Trends in frequency and in vitro susceptibilities to antifungal agents, including voriconazole and anidulafungin, of Candida bloodstream isolates. Results from a six-year study (1996-2001)

Current Aspects in the Biology, Pathogeny, and Treatment of Candida krusei, a Neglected Fungal Pathogen

Fungal infections represent a constant and growing menace to human health, because of the emergence of new species as causative agents of diseases and the increment of antifungal drug resistance. Candidiasis is one of the most common fungal infections in humans and is associated with a high mortality rate when the fungi infect deep-seated organs. Candida krusei belongs to the group of candidiasis etiological agents, and although it is not isolated as frequently as other Candida species, the infections caused by this organism are of special relevance in the clinical setting because of its intrinsic resistance to fluconazole. Here, we offer a thorough revision of the current literature dealing with this organism and the caused disease, focusing on its biological aspects, the host-fungus interaction, the diagnosis, and the infection treatment. Of particular relevance, we provide the most recent genomic information, including the gene prediction of some putative virulence factors, like proteases, adhesins, regulators of biofilm formation and dimorphism. Moreover, C. krusei veterinary aspects and the exploration of natural products with anti-C. krusei activity are also included.

Candida parapsilosis: from Genes to the Bedside

Patients with suppressed immunity are at the highest risk for hospital-acquired infections. Among these, invasive candidiasis is the most prevalent systemic fungal nosocomial infection. Over recent decades, the combined prevalence of non-albicans Candida species outranked Candida albicans infections in several geographical regions worldwide, highlighting the need to understand their pathobiology in order to develop effective treatment and to prevent future outbreaks. Candida parapsilosis is the second or third most frequently isolated Candida species from patients. Besides being highly prevalent, its biology differs markedly from that of C. albicans, which may be associated with C. parapsilosis' increased incidence. Differences in virulence, regulatory and antifungal drug resistance mechanisms, and the patient groups at risk indicate that conclusions drawn from C. albicans pathobiology cannot be simply extrapolated to C. parapsilosis Such species-specific characteristics may also influence their recognition and elimination by the host and the efficacy of antifungal drugs. Due to the availability of high-throughput, state-of-the-art experimental tools and molecular genetic methods adapted to C. parapsilosis, genome and transcriptome studies are now available that greatly contribute to our understanding of what makes this species a threat. In this review, we summarize 10 years of findings on C. parapsilosis pathogenesis, including the species' genetic properties, transcriptome studies, host responses, and molecular mechanisms of virulence. Antifungal susceptibility studies and clinician perspectives are discussed. We also present regional incidence reports in order to provide an updated worldwide epidemiology summary.

D-Cateslytin: a new antifungal agent for the treatment of oral Candida albicans associated infections

The excessive use of antifungal agents, compounded by the shortage of new drugs being introduced into the market, is causing the accumulation of multi-resistance phenotypes in many fungal strains. Consequently, new alternative molecules to conventional antifungal agents are urgently needed to prevent the emergence of fungal resistance. In this context, Cateslytin (Ctl), a natural peptide derived from the processing of Chromogranin A, has already been described as an effective antimicrobial agent against several pathogens including Candida albicans. In the present study, we compared the antimicrobial activity of two conformations of Ctl, L-Ctl and D-Ctl against Candida albicans. Our results show that both D-Ctl and L-Ctl were potent and safe antifungal agents. However, in contrast to L-Ctl, D-Ctl was not degraded by proteases secreted by Candida albicans and was also stable in saliva. Using video microscopy, we also demonstrated that D-Ctl can rapidly enter C. albicans, but is unable to spread within a yeast colony unless from a mother cell to a daughter cell during cellular division. Besides, we revealed that the antifungal activity of D-Ctl could be synergized by voriconazole, an antifungal of reference in the treatment of Candida albicans related infections. In conclusion, D-Ctl can be considered as an effective, safe and stable antifungal and could be used alone or in a combination therapy with voriconazole to treat Candida albicans related diseases including oral candidosis.

A single center's experience with Candida parapsilosis related long-term central venous access device infections: the port removal decision and its outcomes

Pediatric cancer patients have an increased risk of potentially life-threatening fungal infections such as Candida parapsilosis, associated with long-term CVADs. The Infectious Diseases Society of America (IDSA) guidelines on Candida catheter-related bloodstream infections recommend systemic antifungal therapy and catheter removal. In this study, we focused on our experience with antifungal failure due to totally implanted catheter-associated C. parapsilosis bloodstream infections. We investigated cases leading to port removal in pediatric malignancy patients and the associated patient outcomes. In the first phase of the study, a retrospective chart review was performed to collect patient information, including primary disease; time from hospitalization to port-related candidemia; antifungal drug choice; and the time at which port removal occurred. During the second phase, antifungal susceptibility tests for C. parapsilosis were performed in our microbiology laboratory. All patients had fevers and were neutropenic at the time of candidemia diagnosis. The mean duration between the first isolation of Candida parapsilosis from the port samples to the port removal was 9.75 ± 5.29 days for 11 patients. Patient fevers lasted for a mean time of 16.22 ± 6.51 days. The median recovery duration from fever after CVC removal was four days (range 2-12 days). The median duration for achieving negative blood cultures, following antifungal treatment was 18 days (range 10-27 days). Our data favored the removal of catheters in the presence of ongoing fever, as suggested by the guidelines, independent of the chosen antifungal treatment. Future studies with large samples are needed to evaluate the effects of catheter removal on mortality rates and patient outcomes.

Anidulafungin: advantage for the newcomer?

Anidulafungin is the most recently approved compound of the echinocandin antifungal class. Its mode of action is the noncompetitive inhibition of β-(1,3)-D-glucan synthesis. Potent fungicidal activity has been demonstrated against many Candida spp., including non-albicansCandida spp. and fluconazole-resistant strains, as well as fungistatic activity against Aspergillus spp. Owing to low oral bioavailability, it can only be administered intravenously. Anidulafungin is not metabolized by the liver and renal clearance is negligible, thus rendering dosage adjustments in patients with impaired hepatic or renal function unnecessary. Due to lack of interference with the cytochrome P450 pathway, it displays minimal drug-drug interaction. Anidulafungin has been approved by the US FDA for the treatment of esophageal and invasive candidiasis after clinical trials demonstrated its noninferiority to fluconazole. In September 2007, anidulafungin gained EMEA approval for the treatment of invasive candidiasis in adult non-neutropenic patients. For those with invasive or noninvasive candidiasis with resistance or intolerance to fluconazole in particular, as well as those requiring antifungal medication, that anidulafungin does not interact with concomitant medication means it may be regarded as a safe and efficacious treatment option. Promising results from animal models and experience with the other echinocandins indicate several potential lines of investigation: invasive aspergillosis, prophylaxis and treatment of transplant patients, and empirical treatment in patients with febrile neutropenia. Significant differences in clinical efficacy or safety favoring anidulafungin over the other echinocandins are yet to be discovered.

Echinocandin antifungals: review and update

The echinocandins are a new and unique class of antifungal agents that act on the fungal cell wall by way of noncompetitive inhibition of the synthesis of 1,3-beta-glucans. All agents of this class are of parenteral formulation, with no oral preparations available. Caspofungin (Cancidas) was the first approved echinocandin, followed recently by micafungin (Mycamine) and anidulafungin (Eraxis). The precise role of the echinocandins in the antifungal armamentarium is still unfolding. Caspofungin is approved for the treatment of candidal esophagitis and candidemia, salvage therapy of Aspergillus infections and for empirical therapy of febrile neutropenia. Micafungin is likewise approved for candidal esophagitis, in addition to antifungal prophylaxis for hematopoietic stem cell transplant recipients. Anidulafungin is also approved for treatment of candidal esophagitis, as well as therapy of candidemia. There has been anecdotal use of these agents to treat less common fungal pathogens, as well as limited use as a component of combination antifungal therapy. The echinocandins are an important addition to the antifungal armamentarium in the treatment of fungal infections in both immunocompromised patients and those with normal immunity.

Rapid identification of drug resistant Candida species causing recurrent vulvovaginal candidiasis

Some yeast agents including Candida albicans, Candida tropicalis and Candida glabrata have a role in recurrent vulvovaginal candidiasis. We studied the frequency of both common and recurrent vulvovaginal candidiasis in symptomatic cases which were referred to Urmia Medical Sciences University related gynecology clinics using morphologic and molecular methods. The aim of this study was the identification of Candida species isolated from recurrent vulvovaginal candidiasis cases using a rapid and reliable molecular method. Vaginal swabs obtained from each case, were cultured on differential media including cornmeal agar and CHROM agar Candida. After 48 hours at 37℃, the cultures were studied for growth characteristics and color production respectively. All isolates were identified using the molecular method of PCR - restriction fragment length polymorphism. Among all clinical specimens, we detected 19 ( 16 % ) non fungal agents, 87 ( 82.1 % ) yeasts and 2 ( 1.9 % ) multiple infections. The yeast isolates identified morphologically included Candida albicans ( n = 62 ), Candida glabrata ( n = 9 ), Candida tropicalis ( n = 8 ), Candida parapsilosis ( n = 8 ) and Candida guilliermondii and Candida krusei ( n = 1 each ). We also obtained very similar results for Candida albicans, Candida glabrata and Candida tropicalis as the most common clinical isolates, by using PCR - Restriction Fragment Length Polymorphism. Use of two differential methods, morphologic and molecular, enabled us to identify most medically important Candida species which particularly cause recurrent vulvovaginal candidiasis.

Epidemiology and echinocandin susceptibility of Candida parapsilosis sensu lato species isolated from bloodstream infections at a Spanish university hospital

OBJECTIVES

The aims of this work were to study the epidemiological profiles, differences in echinocandin susceptibilities and clinical relevance of the Candida parapsilosis sensu lato species isolated from proven fungaemia cases at La Fe University Hospital of Valencia (Spain) from 1995 to 2007.

RESULTS

The prevalence of these species was: C. parapsilosis sensu stricto, 74.4%; Candida orthopsilosis, 23.54%; and Candida metapsilosis, 2.05%. The incidence of the species complex as agents of fungaemia remained stationary until 2005 and doubled in 2006. The incidence of C. orthopsilosis showed an increasing trend during the study period, while C. parapsilosis sensu stricto incidence diminished. Also, an important epidemiological change was observed starting in 2004, when 86.5% of the C. parapsilosis sensu lato strains were found in adult patients, while before that year only 13.5% of the isolates were found in this population.

CONCLUSIONS

Echinocandin drug susceptibility testing using the CLSI M27-A3 document showed a wide range of MIC values (0.015-4 mg/L), with micafungin being the most potent in vitro inhibitor followed by anidulafungin and caspofungin (MIC geometric mean of 0.68, 0.74 and 0.87 mg/L, respectively). C. metapsilosis was the most susceptible species of the complex to anidulafungin and micafungin in vitro (MIC(50) for anidulafungin and micafungin: 0.06 mg/L), while there were no differences between C. parapsilosis sensu lato species when caspofungin MIC(50)s were compared (MIC(50) 1.00 mg/L). Differences in caspofungin in vitro susceptibility were observed between the different clinical service departments of La Fe Hospital.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00058682.

Candida non-albicans versus Candida albicans fungemia in the non-neonatal pediatric population

BACKGROUND

Non-albicans Candida (NAC) species have been implicated as major pathogens in patients with hospital-acquired candidemia. Few studies have investigated the impact of NAC fungemia among pediatric patients outside of the neonatal age group.

MATERIALS/METHODS

Between 2000 and 2009, we performed a retrospective case-control study in children aged 6 months to ≤18 years with blood culture proven candidemia at Texas Children's Hospital, Houston, TX.

RESULTS

A total of 276 episodes of candidemia occurred in 226 patients. The overall incidence ranged between 0.06 and 0.3 per 1000 inpatient days. The median patient age was 50 months (range, 6 months to ≤18 years) with 55.4% males; 40.2% Hispanics; and 31.8% whites. Candida albicans (CA) was the most common (44.2%) species although, collectively, NAC was more frequently (55.8%) isolated. Among the NAC group, Candida parapsilosis was most common (23.9%) followed by Candida tropicalis (14.8%), Candida glabrata (6.5%), and Candida lusitaniae (5.4%). No difference was found between CA and NAC candidemia in terms of demographics, underlying diagnosis, risk factors, clinical features, dissemination, or 30-day mortality. Disseminated candidiasis was independently associated with the use of vasopressors (adjusted odds ratio [OR], 4.58; confidence interval [CI]: 1.03-20.5; P = 0.05), prolonged fungemia (≥3 days of persistently positive cultures) after catheter removal (OR, 3.2; CI: 1.08-9.3; P = 0.04), and neutropenia (OR, 4.06; CI: 1.2-13.2; P = 0.02), but not with NAC fungemia.

CONCLUSIONS

Though CA was the single most common species, NAC species collectively have emerged as the predominant pathogens responsible for candidemia in non-neonatal patients at our institution. Risk factors, clinical features, and outcomes were not different between the 2 groups.

Voriconazole in the management of nosocomial invasive fungal infections

Voriconazole is a new triazole developed for the treatment of life-threatening fungal infections. The drug is available for both oral and intravenous administration; the oral formulation has excellent bioavailability. The side-effect profile of voriconazole presents an acceptable safety and tolerability spectrum: transient visual disturbances, liver enzyme abnormalities, and skin rashes are the most frequently reported side effects but rarely lead to discontinuation. The potential for drug–drug interactions is high, because of its extensive hepatic metabolism. Careful attention to dosage is required, and serum levels and the effects of interacting drugs should be monitored. Review of 25 470 isolates of yeasts and 3216 isolates of filamentous fungi showed voriconazole to have broad-spectrum activity against pathogenic yeasts including intrinsically fluconazole-resistant isolates such as Candida krusei, dimorphic fungi, and opportunistic moulds like Aspergillus spp, amphotericin-B-resistant Aspergillus terreus, Fusarium spp, and Scedosporium apiospermum. It displays excellent clinical efficacy in patients with fluconazole-resistant and -susceptible Candida infections, invasive bone and central nervous system aspergillosis, and various refractory fungal infections. Voriconazole has been approved by the US Food and Drug Administration and by the European Medicines Agency for the treatment of invasive aspergillosis, serious infections caused by Fusarium and S. apiospermum, fluconazole-resistant invasive Candida infections, and candidemia in nonneutropenic patients.

Are anidulafungin or voriconazole released from polymethylmethacrylate in vitro?

BACKGROUND

Depot delivery of antimicrobial agents is used for treatment and prevention of bacterial orthopaedic infections; there is little information regarding newer antifungal agents and their potential use in polymethylmethacrylate (PMMA) depot delivery.

QUESTIONS/PURPOSES

We determined the percent of anidulafungin or voriconazole present after polymerization in PMMA beads loaded with anidulafungin or voriconazole, and we assessed elution of anidulafungin or voriconazole from beads loaded with anidulafungin or voriconazole.

MATERIALS AND METHODS

Beads containing 7.5% anidulafungin or voriconazole were pulverized and incubated in Kreb's ringer buffer for 48 hours; the buffer was assayed for anidulafungin or voriconazole concentration. The in vitro release of anidulafungin and voriconazole from PMMA beads loaded with 7.5% anidulafungin or voriconazole was determined in triplicate in a continuous flow chamber.

RESULTS

0.7% of anidulafungin and 5.6% of voriconazole loaded in the beads were detected after polymerization. No anidulafungin was detected in the elution studies. The mean peak voriconazole concentration in the elution studies was 0.9 μg/mL.

CONCLUSIONS

Anidulafungin may not be suitable for depot delivery in PMMA.

New triazoles and echinocandins: mode of action, in vitro activity and mechanisms of resistance

Different types of mycoses, especially invasive mycoses caused by yeasts and molds, are a growing problem in healthcare. The most notable explanation for this increase is a rise in the number of immunocompromised patients owing to advances in transplantation, the emergence of AIDS and a rise in the number of invasive surgical procedures. Despite advances in medical practice, some therapeutic problems remain. In addition, intrinsic or acquired antifungal resistance may pose a serious problem to antifungal therapy. A new generation of triazole agents (voriconazole, posaconazole, isavuconazole, ravuconazole and albaconazole) and the recent class of the echinocandins (caspofungin, micafungin and anidulafungin) have become available, and represent an alternative to conventional antifungals for serious fungal infection management. Currently, only two of the recent triazole generation (voriconazole and posaconazole) and all three echinocandins are available for clinical use. More precisely, voriconazole and posaconazole are indicated for the treatment of invasive fungal infections and the echinocandins for the treatment of specific candidiasis. Voriconazole and posaconazole have a very broad spectrum of antifungal activity that includes Candida species, and filamentous and dimorphic fungi. Their activity extends to both fluconazole- and itraconazole-resistant strains of Candida. A major difference between posaconazole and voriconazole is that posaconazole has activity against Zygomycetes including Mucor spp., Rhizopus spp. and Cunninghamella spp., and voriconazole has no activity against this class of fungi. Ravuconazole, isavuconazole and albaconazole have shown very potent in vitro activity against species of Candida, Cryptococcus and Aspergillus, and they are currently in various stages of development. All three echinocandin agents, caspofungin, micafungin and anidulafungin, are similar in their spectrum of activity. Echinocandins do not possess in vitro activity against important basidiomycetes, including Cryptococcus, Rhodotorula and Trichosporon. This review attempts to deliver the most up-to-date knowledge on the mode of action and mechanisms of resistance to triazoles and echinocandins in fungal pathogens. In addition, the in vitro activity data available on triazoles and echinocandins are reported.

Candida parapsilosis: a review of its epidemiology, pathogenesis, clinical aspects, typing and antimicrobial susceptibility

The Candida parapsilosis family has emerged as a major opportunistic and nosocomial pathogen. It causes multifaceted pathology in immuno-compromised and normal hosts, notably low birth weight neonates. Its emergence may relate to an ability to colonize the skin, proliferate in glucose-containing solutions, and adhere to plastic. When clusters appear, determination of genetic relatedness among strains and identification of a common source are important. Its virulence appears associated with a capacity to produce biofilm and production of phospholipase and aspartyl protease. Further investigations of the host-pathogen interactions are needed. This review summarizes basic science, clinical and experimental information about C. parapsilosis.

Epidemiology of candidemia at a Children's hospital, 2002 to 2006

BACKGROUND

There are few recent studies evaluating trends in the epidemiology of candidemia including changes in species or utilization of antifungal agents in children.

METHODS

We performed a retrospective case series of candidemia at our children's hospital from 2002 to 2006. Our objectives were to study trends in the rates of candidemia, demographic characteristics, Candida species, antifungal susceptibility, and antifungal utilization. These data were obtained from the electronic medical records.

RESULTS

There were 203 episodes of candidemia in 154 subjects. During the study period, the average rate of candidemia was 5.52 per 1000 patient-discharges and did not change throughout the study. The mean and median ages of subjects were 3 years versus 9 months, respectively, and 38% were less than 3 months of age. Gastrointestinal disorders were a common comorbid condition (33%), especially for subjects with multiple episodes of candidemia. Overall, Candida parapsilosis and Candida albicans caused 43% and 26% of episodes, respectively, and candidemia caused by Candida glabrata (5.3%-23%) and Candida krusei (0%-8.5%) increased during the study. Ninety-eight percent of C. albicans and C. parapsilosis isolates remained susceptible to all antifungal drugs. From 2003-2006, the use of antifungal agents increased from 79 days to 150 days per 1000 hospital-days.

CONCLUSIONS

While antifungal use at our hospital increased, candidemia rates remained stable. C. parapsilosis was the most common species but other non-C. albicans species increased during the study period. Local epidemiology should be monitored in pediatric populations for potential impact on management strategies.

Candida parapsilosis, an emerging fungal pathogen

SUMMARY

Candida parapsilosis is an emerging major human pathogen that has dramatically increased in significance and prevalence over the past 2 decades, such that C. parapsilosis is now one of the leading causes of invasive candidal disease. Individuals at the highest risk for severe infection include neonates and patients in intensive care units. C. parapsilosis infections are especially associated with hyperalimentation solutions, prosthetic devices, and indwelling catheters, as well as the nosocomial spread of disease through the hands of health care workers. Factors involved in disease pathogenesis include the secretion of hydrolytic enzymes, adhesion to prosthetics, and biofilm formation. New molecular genetic tools are providing additional and much-needed information regarding C. parapsilosis virulence. The emerging information will provide a deeper understanding of C. parapsilosis pathogenesis and facilitate the development of new therapeutic approaches for treating C. parapsilosis infections.

One year prospective survey of Candida bloodstream infections in Scotland

A 12 month survey of candidaemia in Scotland, UK, in which every Scottish hospital laboratory submitted all blood isolates of yeasts for identification, strain typing and susceptibility testing, provided 300 isolates from 242 patients, generating incidence data of 4.8 cases per 100,000 population per year and 5.9 cases per 100,000 acute occupied bed days; 27.9 % of cases occurred in intensive care units. More than half the patients with candidaemia had an underlying disease involving the abdomen, 78 % had an indwelling intravenous catheter, 62 % had suffered a bacterial infection within the 2 weeks prior to candidaemia and 37 % had undergone a laparotomy. Candida albicans was the infecting species in 50 % of cases, followed by Candida glabrata (21 %) and Candida parapsilosis (12 %). Seven cases of candidaemia were caused by Candida dubliniensis, which was more prevalent even than Candida lusitaniae and Candida tropicalis (six cases each). Among C. glabrata isolates, 55 % showed reduced susceptibility to fluconazole, but azole resistance among other species was extremely low. Multilocus sequence typing showed isolates with high similarity came from different hospitals across the country, and many different types came from the hospitals that submitted the most isolates, indicating no tendency towards hospital-specific endemic strains. Multiple isolates of C. albicans and C. glabrata from individual patients were of the same strain type with single exceptions for each species. The high prevalence of candidaemia in Scotland, relative to other population-based European studies, and the high level of reduced fluconazole susceptibility of Scottish C. glabrata isolates warrant continued future surveillance of invasive Candida infections.

Antifungal drug susceptibility profile of Pichia anomala isolates from patients presenting with nosocomial fungemia

In vitro susceptibility of 58 isolates of Pichia anomala to five antifungal drugs using two broth microdilution methods (CLSI and EUCAST) was analyzed. Low susceptibility to itraconazole was observed. Fluconazole, voriconazole, amphotericin B, and caspofungin showed good antifungal activity, although relatively high drug concentrations were necessary to inhibit the isolates.

Los aspectos epidemiológicos cambiantes de la candidemia y sus implicaciones clinicoterapéuticas

Candida species are a major cause of healthcare-related bloodstream and invasive infections. Studies assessing nosocomial bloodstream infections during the two last decades ranked Candida species as the fourth most common nosocomial bloodstream pathogen. The incidence of Candida species has risen steadily during this period due to the increase in the number and type of patients at risk for these yeasts. Infections caused by Candida are especially frequent and serious in onco-hematological patients. Over the past decade, the introduction of azole antifungals as prophylactic agents, together with other factors, has led to a shift in the species of Candida that cause infection. During the period under review (1996 to 2005) several studies have confirmed the impact of antifungal prophylaxis with azoles on the emergence of Candida species other than Candida albicans. The widespread use of fluconazole has contributed to a relative decrease in the prevalence of C. albicans, while species inherently less susceptible, such as Candida glabrata and Candida krusei, appear to be isolated with greater frequency. Moreover, laboratory studies to determine the antifungal susceptibilities and virulence of non-albicans Candida species have enabled the design of microbe-specific management strategies. More of these studies will be necessary as we enter an age in which multiple antifungal compounds (echinocandins, new azoles) will become available for clinical use in invasive candidiasis or candidemia. The present review aims to highlight the different trends in the incidence, distribution and behavior of Candida bloodstream infections in the distinct types of patients at risk.

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.

Candida guilliermondii fungemia in patients with hematologic malignancies

The microbiological, clinical, and epidemiological features of most non-Candida albicans Candida species are well known, but much less is known about species such as Candida guilliermondii, an uncommon pathogen causing a variety of deep-seated infections in immunocompromised hosts. To characterize C. guilliermondii fungemia in patients with hematological malignancies and its susceptibility to antifungal drugs, all cases of C. guilliermondii fungemia diagnosed in our department between 1983 and 2005 were retrospectively analyzed and the literature was reviewed. C. guilliermondii caused 29/243 (11.7%) candidemia episodes diagnosed during the study period. Central venous catheters were the documented sources of candidemia in 19/29 episodes (65.5%), and invasive tissue infections were documented in 2 (6.9%). In the remaining eight, the catheter was not removed and the source of the fungemia remained obscure. Seven episodes ended in death, but only one could be attributed to invasive C. guilliermondii infection. Molecular typing data reveal no evidence of common infection sources. Isolates displayed high rates of in vitro susceptibility to amphotericin B (100%), voriconazole (95%), and fluconazole (90%) and lower rates of in vitro susceptibility to flucytosine (86%), itraconazole (76%), and caspofungin (33%). Our literature review confirms that C. guilliermondii is a significantly more frequent cause of candidemia among cancer patients compared with the general hospital population. It accounted for <1% of the total number of Candida bloodstream isolates reported in the articles we reviewed, with higher rates in Europe (1.4%) and Asia (1.8%) compared with North America (0.3%).

Newer triazole antifungal agents: pharmacology, spectrum, clinical efficacy and limitations

New triazole antifungals (voriconazole, posaconazole, ravuconazole and albaconazole) have been developed to meet the increasing need for new antifungals, and address the rising incidence of invasive fungal infections and the emergence of fungal resistance. This report describes the spectrum of activity of the newer-generation triazoles based on data from in vitro, animal and clinical studies. The authors discuss the use of these agents in combination with other antifungals, the extent of cross-resistance, their toxicity profile and pharmacokinetic properties. A total of two agents are currently available: voriconazole (which is becoming a primary treatment for the management of invasive aspergillosis) and posaconazole (which demonstrates a broad antifungal spectrum). A further two agents, albaconazole and ravuconazole, are undergoing early clinical evaluation and their future is uncertain. For all newer triazoles, concerns about emerging drug-resistant fungi and the incidence and management of breakthrough infections will dictate their role in antifungal prophylaxis and treatment.

Resistance mechanisms in fluconazole-resistant Candida albicans isolates from vaginal candidiasis

Candida albicans is the most frequently identified yeast species causing mycotic vaginitis. A significant number of vaginal yeast isolates are resistant to azole antifungal agents in vitro. Here we investigated the molecular mechanisms of resistance in 22 randomly selected fluconazole-resistant vaginal C. albicans isolates. Twelve isolates in this collection were found to be cross-resistant to itraconazole and 15 to voriconazole. Most of them also displayed decreased susceptibility to terbinafine. Northern blot analyses revealed overexpression of the MDR1 gene in all isolates, which in some isolates was accompanied by elevated levels of CDR1/CDR2 and ERG11 expression. Sequence analysis of the polymerase chain reaction-amplified ERG11 gene of selected azole-resistant isolates identified D116E and V488I amino acid alterations in Erg11p that are known to be conserved in fluconazole-resistant strains. The results demonstrate that decreased susceptibilities of vaginal yeast isolates to clinically used azole derivatives are the result of a combination of several molecular mechanisms involving drug efflux and alterations in the structure or cellular amount of 14-alpha-lanosterol demethylase.

(B1) Candida and mycotic infections

Oral candidiasis (OC) is the most common mucosal manifestation of HIV infection. This workshop examined OC and other mycoses associated with HIV infection. Historically, blood CD4 cell numbers were the primary prognosticator for the development of OC. However, a study that statistically evaluated the predictive role of HIV viral load vs. CD4 cell counts revealed viral load to be a stronger predictor for OC. The role of biofilms and antifungal resistance in recalcitrant OC is unclear at present. In general, micro-organisms including yeasts in biofilms are more resistant to antifungals than their planktonic counterparts. When the remaining organisms are eliminated, the few resistant organisms may not be problematic, because they are present in low numbers. Unusual exotic mycoses in HIV-infected patients are more common in patients from the developing than the developed world. These infections may be recurrent and recalcitrant to therapy, be present in multiple and uncommon sites, increase with the progression of HIV disease, and may play a role similar to that of the more common mycoses. Typing and subtyping of yeasts are probably not critical to the clinical management of candidiasis caused by Candida albicans and non-albicans strains, including C. dubliniensis, because it is responsive to antifungal therapy. C. glabrata is probably the only exception. The presence of oral thrush in infants younger than 6 months of age is associated with an increased post-natal transmission risk of HIV infection. Thus, perinatal retroviral therapy should be combined with the treatment of oral thrush to prevent the post-natal acquisition of HIV.

Neutropenia febril: pasado, presente y futuro

The present review aims to provide an overall view of the changes that have occurred in the last 40 years in the etiological agents isolated in febrile neutropenic patients, as well as in their antibacterial susceptibility patterns and their involvement in empirical treatment regimes. This overall view allows us to observe how the modifications introduced in the treatment of these patients has been accompanied by continual changes in the causative microorganisms, which in turn has required treatment regimens to be redesigned. Because of these constant changes, the significant advances achieved in diagnostic techniques and the recognition of subpopulations of patients with distinct degrees of morbidity and mortality, specialists in the various fields involved in the management of febrile neutropenic patients must constantly update their knowledge.

Colonization of Candida species in denture wearers with emphasis on HIV infection: a literature review

Candida colonization in denture wearers, especially immunocompromised patients, can be disruptive to dental treatment and may be a barrier to patient health. The surface irregularities of acrylic resin are a factor in the entrapment of microorganisms. Consequently, controlling the spread of fungal infection in HIV-infected patients who wear removable prostheses and who are more susceptible to fungal infections because of their immunosuppression is of critical importance. This article reviews the literature on the colonization of Candida species in HIV-infected denture wearers using keywords such as complete dentures, candidiasis, and HIV-infection . The source for this review was representative English-language, peer-reviewed articles between the period of 1885 to 2003 obtained using Medline, as well as a hand search.

In vitro susceptibilities of bloodstream isolates of Candida species to six antifungal agents: results from a population-based active surveillance programme, Barcelona, Spain, 2002–2003

OBJECTIVES

The antifungal drug susceptibilities of 351 isolates of Candida species, obtained through active laboratory-based surveillance in the period January 2002-December 2003, were determined (Candida albicans 51%, Candida parapsilosis 23%, Candida tropicalis 10%, Candida glabrata 9%, Candida krusei 4%).

METHODS

The MICs of amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole and caspofungin were established by means of the broth microdilution reference procedure of the European Committee on Antibiotic Susceptibility Testing.

RESULTS AND CONCLUSIONS

Amphotericin B and flucytosine were active in vitro against all strains. A total of 24 isolates (6.8%) showed decreased susceptibility to fluconazole (MIC > or = 16 mg/L) and 43 (12.3%) showed decreased susceptibility to itraconazole (MIC > or = 0.25 mg/L). Voriconazole and caspofungin were active in vitro against the majority of isolates, even those that were resistant to fluconazole.

New agents for invasive mycoses in children

PURPOSE OF REVIEW

Invasive fungal infections are an important cause of morbidity and mortality in immunocompromised children of all ages. This review summarizes information on new antifungal agents, including current data on their clinical use in children, as well as alternative strategies such as antifungal combination and immunomodulation therapy.

RECENT FINDINGS

Novel antifungal agents, such as the echinocandins and the second-generation triazoles, were recently introduced that exhibit promising efficacy against Candida spp., Aspergillus spp., and other opportunistic fungal pathogens. These compounds are generally well tolerated and show substantial efficacy as salvage treatment and equal or even superior efficacy compared with older azoles or amphotericin B as first-line or empiric therapy for fungal infections. Clinical studies of pharmacokinetics and efficacy of the new agents in the pediatric population are, however, limited.

SUMMARY

The response rates observed with the recently introduced drugs, although superior in some cases compared with older antifungal agents, are still far from satisfactory. The development of new antifungal compounds as well as the use of alternative approaches of combination therapy and immunomodulation should be pursued through well-designed laboratory and clinical studies in pediatric patients.

Treatment of Candida Chorioretinitis with Voriconazole

A 63-year-old female with candidemia following necrotizing pancreatitis developed clinical signs of chorioretinitis and underwent the systemic administration of voriconazole, after which anterior chamber inflammation and multiple, white, fluffy, chorioretinal lesions, under 1mm in diameter, were gradually resolved and visual acuity improved. We report the first Korean case of candida chorioretinitis successfully treated with the systemic administration of voriconazole.

Epidemiology and antifungal susceptibility of Candida species isolated from blood: results of a 2-year multicentre study in Spain

This study, included in the prospective survey of candidaemia in Europe supported by the European Confederation of Medical Mycology, presents the epidemiological and antifungal susceptibility results of 290 cases of candidaemia (80 in children <15 years old) reported from September 1997 to August 1999 by 19 Spanish hospitals. Presence of an intravenous catheter and previous antibiotic therapy were the most frequent risk factors. The percentages of the four most common species isolated (adults/children) were as follows: Candida albicans (46/36.2), C. parapsilosis (21.9/50), C. tropicalis (12.8/3.75), and C. glabrata (10.1/5). As initial therapy, fluconazole was preferred in adults (54%) and liposomal amphotericin B in children (58%). The 30-day mortality rate was 40.6%, and the species most frequently associated with a fatal outcome was C. krusei (60%). The rates of susceptibility to antifungal agents were as follows: amphotericin B, 91%; flucytosine, 99%; fluconazole, 93.6%; itraconazole, 87.4%; and voriconazole, 92%. These results provide baseline data for future epidemiological and susceptibility studies and for evaluating the impact of new antifungal agents on the distribution of species and the mortality rates associated with candidaemia in Spain.

Impact of real-time fungal susceptibility on clinical practices

PURPOSE OF REVIEW

In the past two decades standardized in-vitro antifungal susceptibility tests have been developed in response to increasing invasive fungal infections. Our purpose is to review the utility of real-time Candida antifungal susceptibility testing and its effects on clinical outcomes in the context of the new antifungal agents, existing antifungal susceptibility testing methods, and the changing epidemiology and susceptibilities of Candida spp.

RECENT FINDINGS

New antifungal agents active against Candida spp. are now available. Caspofungin is approved for the treatment of invasive candidiasis but standardized antifungal susceptibility testing has not been developed. The newer triazoles, such as voriconazole, posaconazole and ravuconazole, are not yet approved for invasive candidiasis. As infections caused by non-albicans Candida spp. with growing resistance to fluconazole increase, antifungal susceptibility testing may be important to guide therapy. Unfortunately, few studies exist describing the impact of real-time antifungal susceptibility testing on the treatment of invasive fungal infections.

SUMMARY

Newer antifungal agents with broader anti-Candida activity, fewer adverse events and minimal resistance are currently available. The challenge clinicians face is choosing when to use these agents appropriately, while considering the changing Candida epidemiology and susceptibility trends without over-treating fluconazole-sensitive pathogens. Unfortunately, the correlation of antifungal susceptibility testing results by any method and clinical outcome is mostly lacking. We suggest that a concerted examination of the utility of real-time antifungal susceptibility testing and its effect on clinical outcomes by guiding appropriate antifungal therapy for high-risk patients with invasive candidiasis is warranted.

Initial results from a longitudinal international surveillance programme for anidulafungin (2003)

OBJECTIVES

This longitudinal study evaluated the in vitro activity of anidulafungin against 880 clinical yeast isolates and 68 mould isolates from 64 medical centres in North America, Latin America and Europe.

METHODS

MICs of anidulafungin, amphotericin B, 5-fluorocytosine, fluconazole, itraconazole, ketoconazole and voriconazole were determined using reference method (M27-A2) guidelines. The M38-A reference method was used for the filamentous fungi, including determination of minimum effective concentrations (MECs) of anidulafungin.

RESULTS

Anidulafungin was more active when compared with fluconazole and itraconazole for Candida albicans (MIC(90), 0.06 mg/L), Candida tropicalis (MIC(90), 0.06 mg/L), Candida glabrata (MIC(90), 0.12 mg/L), Candida krusei (MIC(90), 0.06 mg/L) and Candida lusitaniae (MIC(90), 1 mg/L) as well as the less-often encountered yeast species. Anidulafungin was less active against Candida parapsilosis, Candida guilliermondii and Candida famata (MIC(50), 1-2 mg/L). Anidulafungin also exhibited excellent activity against all Aspergillus spp. (MEC(90), < or =0.03 mg/L). Anidulafungin was also evaluated comparing two end point reading criteria and two incubation intervals. Data indicate that longer incubation periods do not significantly influence overall MIC ranges. These international surveillance results for anidulafungin confirm the activity observed in studies of smaller numbers of isolates.

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Fungal infections in bone marrow transplant patients

PURPOSE OF REVIEW

Invasive fungal infections have become the leading infectious cause of death in recipients of hematopoietic cell transplantation. Several factors have led to a renaissance in the study of invasive fungal infections. The growing incidence of both commonly encountered as well as emerging pathogens and the lethality of these infections coupled with the unprecedented number of available broad-spectrum antifungal drugs has lent a renewed vigor and enthusiasm to attempts to understand the pathogenesis of these diseases and, by doing so, improve prevention, diagnosis, and treatment. The following is a review of the primary research published from 2003 to the present that is pertinent to invasive fungal infection in the setting of hematopoietic cell transplantation.

RECENT FINDINGS

The main themes of published primary research during 2003 to the present include the efficacy and tolerability of antifungal prophylaxis, epidemiologic analyses of risk factors following nonmyeloablative preparative regimens, and more-detailed analyses of nonmyeloid immune responses.

SUMMARY

Although few definitive recommendations emerged from the studies during the review period, these investigations do contribute to a greater understanding of the immunobiology of invasive fungal infection and of the utility and limitations of newer antifungal agents in the prophylaxis or treatment of invasive fungal infection.

The diagnosis of hepatosplenic candidiasis by DNA analysis of tissue biopsy and serum

Hepatosplenic candidiasis is traditionally diagnosed by blood culture, magnetic resonance imaging (MRI), and histological analysis. The limitations of these methods include: low sensitivity (blood culture) and failure to isolate the organism (MRI/histology). This report describes a case of hepatosplenic candidiasis diagnosed by simultaneous polymerase chain reaction (PCR) analysis of liver biopsy and serum. PCR of biopsy and/or serum may offer a sensitive and specific diagnostic test for hepatosplenic candidiasis. Candida species can be identified, which helps guide antifungal chemotherapy, an important aspect in this difficult to treat infection.

Anidulafungin

Anidulafungin is a novel antifungal agent which, like other echinocandins, inhibits beta-(1,3)-D-glucan synthase and disrupts fungal cell-wall synthesis. It has marked antifungal activity against a broad spectrum of Candida spp. and Aspergillus spp., including amphotericin B- and triazole-resistant strains. In clinical trials, anidulafungin has primarily been evaluated in patients with oesophageal and invasive candidiasis. Preliminary data are emerging for other indications such as invasive aspergillosis. In a large, multicentre, double-blind, double-dummy, randomised trial in patients with oesophageal candidiasis, intravenous anidulafungin 50 mg/day was as effective as oral fluconazole 100 mg/day regarding end-of-treatment rates of endoscopic cure and clinical and microbiological success. Duration of treatment was approximately 2-3 weeks, and patients in both groups received a loading dose of study drug (twice the daily maintenance dose) on day 1. Anidulafungin is generally well tolerated. Across the dosage range 50-100 mg/day, adverse events appear not to be dose- or infusion-related. In the largest clinical trial to date, the most common treatment-related adverse events were phlebitis/thrombophlebitis, headache, nausea, vomiting and pyrexia.