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

Susceptibility patterns of amphotericin B, itraconazole, posaconazole, voriconazole and caspofungin for isolates causing invasive mould infections from the SENTRY Antifungal Surveillance Program (2018-2021) and application of single-site epidemiological cutoff values to evaluate amphotericin B activity

We evaluated the activity of amphotericin B, itraconazole, posaconazole, voriconazole and caspofungin against 1468 invasive moulds collected worldwide from 2018 to 2021. Most (>92%) of the Aspergillus spp. isolates were wildtype (WT) to amphotericin B, caspofungin and the azoles. Azole-non-wildtype A. fumigatus rates were higher in Europe (9.5%) and North America (9.1%) than Latin America (0.0%; only 12 isolates) and the Asia-Pacific region (5.3%). Amphotericin B and caspofungin were active against azole-non-wildtype A. fumigatus isolates. Posaconazole and amphotericin B were the most active agents against the Mucorales. Among the less common moulds, several expressed a pan-azole-resistant phenotype; many of these species also showed elevated MIC values (MIC, >2 mg/L) for amphotericin B and caspofungin. Although most isolates of Aspergillus spp. remain WT to the azoles, azole resistance is increasing in both North America and Europe. Amphotericin B and caspofungin exhibit potentially useful activity against azole-resistant A. fumigatus.

In Vitro Activity of Isavuconazole and Other Mould-Active Azoles against Aspergillus fumigatus with and without CYP51 Alterations

Azole resistance in Aspergillus fumigatus (AFM) is mainly associated with mutations in CYP51A and its promoter region or its homologue CYP51B. We evaluated the in vitro activity of isavuconazole, itraconazole, posaconazole, and voriconazole against 660 AFM collected during 2017-2020. Isolates were tested via CLSI broth microdilution. CLSI epidemiological cutoff values were applied. Non-wildtype (NWT) isolates to azoles were screened for alterations in the CYP51 sequences using whole genome sequencing. Azoles had similar activities against 660 AFM isolates. Overall, AFM displayed WT MIC values to isavuconazole (92.7%), itraconazole (92.9%), posaconazole (97.3%), and voriconazole (96.7%). Only 66 isolates (10.0%) were NWT to 1 or more of the azoles, and 32 harbored one or more alterations in the CYP51 sequences. Of these, 29/32 (90.1%) were NWT to itraconazole, 25/32 (78.1%) were NWT to isavuconazole, 17/32 (53.1%) were NWT to voriconazole, and 11/32 (34.4%) were NWT to posaconazole. The most frequent alteration was CYP51A TR34/L98H, carried by 14 isolates. Four isolates carried the alteration I242V in CYP51A, and G448S; A9T, or G138C was carried by one isolate each. Multiple alterations in CYP51A were detected in five isolates. Alterations in CYP51B were noted in seven isolates. Among 34 NWT isolates without -CYP51 alterations, WT rates to isavuconazole, itraconazole, voriconazole, and posaconazole were 32.4%, 47.1%, 85.3%, and 82.4%, respectively. Ten different CYP51 alterations were detected in 32/66 NWT isolates. Alterations in AFM CYP51 sequences can have variable effects on the in vitro activity of the azoles that are best delineated by testing all triazoles.

Management of early graft candidiasis in a kidney transplant recipient

Balancing adequate immunosuppression with the risk of infection after renal transplantation remains a challenge. The presence of comorbidities adds to the challenge. Although infrequent, invasive fungal infections result in high morbidity and mortality risk in renal transplant recipients. This can be attributed to the intense immunosuppression in the first 6 months after renal transplantation, minimal symptomatology and the high mortality associated with fungal infections.

Due to minimal available evidence, clinical judgement guides management of graft candidiasis. There is a need to develop evidence-based management guidelines for the treatment of fungal infections in renal transplants. Here, we report a case of early-onset candidiasis in a transplanted kidney and present the histological findings, multidisciplinary discussions and treatment given.

Therapeutic Drug Monitoring of Antifungal Agents in Critically Ill Patients: Is There a Need for Dose Optimisation?

Invasive fungal infections are an important cause of morbidity and mortality, especially in critically ill patients. Increasing resistance rates and inadequate antifungal exposure have been documented in these patients, due to clinically relevant pharmacokinetic (PK) and pharmacodynamic (PD) alterations, leading to treatment failure. Physiological changes such as third spacing (movement of fluid from the intravascular compartment to the interstitial space), hypoalbuminemia, renal failure and hepatic failure, as well as common interventions in the intensive care unit, such as renal replacement therapy and extracorporeal membrane oxygenation, can lead to these PK and PD alterations. Consequently, a therapeutic target concentration that may be useful for one patient may not be appropriate for another. Regular doses do not take into account the important PK variations in the critically ill, and the need to select an effective dose while minimising toxicity advocates for the use of therapeutic drug monitoring (TDM). This review aims to describe the current evidence regarding optimal PK/PD indices associated with the clinical efficacy of the most commonly used antifungal agents in critically ill patients (azoles, echinocandins, lipid complexes of amphotericin B, and flucytosine), provide a comprehensive understanding of the factors affecting the PK of each agent, document the PK parameters of critically ill patients compared to healthy volunteers, and, finally, make recommendations for therapeutic drug monitoring (TDM) of antifungals in critically ill patients.

Therapeutic Drug Monitoring of the Echinocandin Antifungal Agents: Is There a Role in Clinical Practice? A Position Statement of the Anti-Infective Drugs Committee of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology

PURPOSE

Reduced exposure to echinocandins has been reported in specific patient populations, such as critically ill patients; however, fixed dosing strategies are still used. The present review examines the accumulated evidence supporting echinocandin therapeutic drug monitoring (TDM) and summarizes available assays and sampling strategies.

METHODS

A literature search was conducted using PubMed in December 2020, with search terms such as echinocandins, anidulafungin, caspofungin, micafungin, or rezafungin with pharmacology, pharmacokinetics (PKs), pharmacodynamics (PDs), drug-drug interactions, TDM, resistance, drug susceptibility testing, toxicity, adverse drug reactions, bioanalysis, chromatography, and mass spectrometry. Data on PD/PD (PK/PD) outcome markers, drug resistance, PK variability, drug-drug interactions, assays, and TDM sampling strategies were summarized.

RESULTS

Echinocandins demonstrate drug exposure-efficacy relationships, and maximum concentration/minimal inhibitory concentration ratio (Cmax/MIC) and area under the concentration-time curve/MIC ratio (AUC/MIC) are proposed PK/PD markers for clinical response. The relationship between drug exposure and toxicity remains poorly clarified. TDM could be valuable in patients at risk of low drug exposure, such as those with critical illness and/or obesity. TDM of echinocandins may also be useful in patients with moderate liver impairment, drug-drug interactions, hypoalbuminemia, and those undergoing extracorporeal membrane oxygenation, as these conditions are associated with altered exposure to caspofungin and/or micafungin. Assays are available to measure anidulafungin, micafungin, and caspofungin concentrations. A limited-sampling strategy for anidulafungin has been reported.

CONCLUSIONS

Echinocandin TDM should be considered in patients at known risk of suboptimal drug exposure. However, for implementing TDM, clinical validation of PK/PD targets is needed.

Susceptibility Testing of Candida auris Isolates

Susceptibility testing of isolates of Candida auris is helpful as a guide to the selection of the most appropriate antifungal agent for treatment as different clades and strains within clades often demonstrate markedly different susceptibility profiles. Some strains are relatively susceptible to all antifungal drugs, but most demonstrate innate resistance to fluconazole, many are cross-resistant to other azoles and others demonstrate resistance to other classes of antifungal. The finding of multi-drug resistance, where an isolate is resistant to two or more classes of antifungal agent, is not uncommon, and development of resistance during a course of treatment has also been documented. This chapter describes a reference broth microdilution method for susceptibility testing and a commercially available gradient strip method.

Update on Candida krusei, a potential multidrug-resistant pathogen

Although Candida albicans remains the main cause of candidiasis, in recent years a significant number of infections has been attributed to non-albicans Candida (NAC) species, including Candida krusei. This epidemiological change can be partly explained by the increased resistance of NAC species to antifungal drugs. C. krusei is a diploid, dimorphic ascomycetous yeast that inhabits the mucosal membrane of healthy individuals. However, this yeast can cause life-threatening infections in immunocompromised patients, with hematologic malignancy patients and those using prolonged azole prophylaxis being at higher risk. Fungal infections are usually treated with five major classes of antifungal agents which include azoles, echinocandins, polyenes, allylamines, and nucleoside analogues. Fluconazole, an azole, is the most commonly used antifungal drug due to its low host toxicity, high water solubility, and high bioavailability. However, C. krusei possesses intrinsic resistance to this drug while also rapidly developing acquired resistance to other antifungal drugs. The mechanisms of antifungal resistance of this yeast involve the alteration and overexpression of drug target, reduction in intracellular drug concentration and development of a bypass pathway. Antifungal resistance menace coupled with the paucity of the antifungal arsenal as well as challenges involved in antifungal drug development, partly due to the eukaryotic nature of both fungi and humans, have left researchers to exploit alternative therapies. Here we briefly review our current knowledge of the biology, pathophysiology and epidemiology of a potential multidrug-resistant fungal pathogen, C. krusei, while also discussing the mechanisms of drug resistance of Candida species and alternative therapeutic approaches.

Elevated Vacuolar Uptake of Fluorescently Labeled Antifungal Drug Caspofungin Predicts Echinocandin Resistance in Pathogenic Yeast

Echinocandins are the newest class of antifungal drugs in clinical use. These agents inhibit β-glucan synthase, which catalyzes the synthesis of β-glucan, an essential component of the fungal cell wall, and have a high clinical efficacy and low toxicity. Echinocandin resistance is largely due to mutations in the gene encoding β-glucan synthase, but the mode of action is not fully understood. We developed fluorescent probes based on caspofungin, the first clinically approved echinocandin, and studied their cellular biology in Candida species, the most common cause of human fungal infections worldwide. Fluorescently labeled caspofungin probes, like the unlabeled drug, were most effective against metabolically active cells. The probes rapidly accumulated in Candida vacuoles, as shown by colocalization with vacuolar proteins and vacuole-specific stains. The uptake of fluorescent caspofungin is facilitated by endocytosis: The labeled drug formed vesicles similar to fluorescently labeled endocytic vesicles, the vacuolar accumulation of fluorescent caspofungin was energy-dependent, and inhibitors of endocytosis reduced its uptake. In a panel comprised of isogenic Candida strains carrying different β-glucan synthase mutations as well as clinical isolates, resistance correlated with increased fluorescent drug uptake into vacuoles. Fluorescent drug uptake also associated with elevated levels of chitin, a sugar polymer that increases cell-wall rigidity. Monitoring the intracellular uptake of fluorescent caspofungin provides a rapid and simple assay that can enable the prediction of echinocandin resistance, which is useful for research applications as well as for selecting the appropriate drugs for treatments of invasive fungal infections.

Antioxidant, antimicrobial and cytotoxic activities of gold nanoparticles capped with quercetin

In the present work, we report the antioxidant, antimicrobial and cytotoxic activities of quercetin-capped gold nanoparticles (AuNPsQct). The synthesis of AuNPsQct was confirmed by UV-Vis spectroscopy, FTIR and transmission electron microscopy (TEM) analyses. The FTIR spectrum showed the integrity of the quercetin molecules on the nanoparticle surface. The TEM images showed sizes less than 100 nm and a slight spherical shape. The electrostatic stability was confirmed by the zeta potential method. The antioxidant activity of quercetin, evaluated by DPPH, ABTS and nitric oxide free radical scavenging methods, was preserved in the gold nanoparticles, furthermore quercetin-capped gold nanoparticles (IR₅₀ 0.37 µg/mL) demonstrated a higher antioxidant activity than free quercetin (IR₅₀ 0.57 µg/mL) by nitric oxide free radical scavenging method. Strong antifungal activity was observed for Aspergillus fumigatus with concentrations ranging from 0.1 to 0.5 mg/mL. The nanoparticles with quercetin did not exhibit cytotoxicity to human fibroblasts (L929 cells). In conclusion, these results suggest that AuNPsQct, produced by cost-effective method, can act as a promising candidate for different medical applications.

Change in the clinical antifungal sensitivity profile of Aspergillus flavus induced by azole and a benzimidazole fungicide exposure

The study evaluated the change in the clinical antifungal sensitivity profile of A. flavus strains after exposure to azole and benzimidazole fungicide. Exposure to fungicide altered the sensitivity profile for the antifungal itraconazole, voriconazole and posaconazole. This change was characterized by an increase in the minimum inhibitory concentration (MIC) from 16 to 32 times, evidencing the development of resistance phenotypes. The most significant changes were found after exposure to a pool of the fungicide with MIC of up to 256 times, which is considered, to the best of our knowledge, the first case report of such a high level of resistance induced by azole fungicide exposure. This observation probably indicates a synergistic action among azole compounds that potentiates the development of resistance phenotypes. In addition, exposure to fungicide changed the pigmentation of the colonies from green to white. The development of resistance to fungicides represents risks to human health, since azole fungicides are used widely in the agriculture, and a single agricultural fungicide spray often includes more than one azole compound.

Inflammatory Cell Recruitment in Candida glabrata Biofilm Cell-Infected Mice Receiving Antifungal Chemotherapy

(1) Background: Due to a high rate of antifungal resistance, Candida glabrata is one of the most prevalent Candida spp. linked to systemic candidiasis, which is particularly critical in catheterized patients. The goal of this work was to simulate a systemic infection exclusively derived from C. glabrata biofilm cells and to evaluate the effectiveness of the treatment of two echinocandins—caspofungin (Csf) and micafungin (Mcf). (2) Methods: CD1 mice were infected with 48 h-biofilm cells of C. glabrata and then treated with Csf or Mcf. After 72 h, the efficacy of each drug was evaluated to assess the organ fungal burden through colony forming units (CFU) counting. The immune cell recruitment into target organs was evaluated by flow cytometry or histopathology analysis. (3) Results: Fungal burden was found to be higher in the liver than in the kidneys. However, none of the drugs was effective in completely eradicating C. glabrata biofilm cells. At the evaluated time point, flow cytometry analysis showed a predominant mononuclear response in the spleen, which was also evident in the liver and kidneys of the infected mice, as observed by histopathology analysis. (4) Conclusions: Echinocandins do not have a significant impact on liver and kidney fungal burden, or recruited inflammatory infiltrate, when mice are intravenously (i.v.) infected with C. glabrata biofilm-grown cells.

Drug susceptibility profile of Candida glabrata clinical isolates from Iran and genetic resistant mechanisms to caspofungin

BACKGROUND

Candida glabrata is a yeast that can cause hazardous fungal infections with high mortality and drug resistance.

AIMS

The aim of this study was to determine the profile of drug susceptibility in clinical isolates of C. glabrata and review the resistance mechanisms to caspofungin.

METHODS

A total of 50 C. glabrata clinical isolates from Iran were tested for in vitro susceptibilities to amphotericin B, caspofungin, fluconazole and voriconazole. To investigate the mechanism of resistance to caspofungin, hotspot areas of FKS1 and FKS2 genes were sequenced and gene expression profile was evaluated.

RESULTS

All the isolates were susceptible to amphotericin B and caspofungin. Fluconazole resistance was exhibited in four isolates. In addition, only one isolate was resistant to voriconazole. FKS2 with 12 point mutations showed more mutations compared to FKS1 that had only two mutations. All substitutions were synonymous. FKS genes were expressed at comparable levels (no statistical significance) in caspofungin-treated and non-treated cultures.

CONCLUSIONS

The silent mutations in the hotspot areas of FKS genes and inconsiderable changes in gene expression were not associated with increased MIC (0.25μg/ml). Other mechanisms of resistance which include mutations outside the hotspot area of FKS genes could be involved in a slight increase of MIC, and they should be identified through complete FKS gene sequencing.

Antifungal susceptibility testing results of New Zealand yeast isolates, 2001-2015: Impact of recent CLSI breakpoints and epidemiological cut-off values for Candida and other yeast species

OBJECTIVES

We reviewed the antifungal susceptibility testing results of local yeast isolates (2001-2015) to record the impact of recently updated interpretive criteria and epidemiological cut-off values (ECVs) for yeast species.

METHODS

Susceptibility testing was performed using Sensititre^® YeastOne^®. The results were interpreted following CLSI criteria or YeastOne-derived ECVs.

RESULTS

A total of 2345 isolates were tested; 62.0% were from sterile body sites or tissue. Application of new CLSI interpretative criteria for fluconazole increased the proportion of non-susceptible isolates of Candida parapsilosis, Candida tropicalis and Candida glabrata (P≤0.03 for all species). For voriconazole, the greatest increase was for C. tropicalis (P<0.0001). Application of new CLSI interpretive criteria for caspofungin increased the proportion of non-susceptible isolates for C. glabrata and Pichia kudriavzevii (P<0.0001 for both). The new amphotericin ECV (≤2mg/L) did not reveal any non-wild-type (non-WT) isolates in the five species covered. YeastOne itraconazole ECVs detected 2%, 5% and 6% non-WT isolates for P. kudriavzevii, C. tropicalis and C. glabrata, respectively. No itraconazole non-WT isolates of Clavispora lusitaniae were detected.

CONCLUSIONS

Whilst most results are similar to other large surveys of fungal susceptibility, the new CLSI interpretive criteria significantly altered the proportion of non-susceptible isolates to fluconazole, voriconazole and caspofungin for several Candida spp. Application of CLSI and YeastOne-derived ECVs revealed the presence of a low proportion of non-WT isolates for many species. The results serve as a baseline to monitor the susceptibility of Candida and other yeast species in New Zealand over time.

Caspofungin resistant disseminated candidiasis in a 7-year-old girl with T cell lymphoma: a case report

Immunocompromised patients are at increased risk of disseminated candidiasis. Guidelines for the treatment of invasive candidiasis were last published in 2009, but resistance to the recommended treatment has recently been described in the literature. Here we present the case of an immunocompromised child with T-cell lymphoma who died secondary to disseminated candidiasis despite prolonged antifungal therapy. Awareness of the increasing resistance patterns of Candida when caring for immunocompromised patients, especially pediatric patients, may improve treatment and create better patient outcomes.

Patterns of antimicrobial resistance in Streptococcus suis isolates from pigs with or without streptococcal disease in England between 2009 and 2014

Antimicrobial resistance in Streptococcus suis, a global zoonotic pathogen of pigs, has been mostly studied only in diseased animals using surveys that have not evaluated changes over time. We compared patterns of resistance between S. suis isolates from clinical cases of disease (CC) and non-clinical case (NCC) pigs in England, collected over two discrete periods, 2009-2011 and 2013-2014. Minimum inhibitory concentrations (MIC) of 17 antimicrobials (nine classes) were determined on 405 S. suis isolates categorised by sampling period and disease association to assess changes in resistance over time and association with disease. First, isolates were characterized as resistant or susceptible using published clinical breakpoints. Second, epidemiological cut-offs (ECOFF) were derived from MIC values, and isolates classified as wild type (WT) below the ECOFF and non-wild type (NWT) above the ECOFF. Finally, isolate subsets were analysed for shifts in MIC distribution. NCC isolates were more resistant than CC isolates to cephalosporins, penams, pleuromutilins, potentiated sulphonamides and tetracyclines in both study periods. Resistance levels among CC isolates increased in 2013-2014 relative to 2009-2011 for antimicrobials including aminoglycosides, cephalosporins, fluoroquinolones, pleuromutilins, potentiated sulphonamides and tetracyclines. The prevalence of isolates categorised as NWT for five or more classes of antimicrobials was greater among NCC than CC isolates for both time periods, and increased with time. This study used standardised methods to identify significant shifts in antimicrobial resistance phenotypes of S. suis isolated from pigs in England, not only over time but also between isolates from known clinical cases or disease-free pigs.

Tolerance to Caspofungin in Candida albicans Is Associated with at Least Three Distinctive Mechanisms That Govern Expression of FKS Genes and Cell Wall Remodeling

Expanding echinocandin use to prevent or treat invasive fungal infections has led to an increase in the number of breakthrough infections due to resistant Candida species. Although it is uncommon, echinocandin resistance is well documented for Candida albicans, which is among the most prevalent bloodstream organisms. A better understanding is needed to assess the cellular factors that promote tolerance and predispose infecting cells to clinical breakthrough. We previously showed that some mutants that were adapted to growth in the presence of toxic sorbose due to loss of one chromosome 5 (Ch5) also became more tolerant to caspofungin. We found here, following direct selection of mutants on caspofungin, that tolerance can be conferred by at least three mechanisms: (i) monosomy of Ch5, (ii) combined monosomy of the left arm and trisomy of the right arm of Ch5, and (iii) an aneuploidy-independent mechanism. Tolerant mutants possessed cell walls with elevated chitin and showed downregulation of genes involved in cell wall biosynthesis, namely, FKS, located outside Ch5, and CHT2, located on Ch5, irrespective of Ch5 ploidy. Also irrespective of Ch5 ploidy, the CNB1 and MID1 genes on Ch5, which are involved in the calcineurin signaling pathway, were expressed at the diploid level. Thus, multiple mechanisms can affect the relative expression of the aforementioned genes, controlling them in similar ways. Although breakthrough mutations in two specific regions of FKS1 have previously been associated with caspofungin resistance, we found mechanisms of caspofungin tolerance that are independent of FKS1 and thus represent an earlier event in resistance development.

Micafungin: A Review in the Prophylaxis and Treatment of Invasive Candida Infections in Paediatric Patients

Intravenous micafungin (Mycamine^®; Funguard^®), an echinocandin, is approved in the EU for the treatment of invasive candidiasis in children (including neonates) and adolescents (<16 years of age) and as prophylaxis against Candida infections in patients undergoing haematopoietic stem cell transplantation (HSCT) or who are expected to have neutropenia for ≥10 days. This narrative review focuses on the use of micafungin in paediatric indications approved in the EU, which may vary from those approved elsewhere in the world. Micafungin has a broad spectrum of in vitro activity against clinically relevant isolates of Candida spp. (including fluconazole-resistant Candida glabrata isolates), a low propensity for emergence of resistant isolates and a convenient once-daily regimen. In paediatric substudies and a small multinational, phase 3 trial in neonates with proven invasive candidiasis, intravenous micafungin was effective and generally well tolerated in the treatment of candidaemia and other types of invasive candidiasis and as prophylaxis against fungal infections in patients undergoing HSCT. Hence, micafungin remains an important option for the prophylaxis and treatment of invasive Candida infections in paediatric and adult patients.

The epidemiology and outcomes of invasive Candida infections among organ transplant recipients in the United States: results of the Transplant-Associated Infection Surveillance Network (TRANSNET)

BACKGROUND

Invasive candidiasis (IC) is a common cause of mortality in solid organ transplant recipients (OTRs), but knowledge of epidemiology in this population is limited.

METHOD

The present analysis describes data from 15 US centers that prospectively identified IC from nearly 17 000 OTRs. Analyses were undertaken to determine predictors of infection and mortality.

RESULTS

A total of 639 cases of IC were identified. The most common species was Candida albicans (46.3%), followed by Candida glabrata (24.4%) and Candida parapsilosis (8.1%). In 68 cases >1 species was identified. The most common infection site was bloodstream (44%), followed by intra-abdominal (14%). The most frequently affected allograft groups were liver (41.1%) and kidney (35.3%). All-cause mortality at 90 days was 26.5% for all species and was highest for Candida tropicalis (44%) and C. parapsilosis (35.2%). Non-white race and female gender were more commonly associated with non-albicans species. A high rate of breakthrough IC was seen in patients receiving antifungal prophylaxis (39%). Factors associated with mortality include organ dysfunction, lung transplant, and treatment with a polyene antifungal. The only modifiable factor identified was choice of antifungal drug class based upon infecting Candida species.

CONCLUSION

These data highlight the common and distinct features of IC in OTRs.

Antifungal susceptibility of 175 Aspergillus isolates from various clinical and environmental sources

Some environmental Aspergillus spp. isolates have been described as resistant to antifungals, potentially causing an emerging medical problem. In the present work, the antifungal susceptibility profile of 41 clinical and 134 environmental isolates of Aspergillus was determined using the CLSI microdilution method. The aim of this study was to compare environmental and clinical isolates with respect to their susceptibility, and assess the potential implications for therapy of isolates encountered in different environments. To our knowledge, this is the first report comparing antifungal susceptibility profiles of Aspergillus collected from different environmental sources (poultries, swineries, beach sand, and hospital environment). Significant differences were found in the distribution of the different species sections for the different sources. Significant differences were also found in the susceptibility profile of the different Aspergillus sections recovered from the various sources. Clear differences were found between the susceptibility of clinical and environmental isolates for caspofungin, amphotericin B and posaconazole, with clinical isolates showing overall greater susceptibility, except for caspofungin. In comparison to clinical isolates, hospital environmental isolates showed significantly less susceptibility to amphotericin B and posaconazole. These data indicate that species section identity and the site from which the isolate was recovered influence the antifungal susceptibility profile, which may affect initial antifungal choices.

Antifungal drug resistance among Candida species: mechanisms and clinical impact

The epidemiology of Candida infections has changed in recent years. Although Candida albicans is still the main cause of invasive candidiasis in most clinical settings, a substantial proportion of patients is now infected with non-albicans Candida species. The various Candida species vary in their susceptibility to the most commonly used antifungal agents, and the intrinsic resistance to antifungal therapy seen in some species, along with the development of acquired resistance during treatment in others, is becoming a major problem in the management of Candida infection. A better understanding of the mechanisms and clinical impact of antifungal drug resistance is essential for the efficient treatment of patients with Candida infection and for improving treatment outcomes. Herein, we report resistance to the azoles and echinocandins among Candida species.

Using the number needed to treat to assess appropriate antimicrobial therapy as a determinant of outcome in severe sepsis and septic shock

OBJECTIVE

To assess appropriate antimicrobial therapy as an outcome determinant in severe sepsis and septic shock using the number needed to treat.

DESIGN

Single-center cohort study (January 2008 to December 2012).

SETTING

One thousand two hundred fifty-bed academic hospital.

PATIENTS

Two thousand five hundred ninety-four patients with positive blood culture.

INTERVENTIONS

We retrospectively identified patients with severe sepsis or septic shock. Inappropriate antimicrobial treatment was defined as an antimicrobial regimen that lacked in vitro activity against the isolated pathogen. Information regarding demographics, severity of illness, comorbidities, microbiology, and antimicrobial treatment was recorded. Logistic regression was used to identify risk factors for hospital mortality and inappropriate treatment.

MEASUREMENTS AND MAIN RESULTS

Seven hundred eighty-seven patients (30.3%) were nonsurvivors. Inappropriate antimicrobial treatment had the greatest adjusted odds ratio for hospital mortality (adjusted odds ratio, 3.4; 95% CI, 2.8-4.1; p < 0.001). Multivariate logistic regression analysis identified resistance to cefepime, resistance to meropenem, presence of multidrug resistance, nonabdominal surgery, and prior antibiotic use as being independently associated with the administration of inappropriate antimicrobial treatment. For the entire cohort, the number needed to treat with appropriate antimicrobial therapy to prevent one patient death was 4.0 (95% CI, 3.7-4.3). The prevalence-adjusted pathogen-specific number needed to treat (PNNT) with appropriate antimicrobial therapy to prevent one patient death was lowest for multidrug-resistant bacteria (PNNT = 20) followed by Candida species (PNNT = 34), methicillin-resistant Staphylococcus aureus (PNNT = 38), Pseudomonas aeruginosa (PNNT = 38), Escherichia coli (PNNT = 40), and methicillin-susceptible S. aureus (PNNT = 47).

CONCLUSIONS

Our results support the importance of appropriate antimicrobial treatment as a determinant of outcome in patients with severe sepsis and septic shock. Our analyses suggest that improved targeting of empiric antimicrobials for multidrug-resistant bacteria, Candida species, methicillin-resistant S. aureus, and P. aeruginosa would have the greatest impact in reducing mortality from inappropriate antimicrobial treatment in patients with severe sepsis and septic shock.

Invasive mycosis due to species of Blastobotrys in immunocompromised patients with reduced susceptibility to antifungals

Cases of invasive mycosis due to Blastobotrys serpentis and B. proliferans identified by sequencing in a preterm patient and a rhabdomyosarcoma patient, respectively, are reported. Both species revealed elevated fluconazole and echinocandin MICs by the CLSI broth microdilution method. Additionally, B. serpentis exhibited high amphotericin B MICs, thus posing serious therapeutic challenges.

DL-2-hydroxyisocaproic acid attenuates inflammatory responses in a murine Candida albicans biofilm model

Chronic biofilm infections are often accompanied by a chronic inflammatory response, leading to impaired healing and increased, irreversible damage to host tissues. Biofilm formation is a major virulence factor for Candida albicans and a challenge for treatment. Most current antifungals have proved ineffective in eradicating infections attributed to biofilms. The biofilm structure protects Candida species against antifungals and provides a way for them to evade host immune systems. This leads to a very distinct inflammatory response compared to that seen in planktonic infections. Previously, we showed the superior efficacy of dl-2-hydroxyisocaproic acid (HICA) against various bacteria and fungi. However, the immunomodulatory properties of HICA have not been studied. Our aim was to investigate the potential anti-inflammatory response to HICA in vivo. We hypothesized that HICA reduces the levels of immune mediators and attenuates the inflammatory response. In a murine model, a robust biofilm was formed for 5 days in a diffusion chamber implanted underneath mouse skin. The biofilm was treated for 12 h with HICA, while caspofungin and phosphate-buffered saline (PBS) were used as controls. The pathophysiology and immunoexpression in the tissues surrounding the chamber were determined by immunohistochemistry. Histopathological examination showed an attenuated inflammatory response together with reduced expression of matrix metalloproteinase 9 (MMP-9) and myeloperoxidase (MPO) compared to those of chambers containing caspofungin and PBS. Interestingly, the expression of developmental endothelial locus 1 (Del-1), an antagonist of neutrophil extravasation, increased after treatment with HICA. Considering its anti-inflammatory and antimicrobial activity, HICA may have enormous therapeutic potential in the treatment of chronic biofilm infections and inflammation, such as those seen with chronic wounds.

Role of FKS Mutations in Candida glabrata: MIC values, echinocandin resistance, and multidrug resistance

Candida glabrata is the second leading cause of candidemia in U.S. hospitals. Current guidelines suggest that an echinocandin be used as the primary therapy for the treatment of C. glabrata disease due to the high rate of resistance to fluconazole. Recent case reports indicate that C. glabrata resistance to echinocandins may be increasing. We performed susceptibility testing on 1,380 isolates of C. glabrata collected between 2008 and 2013 from four U.S. cities, Atlanta, Baltimore, Knoxville, and Portland. Our analysis showed that 3.1%, 3.3%, and 3.6% of the isolates were resistant to anidulafungin, caspofungin, and micafungin, respectively. We screened 1,032 of these isolates, including all 77 that had either a resistant or intermediate MIC value with respect to at least one echinocandin, for mutations in the hot spot regions of FKS1 and FKS2, the major mechanism of echinocandin resistance. Fifty-one isolates were identified with hot spot mutations, 16 in FKS1 and 35 in FKS2. All of the isolates with an FKS mutation except one were resistant to at least one echinocandin by susceptibility testing. Of the isolates resistant to at least one echinocandin, 36% were also resistant to fluconazole. Echinocandin resistance among U.S. C. glabrata isolates is a concern, especially in light of the fact that one-third of those isolates may be multidrug resistant. Further monitoring of U.S. C. glabrata isolates for echinocandin resistance is warranted.

Antifungal resistance to fluconazole and echinocandins is not emerging in yeast isolates causing fungemia in a Spanish tertiary care center

Accurate knowledge of fungemia epidemiology requires identification of strains to the molecular level. Various studies have shown that the rate of resistance to fluconazole ranges from 2.5% to 9% in Candida spp. isolated from blood samples. However, trends in antifungal resistance have received little attention and have been studied only using CLSI M27-A3 methodology. We assessed the fungemia epidemiology in a large tertiary care institution in Madrid, Spain, by identifying isolates to the molecular level and performing antifungal susceptibility testing according to the updated breakpoints of European Committee for Antimicrobial Susceptibility Testing (EUCAST) definitive document (EDef) 7.2. We studied 613 isolates causing 598 episodes of fungemia in 544 patients admitted to our hospital (January 2007 to December 2013). Strains were identified after amplification and sequencing of the ITS1-5.8S-ITS2 region and further tested for in vitro susceptibility to amphotericin B, fluconazole, posaconazole, voriconazole, micafungin, and anidulafungin. Resistance was defined using EUCAST species-specific breakpoints, and epidemiological cutoff values (ECOFFs) were applied as tentative breakpoints. Most episodes were caused by Candida albicans (46%), Candida parapsilosis (28.7%), Candida glabrata (9.8%), and Candida tropicalis (8%). Molecular identification enabled us to better detect cryptic species of Candida guilliermondii and C. parapsilosis complexes and episodes of polyfungal fungemia. The overall percentage of fluconazole-resistant isolates was 5%, although it was higher in C. glabrata (8.6%) and non-Candida yeast isolates (47.4%). The rate of resistance to echinocandins was 4.4% and was mainly due to the presence of intrinsically resistant non-Candida species. Resistance mainly affected non-Candida yeasts. The rate of resistance to fluconazole and echinocandins did not change considerably during the study period.

A novel antifungal is active against Candida albicans biofilms and inhibits mutagenic acetaldehyde production in vitro

The ability of C. albicans to form biofilms is a major virulence factor and a challenge for management. This is evident in biofilm-associated chronic oral-oesophageal candidosis, which has been shown to be potentially carcinogenic in vivo. We have previously shown that most Candida spp. can produce significant levels of mutagenic acetaldehyde (ACH). ACH is also an important mediator of candidal biofilm formation. We have also reported that D,L-2-hydroxyisocaproic acid (HICA) significantly inhibits planktonic growth of C. albicans. The aim of the present study was to investigate the effect of HICA on C. albicans biofilm formation and ACH production in vitro. Inhibition of biofilm formation by HICA, analogous control compounds or caspofungin was measured using XTT to measure biofilm metabolic activity and PicoGreen as a marker of biomass. Biofilms were visualised by scanning electron microscopy (SEM). ACH levels were measured by gas chromatography. Transcriptional changes in the genes involved in ACH metabolism were measured using RT-qPCR. The mean metabolic activity and biomass of all pre-grown (4, 24, 48 h) biofilms were significantly reduced after exposure to HICA (p<0.05) with the largest reductions seen at acidic pH. Caspofungin was mainly active against biofilms pre-grown for 4 h at neutral pH. Mutagenic levels (>40 µM) of ACH were detected in 24 and 48 h biofilms at both pHs. Interestingly, no ACH production was detected from D-glucose in the presence of HICA at acidic pH (p<0.05). Expression of genes responsible for ACH catabolism was up-regulated by HICA but down-regulated by caspofungin. SEM showed aberrant hyphae and collapsed hyphal structures during incubation with HICA at acidic pH. We conclude that HICA has potential as an antifungal agent with ability to inhibit C. albicans cell growth and biofilm formation. HICA also significantly reduces the mutagenic potential of C. albicans biofilms, which may be important when treating bacterial-fungal biofilm infections.

[Susceptibility of Candida albicans blood isolates to 3 antifungal drugs: retrospective study in Rio Grande do Sul, Brazil, 1999-2009]

BACKGROUND

Candidiasis is one of the most important among recurrent invasive yeast infections in patients, thus antifungal treatment becomes a challenge.

AIMS

The aim of this study was to evaluate the in vitro activity of clinical Candida albicans isolates from blood cultures to fluconazole, amphotericin B and anidulafungin, in a hospital from Rio Grande do Sul, Brazil.

METHODS

The susceptibility of 153 isolates to the 3 drugs mentioned was tested according to Clinical and Laboratory Standars Institute. Minimal inhibitory and fungicidal concentrations (MIC, MFC, respectively) of each drug were determined, as well as the epidemiological cutoff value (ECV).

RESULTS

All of the isolates were susceptible to anidulafungin, MIC and MFC ≤ 1 μg/ml; however, when compared with ECV, 3% of the isolates exhibited higher values against fluconazole, 96% were susceptible, 3% susceptible dose-dependent, and 1% resistant. Also, it was observed that 21% of the isolates exhibited higher values than ECV. One isolate was resistant to amphotericin B; the other ones, susceptible, based on the MFC; furthermore, 1.5% of the isolates exhibited higher values.

CONCLUSIONS

C. albicans isolates exhibited more susceptibility to anidulafungin, and 90% of them (MIC90) exhibited the lowest values against amphotericin B. Based on ECV and Pfaller classification, isolates could be resistant to fluconazole, demonstrating the importance of the combination of these parameters.

Increasing echinocandin resistance in Candida glabrata: clinical failure correlates with presence of FKS mutations and elevated minimum inhibitory concentrations

BACKGROUND

Fluconazole (FLC) resistance is common in C. glabrata and echinocandins are often used as first-line therapy. Resistance to echinocandin therapy has been associated with FKS1 and FKS2 gene alterations.

METHODS

We reviewed records of all patients with C. glabrata bloodstream infection at Duke Hospital over the past decade (2001-2010) and correlated treatment outcome with minimum inhibitory concentration (MIC) results and the presence of FKS gene mutations. For each isolate, MICs to FLC and echinocandins (anidulafungin, caspofungin, and micafungin) and FKS1 and FKS2 gene sequences were determined.

RESULTS

Two hundred ninety-three episodes (313 isolates) of C. glabrata bloodstream infection were analyzed. Resistance to echinocandins increased from 4.9% to 12.3% and to FLC from 18% to 30% between 2001 and 2010, respectively. Among the 78 FLC resistant isolates, 14.1% were resistant to 1 or more echinocandin. Twenty-five (7.9%) isolates harbored a FKS mutation. The predictor of a FKS mutant strain was prior echinocandin therapy (stepwise multivariable analysis, odds ratio, 19.647 [95% confidence interval, 7.19-58.1]). Eighty percent (8/10) of patients infected with FKS mutants demonstrating intermediate or resistant MICs to an echinocandin and treated with an echinocandin failed to respond or responded initially but experienced a recurrence.

CONCLUSIONS

Echinocandin resistance is increasing, including among FLC-resistant isolates. The new Clinical and Laboratory Standards Institute clinical breakpoints differentiate wild-type from C. glabrata strains bearing clinically significant FKS1/FKS2 mutations. These observations underscore the importance of knowing the local epidemiology and resistance patterns for Candida within institutions and susceptibility testing of echinocandins for C. glabrata to guide therapeutic decision making.

Candida parapsilosis and the neonate: epidemiology, virulence and host defense in a unique patient setting

Invasive candidiasis is a common problem in premature infants that leads to high morbidity and mortality. Although Candida albicans has historically been the most prominent species involved in these infections and has therefore been the subject of the most study, Candida parapsilosis is increasing in frequency, and neonates are disproportionately affected. This article reviews unique aspects of the epidemiology of this organism as well as strategies for prophylaxis against invasive candidiasis in general. Additionally, important differences between C. parapsilosis and C. albicans are coming to light related to virulence determinants and interactions with components of host immunity. These developments are reviewed while highlighting the significant gaps in our understanding that remain to be elucidated.

Evaluation of caspofungin susceptibility testing by the new Vitek 2 AST-YS06 yeast card using a unique collection of FKS wild-type and hot spot mutant isolates, including the five most common candida species

FKS mutant isolates associated with breakthrough or failure cases are emerging in clinical settings. Discrimination of these from wild-type (wt) isolates in a routine laboratory setting is complicated. We evaluated the ability of caspofungin MIC determination using the new Vitek 2 AST-Y06 yeast susceptibility card to correctly identify the fks mutants from wt isolates and compared the performance to those of the CLSI and EUCAST reference methods. A collection of 98 Candida isolates, including 31 fks hot spot mutants, were included. Performance was evaluated using the FKS genotype as the "gold standard" and compared to those of the CLSI and EUCAST methodologies. The categorical agreement for Vitek 2 was 93.9%, compared to 88.4% for the CLSI method and 98.7% for the EUCAST method. Vitek 2 misclassified 19.4% (6/31) of the fks mutant isolates as susceptible, in contrast to <4% for each of the reference methods. The overall essential agreement between the CLSI method and Vitek 2 MICs was 92.6% (88/95) but was substantially lower for fks mutant isolates (78.6% [22/28]). Correct discrimination between susceptible and intermediate Candida glabrata isolates was not possible, as the revised species-specific susceptibility breakpoint was not included in the Vitek 2 detection range (MIC of ≤0.250 to ≥4 mg/liter). In conclusion, the Vitek 2 allowed correct categorization of all wt isolates as susceptible. However, despite an acceptable categorical agreement, it failed to reliably classify isolates harboring fks hot spot mutations as intermediate or resistant, which was in part due to the fact that the detection range did not span the susceptibility breakpoint for C. glabrata.

Fks1 and Fks2 are functionally redundant but differentially regulated in Candida glabrata: implications for echinocandin resistance

The echinocandins caspofungin, micafungin, and anidulafungin, inhibitors of cell wall β-1,3-glucan synthesis, were recently elevated to first-line agents for treating infections due to the azole-refractory yeast Candida glabrata. In Candida albicans, echinocandin resistance is strictly associated with mutations in Fks1, a large integral membrane protein and putative β-1,3-glucan synthase, while mutations in both Fks1 and its paralog Fks2 (but not Fks3) have been associated with resistance in C. glabrata. To further explore their function, regulation, and role in resistance, C. glabrata fks genes were disrupted and subjected to mutational analysis, and their differential regulation was explored. An fks1Δ fks2Δ double disruptant was not able to be generated; otherwise, all three single and remaining two double disruptants displayed normal growth and echinocandin susceptibility, indicating Fks1-Fks2 redundancy. Selection on echinocandin-containing medium for resistant mutants was dependent on strain background: only fks1Δ and fks1Δ fks3Δ strains consistently yielded mutants exhibiting high-level resistance, all with Fks2 hot spot 1 mutations. Thus, Fks1-Fks2 redundancy attenuates the rate of resistance; further analysis showed that it also attenuates the impact of resistance-conferring mutations. Growth of the fks1Δ and, especially, fks1Δ fks3Δ strains was specifically susceptible to the calcineurin inhibitor FK506. Relatedly, FK506 addition or calcineurin gene CMP2 disruption specifically reversed Fks2-mediated resistance of laboratory mutants and clinical isolates. RNA analysis suggests that transcriptional control is not the sole mechanism by which calcineurin modulates Fks2 activity.

CRS-MIS in Candida glabrata: sphingolipids modulate echinocandin-Fks interaction

Infections with the azole-refractory yeast Candida glabrata are now commonly treated with the echinocandins caspofungin (CSF) or micafungin (MCF). True resistance (>  32-fold decreased susceptibility) to these lipopeptide inhibitors of cell wall synthesis is rare and strictly associated with mutations in integral membrane proteins Fks1 or Fks2. In contrast, mutants exhibiting 4- to 32-fold CSF reduced susceptibility (CRS) were readily selected in vitro, and surprisingly demonstrated 4- to 32-fold MCF increased susceptibility (MIS). Sequencing and gene deletion demonstrated that CRS-MIS is Fks-independent. To explore alternative mechanisms, we initially employed Saccharomyces cerevisiae, and observed that CRS was conferred by multiple mutations (fen1Δ, sur4Δ, cka2Δ and tsc10-ts) disrupting sphingolipid biosynthesis. Following this lead, C. glabrata fen1Δ and cka2Δ deletants were constructed, and shown to exhibit CRS-MIS. Sphingolipid analysis of CRS-MIS laboratory mutants and clinical isolates demonstrated elevated dihydrosphingosine (DHS) and phytosphingosine (PHS) levels, and consistent with this sequencing revealed fen1, sur4, ifa38 and sur2 mutations. Moreover, exogenous DHS or PHS conferred a CRS-MIS phenotype on wild-type C. glabrata. Exogenous PHS failed, however, to suppress CRS-MIS in a sur2 mutant blocked in conversion of DHS to PHS, implying that accumulation of these intermediates confers CRS-MIS. We conclude that membrane sphingolipids modulate echinocandin-Fks interaction.

The presence of an FKS mutation rather than MIC is an independent risk factor for failure of echinocandin therapy among patients with invasive candidiasis due to Candida glabrata

Echinocandins are frontline agents against invasive candidiasis (IC), but predictors for echinocandin therapeutic failure have not been well defined. Mutations in Candida FKS genes, which encode the enzyme targeted by echinocandins, result in elevated MICs and have been linked to therapeutic failures. In this study, echinocandin MICs by broth microdilution and FKS1 and FKS2 mutations among C. glabrata isolates recovered from patients with IC at our center were correlated retrospectively with echinocandin therapeutic responses. Thirty-five patients with candidemia and 4 with intra-abdominal abscesses were included, 92% (36/39) of whom received caspofungin. Twenty-six percent (10) and 74% (29) failed and responded to echinocandin therapy, respectively. Caspofungin, anidulafungin, and micafungin MICs ranged from 0.5 to 8, 0.03 to 1, and 0.015 to 0.5 μg/ml, respectively. FKS mutations were detected in 18% (7/39) of C. glabrata isolates (FKS1, n = 2; FKS2, n = 5). Median caspofungin and anidulafungin MICs were higher for patients who failed therapy (P = 0.04 and 0.006, respectively). By receiver operating characteristic (ROC) analyses, MIC cutoffs that best predicted failure were >0.5 (caspofungin), >0.06 (anidulafungin), and >0.03 μg/ml (micafungin), for which sensitivity/specificity were 60%/86%, 50%/97%, and 40%/90%, respectively. Sensitivity/specificity of an FKS mutation in predicting failure were 60%/97%. By univariate analysis, recent gastrointestinal surgery, prior echinocandin exposure, anidulafungin MIC of >0.06 μg/ml, caspofungin MIC of >0.5 μg/ml, and an FKS mutation were significantly associated with failure. The presence of an FKS mutation was the only independent risk factor by multivariate analysis (P = 0.002). In conclusion, detection of C. glabrata FKS mutations was superior to MICs in predicting echinocandin therapeutic responses among patients with IC.

Recurrent episodes of candidemia due to Candida glabrata with a mutation in hot spot 1 of the FKS2 gene developed after prolonged therapy with caspofungin

We report two episodes of recurrent candidemia caused by echinocandin-resistant Candida glabrata in a 69-year-old patient who underwent repeated abdominal surgery. In the first episode of candidemia, an echinocandin-susceptible Candida glabrata strain was isolated, and the patient was treated with caspofungin. The isolates from the later episodes showed resistance to echinocandins. Analysis of the HS1 region of the FKS2 gene showed the amino acid substitution S663P. Microsatellite analysis demonstrated a strong genetic relationship between the isolates.

Frequency of decreased susceptibility and resistance to echinocandins among fluconazole-resistant bloodstream isolates of Candida glabrata

The echinocandin class of antifungal agents is considered to be the first-line treatment of bloodstream infections (BSI) due to Candida glabrata. Recent reports of BSI due to strains of C. glabrata resistant to both fluconazole and the echinocandins are of concern and prompted us to review the experience of two large surveillance programs, the SENTRY Antimicrobial Surveillance Program for the years 2006 through 2010 and the Centers for Disease Control and Prevention population-based surveillance conducted in 2008 to 2010. The in vitro susceptibilities of 1,669 BSI isolates of C. glabrata to fluconazole, voriconazole, anidulafungin, caspofungin, and micafungin were determined by CLSI broth microdilution methods. Fluconazole MICs of ≥64 μg/ml were considered resistant. Strains for which anidulafungin and caspofungin MICs were ≥0.5 μg/ml and for which micafungin MICs were ≥0.25 μg/ml were considered resistant. A total of 162 isolates (9.7%) were resistant to fluconazole, of which 98.8% were nonsusceptible to voriconazole (MIC > 0.5 μg/ml) and 9.3%, 9.3%, and 8.0% were resistant to anidulafungin, caspofungin, and micafungin, respectively. There were 18 fluconazole-resistant isolates that were resistant to one or more of the echinocandins (11.1% of all fluconazole-resistant isolates), all of which contained an acquired mutation in fks1 or fks2. By comparison, there were no echinocandin-resistant strains detected among 110 fluconazole-resistant isolates of C. glabrata tested in 2001 to 2004. These data document the broad emergence of coresistance over time to both azoles and echinocandins in clinical isolates of C. glabrata.

Antifungal use influences Candida species distribution and susceptibility in the intensive care unit

OBJECTIVES

Antifungal prescription practices have changed over the last decade, and the impact of these changes is unclear. Our objective here was to evaluate the effect of antifungal drug use on the distribution and drug susceptibility of Candida spp. in a French intensive care unit (ICU).

METHODS

Antifungal drug use was measured as the number of defined daily doses per 1000 hospital days (DDDs/1000HD). The distribution of Candida spp. over a 6 year period (2004-09) and the MICs of antifungal drugs over 2007-09 were determined. Statistical analyses were performed to assess relationships between antifungal drug use, Candida spp. distribution and MIC changes over time.

RESULTS

Of 26,450 samples from 3391 patients, 1511 were positive for Candida spp. Candida albicans predominated (52.5%), followed by Candida glabrata (16.6%) and Candida parapsilosis (7.5%). C. parapsilosis increased significantly, from 5.7% in 2004 to 12.5% in 2009 (P = 0.0005). Caspofungin use increased significantly between 2004 (17.9 DDDs/1000HD) and 2009 (69.9 DDDs/1000HD) (P < 0.0001). Between 2007 and 2009, the increase in caspofungin use correlated significantly with the increase in caspofungin MICs displayed by C. parapsilosis (P < 0.0001) and C. glabrata (P = 0.03). Amphotericin B consumption changed over time and correlated with an increase in amphotericin B MICs for C. albicans (P = 0.0002) and C. glabrata (P = 0.0005). Significant declines occurred in both fluconazole use (P < 0.0001) and fluconazole MICs of C. albicans (P < 0.001)

CONCLUSIONS

Antifungal drug use in the ICU is associated with major changes in the distribution and drug susceptibility of Candida spp.

Prior caspofungin exposure in patients with hematological malignancies is a risk factor for subsequent fungemia due to decreased susceptibility in Candida spp.: a case-control study in Paris, France

Infections due to caspofungin-resistant Candida isolates in patients exposed to caspofungin therapy are increasing. We report here a nested case-control study which aimed at identifying factors associated with bloodstream infections caused by Candida spp. having reduced susceptibility to caspofungin (CRSC) in adults suffering from hematological malignancies. In univariate and multivariate analyses, infections with CRSC were associated with caspofungin exposure in the previous 30 days (odds ratio [OR] = 5.25; 95% confidence interval [95% CI], 1.68-16.35) and with an age of ≤ 65 years (OR = 3.27; 95% CI, 1.26-8.50).

Candida glabrata mutants demonstrating paradoxical reduced caspofungin susceptibility but increased micafungin susceptibility

Echinocandins, including caspofungin (CSP) and micafungin (MCF), are highly active versus Candida glabrata (MIC of ≤0.06 μg/ml). True resistance (MIC of ≥1 μg/ml) is a rare event and strictly associated with mutations in β-1,3-glucan synthase gene FKS1 or FKS2. In contrast, we show here that mutants exhibiting reduced susceptibility to CSP (CRS; MICs of 0.12 to 0.5 μg/ml) are readily selected in vitro and, paradoxically, demonstrate increased susceptibility to MCF (MIS) ranging from 4- to 32-fold. CRS-MIS mutants were generated from all 10 C. glabrata strains tested and were tentatively identified within a collection of clinical isolates. Intriguingly, sequencing and gene disruption demonstrated that CRS-MIS is Fks independent.