Rationale for reading fluconazole MICs at 24 hours rather than 48 hours when testing Candida spp. by the CLSI M27-A2 standard method

Twenty Years in EUCAST Anti-Fungal Susceptibility Testing: Progress & Remaining Challenges

Since its inception in 2002, the EUCAST Antifungal Susceptibility Testing Subcommittee (AFST) has developed and refined susceptibility testing methods for yeast, moulds and dermatophytes, and established epidemiological cut-off values and breakpoints for antifungals. For yeast, three challenges have been addressed. Interpretation of trailing growth in fluconazole susceptibility testing, which has been proven without impact on efficacy if below the 50% endpoint. Variability in rezafungin MIC testing due to laboratory conditions, which has been solved by the addition of Tween 20 to the growth medium in E.Def 7.4. And third, interpretation of MICs for rare yeast with no breakpoints, where recommendations have been established for MIC-based clinical advice. For moulds, refinements include the validation of spectrophotometer reading for A. fumigatus to facilitate objective MIC determination, and for dermatophytes the establishment of a microdilution method with automated reading and a selective medium to minimise the risk of contaminations. Recent initiatives involve development and validation of agar-based screening assays for detection of potential azole and echinocandin resistance in A. fumigatus and Aspergillus species, respectively, and of terbinafine resistance in Trichophyton species. Moreover, the development of a EUCAST guidance document for molecular resistance testing represents an advancement, particularly for identifying target gene alterations associated with resistance. In summary, EUCAST AFST continues to play a pivotal role in standardizing AFST and facilitating accurate interpretation of susceptibility data for clinical decision-making. Adoption of EUCAST breakpoints for commercial test methods, however, requires thorough validation to ensure concordance with EUCAST reference testing species-specific MIC distributions.

Systematic truncations of chromosome 4 and their responses to antifungals in Candida albicans

BACKGROUND

Candida albicans is an opportunistic human fungal pathogen responsible for superficial and systemic life-threatening infections. Treating these infections is challenging as many clinical isolates show increased drug resistance to antifungals. Chromosome (Chr) 4 monosomy was implicated in a fluconazole-resistant mutant. However, exposure to fluconazole adversely affects Candida cells and can generate numerous mutations. Hence, the present study aimed to truncate Chr4 and challenge the generated Candida strains to antifungals and evaluate their role in drug response.

RESULTS

Herein, Chr4 was truncated in C. albicans using the telomere-mediated chromosomal truncation method. The resulting eight Candida strains carrying one truncated homolog of Chr4 were tested for response to multiple antifungals. The minimal inhibitory concentration (MIC) for these strains was determined against three classes of antifungals. The MIC values against fluconazole, amphotericin B, and caspofungin were closer to that of the wild type strain. Microdilution assay against fluconazole showed that the mutants and wild type strains had similar sensitivity to fluconazole. The disc diffusion assay against five azoles and two polyenes revealed that the zones of inhibition for all the eight strains were similar to those of the wild type. Thus, none of the generated strains showed any significant resistance to the tested antifungals. However, spot assay exhibited a reasonably high tolerance of a few generated strains with increasing concentrations of fluconazole.

CONCLUSION

This analysis suggested that Chr4 aneuploidy might not underlie drug resistance but rather drug tolerance in Candida albicans.

Influences of γ-ray irradiation on physico-chemical, structural, X-ray diffraction, thermal and antimicrobial activity of some γ-irradiated N',N'''-((Z)-ethane-1,2-diylidine)bis(2-aminobenzohydrazide) metal complexes

A series of Co(II), Ni(II), Cu(II), Th(IV) and UO₂(II) complexes have been synthesized from reaction of nitrogen based ligand (L) i.e. N',N'''-((Z)-ethane-1,2-diylidine)bis(2-aminobenzohydrazide)(L) with their salts. Investigation of synthesized metal complexes was achieved by using elemental analyses, magnetic moment, molar conductance, FT-IR, UV/Vis. spectroscopy, thermal techniques and 3D molecular modeling. An octahedral geometry has been suggested for all complexes except for Ni(II) complex (2) which adopted tetrahedral geometry. To through a light on the probability of structure changes with γ-irradiation, the effect of gamma irradiation on powder samples of the complexes [Co(L)Cl₂].4H₂O (1); [Ni₂(L)(OAc)₄].5H₂O (2) and [Cu(L)Br₂].5H₂O (3) was investigated after being exposed to high energetic γ-rays at 100 kGy dose (hereafter referred to as (1A,2A,3A, respectively). Spectral, thermal, magnetic susceptibility, molar conductance and powder X-ray diffraction patterns (XRD) were performed before and after irradiation. In addition, the in vitro antimicrobial activity of the complexes against Staphylococcus aureus as Gram-positive strain, Escherichia coli as Gram-negative strain and antifungal Candida albicans was performed for both unirradiated and irradiated samples. The obtained results showed that the irradiated complexes were affected, but not greatly by the applied γ-irradiation dose.

Early Stepdown From Echinocandin to Fluconazole Treatment in Candidemia: A Post Hoc Analysis of Three Cohort Studies

Background

There are no clear criteria for antifungal de-escalation after initial empirical treatments. We hypothesized that early de-escalation (ED) (within 5 days) to fluconazole is safe in fluconazole-susceptible candidemia with controlled source of infection.

Methods

This is a multicenter post hoc study that included consecutive patients from 3 prospective candidemia cohorts (2007–2016). The impact of ED and factors associated with mortality were assessed.

Results

Of 1023 candidemia episodes, 235 met inclusion criteria. Of these, 54 (23%) were classified as the ED group and 181 (77%) were classified as the non-ED group. ED was more common in catheter-related candidemia (51.9% vs 31.5%; P = .006) and episodes caused by Candida parapsilosis, yet it was less frequent in patients in the intensive care unit (24.1% vs 39.2%; P = .043), infections caused by Nakaseomyces glabrata (0% vs 9.9%; P = .016), and candidemia from an unknown source (24.1% vs 47%; P = .003). In the ED and non-ED groups, 30-day mortality was 11.1% and 29.8% (P = .006), respectively. Chronic obstructive pulmonary disease (odds ratio [OR], 3.97; 95% confidence interval [CI], 1.48–10.61), Pitt score > 2 (OR, 4.39; 95% CI, 1.94–9.20), unknown source of candidemia (OR, 2.59; 95% CI, 1.14–5.86), candidemia caused by Candida albicans (OR, 3.92; 95% CI, 1.48–10.61), and prior surgery (OR, 0.29; 95% CI, 0.08–0.97) were independent predictors of mortality. Similar results were found when a propensity score for receiving ED was incorporated into the model. ED had no significant impact on mortality (OR, 0.50; 95% CI, 0.16–1.53).

Conclusions

Early de-escalation is a safe strategy in patients with candidemia caused by fluconazole-susceptible strains with controlled source of bloodstream infection and hemodynamic stability. These results are important to apply antifungal stewardship strategies.

Identification of Candida Species and Antifungal Susceptibility in Cancer Patients with Oral Lesions in Ahvaz, Southern West of Iran

Background

Oral candidiasis is a common disease in cancer patients subject to chemotherapy. The aim of this study was to evaluate the risk factors of rising oral candidiasis incidence and to identify the Candida species isolated from oral lesions of cancer patients and their antifungal sensitivity.

Materials and Methods

A total of 645 patients with cancer were examined. Several Candida species were isolated from specimens and identified by morphological and molecular methods. The susceptibility of isolates to amphotericin B, fluconazole, and nystatin was also investigated.

Results

A total of 74 isolates of Candida were recovered from oral cavity of 61 cancer patients with oral candidiasis. The isolates included Candida albicans (n = 56; 75.5%), Candida glabrata (n = 4; 5.4%), Candida krusei (n = 5; 7%), Candida tropical (n = 7; 9.4%), and Candida kefyr (n = 2; 2.7%). A total (n = 72; 98.65%) of isolates were susceptible to nystatin, (n = 58; 78.4%) of them were susceptible to fluconazole, and (n = 8; 10.8%) of susceptible dose-dependent isolates were specified, (n = 46; 62.16%) of isolates were susceptible to amphotericin B.

Conclusion

Finally, in addition to emphasis on topical nystatin application in the first stage of oral candidiasis in these patients, using alternative systemic drugs such as fluconazole and amphotericin B can be considered for the resistant candida isolates to nystatin.

Factors influencing susceptibility testing of antifungal drugs: a critical review of document M27-A4 from the Clinical and Laboratory Standards Institute (CLSI)

Due to the increasing numbers of fungal infections and the emergence of drug-resistant fungi, optimization and standardization of diagnostic methods for the measurement of antifungal susceptibility are ongoing. The M27-A4 document by the US Clinical and Laboratory Standards Institute (CLSI) is presently used for the interpretation of minimum inhibitory concentrations of major opportunistic yeast species as measured by broth microdilution testing in many countries. Although microdilution is considered a benchmark for reproducible and accurate results, increased testing capacity, and limited human bias, the method is often inaccessible to routine clinical laboratories and researchers, especially in low-income countries. Furthermore, several studies suggest that there are still a considerable number of factors that make the estimation of in vitro activity of antifungal agents challenging. This review article summarizes the limitations of the M27-A4 standard which, despite the advances and improvements obtained by the standardization of antimicrobial resistance testing methods by CLSI, still persist.

Usefulness of guideline recommendations for prognosis in patients with candidemia

We aimed to analyze whether the lack of inclusion of specific recommendations for the management of candidemia is an independent risk factor for early and overall mortality. Multicenter study of adult patients with candidemia in 13 hospitals. We assessed the proportion of patients on whom nine specific ESCMID and IDSA guidelines recommendations had been applied, and analyzed its impact on mortality. 455 episodes of candidemia were documented. Patients who died within the first 48 hours were excluded. Sixty-two percent of patients received an appropriate antifungal treatment. Either echinocandin or amphotericin B therapy were administered in 43% of patients presenting septic shock and in 71% of those with neutropenia. Sixty-one percent of patients with breakthrough candidemia underwent a change in antifungal drug class. Venous catheters were removed in 79% of cases. Follow-up blood cultures were performed in 72% of cases. Ophthalmoscopy and echocardiogram were performed in 48% and 50% of patients, respectively. Length of treatment was appropriate in 78% of cases. Early (2-7 days) and overall (2-30 days) mortality were 8% and 27.7%, respectively. Inclusion of less than 50% of the specific recommendations was independently associated with a higher early (HR = 7.02, 95% CI: 2.97-16.57; P < .001) and overall mortality (HR = 3.55, 95% CI: 2.24-5.64; P < .001). In conclusion, ESCMID and IDSA guideline recommendations were not performed on a significant number of patients. Lack of inclusion of these recommendations proved to be an independent risk factor for early and overall mortality.

Echinocandins Compared to Fluconazole for Candidemia of a Urinary Tract Source: A Propensity Score Analysis

Background

Whether echinocandins could be used to treat candidemia of a urinary tract source (CUTS) is unknown. We aimed to provide current epidemiological information of CUTS and to compare echinocandin to fluconazole treatment on CUTS outcomes.

Methods

A multicenter study of adult patients with candidemia was conducted in 9 hospitals. CUTS was defined as a candidemia with concomitant candiduria by the same organism associated with significant urological comorbidity. The primary outcome assessed was clinical failure (defined by 7-day mortality or persistent candidemia) in patients treated with either an echinocandin or fluconazole. A propensity score was calculated and then entered into a regression model.

Results

Of 2176 episodes of candidemia, 128 were CUTS (5.88%). Most CUTS cases were caused by Candida albicans (52.7%), followed by Candida glabrata (25.6%) and Candida tropicalis (16.3%). Clinical failure occurred in 7 patients (20%) treated with an echinocandin and in 15 (17.1%) treated with fluconazole (P = .730). Acute renal failure (adjusted odds ratio [AOR], 3.01; 95% confidence interval [CI], 1.01-8.91; P = .047) was the only independent factor associated with clinical failure, whereas early urinary tract drainage procedures (surgical, percutaneous, or endoscopic) were identified as protective (AOR, 0.08; 95% CI, .02-.31; P < .001). Neither univariate nor multivariate analysis showed that echinocandin therapy altered the risk of clinical failure.

Conclusions

Initial echinocandin therapy was not associated with clinical failure in patients with CUTS. Notably, acute renal failure predicted worse outcomes and performing an early urologic procedure was a protective measure.

Identification of Candida species in patients with oral lesion undergoing chemotherapy along with minimum inhibitory concentration to fluconazole

Background:

Various species of Candida, especially Candida albicans was known as the most important etiological agent of fungal infections. Oral candidiasis is the most common fungal infection in patients undergoing chemotherapy. The purpose of this study was to identify Candida species from oral lesions of these patients and antifungal susceptibility of the clinical isolates.

Materials and Methods:

Among 385 patients with cancer, 55 (14.3%) showed oral lesions. Oral swabs were performed to identify the yeasts using direct smear and CHROMagar medium. Micro dilution method was prepared in different concentrations of fluconazole and minimum inhibitory concentration and minimum fungicidal concentration of each species were compared.

Results:

Oral candidiasis confirmed in 36 cases by direct examination and culture. C. albicans and non-albicans represented in 26 (72.2%) and 10 (27.8%) of the isolates, respectively. 76.5% of C. albicans and 23.5% non-albicans isolates were resistant to fluconazole. Data were shown that 62% and 30.7% of resistant strains of C. albicans were found in patient with gastrointestinal cancer and lymphoma respectively.

Conclusion:

Data were shown that C. albicans is the most commonly identified species in oral candidiasis and majority of fluconazole resistant C. albicans were found in patients with gastrointestinal cancer and lymphoma. Therefore, we recommend an alternative drug instead of fluconazole as a first line of treatment for these type of cancers and administration of fluconazole in patients undergoing chemotherapy should be prescribed in accordance with the type of cancer.

Propensity Score Analysis of the Role of Initial Antifungal Therapy in the Outcome of Candida glabrata Bloodstream Infections

Candida glabrata isolates have reduced in vitro susceptibility to azoles, which raises concerns about the clinical effectiveness of fluconazole for treating bloodstream infection (BSI) by this Candida species. We aimed to evaluate whether the choice of initial antifungal treatment (fluconazole versus echinocandins or liposomal amphotericin B [L-AmB]-based regimens) has an impact on the outcome of C. glabrata BSI. We analyzed data from a prospective, multicenter, population-based surveillance program on candidemia conducted in 5 metropolitan areas of Spain (May 2010 to April 2011). Adult patients with an episode of C. glabrata BSI were included. The main outcomes were 14-day mortality and treatment failure (14-day mortality and/or persistent C. glabrata BSI for ≥48 h despite antifungal initiation). The impact of using fluconazole as initial antifungal treatment on the patients' prognosis was assessed by logistic regression analysis with the addition of a propensity score approach. A total of 94 patients with C. glabrata BSI were identified. Of these, 34 had received fluconazole and 35 had received an echinocandin/L-AmB-based regimen. Patients in the echinocandin/L-AmB group had poorer baseline clinical status than did those in the fluconazole group. Patients in the fluconazole group were more frequently (55.9% versus 28.6%) and much earlier (median time, 3 versus 7 days) switched to another antifungal regimen. Overall, 14-day mortality was 13% (9/69) and treatment failure 34.8% (24/69), with no significant differences between the groups. On multivariate analysis, after adjusting for baseline characteristics by propensity score, fluconazole use was not associated with an unfavorable evolution (adjusted odds ratio [OR] for 14-day mortality, 1.16, with 95% confidence interval [CI] of 0.22 to 6.17; adjusted OR for treatment failure, 0.83, with 95% CI of 0.27 to 2.61). In conclusion, initial fluconazole treatment was not associated with a poorer outcome than that obtained with echinocandins/L-AmB regimens in patients with C. glabrata BSI. (This study has been registered at ClinicalTrials.gov under registration no. NCT01236261.).

Progress in antifungal susceptibility testing of Candida spp. by use of Clinical and Laboratory Standards Institute broth microdilution methods, 2010 to 2012

Antifungal susceptibility testing of Candida has been standardized and refined and now may play a useful role in managing Candida infections. Important new developments include validation of 24-h reading times for all antifungal agents and the establishment of species-specific epidemiological cutoff values (ECVs) for the systemically active antifungal agents and both common and uncommon species of Candida. The clinical breakpoints (CBPs) for fluconazole, voriconazole, and the echinocandins have been revised to provide species-specific interpretive criteria for the six most common species. The revised CBPs not only are predictive of clinical outcome but also provide a more sensitive means of identifying those strains with acquired or mutational resistance mechanisms. This brief review serves as an update on the new developments in the antifungal susceptibility testing of Candida spp. using Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) methods.

Validation of 24-hour flucytosine MIC determination by comparison with 48-hour determination by the Clinical and Laboratory Standards Institute M27-A3 broth microdilution reference method

Flucytosine and itraconazole are the only antifungal agents for which the Clinical Laboratory and Standards Institute recommendations include MIC breakpoint readings at 48 h only. Here we show good essential and categorical agreement between the flucytosine MIC readings at 48 and 24 h for Candida species.

Anidulafungin compared with fluconazole for treatment of candidemia and other forms of invasive candidiasis caused by Candida albicans: a multivariate analysis of factors associated with improved outcome

BACKGROUND

Candida albicans is the most common cause of candidemia and other forms of invasive candidiasis. Systemic infections due to C. albicans exhibit good susceptibility to fluconazole and echinocandins. However, the echinocandin anidulafungin was recently demonstrated to be more effective than fluconazole for systemic Candida infections in a randomized, double-blind trial among 245 patients. In that trial, most infections were caused by C. albicans, and all respective isolates were susceptible to randomized study drug. We sought to better understand the factors associated with the enhanced efficacy of anidulafungin and hypothesized that intrinsic properties of the antifungal agents contributed to the treatment differences.

METHODS

Global responses at end of intravenous study treatment in patients with C. albicans infection were compared post-hoc. Multivariate logistic regression analyses were performed to predict response and to adjust for differences in independent baseline characteristics. Analyses focused on time to negative blood cultures, persistent infection at end of intravenous study treatment, and 6-week survival.

RESULTS

In total, 135 patients with C. albicans infections were identified. Among these, baseline APACHE II scores were similar between treatment arms. In these patients, global response was significantly better for anidulafungin than fluconazole (81.1% vs 62.3%; 95% confidence interval [CI] for difference, 3.7-33.9). After adjusting for baseline characteristics, the odds ratio for global response was 2.36 (95% CI, 1.06-5.25). Study treatment and APACHE II score were significant predictors of outcome. The most predictive logistic regression model found that the odds ratio for study treatment was 2.60 (95% CI, 1.14-5.91) in favor of anidulafungin, and the odds ratio for APACHE II score was 0.935 (95% CI, 0.885-0.987), with poorer responses associated with higher baseline APACHE II scores. Anidulafungin was associated with significantly faster clearance of blood cultures (log-rank p < 0.05) and significantly fewer persistent infections (2.7% vs 13.1%; p < 0.05). Survival through 6 weeks did not differ between treatment groups.

CONCLUSIONS

In patients with C. albicans infection, anidulafungin was more effective than fluconazole, with more rapid clearance of positive blood cultures. This suggests that the fungicidal activity of echinocandins may have important clinical implications.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00058682.

Validation of 24-hour posaconazole and voriconazole MIC readings versus the CLSI 48-hour broth microdilution reference method: application of epidemiological cutoff values to results from a global Candida antifungal surveillance program

We performed 24- and 48-h MIC determinations of posaconazole and voriconazole against more than 16,000 clinical isolates of Candida species. By using the 24- and 48-h epidemiological cutoff values (ECVs), the categorical agreement between the 24-h and reference 48-h broth microdilution results ranged from 97.1% (C. parapsilosis and voriconazole) to 99.8% (C. krusei and voriconazole), with 0.0 to 2.9% very major discrepancies (VMD). The essential agreement (within 2 log(2) dilutions) between the 24- and 48-h results was 99.6% for both posaconazole and voriconazole. The MIC results obtained for both posaconazole and voriconazole after only 24 h of incubation may be used to determine the susceptibilities of Candida spp. to these important antifungal agents. The applications of ECVs to this large collection of Candida isolates suggests the potential to develop 24-h species-specific clinical breakpoints for both posaconazole and voriconazole.

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

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

Evaluation of the VITEK 2 system to test the susceptibility of Candida spp., Trichosporon asahii and Cryptococcus neoformans to amphotericin B, flucytosine, fluconazole and voriconazole: a comparison with the M27-A3 reference method

We compared the susceptibilities of 302 isolates (209 Candida spp., 89 Cryptococcus neoformans and four Trichosporon asahii) against amphotericin B (AMB), flucytosine (5FC), fluconazole (FLC) and voriconazole (VRC) obtained with an automated commercial system (VITEK 2, bioMérieux, Spain) and the Clinical and Laboratory Standards Institute (CLSI M27-A3) reference broth microdilution method (BMD). Reference BMD MIC endpoints were determined visually after 24-72 h of incubation, depending on the species, and VITEK 2 system MIC endpoints were determined spectrophotometrically by automated components of this equipment. For Candida spp. and T. asahii, the overall MIC agreement between of the results of the VITEK 2 system and the 24/48-h BMD was: 34/62% for AMB; 96.3% at 24/48-h for 5FC; 87.8/87.3% for FLC and 95.3/92% for VRC, respectively. The overall categorical agreement between both methods was: 98.5/97.6% for AMB at 24/48-h; 95.3% for 5FC at 24/48-h; 85.4/84.4% at 24/48-h for FLC; and 97.6/92.95% at 24/48-h for VRC. For C. neoformans, essential agreement was good for FLC (91%) and 5FC (84.2%) but not so good for AMB (69%). Excellent categorical agreement was obtained for all antifungal agents tested except for 5FC (69.7%). This new system could play an important role in the clinical laboratory, but more studies are necessary to verify its ability to identify resistant isolates.

The distribution of species and susceptibility of amphotericin B and fluconazole of yeast pathogens isolated from sterile sites in Taiwan

To study the demographic changes of yeasts causing invasive infections in Taiwan, especially with respect to species distribution and antifungal susceptibility, we analyzed isolates obtained from four sterile sites of patients in 19 hospitals in 2002 (155 strains) and again from the same hospitals in 2006 (208 strains). Blood was the most common source of the yeasts, accounting for 73.8% of the total isolates, followed by ascites (21.5%), cerebrospinal fluid (3%), and synovia (1.7%). Candida albicans was the most frequently recovered species (50.1% of the total), followed by Candida tropicalis (20.7%), Candida glabrata (11.6%), Candida parapsilosis (8.5%), Cryptococcus neoformans (3.9%), Candida krusei (0.8%), and nine other species (4.3%). There were one (0.3%) and seven (1.9%) isolates with minimum inhibitory concentrations (MICs) of amphotericin B > or =2 mg/l after 24 h and 48 h incubation, respectively. In addition, there were 15 (4.3%) and 31 (8.6%) isolates with MICs of fluconazole > or =64 mg/l under the same conditions. The MIC(90) value of amphotericin B was 1 mg/l. The MIC(90) values of fluconazole were 4 mg/l after 24 h incubation and 32 mg/l after 48 h incubation. Interestingly, MICs for fluconazole > or =64 mg/l after 24 h were significantly higher for isolates obtained in 2006 than those in 2002 after 24 h (7.1% vs. 0.7%, p =0.009) and 48 h (13.5% vs. 2%, p =0.0003) incubations. The demographic difference between these two surveys is mainly due to one species, C. tropicalis.

Rapid antifungal susceptibility determination for yeast isolates by use of Etest performed directly on blood samples from patients with fungemia

We prospectively determined the antifungal susceptibility of yeast isolates causing fungemia using the Etest on direct blood samples (195 prospectively collected and 133 laboratory prepared). We compared the Etest direct (24 h of incubation) with CLSI M27-A3 and the standard Etest methodologies for fluconazole, voriconazole, posaconazole, isavuconazole, caspofungin, and amphotericin B. Strains were classified as susceptible, resistant, or nonsusceptible using CLSI breakpoints (voriconazole breakpoints were used for posaconazole and isavuconazole). Categorical errors between Etest direct and CLSI M27-A3 for azoles were mostly minor. No errors were detected for caspofungin, and high percentages of major errors were detected for amphotericin B. For the azoles, false susceptibility (very major errors) was found in only two (0.6%) isolates (Candida tropicalis and C. glabrata). False resistance (major errors) was detected in 46 (14%) isolates for the three azoles (in 23 [7%] after excluding posaconazole). Etest direct of posaconazole yielded a higher number of major errors than the remaining azoles, especially for C. glabrata, Candida spp., and other yeasts. Excluding C. glabrata, Candida spp., and other yeasts, the remaining species did not yield major errors. Etest direct for fluconazole, voriconazole, isavuconazole, and caspofungin shows potential as an alternative to the CLSI M27-A3 procedure for performing rapid antifungal susceptibility tests on yeast isolates from patients with fungemia. Etest direct is a useful tool to screen for the presence of azole-resistant and caspofungin-nonsusceptible strains.

[A study for testing the antifungal susceptibility of yeast by the Japanese Society for Medical Mycology (JSMM) method. The proposal of the modified JSMM method 2009]

The Japanese Society for Medical Mycology (JSMM) method used for testing the antifungal susceptibility of yeast, the MIC end point for azole antifungal agents, is currently set at IC(80). It was recently shown, however that there is an inconsistency in the MIC value between the JSMM method and the CLSI M27-A2 (CLSI) method, in which the end- point was to read as IC(50). To resolve this discrepancy and reassess the JSMM method, the MIC for three azoles, fluconazole, itraconazole and voriconazole were compared to 5 strains of each of the following Candida species: C. albicans, C. glabrata, C. tropicalis, C. parapsilosis and C. krusei, for a total of 25 comparisons, using the JSMM method, a modified JSMM method, and the CLSI method. The results showed that when the MIC end- point criterion of the JSMM method was changed from IC(80) to IC(50) (the modified JSMM method) , the MIC value was consistent and compatible with the CLSI method. Finally, it should be emphasized that the JSMM method, using a spectrophotometer for MIC measurement, was superior in both stability and reproducibility, as compared to the CLSI method in which growth was assessed by visual observation.

Comparison of 24-hour and 48-hour voriconazole MICs as determined by the Clinical and Laboratory Standards Institute broth microdilution method (M27-A3 document) in three laboratories: results obtained with 2,162 clinical isolates of Candida spp. and other yeasts

We evaluated the performance of the 24-h broth microdilution voriconazole MIC by obtaining MICs for 2,162 clinical isolates of Candida spp. and other yeasts; the 24-h results were compared to 48-h reference MICs to assess essential, as well as categorical, agreement. Although the overall essential agreement was 88.6%, it ranged from 96.4 to 100% for 6 of the 11 species or groups of yeasts tested. The overall categorical agreement was 93.2%, and it was above 90% for eight species. However, unacceptable percentages of very major errors (false susceptibility) were observed for Candida albicans (2.7%), C. glabrata (4.1%), C. tropicalis (9.7%), and other less common yeast species (9.8%). Since it is essential to identify potentially resistant isolates and breakpoints are based on 48-h MICs, it appears that the 24-h MIC is not as clinically useful as the 48-h reference MIC. However, further characterization of these falsely susceptible MICs for three of the four common Candida spp. is needed to understand whether these errors are due to trailing misinterpretation or if the 48-h incubation is required to detect voriconazole resistance. Either in vivo versus in vitro correlations or the determination of resistance mechanisms should be investigated.

Reliability of the Vitek 2 yeast susceptibility test for detection of in vitro resistance to fluconazole and voriconazole in clinical isolates of Candida albicans and Candida glabrata

The Vitek 2 yeast susceptibility test was evaluated by testing 122 Candida isolates against fluconazole and voriconazole. Excellent categorical agreement with the CLSI broth microdilution method was observed (97.5% for both the azoles). Moreover, the Vitek 2 system was able to identify all but 2 of 59 investigated fluconazole-resistant organisms.

Validation of 24-hour fluconazole MIC readings versus the CLSI 48-hour broth microdilution reference method: results from a global Candida antifungal surveillance program

We performed 24- and 48-h MIC determinations and disk diffusion testing of fluconazole against more than 11,000 clinical isolates of Candida species. By using the reference MIC breakpoints, the categorical agreement between the 24-h and reference 48-h broth microdilution results ranged from 93.8% (all Candida species) to 94.9% (all Candida species minus Candida krusei), with only 0.1% very major errors (VME). The essential agreement (within 2 log(2) dilutions) between the 24-h and 48-h results was 99.6%. The categorical agreement between the 24-h disk diffusion results and the 24-h MIC results, using the previously established breakpoints, was 94.4%, with 0.1% VME. Both the MIC and the disk diffusion results obtained for fluconazole after only 24 h of incubation may be used to determine the susceptibilities of Candida spp. to this widely used antifungal agent.