Twelve years of fluconazole in clinical practice: global trends in species distribution and fluconazole susceptibility of bloodstream isolates of Candida

Trends in candidemia and antifungal susceptibility in a university hospital in Northern Ireland 2001-2006

OBJECTIVES

To describe the species distribution and antifungal susceptibility trends for documented episodes of candidemia at the Royal Hospitals, Belfast, 2001-2006.

METHODS

Laboratory-based retrospective observational study of all episodes of candidemia.

RESULTS

There were 151 episodes of candidemia. The species recovered were: 96 C. albicans; 26 C. glabrata; 18 C. parapsilosis; five C. tropicalis; four C. guilliermondii; one C. famata and one C. dubliniensis. We separated the data into two periods 2001-2003 and 2004-2006; contrary to the findings of other investigators, there was a notable trends toward increasing frequency of C. albicans and decreasing frequency of non-albicans species over time. Although the proportion of C. albicans, C. parapsilosis and C. tropicalis isolates susceptible to fluconazole was unchanged over time, a trend of decreased susceptibility of C. glabrata to fluconazole was noted over the six-year period. Overall, 73% and 7.7% of C. glabrata isolates had susceptible-dose-dependent and resistant phenotypes, respectively. The percentage of C. glabrata isolates susceptible to fluconazole (MIC <8 microg/ml) decreased from 36% in 2001-2003 to 0% in 2004-2006. Flucytosine resistance was detected in only 4 (2.7%) isolates. None of the isolates had an amphotericin B MIC <1 microg/ml.

CONCLUSION

A shift towards increasing dominance of C. albicans contrasts both with reports from other countries and previous data from Northern Ireland. Upwards fluconazole MIC drift among C. glabrata has important implications for empirical therapeutic decisions.

Assessment of Candida glabrata strain relatedness by pulsed-field gel electrophoresis and multilocus sequence typing

In this study, 80 Candida glabrata isolates from intensive care unit and human immunodeficiency virus (HIV)-infected patients were typed by multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and mating type class determination. Among the 25 patients with multiple isolates, 19 patients (76%) contained multiple isolates exhibiting identical or highly related PFGE and MLST genotypes, which may indicate the maintenance or microvariation of one C. glabrata strain in each patient. However, isolates from six patients (24%) displayed different sequence types, PFGE genotypes, or mating type classes, which may indicate colonization with more than one clone over time or strain replacement. High correlations among PFGE genotypes, sequence types, and mating types were found (P < 0.01). MLST exhibited less discriminatory power than PFGE with BssHII. The genotypes, sequence types, and mating type classes were independent of anatomic sources, drug susceptibility, and HIV infection status.

Biofilm production by Candida species and inadequate antifungal therapy as predictors of mortality for patients with candidemia

Nosocomial Candida bloodstream infections rank among infections with highest mortality rates. A retrospective cohort analysis was conducted at Catholic University Hospital to estimate the risk factors for mortality of patients with candidemia. We reviewed records for patients with a Candida bloodstream infection over a 5-year period (January 2000 through December 2004). Two hundred ninety-four patients (42.1% male; mean age +/- standard deviation, 65 +/- 12 years) were studied. Patients most commonly were admitted with a surgical diagnosis (162 patients [55.1%]), had a central venous catheter (213 [72.4%]), cancer (118 [40.1%]), or diabetes (58 [19.7%]). One hundred fifty-four (52.3%) patients died within 30 days. Of 294 patients, 168 (57.1%) were infected by Candida albicans, 64 (21.7%) by Candida parapsilosis, 28 (9.5%) by Candida tropicalis, and 26 (8.8%) by Candida glabrata. When fungal isolates were tested for biofilm formation capacity, biofilm production was most commonly observed for isolates of C. tropicalis (20 of 28 patients [71.4%]), followed by C. glabrata (6 of 26 [23.1%]), C. albicans (38 of 168 [22.6%]), and C. parapsilosis (14 of 64 [21.8%]). Multivariable analysis identified inadequate antifungal therapy (odds ratio [OR], 2.35; 95% confidence interval [95% CI], 1.09 to 5.10; P = 0.03), infection with overall biofilm-forming Candida species (OR, 2.33; 95% CI, 1.26 to 4.30; P = 0.007), and Acute Physiology and Chronic Health Evaluation III scores (OR, 1.03; 95% CI, 1.01 to 1.15; P < 0.001) as independent predictors of mortality. Notably, if mortality was analyzed according to the different biofilm-forming Candida species studied, only infections caused by C. albicans (P < 0.001) and C. parapsilosis (P = 0.003) correlated with increased mortality. Together with well-established factors, Candida biofilm production was therefore shown to be associated with greater mortality of patients with candidemia, probably by preventing complete organism eradication from the blood.

Candida glabrata: an emerging oral opportunistic pathogen

Following the widespread use of immunosuppressive therapy and broad-spectrum antimycotic prophylaxis, C. glabrata has emerged as an important opportunistic pathogen in the oral mucosa. In the past, studies on the virulence factors and host-pathogen interactions of this organism were scarce, but continued to rise in recent years. Denture-wearing, immunosuppression, antibiotic therapy, and aging are risk factors for oral colonization or infection with C. glabrata. Compared with C. albicans, C. glabrata exhibits lower oral keratinocyte-adherence capacity, but higher denture-surface-adherence ability. The role of extracellular hydrolase production in the virulence of this organism does not appear to be as important as it is in C. albicans pathogenesis. Although traditionally thought of as a non-transforming yeast organism, both phenotypic switching and pseudohyphal formation have recently been identified in C. glabrata, but their role in pathogenesis is not known. With the exception of granulocyte monocyte colony-stimulating factor, C. glabrata triggers a lower proinflammatory cytokine response in oral epithelial cells than does C. albicans, in a strain-dependent manner. C. glabrata is less susceptible to killing by human beta-defensins than is C. albicans and exhibits various degrees of resistance to the antifungal activity of salivary histatins and mucins. In addition, C. glabrata possesses both innate and acquired resistance against antifungal drugs, due to its ability to modify ergosterol biosynthesis, mitochondrial function, or antifungal efflux. This resistance allows for its relative overgrowth over other susceptible species and may contribute to the recent emergence of C. glabrata infections in chronically immunocompromised populations. Further investigations on the virulence and host-pathogen interactions of C. glabrata are needed to better define the pathogenesis of oral C. glabrata infection in susceptible hosts.

Epidemiology of invasive candidiasis: a persistent public health problem

Invasive candidiasis (IC) is a leading cause of mycosis-associated mortality in the United States. We examined data from the National Center for Health Statistics and reviewed recent literature in order to update the epidemiology of IC. IC-associated mortality has remained stable, at approximately 0.4 deaths per 100,000 population, since 1997, while mortality associated with invasive aspergillosis has continued to decline. Candida albicans remains the predominant cause of IC, accounting for over half of all cases, but Candida glabrata has emerged as the second most common cause of IC in the United States, and several less common Candida species may be emerging, some of which can exhibit resistance to triazoles and/or amphotericin B. Crude and attributable rates of mortality due to IC remain unacceptably high and unchanged for the past 2 decades. Nonpharmacologic preventive strategies should be emphasized, including hand hygiene; appropriate use, placement, and care of central venous catheters; and prudent use of antimicrobial therapy. Given that delays in appropriate antifungal therapy are associated with increased mortality, improved use of early empirical, preemptive, and prophylactic therapies should also help reduce IC-associated mortality. Several studies have now identified important variables that can be used to predict risk of IC and to help guide preventive strategies such as antifungal prophylaxis and early empirical therapy. However, improved non-culture-based diagnostics are needed to expand the potential for preemptive (or early directed) therapy. Further research to improve diagnostic, preventive, and therapeutic strategies is necessary to reduce the considerable morbidity and mortality associated with IC.

Incidence, risk factors, and predictors of outcome of candidemia. Survey in 2 Italian university hospitals

In recent decades, Candida spp. emerged as the fourth most common cause of nosocomial bloodstream infections. The incidence of candidemia was 0.13 per 100 persons. Eighty-three cases (61%) of candidemia were due to Candida albicans and 53 (39%) to nonalbicans Candida spp. Twelve strains of Candida (9%) had shown in vitro resistance to fluconazole, 5 (4%) to itraconazole, 2 (1.5%) to voriconazole, 12 (9%) to 5-flucytosine, and 1 (0.7%) to amphotericin B. Multivariate logistic regression analysis of risk factors showed that length of hospitalization, presence of a central venous catheter, previous episodes of candidemia or bacteremia, parenteral nutrition, and chronic renal failure were variables independently associated with the development of candidemia. Multivariate logistic regression analysis of prognostic indicators showed that the independent variables associated with poor prognosis were inadequate initial therapy (P < .001) and high APACHE III score (P = .004). The inadequate initial therapy associated with mortality indicates the need for additional investigations to define high-risk patients for beneficial antifungal prophylaxis.

Use of prophylactic antifungals in the immunocompromised host

Oral candidiasis is a significant infection in patients being treated with chemotherapy and radiotherapy for cancer, and in patients who are immunocompromised because of HIV infection and AIDS. Candida albicans is the most common fungal pathogen and has developed an extensive array of putative virulent mechanisms that allows successful colonization and infection of the host under suitable predisposing conditions. The purpose of this review of the literature was to assess the effectiveness of interventions for the prevention of oral candidiasis in immunocompromised patients and in patients treated for cancer with radiotherapy and/or chemotherapy. These patient categories were selected because they have been the topic of published randomized controlled clinical trials. The studies reviewed provide strong evidence that oral candidiasis is associated with greater morbidity and mortality in these populations, which substantiates the aggressive treatment and prophylaxis of this infection. The literature supports the recommendation that systemically applied antifungal drugs have the greatest efficacy for the treatment of oral candidiasis in cancer and immunocompromised patients; however, these therapies must be prescribed with a thorough assessment for the risk for developing drug-induced toxicities. Guidelines on the prevention of drug-resistant oral candidiasis in these patients are not available and require elucidation. Further studies are required to expand the knowledge base of evidence-based antifungal therapies in a wider variety of immunocompromised patients and conditions, such as Sjögren's syndrome, diabetes, and denture wearers. Additional exploration is needed to determine which antifungal drug formulation, dose, and method of delivery is preferable for the type of fungal infection and the underlying etiology.

Multicenter comparison of the VITEK 2 yeast susceptibility test with the CLSI broth microdilution reference method for testing fluconazole against Candida spp

A fully automated commercial antifungal susceptibility test system (VITEK 2 yeast susceptibility test; bioMerieux, Inc., Hazelwood, Mo.) was compared in three different laboratories with Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution (BMD) method by testing two quality control strains and a total of 426 isolates of Candida spp. (103 to 135 clinical isolates in each laboratory plus 80 challenge isolates in one laboratory) against fluconazole. Reference BMD MIC endpoints were established after 24 and 48 h of incubation. VITEK 2 endpoints were determined spectrophotometrically after 10 to 26 h of incubation (mean, 13 h). Excellent essential agreement (within two dilutions) between the VITEK 2 and the 24- and 48-h BMD MICs was observed. The overall agreement values were 97.9 and 93.7%, respectively. Both intra- and interlaboratory agreement was 100%. The overall categorical agreement between VITEK 2 and BMD was 97.2% at the 24-h BMD time point and 88.3% at the 48-h BMD time point. Decreased categorical agreement at 48 h was attributed to trailing growth observed with Candida glabrata. The VITEK 2 system reliably detected fluconazole resistance among Candida spp. and demonstrated excellent quantitative and qualitative agreement with the reference BMD method.

Fungal infections and their treatment in the intensive care unit

PURPOSE OF REVIEW

To describe and bring together recent development in the diagnosis and treatment of both community-acquired and opportunistic fungal infections in the intensive care unit.

RECENT FINDINGS

The past few years have brought major advances to both the diagnosis and treatment of fungal infections. The development of newer therapeutic modalities to supplement existing treatment options includes a new class of antifungal agents, the echinocandins. Newer and improved agents of the azole class have arrived as well as better delineation for the role of liposomal amphotericins. Newer, nonculture-based diagnostic tests have allowed earlier, more timely diagnosis of opportunistic fungal infections, allowing more rapid initiation of therapy.

SUMMARY

Improved diagnostic tests and newer antifungal agents have been introduced, leading to earlier diagnosis and treatment.

Trends in the Epidemiology of Invasive Fungal Infections

Invasive fungal infections have increased in importance, largely because of the increasing size of the population at risk. Candida species remain the fourth most important cause of hospital-acquired bloodstream infections. Infections with Candida species other than C. albicans appear to have become more common, but significant geographic variation has been reported. Invasive aspergillosis and other mould infections are a leading cause of infection-related death in hematopoietic stem cell transplant recipients. Although Aspergillus fumigatus remains the most frequent cause of infection, A. terreus has emerged as an important pathogen, at least among certain populations. Despite marked reductions in the rates of AIDS-associated fungal infections, such as cryptococcosis, in the United States and other developed countries, the burden of these diseases in developing countries is large and increasing. Enhanced surveillance and reporting will be critical to improve our understanding of the importance of invasive fungal infections, to enable prioritization of research and prevention efforts, and to evaluate prevention strategies.

Global surveillance of in vitro activity of micafungin against Candida: a comparison with caspofungin by CLSI-recommended methods

Micafungin is an echinocandin antifungal agent that has recently been approved for the prevention of invasive fungal infection and the treatment of esophageal candidiasis. Prospective sentinel surveillance for the emergence of in vitro resistance to micafungin among invasive Candida sp. isolates is indicated. We determined the in vitro activity of micafungin against 2,656 invasive (bloodstream or sterile site) unique patient isolates of Candida spp. collected from 60 medical centers worldwide in 2004 and 2005. We performed antifungal susceptibility testing according to the Clinical and Laboratory Standards Institute (CLSI) M27-A2 method and used a 24-hour prominent inhibition endpoint for determination of the MIC. Caspofungin was tested in parallel against all isolates. Of 2,656 invasive Candida sp. isolates, species distribution was 55.6% Candida albicans, 14.4% Candida parapsilosis, 13.4% Candida glabrata, 10.1% Candida tropicalis, 2.4% Candida krusei, 1.7% Candida guilliermondii, 0.9% Candida lusitaniae, 0.6% Candida kefyr, and 0.9% other Candida species. Overall, micafungin was very active against Candida (MIC50/MIC at which 90% of the isolates tested are inhibited [MIC90], 0.015/1 microg/ml; 96% inhibited at a MIC of < or =1 microg/ml, 100% inhibited at a MIC of < or =2 microg/ml) and comparable to caspofungin (MIC50/MIC90, 0.03/0.25 mug/ml; 99% inhibited at a MIC of < or =2 microg/ml). Results by species, expressed as MIC50/MIC90 (micrograms per milliliter), were as follows: C. albicans, 0.015/0.03; C. glabrata, 0.015/0.015; C. tropicalis, 0.03/0.06; C. krusei, 0.06/0.12; C. kefyr, 0.06/0.06; C. parapsilosis, 1/2; C. guilliermondii, 0.5/1; C. lusitaniae, 0.12/0.25; other Candida spp., 0.25/1. Although the species distribution varied considerably among the different geographic regions, there was no difference in micafungin activity across the regions. Micafungin has excellent in vitro activity against invasive clinical isolates of Candida from centers worldwide.

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

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

The emergence of non-albicans Candida species as causes of invasive candidiasis and candidemia

The last three decades have seen an expanding pool of high-risk patients susceptible to the opportunistic pathogen Candida. Accordingly, a dramatic increase in nosocomial blood stream infections (BSIs) due to Candida spp has been reported throughout the world, starting in tertiary care centers and spreading to community hospitals. This absolute increase in Candida BSIs was accompanied by both an absolute and then a proportional increase in invasive infection caused by reduced fluconazole-susceptible non-albicans Candida spp. Currently, the incidence trend of BSI has stabilized, and Candida albicans remains the most common species causing fungal BSI. Clinicians must be aware of the importance and implications of non-albicans Candida spp when selecting antifungal drugs, although most studies have not shown significant outcome differences with use of the various antifungal classes.

Caspofungin for invasive candidiasis at a tertiary care medical center

BACKGROUND

Caspofungin is emerging as first-line therapy for invasive candidiasis. Data on the use of caspofungin for treatment for invasive candidiasis are limited to clinical trials and case reports. We report a single-center experience with 104 consecutive courses of caspofungin for the treatment of invasive candidiasis to evaluate a real-world performance of this drug.

METHODS

A retrospective chart review of patients receiving caspofungin at a tertiary care medical center was performed. Patient information and microbiologic data were abstracted from patient charts and electronic medical records.

RESULTS

Of 241 patients receiving caspofungin for all indications, 122 (51%) had proven invasive candidiasis. There were 104 treatment courses for candidiasis in 99 patients available for review. Bloodstream (66%) and abdominal infections (25%) were the most common sites of infection. Most infections were non-albicans (80/104, 77%; including patients infected with more than one species). Clinical cure rates at the end of therapy were 83% (57/69) for bloodstream infections and 84% (22/26) for abdominal infections. Caspofungin did not clear candidiasis in 14 episodes (microbiologic cure rate 75%, 42/56).

CONCLUSIONS

The clinical use of caspofungin has been successful in the treatment of invasive candidiasis, even in patients with prior antifungal exposure. In this unselected review, caspofungin performed similarly as in clinical trials, and clinicians should consider caspofungin as first-line therapy for invasive candidiasis, particularly non-albicans species.

Use of fluconazole as a surrogate marker to predict susceptibility and resistance to voriconazole among 13,338 clinical isolates of Candida spp. Tested by clinical and laboratory standards institute-recommended broth microdilution methods

Clinical laboratories frequently face the problem of delayed availability of commercially prepared approved reagents for performing susceptibility testing of new antimicrobials. Although this problem is encountered more often with antibacterial agents, it is also an issue with antifungal agents. A current example is voriconazole, a new triazole antifungal with an expanded spectrum and potency against Candida spp., Aspergillus spp., and other opportunistic fungal pathogens. The present study addresses the use of fluconazole as a surrogate marker to predict the susceptibility of Candida spp. to voriconazole. Reference broth microdilution MIC results for 13,338 strains of Candida spp. isolated from more than 200 medical centers worldwide were used. Voriconazole MICs and interpretive categories (susceptible, < or =1 microg/ml; susceptible dose dependent, 2 microg/ml; resistant, > or =4 microg/ml) were compared with those of fluconazole by regression statistics and error rate bounding analyses. For all 13,338 isolates, the absolute categorical agreement was 91.6% (false susceptible or very major error [VME], 0.0%). Since voriconazole is 16- to 32-fold more potent than fluconazole, the performance of fluconazole as a surrogate marker for voriconazole susceptibility was improved by designating those isolates with fluconazole MICs of < or =32 microg/ml as being susceptible to voriconazole, resulting in a categorical agreement of 97% with 0.1% VME. Clinical laboratories performing antifungal susceptibility testing of fluconazole against Candida spp. can reliably use these results as surrogate markers until commercial FDA-approved voriconazole susceptibility tests become available.

Épidémiologie des fongémies dans les hôpitaux français non universitaires en 2004 : enquête multicentrique ColBVH

INTRODUCTION

The aim of our study was to determinate the frequency of candidemia, the species encountered and their susceptibility to antifungal agents in French hospitals in 2004.

METHODS

A prospective survey of septicaemia, including candidaemia was conducted among 193 non teaching French hospitals during October 2004. All bloodstream infections were reported and the bloodstream isolates sent to two coordinating centers. Species identification and susceptibility were performed by biologists as usual, and further confirmed by use of alternative methods, including Minimal Inhibitory Concentration (MIC) determination.

RESULTS

The survey was effective in 93 hospitals, where 2013 bloodstream infections were noticed, including 46 candidaemia (2.3%). Candida sp. Is the 7th pathogen responsible for bloodstream infection, without concern of the origin of the infection. Candidaemia was hospital acquired in 80.4% of cases (N=37/46). Candidaemia represents 0.7% (N=9/1211) of community-acquired bloodstream infections but 4.5% (N=37/802) of nosocomial cases, placing Candida sp. at the 5th row of frequency in this last group. No mistakes were noticed during identification, but two strains were not named. After confirmation of identification, species are distributed as follows: 23 C.albicans (50%), 13 C.glabrata (28.3%), 5 C.tropicalis (10.9%), 3 C.parapsilosis (6.5%), 1 C.krusei (2.2%), and 1 C.kefyr (2.2%). The overall susceptibility is 97.7% for amphotericin B, 93.2% for 5-fluorocytosin, 88.6% for fluconazole, 70.5% for itraconazole, 95.5% for voriconzole and 100% of strains had very low MIC for caspofungin. Concerning the two main species isolated, 95.5% of C.albicans strains remain susceptible to fluconazole, but only 69% of C.glabrata strains. Two strains, 1 C.albicans and 1 C.glabrata exhibit cross resistance to azoles. The majority of amphotericin, fluconazole, and itraconazole decreased susceptibility strains are found into C.glabrata strains, but susceptibility to 5-fluorocytosin and very low MCI to caspofungin remained in this species.

CONCLUSION

Our survey allowed us to get data from French non-teaching hospitals in 2004 about frequency of candidaemia among septicaemia. Candida species distribution and in vitro susceptibility patterns of the strains isolated. Candidaemia is not a rare event, specially when septicaemia is nosocomially acquired. C.albicans is the main species isolated and remains highly in vitro susceptible to antifungals. One important feature is the frequency of C.glabrata in our survey. Considering its decreased susceptibility to azoles, this finding confirms the need for rapid identification of yeast isolated from bloodstream samples, and antifungal susceptibility testing each time it is available.

Kefir: a symbiotic yeasts-bacteria community with alleged healthy capabilities

Kefir is a fermented milk beverage. The milk fermentation is achieved by the of kefir grains, a cluster of microorganisms held together by a polysaccharide matrix named kefiran. Kefir grains are an example of symbiosis between yeast and bacteria. They have been used over years to produce kefir, a fermented beverage that is consumed all over the world, although its origin is Caucasian. A vast variety of different species of organisms forming the kefir grains, comprising yeast and bacteria, have been isolated and identified. Kefir is a probiotic food. Probiotics have shown to be beneficial to health, being presently of great interest to the food industry. Kefir has been accredited with antibacterial, antifungal and antitumoural activities among other beneficial attributes. This review includes a critical revision of the microbiological composition of kefir along with its beneficial properties to human health.

Echinocandins in the management of invasive fungal infections, part 1

PURPOSE

The chemistry, pharmacology, spectrum of activity, resistance, pharmacokinetics, pharmacodynamics, clinical efficacy, adverse effiects, drug interactions, dosage and administration, cost, and place in therapy of echinocandins are reviewed.

SUMMARY

Three echinocandins are currently available: caspofungin, micafungin, and anidulafungin. The principal mechanism of action of the echinocandins is the noncompetitive inhibition of beta-(1,3)-dglucan synthase, an essential component of the cell wall of many fungi that is not present in mammalian cells. Echinocandins exhibit fungicidal activity against Candida species, including triazole-resistant isolates, and fungistatic activity against Aspergillus species. While fungistatic against mold, echinocandins may hold promise for the treatment of these pathogens when given in combination with amphotericin B or broad-spectrum triazoles, such as voriconazole. To date, resistance to echinocandins has been reported in only two patients. Echinocandins exhibit concentration- dependent activity against Candida species. In clinical trials, caspofungin has demonstrated efficacy in treating candidemia, esophageal candidiasis, and febrile neutropenia. Micafungin has demonstrated efficacy as antifungal prophylaxis in hematopoietic stem cell transplant recipients and in the treatment of esophageal candidiasis. Anidulafungin received approved labeling from the Food and Drug Administration in February 2006. Clinical efficacy data will be forthcoming.

CONCLUSION

Echinocandins are fungicidal against yeast and fungistatic against mold. Their limited toxicity profile and minimal drug-drug interactions make them an attractive new option for the treatment of invasive fungal infections. Their cost may limit their use as initial therapy for patients with fungemia in medical centers or intensive care units with a high rate of triazoleresistant Candida infections.

Invasive Candidiasis

Invasive candidiasis remains an important nosocomial infection that continues to present major diagnostic and therapeutic challenges to the clinician. Changes in the epidemiology of this disorder have occurred for many reasons, and included especially the extensive use of prophylactic antifungal agents, broad-spectrum antibacterial agents, and medical devices (eg, chronic indwelling intravascular catheters). The diagnosis of IC remains elusive in many patients, and there is a critical need for improved diagnostics that will provide clinicians the opportunity to intervene earlier in the course of disease. Newer antifungal agents offer promise in the treatment of candidemia and other forms of IC, but the optimal use of these agents, particularly in the approach to non-albicans Candida infections, needs to be explored in more detail. Furthermore, despite an overwhelming amount of data concerning risk factors and excess mortality associated with the development of IC, there is no consistent approach to treatment and primary prevention among individuals who are deemed to be at highest risk for this complication. Research that focuses on these important clinical areas could provide valuable insights into the diagnosis and management of this common and evolving infection.

Control of a Candida glabrata prosthetic endovascular infection with posaconazole

A 63-year-old man with a history of cirrhosis of the liver developed Candida glabrata fungemia after undergoing transjugular intrahepatic portosystemic shunt (TIPS) placement. Treatment with oral fluconazole was initially effective, but when the patient became neutropenic, subsequent blood cultures grew C. glabrata and a thrombus developed, which partially occluded the stent. Despite treatment with fluconazole, blood cultures remained positive for C. glabrata. Treatment with posaconazole resulted in clinical improvement and the patient had only intermittently positive fungal cultures for 6 weeks. A CT scan showed resolution of the inferior vena cava thrombus. Subsequently, the patient developed hepatocellular carcinoma and hepatic encephalopathy and became noncompliant with posaconazole. Blood cultures again became positive for C. glabrata. The patient died a few weeks after the diagnosis of hepatocellular carcinoma, but the cause of death was believed to be worsening liver dysfunction, not C. glabrata infection. Posaconazole had controlled the infection for about 3 months prior to his death. In conclusion, posaconazole may be a useful option in the management of prosthetic endovascular infections caused by C. glabrata.

Emerging echinocandins for treatment of invasive fungal infections

The echinocandins are a new class of antifungals, developed in response to the need for safe and effective antifungals for the treatment of invasive fungal infections. These agents work by inhibiting 1,3-beta-d-glucan synthase, an enzyme essential for production of cell walls in select fungi. Echinocandins appear to demonstrate favourable activity in vitro against a variety of yeasts (including both Candida albicans and non-albicans Candida) as well as select moulds (including Aspergillus spp.) In general, all echninocandins demonstrate a favourable safety profile and require once-daily parenteral administration. Caspofungin is the first of these agents to be available in the US, and is approved for empirical antifungal therapy in febrile neutropenic patients, candidaemia and select forms of invasive candidiasis, and for management of invasive aspergillosis in patients refractory to or intolerant of other therapies. Micafungin was recently approved by the FDA for treatment of oesophageal candidiasis, and for the prophylaxis of fungal infections in haematopoietic stem cell transplant recipients. Emerging data indicate micafungin may have an important role in the treatment of invasive forms of candidiasis. Anidulafungin is an echinocandin approved in the US for treatment of candidaemia and oesophageal candidiasis. Aminocandin (HMR-3702, IP-960) is an investigational agent, with published experience limited to in vitro studies and animal models of infection.

Clinical significance of azole antifungal drug cross-resistance in Candida glabrata

Candida glabrata, which can become resistant to fluconazole, is a common cause of bloodstream infection. This study was performed to determine the significance of cross-resistance to new azole drugs among C. glabrata isolates recovered as a cause of infection in azole-treated hematopoietic stem cell transplant (HSCT) recipients. Seven cases of invasive candidiasis caused by C. glabrata occurred in HSCT recipients who were receiving azole therapy between January 2000 and December 2004 in our institution. Case characteristics were ascertained. Sequential colonizing and invasive isolates were examined to determine susceptibilities to fluconazole, itraconazole, and voriconazole, and molecular relatedness by restriction fragment length polymorphism (RFLP) analysis. Twenty-three C. glabrata isolates were recovered from 4 patients who developed candidemia while receiving fluconazole and three patients who developed candidemia while receiving voriconazole. The mode MICs of fluconazole, itraconazole, and voriconazole for these isolates were > or =64 microg/ml (range, 4 to > or =64 microg/ml), 2 microg/ml (range, 0.25 to > or =16 microg/ml), and 1 microg/ml (range, 0.03 to > or =16 microg/ml), respectively. Kendall tau b correlation coefficients demonstrated significant associations between the MICs of voriconazole with fluconazole (P = 0.005) and itraconazole (P = 0.008). Colonizing and invasive isolates exhibiting variable susceptibilities had similar RFLP patterns. These observations suggest that C. glabrata exhibits considerable clinically significant cross-resistance between older azole drugs (fluconazole and itraconazole) and voriconazole. Caution is advised when considering voriconazole therapy for C. glabrata candidemia that occurs in patients with extensive prior azole drug exposure.

Epidemiology, risk factors, and prognosis of Candida parapsilosis bloodstream infections: case-control population-based surveillance study of patients in Barcelona, Spain, from 2002 to 2003

Candida parapsilosis has emerged as an important yeast species causing fungemia. We describe the incidence and epidemiology of C. parapsilosis fungemia. Data from active population-based surveillance in Barcelona, Spain, from January 2002 to December 2003 were analyzed. We focused on 78 episodes of C. parapsilosis fungemia, and we compared them with 175 Candida albicans controls. C. parapsilosis accounted for 23% of all fungemias. The annual incidences were 1 episode per 10(5) patients, 1.2 episodes per 10(4) discharges, and 1.7 episodes per 10(5) patient days. All isolates but one (99%) were fluconazole susceptible. Seventy-two isolates (92%) were inpatient candidemias. Forty-two episodes (51%) were considered catheter-related fungemia, 35 (45%) were considered primary fungemia, and 3 (4%) were considered secondary fungemia. Risk factors for candidemia were vascular catheterization (97%), prior antibiotic therapy (91%), parenteral nutrition (54%), prior surgery (46%), prior immunosuppressive therapy (38%), malignancy (27%), prior antifungal infection (26%), transplant recipient (16%), neutropenia (12%), and prior colonization (11%). Multivariate analysis of the differential characteristics showed that the factors that independently predicted the presence of C. parapsilosis fungemia were neonate patients (odds ratio [OR], 7.5; 95% confidence interval [CI], 2.1 to 26.8; P = 0.002), transplant recipients (OR, 9.2; 95% CI, 1.9 to 43.3; P = 0.005), patients with a history of prior antifungal therapy (OR, 5.4; 95% CI, 1.8 to 15.9; P = 0.002), and patients who received parenteral nutrition (OR, 2.2; 95% CI, 1.09 to 4.6; P = 0.028). The overall mortality rate was lower than that associated with C. albicans candidemia (23% versus 43%; P < 0.01). In summary, C. parapsilosis was responsible for 23% of all candidemias and was more frequent in neonates, in transplant recipients, and in patients who received parenteral nutrition or previous antifungal therapy, mainly fluconazole. The mortality rate was lower than that associated with C. albicans fungemia.

Correlation of MIC with outcome for Candida species tested against voriconazole: analysis and proposal for interpretive breakpoints

Developing interpretive breakpoints for any given organism-drug combination requires integration of the MIC distribution, pharmacokinetic and pharmacodynamic parameters, and the relationship between the in vitro activity and outcome from both in vivo and clinical studies. Using data generated by standardized broth microdilution and disk diffusion test methods, the Antifungal Susceptibility Subcommittee of the Clinical and Laboratory Standards Institute has now proposed interpretive breakpoints for voriconazole and Candida species. The MIC distribution for voriconazole was determined using a collection of 8,702 clinical isolates. The overall MIC90 was 0.25 microg/ml and 99% of the isolates were inhibited at < or = 1 microg/ml of voriconazole. Similar results were obtained for 1,681 Candida isolates (16 species) from the phase III clinical trials. Analysis of the available data for 249 patients from six phase III voriconazole clinical trials demonstrated a statistically significant correlation (P = 0.021) between MIC and investigator end-of-treatment assessment of outcome. Consistent with parallel pharmacodynamic analyses, these data support the following MIC breakpoints for voriconazole and Candida species: susceptible (S), < or = 1 microg/ml; susceptible dose dependent (SDD), 2 microg/ml; and resistant (R), > or = 4 microg/ml. The corresponding disk test breakpoints are as follows: S, > or = 17 mm; SDD, 14 to 16 mm; and R, < or = 13 mm.

Candidemia in Norway (1991 to 2003): results from a nationwide study

A long-term, nationwide prospective candidemia study has been ongoing in Norway since 1991. All medical microbiological laboratories in the country have participated. During the period 1991 to 2003 a total of 1,393 episodes of candidemia occurred in 1,348 patients. The incidence of candidemia episodes per 100,000 inhabitants increased from approximately 2 episodes in the early 1990s to 3 episodes in 2001 to 2003. The average annual incidences varied markedly between the age groups. The incidence was high in patients aged < 1 year and in patients aged > or = 70 years. In patients > or = 80 years of age, the incidence has increased during the last 3 years from an annual average of 6.5 to 15.6 cases/100,000 inhabitants in 2003. Four Candida species (C. albicans [70%], C. glabrata [13%], C. tropicalis [7%], and C. parapsilosis [6%]) accounted for 95.5% of the isolates. The species distribution has been constant during the 13-year study period. The distribution of the most important species varied with the age of the patient. In patients < 1 year of age, the majority of episodes were caused by C. albicans (91%). The occurrence of C. glabrata increased with age. In patients > or = 80 years of age, approximately 1/3 of all episodes were due to this species. All C. albicans strains were susceptible to fluconazole. The percentage of yeast isolates with decreased susceptibility to fluconazole (MICs > or = 16 microg/ml) was 10.7% during the first period of this study (1991 to 1996) and 11.7% during the second period (1997 to 2003).

Candidaemia and antifungal therapy in a French University Hospital: rough trends over a decade and possible links

Background

Evidence for an increased prevalence of candidaemia and for high associated mortality in the 1990s led to a number of different recommendations concerning the management of at risk patients as well as an increase in the availability and prescription of new antifungal agents. The aim of this study was to parallel in our hospital candidemia incidence with the nature of prescribed antifungal drugs between 1993 and 2003.

Methods

During this 10-year period we reviewed all cases of candidemia, and collected all the data about annual consumption of prescribed antifungal drugs

Results

Our centralised clinical mycology laboratory isolates and identifies all yeasts grown from blood cultures obtained from a 3300 bed teaching hospital. Between 1993 and 2003, 430 blood yeast isolates were identified. Examination of the trends in isolation revealed a clear decrease in number of yeast isolates recovered between 1995–2000, whereas the number of positive blood cultures in 2003 rose to 1993 levels. The relative prevalence of Candida albicans and C. glabrata was similar in 1993 and 2003 in contrast to the period 1995–2000 where an increased prevalence of C. glabrata was observed. When these quantitative and qualitative data were compared to the amount and type of antifungal agents prescribed during the same period (annual mean defined daily dose: 2662741; annual mean cost: 615629 €) a single correlation was found between the decrease in number of yeast isolates, the increased prevalence of C. glabrata and the high level of prescription of fluconazole at prophylactic doses between 1995–2000.

Conclusion

Between 1993 and 2000, the number of cases of candidemia halved, with an increase of C. glabrata prevalence. These findings were probably linked to the use of Fluconazole prophylaxis. Although it is not possible to make any recommendations from this data the information is nevertheless interesting and may have considerable implications with the introduction of new antifungal drugs.

Interpretive breakpoints for fluconazole and Candida revisited: a blueprint for the future of antifungal susceptibility testing

Developing interpretive breakpoints for any given organism-drug combination requires integration of the MIC distribution, pharmacokinetic and pharmacodynamic parameters, and the relationship between in vitro activity and outcome from both in vivo and clinical studies. Previously, the Subcommittee for Antifungal Testing of the Clinical and Laboratory Standards Institute (CLSI [formerly National Committee for Clinical Laboratory Standards]) proposed MIC interpretive breakpoints for fluconazole and Candida spp. These breakpoints were considered to be somewhat weak, because the clinical data supporting them came largely from mucosal infections and there were very few infections involving strains with elevated fluconazole MICs. We readdress the issue of fluconazole breakpoints for Candida by using published clinical and microbiologic data to provide further validation of the breakpoints proposed by the CLSI in 1997. We also address interpretive breakpoints for agar disk diffusion testing of fluconazole. The MIC distribution for fluconazole was determined with a collection of 13,338 clinical isolates. The overall MIC at which 90% of the isolates were inhibited was 8 microg/ml: 91% were susceptible (S) at a MIC of or= 64 microg/ml). Similar results were obtained for 2,190 isolates from randomized clinical trials. Analysis of available data for 1,295 patient-episode-isolate events (692 represented mucosal infections and 603 represented invasive infections) from 12 published clinical studies demonstrated an overall success rate of 77%, including 85% for those episodes in which the fluconazole MIC was or= 64 microg/ml) isolates. Pharmacodynamic analysis demonstrated a strong relationship between MIC, fluconazole dose, and outcome. A dose/MIC ratio of approximately 25 was supportive of the following susceptibility breakpoints for fluconazole and Candida spp.: S, MIC or= 64 microg/ml. The corresponding disk test breakpoints are as follows: S, >or=19 mm; SDD, 15 to 18 mm; R, Collapse

Key Words Collapse

MESH Headings

• Antifungal Agents/administration & dosage
• Antifungal Agents/pharmacology
• Antifungal Agents/therapeutic use
• Candida/drug effects
• Candidiasis/drug therapy
• Clinical Trials as Topic
• Dose-Response Relationship, Drug
• Drug Resistance, Fungal
• Fluconazole/pharmacokinetics
• Fluconazole/pharmacology
• Fluconazole/therapeutic use
• Humans
• Microbial Sensitivity Tests/standards
• Treatment Outcome

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Grants Collapse

Affiliation(s)

M A Pfaller Department of Pathology, Medical Microbiology Division, C606 GH, University of Iowa College of Medicine, Iowa City, 52242, USA.
D J Diekema
D J Sheehan

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Fluconazole for the management of invasive candidiasis: where do we stand after 15 years?

Candida spp. are responsible for most of the fungal infections in humans. Available since 1990, fluconazole is well established as a leading drug in the setting of prevention and treatment of mucosal and invasive candidiasis. Fluconazole displays predictable pharmacokinetics and an excellent tolerance profile in all groups, including the elderly and children. Fluconazole is a fungistatic drug against yeasts and lacks activity against moulds. Candida krusei is intrinsically resistant to fluconazole, and other species, notably Candida glabrata, often manifest reduced susceptibility. Emergence of azole-resistant strains as well as discovery of new antifungal drugs (new triazoles and echinocandins) have raised important questions about its use as a first line drug. The aim of this review is to summarize the main available data on the position of fluconazole in the prophylaxis or curative treatment of invasive Candida spp. infections. Fluconazole is still a major drug for antifungal prophylaxis in the setting of transplantation (solid organ and bone marrow), intensive care unit, and in neutropenic patients. Prophylactic fluconazole still has a place in HIV-positive patients in viro-immunological failure with recurrent mucosal candidiasis. Fluconazole can be used in adult neutropenic patients with systemic candidiasis, as long as the species identified is a priori susceptible. Among non-neutropenic patients with candidaemia fluconazole is one of the first line drugs for susceptible species. Cases reports and uncontrolled studies have also reported its efficacy in the setting of osteoarthritis, endophthalmitis, meningitis, endocarditis and peritonitis caused by Candida spp. among immunocompetent adults. In paediatrics, fluconazole is a well tolerated and major prophylactic drug for high-risk neonates, as well as an alternative treatment for neonatal candidiasis. Importantly 15 years after its introduction in the antifungal armamentarium, fluconazole is still a first line treatment option in several cases of invasive candidiasis. Its prophylactic use should however be limited to selected high-risk patients to limit the risk of emergence of azole-resistant strains.

Activities of flucytosine, fluconazole, amphotericin B, and micafungin in a murine model of disseminated infection by Candida glabrata

We compared the efficacies of amphotericin B, fluconazole, flucytosine, and micafungin in a systemic murine infection by three isolates of Candida glabrata. Amphotericin B showed the best results, although none of the drugs dramatically reduced mortality or tissue burden in liver or spleen.

In vitro antifungal effect of amine fluoride-stannous fluoride combination on oral Candida species

OBJECTIVE

The combination of amine fluoride and stannous fluoride (AmF/SnF2) was, by chance, found to be antifungal in a clinical trial. This study investigated its effect on pathogenic Candida species with the hypothesis that the antifungal action on different species is variable.

MATERIALS AND METHODS

Growth inhibition effect of Meridol mouth rinse which contains 250 ppm AmF/SnF2 was evaluated on 43 reference and clinical strains of Candida albicans, C. dubliniensis, C. glabrata, C. guilliermondii, C. krusei, C. parapsilosis, and C. tropicalis. Meridol base solution without AmF/SnF2 was used as a negative control.

RESULTS

Undiluted Meridolmouth rinse killed most study strains within a few minutes. In ascending order, C. parapsilosis, C. tropicalis, C. albicans, C. glabrata, C. krusei and C. dubliniensis showed higher resistance against AmF/SnF2 than C. guilliermondii.

CONCLUSION

AmF/SnF2 could be used as a potent adjunct to antifungal therapy for oral yeasts. Although different Candida species demonstrated variable sensitivity the most prevalent oral yeast C. albicans appeared sensitive to the AmF/SnF2 combination.

Role of birds of prey as carriers and spreaders ofCryptococcus neoformansand other zoonotic yeasts

In the last 20 years, cases of human cryptococcosis, have increased in immunocompromised patients. In several instances, the cases have been associated with the exposure of the patients to bird droppings. In order to investigate birds of prey as potential carriers and spreaders of Cryptococcus neoformans and other yeasts of importance in human infections, 182 swab samples were collected from the cloacae of several species of birds of prey (Group I) and 32 faecal samples from aviaries in which the birds were housed (Group II). Samples were also taken from digestive tract of 60 dead birds (Group III). A total of 454 samples were cultured from which 215 colonies of yeastlike fungi were recovered and identified. Cryptococcusneoformans var. grubii was isolated from three cloacae samples (4.8%) collected from Falco tinnunculus and from one sample (3.1%) obtained from Buteo buteo, as well as from samples collected at the aviaries in which these birds were kept. Overall, 18 samples (9.9%) from Group I, 13 (40.6%) from Group II, 12 crops (20%), three proventriculi (5%) and 12 cloacae (20%) from Group III yielded positive cultures for yeasts. The results indicate that birds of prey and in particular, F. tinnunculus and B. buteo, may act as carriers and spreaders of C. neoformans and other zoonotic yeasts.

Population structure and properties of Candida albicans, as determined by multilocus sequence typing

We submitted a panel of 416 isolates of Candida albicans from separate sources to multilocus sequence typing (MLST). The data generated determined a population structure in which four major clades of closely related isolates were delineated, together with eight minor clades comprising five or more isolates. By Fisher's exact test, a statistically significant association was found between particular clades and the anatomical source, geographical source, ABC genotype, decade of isolation, and homozygosity versus heterozygosity at the mating type-like locus (MTL) of the isolates in the clade. However, these associations may have been influenced by confounding variables, since in a univariate analysis of variance, only the clade associations with ABC type and anatomical source emerged as statistically significant, providing the first indication of possible differences between C. albicans strain type clades and their propensity to infect or colonize different anatomical locations. There were no significant differences between clades with respect to distributions of isolates resistant to fluconazole, itraconazole, or flucytosine. However, the majority of flucytosine-resistant isolates belonged to clade 1, and these isolates, but not flucytosine-resistant isolates in other clades, bore a unique mutation in the FUR1 gene that probably accounts for their resistance. A significantly higher proportion of isolates resistant to fluconazole, itraconazole, and flucytosine were homozygous at the MTL, suggesting that antifungal pressure may trigger a common mechanism that leads both to resistance and to MTL homozygosity. The utility of MLST for determining clade assignments of clinical isolates will form the basis for strain selection for future research into C. albicans virulence.

Results from the ARTEMIS DISK Global Antifungal Surveillance Study: a 6.5-year analysis of susceptibilities of Candida and other yeast species to fluconazole and voriconazole by standardized disk diffusion testing

Fluconazole in vitro susceptibility test results for 140,767 yeasts were collected from 127 participating investigators in 39 countries from June 1997 through December 2003. Data were collected on 79,343 yeast isolates tested with voriconazole from 2001 through 2003. All investigators tested clinical yeast isolates by the CLSI (formerly NCCLS) M44-A disk diffusion method. Test plates were automatically read and results were recorded with the BIOMIC Vision Image Analysis System. Species, drug, zone diameter, susceptibility category, and quality control results were collected quarterly via e-mail for analysis. Duplicate (the same patient, same species, and same susceptible-resistant biotype profile during any 7-day period) and uncontrolled test results were not analyzed. The 10 most common species of yeasts all showed less resistance to voriconazole than to fluconazole. Candida krusei showed the largest difference, with over 70% resistance to fluconazole and less than 8% to voriconazole. All species of yeasts tested were more susceptible to voriconazole than to fluconazole, assuming proposed interpretive breakpoints of > or =17 mm (susceptible) and < or =13 mm (resistant) for voriconazole. MICs reported in this study were determined from the zone diameter in millimeters from the continuous agar gradient around each disk, which was calibrated with MICs determined from the standard CLSI M27-A2 broth dilution method by balanced-weight regression analysis. The results from this investigation demonstrate the broad spectrum of the azoles for most of the opportunistic yeast pathogens but also highlight several areas where resistance may be progressing and/or where previously rare species may be "emerging."

Fluconazole dosing in continuous veno-venous haemofiltration (CVVHF): need for a high daily dose of 800 mg

To cover intermediate sensitive Candida glabrata in ICU patients, fluconazole plasma peak levels at least in the range of 16-32 microg/ml appear necessary for treatment. Previous studies did not reach these fluconazole levels under continuous veno-venous haemofiltration (CVVHF) with dosages of 200-600 mg fluconzole daily. In the present study, nine patients simultaneously requiring CVVHF for treatment of acute oligoanuric renal failure and antimycotic therapy of Candida septicemia received fluconazole 800 mg/day. Fluconazole plasma levels were determined to evaluate whether this dosage is adequate to reach the advised fluconazole levels. Patients were dialysed on two consecutive days with an ultrafiltration rate (UF) of 1000 ml/h or 2000 ml/h, respectively, in a randomized order. The predilution was 800 ml/h and 1800 ml/h, respectively. The treatment was tolerated without adverse effects. All patients reached plasma fluconazole concentrations between 16 and 32 microg/ml, remaining in this range for a minimum of 1 up to 24 h with a mean of 9.6 h and a UF rate of 2000 ml/h, and 15.7 h with a UF rate of 1000 ml/h. So far, there are no in vivo data on the fluconazole plasma concentrations required for effective treatment. However, our data demonstrate, that at least the fluconazole concentrations desirable on the basis of in vitro susceptibility testing can be reached in critically ill patients on CVVHF in an ICU setting. However, in these patients, 800 mg fluconazole/day are necessary to achieve fungicidal drug concentrations.

The Changing Face of Fungal Infections in Health Care Settings

As strategies to prevent invasive fungal infections among both hospitalized and nonhospitalized patients have evolved, the epidemiology of these infections has changed. Several unique features of select Candida species and molds have facilitated the emergence of these pathogens as more-common causes of infection than in previous years. In this context, the changing pathogen profiles, unique antifungal susceptibilities, and approaches to treatment are outlined.

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

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

International, open-label, noncomparative, clinical trial of micafungin alone and in combination for treatment of newly diagnosed and refractory candidemia

Candida spp. are the fourth leading cause of bloodstream infections, and non-albicans species are increasing in importance. Micafungin is a new echinocandin antifungal agent with excellent in vitro activity against Candida spp. Pediatric, neonatal, and adult patients with new or refractory candidemia were enrolled into this open-label, noncomparative, international study. The initial dose of micafungin was 50 mg/d (1 mg/kg for patients <40 kg) for infections due to C. albicans and 100 mg/d (2 mg/kg for patients <40 kg) for infections due to other species. Dose escalation was allowed. Maximum length of therapy was 42 days. A total of 126 patients were evaluable (received at least five doses of micafungin). Success (complete or partial response) was seen in 83.3% patients overall. Success rates for treatment of infections caused by the most common Candida spp. were as follows: C. albicans 85.1%, C. glabrata 93.8%, C. parapsilosis 86.4%, and C. tropicalis 83.3%. Serious adverse events related to micafungin were uncommon. Micafungin shows promise as a safe and effective agent for the treatment of newly diagnosed and refractory cases of candidemia. Large-scale, randomized, controlled trials are warranted.

The use of prophylactic fluconazole in immunocompetent high-risk surgical patients: a meta-analysis

Introduction

High-risk surgical patients are at increased risk of fungal infections and candidaemia. Evidence from observational and small randomised controlled studies suggests that prophylactic fluconazole may be effective in reducing fungal infection and mortality. We evaluated the effects of prophylactic fluconazole on the incidence of candidaemia and hospital mortality in immunocompetent high-risk surgical patients.

Methods

Randomised controlled studies involving the use of fluconazole in immunocompetent high-risk surgical patients from the Cochrane Controlled Trial Register (2005, issue 1) and from the EMBASE and MEDLINE databases (1966–30 April 2005), without any language restriction, were included. Two reviewers reviewed the quality of the studies and performed data extraction independently.

Results

Seven randomised controlled studies with a total of 814 immunocompetent high-risk surgical patients were considered. The use of prophylactic fluconazole was associated with a reduction in the proportion of patients with candidaemia (relative risk [RR] = 0.21, 95% confidence interval [CI] = 0.06–0.72, P = 0.01; I² = 0%) and fungal infections other than lower urinary tract infection (RR = 0.39, 95% CI = 0.24–0.65, P = 0.0003; I² = 0%), but was associated with only a trend towards a reduction in hospital mortality (RR = 0.82, 95% CI = 0.62–1.08, P = 0.15; I² = 7%). The proportion of patients requiring systemic amphotericin B as a rescue therapy for systemic fungal infection was lower after prophylactic use of fluconazole (RR = 0.35, 95% CI = 0.17–0.72, P = 0.004; I² = 0%). The proportion of patients colonised with or infected with fluconazole-resistant fungi was not significantly different between the fluconazole group and the placebo group (RR = 0.66, 95% CI = 0.22–1.96, P = 0.46; I² = 0%).

Conclusion

The use of prophylactic fluconazole in immunocompetent high-risk surgical patients is associated with a reduced incidence of candidaemia but with only a trend towards a reduction in hospital mortality.

An update on antifungal targets and mechanisms of resistance in Candida albicans

Much progress has been made in the last decade in identifying genes responsible for antifungal resistance in Candida albicans. Attention has focused on five major C. albicans genes: ABC transporter genes CDR1 and CDR2, major facilitator efflux gene MDR1, and ergosterol biosynthesis genes ERG11 and ERG3. Resistance involves mutations in 14C-lanosterol demethylase, targeted by fluconazole (FLZ) and encoded by ERG11, and mutations that up-regulate efflux genes that probably efflux the antifungals. Mutations that affect ERG3 mutations have been understudied as mechanism resistance among clinical isolates. In vitro resistance in clinical isolates typically involves step-wise mutations affecting more than one of these genes, and often unidentified genes. Different approaches are needed to identify these other genes. Very little is understood about reversible adaptive resistance of C. albicans despite its potential clinical significance; most clinical failures to control infections other than oropharyngeal candidiasis (OPC) occur with in vitro susceptible strains. Tolerance of C. albicans to azoles has been attributed to the calcineurin stress-response pathway, offering new potential targets for next generation antifungals. Recent studies have identified genes that regulate CDR1 or ERG genes. The focus of this review is C. albicans, although information on Saccharomyces cerevisiae or Candida glabrata is provided in areas in where Candida research is underdeveloped. With the completion of the C. albicans genomic sequence, and new methods for high throughput gene overexpression and disruption, rapid progress towards understanding the regulation of resistance, novel resistance mechanisms, and adaptive resistance is expected in the near future.

Comparison of results of voriconazole disk diffusion testing for Candida species with results from a central reference laboratory in the ARTEMIS global antifungal surveillance program

The accuracy of antifungal susceptibility testing is important for reliable resistance surveillance and for the clinical management of patients with serious infections. Our primary objective was to compare the results of voriconazole disk diffusion testing of Candida spp. performed by centers participating in the ARTEMIS program with disk diffusion and MIC results obtained by the central reference laboratory. A total of 2,934 isolates of Candida spp. were tested by CLSI disk diffusion and reference broth microdilution methods in the central reference laboratory. These results were compared to the results of disk diffusion testing performed in the 54 participating centers. All tests were performed and interpreted following CLSI recommendations, as follows: susceptible (S), MIC of or=17 mm); susceptible dose dependent (SDD), MIC of 2 microg/ml (14 to 16 mm); and resistant (R), MIC of >or=4 microg/ml (or=4 microg/ml) by MIC testing. External quality assurance data obtained by surveillance programs such as the ARTEMIS Global Antifungal Surveillance Program ensure the generation of useful surveillance data and result in the continued improvement of antifungal susceptibility testing practices.

A genome sequence survey shows that the pathogenic yeast Candida parapsilosis has a defective MTLa1 allele at its mating type locus

Candida parapsilosis is responsible for ca. 15% of Candida infections and is of particular concern in neonates and surgical intensive care patients. The related species Candida albicans has recently been shown to possess a functional mating pathway. To analyze the analogous pathway in C. parapsilosis, we carried out a genome sequence survey of the type strain. We identified ca. 3,900 genes, with an average amino acid identity of 59% with C. albicans. Of these, 23 are predicted to be predominantly involved in mating. We identified a genomic locus homologous to the MTLa mating type locus of C. albicans, but the C. parapsilosis type strain has at least two internal stop codons in the MTLa1 open reading frame, and two predicted introns are not spliced. These stop codons were present in MTLa1 of all eight C. parapsilosis isolates tested. Furthermore, we found that all isolates of C. parapsilosis tested appear to contain only the MTLa idiomorph at the presumptive mating locus, unlike C. albicans and C. dubliniensis. MTLalpha sequences are present but at a different chromosomal location. It is therefore likely that all (or at least the majority) of C. parapsilosis isolates have a mating pathway that is either defective or substantially different from that of C. albicans.

Candida dubliniensis: ten years on

Candida dubliniensis was first described as a novel species in 1995. This organism is very closely related to the important human yeast pathogen, Candida albicans. However, despite the very close phylogenetic relationship between C. albicans and C. dubliniensis and the fact that they share a large number of phenotypic traits, epidemiological and virulence model data indicate that the former is a far more successful pathogen. In order to investigate the molecular basis of the lower virulence of C. dubliniensis recent comparative genomic hybridisation studies have revealed the absence and divergence of specific genes implicated in candidal virulence. Data from the C. dubliniensis genome sequencing project will allow a complete comparison between the genomes of the two species to be performed and thus enhance our understanding of candidal virulence and how virulence has evolved in Candida species.

Species distribution and antifungal susceptibility of Candida bloodstream isolates in a tertiary medical center in Israel

To evaluate the species distribution and antifungal susceptibility of Candida isolates in a tertiary institution in Israel, all consecutive isolates of Candida spp. recovered from blood during the last 2 years were studied. The isolates were identified by the germ tube test and the API ID 32C test (bioMérieux, Marcy l'Etoile, France). MICs of antifungal agents were determined by the E test. Candida albicans was the most commonly isolated species, accounting for 44% (63/142) of the isolates, followed by Candida tropicalis (25%; 35/142), Candida parapsilosis (20%; 29/142), Candida glabrata (10%; 14/142), and Candida krusei (0.7%; 1/142). All isolates were sensitive to amphotericin B and voriconazole. Resistance to fluconazole (using a high MIC of >/=256 microg/ml) was found in 1.6% of C. albicans isolates, in 3.4% of C. parapsilosis isolates, and in 21.4% of C. glabrata isolates. Resistance to itraconazole was detected in 3.2% of C. albicans isolates, in 2.9% of C. tropicalis isolates, in 3.4% of C. parapsilosis isolates, and in 93% of C. glabrata isolates. Disparities in species distribution and antifungal susceptibility of Candida isolates from the institute studied versus Candida isolates from other centers and countries are described. The findings emphasize the need for continuous surveillance and further clinical investigational studies.

In vitro susceptibilities of clinical isolates of Candida species, Cryptococcus neoformans, and Aspergillus species to itraconazole: global survey of 9,359 isolates tested by clinical and laboratory standards institute broth microdilution methods

The in vitro activity of itraconazole was determined against 7,299 isolates of Candida spp., 1,615 isolates of Cryptococcus neoformans, and 445 isolates of Aspergillus spp. obtained from over 200 medical centers worldwide. Itraconazole was active against all Candida spp. (96% of MICs were < or =1 microg/ml) with the exception of C. glabrata (77% of MICs were < or =1 microg/ml). Itraconazole inhibited 94% of C. krusei and 84% of other fluconazole-resistant Candida species, exclusive of C. glabrata, at a MIC of < or =1 microg/ml. Itraconazole was not active against fluconazole-resistant isolates of C. glabrata. Only modest activity was seen against C. neoformans (80% of MICs were < or =1 microg/ml); however, itraconazole showed excellent activity against Aspergillus spp. (94% of MICs were < or =1 microg/ml). These results provide an update on the antifungal activity of itraconazole against major opportunistic fungal pathogens. In light of the new intravenous formulation of itraconazole these data suggest that this agent remains a viable systemically active antifungal agent.

Emerging Fungal Diseases

The epidemiology of invasive fungal infection is evolving. Yeasts other than Candida albicans and molds other than Aspergillus fumigatus have emerged as significant causes of invasive mycoses in severely immunocompromised patients. Although, in some instances, these changes may be related to medical interventions, such as the use of antifungal agents in prophylaxis, in the majority of cases, they seem to be a consequence of changes in the host, such as more-severe immunosuppression or different types of immunosuppression impacting both risk periods and the infections that occur. These factors have altered the epidemiology of infection in organ transplant recipients, premature newborns, and critically ill patients. This review discusses the epidemiology of some fungal infections that have emerged in the past few years, with an emphasis on the potential factors associated with their emergence and on practical implications of these epidemiological changes.