BSMM) breakpoints were also compared. One hundred and fifty isolates comprised of Candida albicans, Candida tropicalis, Candida krusei, Candida glabrata, Candida parapsilosis and Candida lusitaniae were tested. Reproducibility was excellent. For C. albicans (n = 65), the correlation between tests was excellent (>75%), with few major discrepancies (<5%). For C. tropicalis (n = 27), correlation was good (59%), but there were a small number of major discrepancies (up to 11%, depending on breakpoint used). Results by the broth macrodilution method were generally higher than both microdilution methods for C. glabrata (n = 16; correlation of 18.8%), but only one major discrepancy was seen. Ten of the 11 C. parapsilosis isolates tested were susceptible by all methods, regardless of breakpoint chosen, with a correlation of 18.2%, but no major discrepancies were seen. A correlation between all methods (50%) was seen with C. lusitaniae (n = 10), with many isolates resistant or intermediate. In contrast, correlation between methods for C. krusei was poor (<5%); NCCLS microtitre modification produced results that were classified as intermediate or resistant, regardless of the breakpoint used. The methodology for susceptibility testing C. albicans is robust. Additional work to optimize susceptibility testing with flucytosine is necessary for non-albicans Candida species, especially C. krusei.     

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.     

Invasive Candida species infections: a 5 year population-based assessment

OBJECTIVES: Candida species have emerged as important causes of invasive infections and rates of resistance to standard antifungal therapies are rising. The objective of this study was to define the occurrence of, risk factors for, and antifungal susceptibilities of invasive Candida species infections in a large Canadian health region. METHODS: Population-based surveillance was conducted for invasive Candida species infections in the Calgary Health Region during a 5 year period and susceptibility testing was performed. RESULTS: The annual incidence of invasive Candida species infection was 2.9 per 100,000 population (0.2 and 2.8 per 100,000 for central nervous system and bloodstream infection, respectively). The very young and elderly were at highest risk for invasive Candida species infections. Several risk factors for developing invasive Candida species infection were identified with chronic haemodialysis, organ transplant recipient, and cancer patients at highest risk. Thirty percent (56/184; 43 susceptible, dose-dependent and 13 resistant) of isolates demonstrated reduced susceptibility to fluconazole. Only one (1%) isolate had reduced susceptibility to amphotericin B and six (3%) and three (2%) isolates had minimum inhibitory concentrations of >or=1 mg/L to voriconazole and caspofungin, respectively. Overall, 40% of patients died in-hospital for an annual mortality rate of 1.2 per 100,000. CONCLUSIONS: Candida species are an important cause of invasive infection and patients with co-morbidities and extremes of age are at highest risk. Alternatives to fluconazole should be considered for initial empiric therapy in patients with severe invasive Candida species infections.     

外阴阴道念珠菌感染与耐药性的研究

目的了解女性外阴阴道的感染情况,研究临床分离的真菌种类及其对药物的敏感性。方法对3133例标本进行回顾性分析,并对其中的344例阳性标本的菌株用API真菌鉴定板条（API 20C AUX）鉴定,用Rosco纸片法对益康唑、克霉唑、氟康唑、伊曲康唑、咪康唑、酮康唑、制霉菌素、两性霉素B进行药物敏感性试验。结果3133例临床标本共检出念株菌1122株,阳性率为35.8%,阳性标本中白念珠菌占71.5%,克柔念珠菌占6.1%、光滑念珠菌占2.5%,其他念珠菌占19.9%。念珠菌对两性霉素B、制霉菌素和酮康唑的敏感性较高,分别为98.5%、97.1%、96.2%;对咪康唑、伊曲康唑、氟康唑的耐药率较高,分别为15.4%、19.5%、15.4%。结论由于不同菌种对药物的敏感性不同,对感染的念珠菌进行菌种鉴定和药敏试验对临床治疗有重要意义。