Prospective, multicenter surveillance study of Candida glabrata: fluconazole and itraconazole susceptibility profiles in bloodstream, invasive, and colonizing strains and differences between isolates from three urban teaching hospitals in New York City (Candida Susceptibility Trends Study, 1998 to 1999)

A prospective observational study on species differentiation and antifungal susceptibility pattern in patients with genital candidiasis

Background

Candidial balanitis, balanoposthitis and vulvovaginitis can be diagnosed by direct microscopy, culture and treated with antifungals. Resistance to antifungals is emerging. Hence, we conducted a study to identify the causative species and antifungal susceptibility.

Aim

To observe the species differentiation and antifungal susceptibility pattern in patients with genital candidiasis.

Materials and Methods

A prospective observational study was carried out that included 54 patients of age group (18-60 years) diagnosed clinically and direct microscopically (KOH) for genital candidiasis. Culture was done using Sabouraud dextrose agar. Species identification and antifungal susceptibility were tested. Descriptive data were expressed in the form of frequency and percentage.

Results

Out of 54 patients, 41 had culture positive candidiasis. Among the isolated species, 68.3% were Candida albicans (28/41) and 31.7% were non- albicans Candida spp. Among non-albicans Candida species (13/41), Candida glabrata (19.5%), Candida tropicalis (7.3%), Candida guilliermondii (2.4%), Candida parapsilosis (2.4%) were identified. Antifungal susceptibility was tested for fluconazole (FLU), clotrimazole (CLTZ), itraconazole (ITZ), ketoconazole (KTZ), voriconazole (VOR), amphotericin-B (AMPH-B). Except C. glabrata and C.parapsilosis, all other species were sensitive to all tested antifungals. All isolated species were sensitive to KTZ, VOR, AMPH-B, and CLTZ. Nearly 22% of isolates were resistant to fluconazole.

Conclusion

C. glabrata causes complicated, severe recurrent vulvovaginitis which is fluconazole resistant. Drug sensitivity prior prescribing antifungal agent identifies appropriate drug, decreases patient's disease morbidity and cross resistance.

Characteristics of infective endocarditis in a cancer population

Background

Infective endocarditis (IE) is more common in patients with cancer as compared with the general population. Due to an immunocompromised state, the need for invasive procedures, hypercoagulability and the presence of indwelling catheters, patients with cancer are particularly predisposed to the development of IE.

Objectives

Limited information exists about IE in patients with cancer. We aimed to evaluate the characteristics of patients with cancer and IE at our tertiary care centre, including a comparison of the microorganisms implicated and their association with mortality.

Methods

A retrospective chart review of patients with cancer who had echocardiography for suspicion of endocarditis was conducted. A total of 56 patients with a confirmed diagnosis of cancer and endocarditis, based on the modified Duke criteria, were included in the study. Baseline demographics, risk factors for developing IE, echocardiography findings, microbiology and mortality data were analysed.

Results

Following the findings of vegetations by echocardiography, the median survival time was 8.5 months. Staphylococcus aureus was the most common organism identified as causing endocarditis. The mitral and aortic valves were the most commonly involved sites of endocarditis. Patients with S. aureus endocarditis (SAE) had a significantly poorer survival when compared with patients without SAE (p=0.0217) over the 12-month period from diagnosis of endocarditis.

Conclusions

Overall survival of patients with cancer and endocarditis is poor, with a worse outcome in patients with SAE.

Genetic Analysis of Candida glabrata from Candiduric Patients Using Microsatellite Length Polymorphism, Antifungal Susceptibility, and Enzymatic Profiles

Background: Candida glabrata is the second agent of candiduria with increased resistance to antifungals. Microsatellite length polymorphism (MLP) is one of the genotyping techniques used in the epidemiological investigation to improve clinical management. Objectives: We aimed to detect different genotypes of C. glabrata isolates using six microsatellite markers and the MLP technique. Moreover, our genotypes' association with other countries' genotypes was illustrated using a minimum spanning tree. We investigated in vitro antifungal susceptibility and enzymatic activity profiles of the isolates. Methods: Six microsatellite markers were amplified using multiplex-PCR for 22 C. glabrata strains isolated from urine in pediatric patients admitted to the Abuzar Children's Hospital in Ahvaz, Iran. The PCR products were presented for fragment analysis, and the size of the alleles was determined. Antifungal susceptibility tests and extracellular enzyme activities were also performed. Results: Nineteen multilocus genotypes were detected so that 22.7% of the strains had identical genotypes. The isolates were wild-type for amphotericin B (0.0625 - 2 µg/mL), itraconazole (0.125 - 2 µg/mL), and voriconazole (0.0078 - 0.00625 µg/mL). All the isolates were sensitive to fluconazole at the minimum inhibitory concentration (MIC) range (0.0312 - 16 μg/mL), and three of them were resistant to caspofungin (MIC ≥ 0.5 μg/mL). Moreover, 72.7 and 68.2% of the isolates had no phospholipase and esterase activities. The highest potency of enzymatic activity was obtained in hemolysin and proteinase enzymes. A high genetic diversity (19 genotypes of the 22 isolates) existed among the urinary C. glabrata isolates. Based on the minimum spanning tree, two clusters of our genotypes were related to C. glabrata genotypes in a previous study in Iran, and the third cluster was entirely connected with Chinese genotypes. Conclusions: Most of the isolates were the non-wild type for posaconazole but were rarely resistant to other antifungals. Hemolysin and proteinase secreted as the main virulence factors among the urinary C. glabrata isolates.

[Bloodstream infections with Candida glabrata in a neonatal intensive care unit that uses prophylaxis with fluconazole]

BACKGROUND

Candida glabrata is an emerging pathogen with the ability to develop tolerance and resistance to azole antifungals, which creates uncertainty about the usefulness of antifungal prophylaxis in newborns.

AIMS

The aim of this study was to describe the factors associated with C. glabrata infection in a NICU that uses prophylaxis with fluconazole.

METHODS

A case-control study paired by gestational age was designed and conducted at the Civil Hospital of Guadalajara Dr. Juan I. Menchaca. Newborns with C. glabrata infection were studied and for each one a matched control was selected by gestational age. Odds ratios (OR) were estimated with 95% confidence intervals (95% CI) and McNemar test for contrast of hypothesis was applied.

RESULTS

Twenty-one infected patients were identified, from whom 66.7% were male; the median gestational age was 31.5 weeks. Increased risk of infection with C. glabrata was observed when there was a prescription of more than one antimicrobial scheme (OR 21, 95% CI, 1.23 - 358.3; p=0.006) and also among patients with surgical comorbidities (OR 8, 95% CI 1.01 - 63.9; p=0.04). During the study period, exposure to fluconazole showed no difference in the risk of infection.

CONCLUSIONS

Neonates with more than one antimicrobial regimen and those with surgical comorbidities had a higher risk of C. glabrata infection.

Characterisation of an ABC transporter of a resistant Candida glabrata clinical isolate

BACKGROUND

Candida glabrata ranks second in epidemiological surveillance studies, and is considered one of the main human yeast pathogens. Treatment of Candida infections represents a contemporary public health problem due to the limited availability of an antifungal arsenal, toxicity effects and increasing cases of resistance. C. glabrata presents intrinsic fluconazole resistance and is a significant concern in clinical practice and in hospital environments.

OBJECTIVE

The aim of this study was to characterise the azole resistance mechanism presented by a C. glabrata clinical isolate from a Brazilian university hospital.

METHODS

Azole susceptibility assays, chemosensitisation, flow cytometry and mass spectrometry were performed.

FINDINGS

Our study demonstrated extremely high resistance to all azoles tested: fluconazole, voriconazole, posaconazole and itraconazole. This isolate was chemosensitised by FK506, a classical inhibitor of ABC transporters related to azole resistance, and Rhodamine 6G extrusion was observed. A mass spectrometry assay confirmed the ABC protein identification suggesting the probable role of efflux pumps in this resistance phenotype.

MAIN CONCLUSIONS

This study emphasizes the importance of ABC proteins and their relation to the resistance mechanism in hospital environments and they may be an important target for the development of compounds able to unsettle drug extrusion.

Bloodstream and non-invasive isolates of Candida glabrata have similar population structures and fluconazole susceptibilities

We have compared multilocus sequence typing (MLST) and fluconazole susceptibility profiles of Candida glabrata bloodstream isolates obtained during active, population-based surveillance to those obtained from non-sterile sites of individuals with no evidence of fungal disease (i.e., non-invasive isolates) in the same US city during an overlapping time period. In each of the two populations, different proportions of the same six major sequence types (STs) encompassed 82% of the isolates. One ST was more prevalent in the candidemia population and two other STs were more prevalent in the non-invasive population, but the overall allelic frequencies within the groups suggested little, if any, genotypic diversity between them. Fluconazole susceptibility profiles of isolates from the patients in the two groups were not significantly different and were not associated with a particular sequence type. Our results support the hypothesis that C. glabrata strains causing bloodstream infections are genetically indistinguishable from those normally residing in/on the host, suggesting that relative pathogenicity may be closely tied to commensalism.

A review of molecular techniques to type Candida glabrata isolates

Candida glabrata has emerged as a common cause of fungal infection causing mucosal and systemic infections. This yeast is of concern because of its reduced antifungal susceptibility to azole antifungals such as fluconazole. A clear understanding of the epidemiology of Candida infection and colonisation required a reliable typing system for the evaluation of strain relatedness. In this study, we discuss the different molecular approaches for typing C. glabrata isolates. Recent advances in the use of molecular biology-based techniques have enabled investigators to develop typing systems with greater sensitivities. Several molecular genotypic approaches have been developed for fast and accurate identification of C. glabrata in vitro. These techniques have been widely used to study diverse aspects such as nosocomial transmission. Molecular typing of C. glabrata could also provide information on strain variation, such as microvariation and microevolution.

Microsatellite analysis and susceptibility to FCZ of Candida glabrata invasive isolates in Sfax Hospital, Tunisia

We have noted that, during the last few years, there has been a redistribution of the most common Candida species with an increase in non-C. albicans Candida species, particularly Candida glabrata. In many countries, the high frequency of Candida glabrata shows the highest resistance rates. The main objective of this investigation was to analyze the genotypic variability of invasive C. glabrata isolates recovered over a period of six years and assess their in vitro susceptibility to fluconazole to determine the possible existence of relationships between genotype and susceptibility. We collected 50 invasive C. glabrata isolates (21.4%) from January 2001 to December 2007. The in vitro susceptibility profiles as determined by the E-test method showed that 8.3% of the isolates were resistant to fluconazole. The typing with three microsatellite markers RPM2, MTI and ERG3 demonstrated 12 multilocus genotypes distributed irregularly with a predominance of G1 (38%). A cluster (G9) was found among isolates collected in the same ward, at the same time period, suggesting cross transmission. Eleven of 13 patients who had previously been colonized by C. glabrata, were infected by their colonizing strains. However, we noted after prolonged treatment with fluconazole that there was an increase of the MIC for an isolate from one patient and in another patient, the selection of a more resistant variant. In our study, we didn't find an association between genotype and susceptibility to fluconazole. In conclusion, the predominance of some genotypes could be explained by nosocomial transmission or a selective ecological advantage rather than an emergence of a resistant isolate.

Effect of Candida glabrata FKS1 and FKS2 mutations on echinocandin sensitivity and kinetics of 1,3-beta-D-glucan synthase: implication for the existing susceptibility breakpoint

Thirteen Candida glabrata strains harboring a range of mutations in hot spot regions of FKS1 and FKS2 were studied. The mutations were linked to an echinocandin reduced susceptibility phenotype. Sequence alignments showed that 11 out of the 13 mutants harbored a mutation in FKS1 or FKS2 not previously implicated in echinocandin reduced susceptibility in C. glabrata. A detailed kinetic characterization demonstrated that amino acid substitutions in Fks1p and Fks2p reduced drug sensitivity in mutant 1,3-beta-D-glucan synthase by 2 to 3 log orders relative to that in wild-type enzyme. These mutations were also found to reduce the catalytic efficiency of the enzyme (Vmax) and to influence the relative expression of FKS genes. In view of the association of FKS mutations and reduced susceptibility of 1,3-beta-D-glucan synthase, an evaluation of the new CLSI echinocandin susceptibility breakpoint was conducted. Only 3 of 13 resistant fks mutants (23%) were considered anidulafungin or micafungin nonsusceptible (MIC > 2 microg/ml) by this criterion. In contrast, most fks mutants (92%) exceeded a MIC of >2 microg/ml with caspofungin. However, when MIC determinations were performed in the presence of 50% serum, all C. glabrata fks mutants showed MICs of > or = 2 microg/ml for the three echinocandin drugs. As has been observed with Candida albicans, the kinetic inhibition parameter 50% inhibitory concentration may be a better predictor of FKS-mediated resistance. Finally, the close association between FKS1/FKS2 hot spot mutations provides a basis for understanding echinocandin resistance in C. glabrata.

The relationship between antifungal usage and antifungal susceptibility in clinical isolates of Candida: a multicenter Korean study

There have been very few multicenter studies of the relationship between the use of antifungals and resistance to them. We investigated the antifungal susceptibility of 1,301 clinical isolates of Candida collected from nine Korean hospitals during a 3-month period in 2006 to explore the existence of this type of relationship. Antifungal usage in the preceding year, defined as the daily dose per 1,000 patient days (DDD/1,000 PD), was calculated for each hospital. Resistance to fluconazole, itraconazole, and amphotericin B was detected in 2, 9, and 0.2% of the isolates, respectively. The MIC(50)/MIC(90) values were 0.03/0.125 mg/L for voriconazole, 0.06/0.25 mg/l for caspofungin, and 0.03/0.125 mg/l for micafungin. The total usage of systemic antifungals varied considerably among the nine hospitals, ranging from 6.1 to 96.2 DDD/1,000 PD. No relationship was found between the use of fluconazole (MIC> or =64 mg/l) or itraconazole (MIC> or =1 mg/l) and resistance in the Candida species (P>0.05). However, significant correlations were found between the percentage of Candida isolates that were non-susceptible to fluconazole (MIC> or =16 mg/l) and fluconazole usage (r=0.733, P=0.025) or total antifungal usage (r=0.767, P=0.016).

Endogenous Candida endophthalmitis

Intraocular Candida infections, although uncommon, represent an important clinical problem owing to the potential for visual loss, which can be bilateral. Candida chorioretinitis and endophthalmitis are complications of systemic candidiasis with extension of the fungal pathogens to the uvea and retina. Early diagnosis and prompt management significantly affect the visual prognosis for these patients. This review evaluates the current literature on Candida endophthalmitis and includes discussion on presentation, diagnosis and management strategies. New systemic and intravitreal antifungal agents are also reviewed in the context of the management of intraocular fungal infection.

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.

Antifungal prophylaxis with azoles in high-risk, surgical intensive care unit patients: A meta-analysis of randomized, placebo-controlled trials*

OBJECTIVE

The use of antifungal prophylaxis remains controversial in most populations including surgical intensive care unit patients. A meta-analysis of randomized controlled trials was performed to evaluate the safety and effectiveness of azoles as antifungal prophylaxis in high-risk patients receiving treatment in the surgical intensive care unit.

DATA SOURCE

Data were obtained from PubMed, Current Contents, Cochrane central register of controlled trials, and references from relevant articles.

STUDY SELECTION

Randomized controlled trials using azoles as antifungal prophylaxis vs. placebo were included in the study.

DATA EXTRACTION

Two independent reviewers extracted data concerning the development of fungal infections (superficial or invasive), adverse effects, and mortality.

SYNTHESIS

Six randomized controlled trials were included in the main analysis. Publication bias and statistically significant heterogeneity were not observed among the analyzed studies. Patients receiving antifungal prophylaxis developed fewer episodes of candidemia (odds ratio [OR] = 0.28, 95% confidence interval [CI] 0.09-0.86), nonbloodstream invasive fungal infections (OR = 0.26, 95% CI 0.12-0.53), and noninvasive (superficial) fungal infections (OR = 0.22, 95% CI 0.11-0.43), respectively. No reduction in mortality was observed among patients who received azole prophylaxis (OR = 0.74, 95% CI 0.52-1.05). There was no significant difference in reported adverse effects (OR = 1.28, 95% CI 0.82-1.98).

CONCLUSIONS

Despite its limitations, our meta-analysis suggests that the prophylactic use of azoles in high-risk surgical intensive care unit patients is associated with a reduction of fungal infections but not in all-cause mortality. However, although not noted in the analyzed randomized controlled trials, there is concern about the use of azoles due to possible shift toward non-albicans species and development of resistance to azoles.

Treatment of Candida glabrata infection in immunosuppressed mice by using a combination of liposomal amphotericin B with caspofungin or micafungin

While Candida albicans remains the most common Candida isolate, Candida glabrata accounts for approximately 15 to 20% of all Candida infections in the United States. In this study we used immunosuppressed mice infected with C. glabrata to investigate the efficacy of liposomal amphotericin B alone or in combination with the echinocandin caspofungin or micafungin. For monotherapy, mice were given six daily doses of liposomal amphotericin B (3 to 20 mg/kg of body weight), caspofungin (1 to 5 mg/kg), or micafungin (2.5 to 10 mg/kg). With concomitant therapy, mice received liposomal amphotericin B (7.5 mg/kg) in addition to caspofungin (2.5 mg/kg) or micafungin (2.5 mg/kg) for 6 days. For sequential therapy, liposomal amphotericin B was administered on days 1 to 3 and caspofungin or micafungin was given on days 4 to 6; conversely, caspofungin or micafungin was administered on days 1 to 3 and liposomal amphotericin B was given on days 4 to 6. Efficacy was based on the number of CFU per gram of kidney 21 days postchallenge. Monotherapy with liposomal amphotericin B (7.5 to 20 mg/kg) was significantly more effective than no drug treatment (control group) (P < 0.05) and demonstrated a dose-dependent response, with 20 mg/kg lowering the CFU/g from 6.3 to 4.2 (significantly different from the value for the control group [P < 0.001]). Monotherapy with all echinocandin doses lowered the CFU/g from 6.0 to 6.4 to 2.7 to 3.3 (significantly different from the value for the control group [P < 0.001]) with no dose-dependent response. Complete clearance of infection could be achieved only when liposomal amphotericin B was given either concomitantly with caspofungin or micafungin or if liposomal amphotericin B was given sequentially with caspofungin. In conclusion, the combination of liposomal amphotericin B with an echinocandin markedly improved the therapeutic outcome in murine C. glabrata systemic infection.

Culture-positive and culture-negative endocarditis in patients with cancer: a retrospective observational study, 1994-2004

Endocarditis is uncommon in patients with cancer. The characteristics of culture-positive (CPE) and culture-negative endocarditis (CNE) in high-risk cancer patients are not known; therefore we sought to evaluate the disease characteristics in patients with endocarditis at a comprehensive cancer center. We retrospectively reviewed the transthoracic (TTE) and transesophageal (TEE) echocardiograms obtained from 654 consecutive cancer patients in whom endocarditis was suspected between 1994 and 2004. Endocarditis was confirmed in 45 (7%) of 654 patients using modified Duke University criteria based on information obtained from hospital records and computerized data systems. In 21 (95%) of 22 cases, TEE examinations were diagnostic, and 16 (42%) of 38 patients with initially nondiagnostic TTE studies had the diagnosis confirmed by TEE study; this difference between diagnostic TEE and initial nondiagnostic TTE was significant (p < 0.0001). Among the 26 (58%) patients with CPE, Staphylococcus aureus (35%) was the most common organism isolated, followed by coagulase-negative Staphylococcus species (23%). Eighteen (78%) of 23 patients with a central venous catheter had CPE, whereas only 8 (36%) of 22 patients without a central venous catheter had CPE (odds ratio [OR], 6.3; 95% confidence interval [CI], 1.69-23.53; p < 0.006). Vegetations were larger in patients with CPE than in patients with CNE (median +/- standard deviation, 10 +/- 8.8 vs. 8.7 +/- 3.9 mm). Fifteen patients (58%) with CPE and 10 (53%) with CNE had embolic complications. We note that cutaneous and septic pulmonary emboli were more common in patients with CPE than in patients with CNE (31% vs. 11% and 15% vs. 0%, respectively), whereas embolic cerebrovascular and fatal embolic coronary events were more common in patients with CNE than in those with CPE (37% vs. 12% and 21% vs. 0%, respectively; p = 0.026). The 4-week endocarditis-attributable death rate did not differ significantly between the groups (CPE, 15% vs. CNE, 32%; p = 0.28). On stepwise multivariate regression analysis, patients with neutropenia (OR, 22.52; 95% CI, 2.25-225.48; p < 0.008) and those with embolic cerebrovascular events (OR, 17.07; 95% CI, 1.63-178.45; p < 0.01) had an increased probability of death due to endocarditis. The clinical spectrums of CPE and CNE differed in these patients with cancer. In patients with CNE, embolic cerebrovascular and fatal myocardial infarction were relatively common.

Susceptibility to antifungal agents of Candida species isolated from paediatric and adult patients with haematological diseases

Summary The susceptibility to six antifungals: amphotericin B (AMF), 5-fluorocytosine (5-F), miconazole (MIK), ketoconazole (KET), fluconazole (FLU) and itraconazole (ITR) was tested among 206 Candida spp. isolated from paediatric and adult patients with haematological malignancies. To determinate the susceptibility the commercial microdilution method Fungitest (Bio-Rad, France) was used. The strains were classified as susceptible, intermediate susceptible, or resistant on the base of the growth in following breakpoint concentrations of particular drugs: 2 and 8 microg ml(-1) for AMF, 2 and 32 microg ml(-1) for 5-F, 0.5 and 8 microg ml(-1) for MIK, 0.5 and 4 microg ml(-1) for KET and ITR, and 8 and 64 microg ml(-1) for FLU. The highest activity to overall species showed AMF (only one resistant strain) and 5-F (85% susceptible strains). Most of C. albicans isolates were susceptible to tested azoles. The percentages of C. albicans resistant to FLU, ITR, KET and MIK were 4, 11, 8, and 0.8%, respectively. The less susceptible to azoles were C. glabrata and C. krusei (14% and 44% isolates resistant to FLU). A non-albicans Candida isolated from adult patients receiving KET prophylaxis was more frequently resistant to FLU than isolates from patients without previous exposure to azoles (P < 0.05). We did not observe differences in the susceptibility of Candida strains isolated from children compared with those from adults.

CHROMagar Candida as the sole primary medium for isolation of yeasts and as a source medium for the rapid-assimilation-of-trehalose test

The chromogenic medium BBL CHROMagar Candida (CAC) was evaluated as a sole primary medium for the isolation of yeasts from clinical specimens in which yeasts are the primary concern. Additionally, the reliability of the rapid-assimilation-of-trehalose (RAT) test in yielding correct results with isolates taken from CAC was assessed. A total of 270 throat, urine, and genital (TUG) specimens were streaked onto CAC, Sabouraud dextrose agar (SDA), inhibitory mold agar (IMA), and Mycosel (MYC). A total of 69 blood culture broths that were smear positive for yeast were streaked onto CAC and SDA. A 1-h RAT test (NCCLS M35-A) was performed simultaneously on isolates from CAC and SDA. A total of 112 TUG specimens yielded yeast colonies (CAC, 111 colonies; IMA, 105; SDA, 103; MYC, 91). The 69 blood culture yeasts grew on both CAC and SDA. Mixed cultures of yeasts were detected on 11 CAC plates but were unrecognized on other media. Colonies suspected of being C. glabrata on 32 CAC plates were all RAT test positive and confirmed to be C. glabrata; of 59 colonies with various characteristics of color and morphology on CAC, none were RAT positive, and all were conventionally identified as yeasts other than C. glabrata (sensitivity and specificity, 100%). The same isolates from SDA tested for RAT produced six false negatives and no false positives (sensitivity, 81%; specificity, 100%). The results show that CAC can be used as the sole primary medium for recovery of yeasts from clinical specimens. Additionally, isolates grown on CAC yield excellent results with the RAT test utilized in this study.

Mechanisms of azole resistance in clinical isolates of Candida glabrata collected during a hospital survey of antifungal resistance

The increasing use of azole antifungals for the treatment of mucosal and systemic Candida glabrata infections has resulted in the selection and/or emergence of resistant strains. The main mechanisms of azole resistance include alterations in the C. glabrata ERG11 gene (CgERG11), which encodes the azole target enzyme, and upregulation of the CgCDR1 and CgCDR2 genes, which encode efflux pumps. In the present study, we evaluated these molecular mechanisms in 29 unmatched clinical isolates of C. glabrata, of which 20 isolates were resistant and 9 were susceptible dose dependent (S-DD) to fluconazole. These isolates were recovered from separate patients during a 3-year hospital survey for antifungal resistance. Four of the 20 fluconazole-resistant isolates were analyzed together with matched susceptible isolates previously taken from the same patients. Twenty other azole-susceptible clinical C. glabrata isolates were included as controls. MIC data for all the fluconazole-resistant isolates revealed extensive cross-resistance to the other azoles tested, i.e., itraconazole, ketoconazole, and voriconazole. Quantitative real-time PCR analyses showed that CgCDR1 and CgCDR2, alone or in combination, were upregulated at high levels in all but two fluconazole-resistant isolates and, to a lesser extent, in the fluconazole-S-DD isolates. In addition, slight increases in the relative level of expression of CgSNQ2 (which encodes an ATP-binding cassette [ABC] transporter and which has not yet been shown to be associated with azole resistance) were seen in some of the 29 isolates studied. Interestingly, the two fluconazole-resistant isolates expressing normal levels of CgCDR1 and CgCDR2 exhibited increased levels of expression of CgSNQ2. Conversely, sequencing of CgERG11 and analysis of its expression showed no mutation or upregulation in any C. glabrata isolate, suggesting that CgERG11 is not involved in azole resistance. When the isolates were grown in the presence of fluconazole, the profiles of expression of all genes, including CgERG11, were not changed or were only minimally changed in the resistant isolates, whereas marked increases in the levels of gene expression, particularly for CgCDR1 and CgCDR2, were observed in either the fluconazole-susceptible or the fluconazole-S-DD isolates. Finally, known ABC transporter inhibitors, such as FK506, were able to reverse the azole resistance of all the isolates. Together, these results provide evidence that the upregulation of the CgCDR1-, CgCDR2-, and CgSNQ2-encoded efflux pumps might explain the azole resistance in our set of isolates.

Pharmacokinetics of fosfluconazole and fluconazole following multiple intravenous administration of fosfluconazole in healthy male volunteers

AIMS

To assess the bioavailability of fluconazole (FLCZ) from phosphate pro-drug (fosfluconazole), to investigate the effect of loading doses on the time to achieve FLCZ steady state plasma concentrations and on safety, and to investigate the pharmacokinetics of fosfluconazole following once daily multiple bolus injection of fosfluconazole in healthy male volunteers.

METHODS

The first study was a randomized, double-blind, double dummy, two-period crossover study. Subject received either 1000 mg fosfluconazole or 800 mg FLCZ once daily for 14 days in random order. The second study was an open label, randomized parallel group study. Subjects received one of three fosfluconazole once daily treatments: 500 mg for 10 days (no loading dose), a loading dose of 1000 mg on day 1 followed by 500 mg for 9 days (one loading dose), or loading doses of 1000 mg on days 1 and 2 followed by 500 mg for 8 days (two loading doses).

RESULTS

The estimated mean (90% CI) bioavailability of FLCZ from fosfluconazole was 96.8% (94.5, 99.2), with a C(max,ss) ratio of 98.3% (93.3, 103.5) in the first study. Less than 1% of the administered dose of fosfluconazole was excreted unchanged in the urine and the majority (85.6%) was eliminated in the urine as FLCZ. In the second study two loading doses regimen led to earlier achievement of target steady state plasma concentrations (by day 3) compared with use of one or no loading dose (towards the end of the dosing period). Similar adverse event profiles were seen in all three treatment groups. Fosfluconazole did not accumulate after multiple dosing.

CONCLUSIONS

Multiple administration of 1000 mg fosfluconazole and 800 mg FLCZ produced equivalent systemic exposure to FLCZ. Steady state FLCZ plasma concentrations were achieved earliest when two loading doses were used.

Geographic variation in the susceptibilities of invasive isolates of Candida glabrata to seven systemically active antifungal agents: a global assessment from the ARTEMIS Antifungal Surveillance Program conducted in 2001 and 2002

We examined the susceptibilities to amphotericin B, flucytosine, fluconazole, posaconazole, ravuconazole, voriconazole, and caspofungin of 601 invasive isolates of Candida glabrata and grouped the isolates by geographic location: North America (331 isolates), Latin America (58 isolates), Europe (135 isolates), and Asia-Pacific (77 isolates). Caspofungin (MIC at which 90% of isolates tested are susceptible [MIC(90)], 0.12 microg/ml; 100% of strains are susceptible [S] at a MIC of Collapse

Key Words Collapse

MESH Headings

• Antifungal Agents/pharmacology
• Candida glabrata/drug effects
• Drug Resistance, Fungal
• Microbial Sensitivity Tests
• Time Factors

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Affiliation(s)

M A Pfaller Department of Pathology, Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
S A Messer
L Boyken
S Tendolkar
R J Hollis
D J Diekema

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In vitro activities of voriconazole (UK-109, 496), fluconazole, itraconazole and amphotericin B against 132 non-albicans bloodstream yeast isolates (CANARI study). In-vitro-Wirkung von Voriconazol (UK-109, 496), Fluconazol, Itraconazol und Amphotericin B gegen 132 Nicht-albicans-Hefepilzisolate aus dem Blut (CANARI-Studie)

The aim was to evaluate the in vitro activity of voriconazole compared with those of amphotericin B, itraconazole and fluconazole against 132 bloodstream isolates of Candida non-albicans and Saccharomyces cerevisiae species. The minimal inhibitory concentrations (MICs) were determined by an adapted National Committee for Clinical Laboratory Standards (NCCLS) M27-A method using RPMI 1640 as test medium supplemented with 2% glucose. MIC end-points were determined with a spectrophotometer after incubation for 48 h at 35 degrees C. Optical density data were used for the calculation of the MIC end-points. For amphotericin B, the end-point was defined as the minimal antifungal concentration that exerts 90% inhibition compared with the control well growth. For the azoles, the end-points were determined at 50% inhibition of growth. Amphotericin B is highly active with 97% of isolates inhibited by < or =1 microg ml(-1). Decreased susceptibility or resistance to fluconazole was the rule among C. krusei, which is intrinsically resistant to fluconazole. For C. glabrata isolates, resistance to fluconazole and itraconazole was measured in 13% and 17% of the isolates respectively. Voriconazole was quite active in vitro against all the isolates with a MIC90% of < or =1 microg ml(-1) and we conclude that it may be useful in the treatment of non-albicans bloodstream infections.

Candidemia in a tertiary care cancer center: in vitro susceptibility and its association with outcome of initial antifungal therapy

Since the 1990s, changing trends have been documented in species distribution and susceptibility to bloodstream infections caused by Candida species in cancer patients. However, few data are available regarding the association between in vitro antifungal susceptibility and outcome of candidemia in this patient population. We therefore evaluated the association of in vitro antifungal susceptibility and other risk factors with failure of initial antifungal therapy in cancer patients with candidemia. Candidemia cases in cancer patients from 1998 to 2001 (n = 144) were analyzed retrospectively along with their in vitro susceptibility to amphotericin B, fluconazole, and itraconazole (National Committee for Clinical and Laboratory Standards M27-A method). Patients were evaluable for outcome analysis if they received continuous unchanged therapy with either fluconazole or amphotericin B for >/=5 days. We excluded cases of mixed candidemia. In vitro susceptibility testing data of the first Candida bloodstream isolate were analyzed. Appropriate therapy was defined as that using an active in vitro antifungal for >/=5 days. For fluconazole susceptible-dose dependent Candida species, we defined appropriate therapy as a fluconazole dose of >/=600 mg/day. The Candida species distribution was 30% Candida albicans, 24% Candida glabrata, 23% Candida parapsilosis, 10% Candida krusei, 9% Candida tropicalis, and 3% other. Overall, amphotericin B was the most active agent in vitro, with only 3% of the isolates exhibiting resistance to it (>1 mg/L). Dose-dependent susceptibility to fluconazole and itraconazole was seen in 13% and 21% of the isolates, respectively, while resistance to fluconazole and itraconazole was seen in 13% and 26%, respectively.Eighty patients were evaluable for outcome analysis. In multivariate analysis, the following factors emerged as independent predictors of failure of initial antifungal therapy: leukemia (p = 0.01), bone marrow transplantation (p = 0.006), and intensive care unit stay at onset of infection (p = 0.02). Inappropriate antifungal therapy, as defined by daily dose and in vitro susceptibility, was not shown consistently to be a significant factor (it was significant in multivariate analysis, p = 0.04, but not in univariate analysis), indicating the complexity of the variables that influence the response to antifungal treatment in cancer patients with candidemia.

Variation in susceptibility of bloodstream isolates of Candida glabrata to fluconazole according to patient age and geographic location

We examined the susceptibilities to fluconazole of 559 bloodstream infection isolates of Candida glabrata and grouped the isolates by patient age and geographic location within the United States. Susceptibility of C. glabrata to fluconazole was lowest in the Pacific (44%) and East South Central (47%) regions and was highest in the West South Central region (82%) (regions are as designated by the U.S. Bureau of the Census). Isolates from pediatric patients were virtually all susceptible to fluconazole, whereas the highest frequency of resistance was observed in isolates from patients 16 to 64 years of age.