Secular trends of candidemia over 12 years in adult patients at a tertiary care hospital

A Prospective Observational Study of Risk Factors for Candida glabrata in an SICU: Role of Fluconazole

Background

Candida glabrata has emerged as a serious nosocomial pathogen, particularly in surgical intensive care units (SICU).

Purpose

To determine potential risk factors for the emergence of C. glabrata colonization or infection (C/I) in the SICU.

Methods

A prospective observational study was conducted collecting and analyzing variables associated with the development of C/I with C. glabrata versus non- glabrata Candida species in our SICU.

Results

Fourteen patients developed C/I with C. glabrata (cases), while 21 patients developed C/I with non- glabrata Candida species (controls). Univariate analyses identified the following continuous variables as being statistically significant for the development of C/I with C. glabrata: number of days prior to antifungal or penicillin class therapy. The following categorical variables were significant by univariate analyses: any prior use of piperacillin/tazobactam, penicillin class, or fluconazole, or at least 5 days of use of fluconazole. Any prior use of levofloxacin was found to be statistically significant for controls. Multivariate-logistic regression analysis identified more than 5 days of fluconazole use and no prior use of levofloxacin as independent risk factors for the development of C. glabrata C/I in the SICU.

Conclusions

Prior fluconazole use was identified as an independent risk factor for development of C. glabrata C/I.

Therapeutic potential of antifungal plant and insect defensins

To defend themselves against invading fungal pathogens, plants and insects largely depend on the production of a wide array of antifungal molecules, including antimicrobial peptides such as defensins. Interestingly, plant and insect defensins display antimicrobial activity not only against plant and insect pathogens but also against human fungal pathogens, including Candida spp. and Aspergillus spp. This review focuses on these defensins as novel leads for antifungal therapeutics. Their mode of action, involving interaction with fungus-specific sphingolipids, and heterologous expression, required for cost-effective production, are major assets for development of plant and insect defensins as antifungal leads. Studies evaluating their in vivo antifungal efficacy demonstrate their therapeutic potential.

Mixed Fungemia: Incidence, Risk Factors, and Mortality in a General Hospital

BACKGROUND

Fungemia has been historically considered to be a disease caused by a single Candida species; the detection of >1 species of yeast in circulating blood was distinctly uncommon using traditional microbiological procedures. We describe episodes of mixed fungemia (MF), detected between 1985 and 2006, in a large teaching hospital.

METHODS

The study was divided into 2 periods that were separated by the introduction, in January 2005, of the CHROmagar Candida medium (CHROMagar) for the routine subculturing of blood cultures in which yeast has been identified. Overall, we documented 747 cases of fungemia. During the first period (1985-1994), we identified 217 episodes of fungemia and no single episode of MF; during the second period (1995-2006), 15 episodes of MF were detected among 530 episodes of fungemia (2.8%). Candida albicans was isolated in 13 patients, non-albicans species of Candida in 16 patients, and Saccharomyces cerevisiae in 1 patient. Each episode of MF was compared with 2 control episodes of monomicrobial fungemia.

RESULTS

Patients with MF had more frequently experienced organ transplantation (13% vs. 0%) and surgery (60% vs. 27%), had less frequently received parenteral nutrition (40% vs. 70%) or had intravenous lines (80% vs. 100%), and had a lower incidence of shock (6% vs. 37%) and a lower mortality (20% vs. 53%).

CONCLUSIONS

Despite the introduction of chromogenic agar, MF is still an uncommon disease and has a less severe outcome than does monomicrobial candidemia.

Candidemia due to Candida tropicalis: clinical, epidemiologic, and microbiologic characteristics of 188 episodes occurring in tertiary care hospitals

Candida tropicalis is the 2nd most frequent agent of candidemia in Brazil (20-24%). We attempted to characterize the epidemiology, microbiology, and outcome of candidemia due to C. tropicalis by comparing patients with candidemia due to C. tropicalis with those with candidemia due to Candida albicans. Among the 924 episodes of candidemia, 188 (20%) were caused by C. tropicalis. These cases were compared with 384 candidemias due to C. albicans. C. tropicalis was the 2nd most frequent species in adults (21.6%) and elderly patients (23.2%), and 3rd in neonates (11.9%) and children (18.5%). Cancer was the most frequent underlying disease, and in adults and elderly patients, diabetes was the 2nd most frequent underlying disease. The only difference between C. tropicalis and C. albicans candidemia was a higher proportion of neutropenic patients in C. tropicalis candidemia. C. tropicalis is a leading cause of candidemia in Brazil, and its epidemiology is similar to that of C. albicans.

Prospective observational study of candidemia in São Paulo, Brazil: incidence rate, epidemiology, and predictors of mortality

BACKGROUND

Studies conducted in tertiary care hospitals of different European countries and the United States have shown incidence rates of candidemia ranging from 0.17 to 0.76 and 0.28 to 0.96 per 1,000 admissions, respectively. So far, only 1 study has evaluated the incidence rates of candidemia in tertiary care hospitals in Latin American countries.

OBJECTIVE

To evaluate the epidemiology of candidemia in 4 tertiary care hospitals in São Paulo, Brazil.

DESIGN

Multicenter, laboratory-based surveillance of candidemia.

RESULTS

A total of 7,038 episodes of bloodstream infection were identified, and Candida species accounted for 282 cases (4%). The incidence rate of candidemia was 1.66 candidemic episodes per 1,000 hospital admissions. Candida albicans was the most frequently isolated Candida species in all hospitals, but Candida species other than C. albicans accounted for 62% of isolates, including predominantly Candida parapsilosis and Candida tropicalis. Azole resistance was restricted to only 2% of all Candida isolates (1 isolate of Candida glabrata and 4 isolates of Candida rugosa). Candidemia was mostly documented in surgical patients with long durations of hospital stay. The crude mortality rate was 61%, and advanced age and high Acute Physiology and Chronic Health Evaluation II score were both conditions independently associated with risk of death.

CONCLUSIONS

We observed in our series a higher incidence rate of candidemia than that reported in European countries and the United States. Advanced age and a high Acute Physiology and Chronic Health Evaluation II score were factors associated with a higher probability of death in candidemic patients. Fluconazole-resistant Candida strains are still a rare finding in our case-based study of candidemia.

Coccidioides immitis fungemia: clinical features and survival in 33 adult patients

Coccidioides immitis is a fungus endemic to the southwestern United States. Susceptible hosts, including blacks, Hispanics, Filipinos, Native Americans, and those with compromised immunity, may develop disseminated disease, including fungemia. We retrospectively reviewed the records of all patients (n = 33) with Coccidioides immitis fungemia (CIF) at a 550-bed public hospital in Phoenix, Arizona, from 1990 to 2002. This is the largest reported series of CIF. The purpose of the study was to review the incidence, signs, symptoms, and outcomes of CIF. Twenty-nine patients had human immunodeficiency virus infection. CIF was associated with sepsis, end-stage alcoholic liver disease, and diabetes in four patients. Survival was poor; 24 of the 33 patients died within 28 days. CIF manifested as a systemic inflammatory response syndrome with progressive cardiorespiratory failure. Despite fluid loading, infusion of vasoactive agents, and mechanical ventilation with positive end-expiratory pressure, patients typically experienced a rapidly progressive course and death. CIF portends an ominous prognosis and typically occurs in the setting of advanced human immunodeficiency virus or medical or surgical crises.

Candida infections in the intensive care unit: epidemiology, risk factors and therapeutic strategies

This article reviews the epidemiology, predisposing risk factors and outcome of systemic Candida spp. infections in the intensive care unit setting. Incidence of systemic Candida infections in patients requiring intensive care has increased substantially in recent years; while diagnosis of serious Candida infection may be difficult, the clinical conditions which predispose patients to these infections are now better understood and effective antifungal therapies are becoming increasingly available. Severe fungal infections are generally associated with poor outcomes in these patients. Patients at highest risk for Candida infection may be potential candidates for early, presumptive therapy. In this article we review antifungal treatment, including the use of polyenes, azoles and echinocandines, and the role of prophylaxis.

Relationship between the initial dose of micafungin and its efficacy in patients with candidemia

Micafungin, the first licensed echinocandin in Japan, has shown excellent in vitro and in vivo activity against all Candida species. However, the appropriate dose for the initial treatment of candidemia remains to be determined. In this study, we retrospectively examined the relationship between the clinical outcome of candidemia and the initial dose of micafungin. Patients were divided into two groups according to the initial dose of micafungin administered: group I (<2.25 mg/kg/day) and group II (>or=2.25 mg/kg/day). Micafungin produced an excellent 30-day clinical response in patients with candidemia, including Candida parapsilosis; the overall 30-day clinical response was 86%. The administration of higher doses of micafungin accelerated the clinical response and duration until the clinical response in group II was significantly shorter than that in group I (P = 0.021). However, no significant differences were observed in the 30-day mortality attributable to the fungal infection between the two groups. Considering these results, we recommend the administration of 2.25 mg/kg/day or more of micafungin in the initial treatment of patients with candidemia.

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.

Epidemiology of candidemia in Brazil: a nationwide sentinel surveillance of candidemia in eleven medical centers

Candidemia studies have documented geographic differences in rates and epidemiology, underscoring the need for surveillance to monitor trends. We conducted prospective candidemia surveillance in Brazil to assess the incidence, species distribution, frequency of antifungal resistance, and risk factors for fluconazole-resistant Candida species. Prospective laboratory-based surveillance was conducted from March 2003 to December 2004 in 11 medical centers located in 9 major Brazilian cities. A case of candidemia was defined as the isolation of Candida spp. from a blood culture. Incidence rates were calculated per 1,000 admissions and 1,000 patient-days. Antifungal susceptibility tests were performed by using the broth microdilution assay, according to the Clinical and Laboratory Standards Institute guidelines. We detected 712 cases, for an overall incidence of 2.49 cases per 1,000 admissions and 0.37 cases per 1,000 patient-days. The 30-day crude mortality was 54%. C. albicans was the most common species (40.9%), followed by C. tropicalis (20.9%) and C. parapsilosis (20.5%). Overall, decreased susceptibility to fluconazole occurred in 33 (5%) of incident isolates, 6 (1%) of which were resistant. There was a linear correlation between fluconazole and voriconazole MICs (r = 0.54 and P < 0.001 [Spearman's rho]). This is the largest multicenter candidemia study conducted in Latin America and shows the substantial morbidity and mortality of candidemia in Brazil. Antifungal resistance was rare, but correlation between fluconazole and voriconazole MICs suggests cross-resistance may occur.

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%).

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.

Critical issues in the clinical management of complicated intra-abdominal infections

Intra-abdominal infections differ from other infections through the broad variety in causes and severity of the infection, the aetiology of which is often polymicrobial, the microbiological results that are difficult to interpret and the essential role of surgical intervention. From a clinical viewpoint, two major types of intra-abdominal infections can be distinguished: uncomplicated and complicated. In uncomplicated intra-abdominal infection, the infectious process only involves a single organ and no anatomical disruption is present. Generally, patients with such infections can be managed with surgical resection alone and no antimicrobial therapy besides perioperative prophylaxis is necessary. In complicated intra-abdominal infections, the infectious process proceeds beyond the organ that is the source of the infection, and causes either localised peritonitis, also referred to as abdominal abscess, or diffuse peritonitis, depending on the ability of the host to contain the process within a part of the abdominal cavity. In particular, complicated intra-abdominal infections are an important cause of morbidity and are more frequently associated with a poor prognosis. However, an early clinical diagnosis, followed by adequate source control to stop ongoing contamination and restore anatomical structures and physiological function, as well as prompt initiation of appropriate empirical therapy, can limit the associated mortality. The biggest challenge with complicated intra-abdominal infections is early recognition of the problem. Antimicrobial management is generally standardised and many regimens, either with monotherapy or combination therapy, have proven their efficacy. Routine coverage against enterococci is not recommended, but can be useful in particular clinical conditions such as the presence of septic shock in patients previously receiving prolonged treatment with cephalosporins, immunosuppressed patients at risk for bacteraemia, the presence of prosthetic heart valves and recurrent intra-abdominal infection accompanied by severe sepsis. In patients with prolonged hospital stay and antibacterial therapy, the likelihood of involvement of antibacterial-resistant pathogens must be taken into account. Antimicrobial coverage of Candida spp. is recommended when there is evidence of candidal involvement or in patients with specific risk factors for invasive candidiasis such as immunodeficiency and prolonged antibacterial exposure. In general, antimicrobial therapy should be continued for 5-7 days. If sepsis is still present after 1 week, a diagnostic work up should be performed, and if necessary a surgical reintervention should be considered.

Invasive candidiasis in the intensive care unit

OBJECTIVE

To review epidemiologic trends, advances in diagnosis and susceptibility testing, therapeutic options and guidelines, and management strategies for invasive candidiasis as relevant to the intensive care unit physician.

DATA SOURCES, STUDY SELECTION, DATA EXTRACTION, DATA SYNTHESIS

Nonstructured review of peer-reviewed original articles, review articles, abstracts, guidelines, and consensus statements appearing in Medline, major scientific journals, and conference proceedings.

CONCLUSIONS

Invasive candidiasis is a problem associated with substantial morbidity and mortality that is highly prevalent in the intensive care unit setting. Recent epidemiologic studies have shown a trend toward increasing numbers of infections and a shift toward infections caused by non-albicans Candida species. Guidelines for the management of these diseases have been published and recommend amphotericin B, fluconazole, or caspofungin as the primary therapeutic option. The choice of agent should depend on local epidemiology and patient factors. The role of newer antifungal agents for this population, such as the new azoles and echinocandins, remains to be determined. Priority areas of research include diagnostics, risk identification, and management strategy assessment such as prophylactic, preemptive, and empirical therapy.

Epidemiología de la candidemia en UCI

During the last decades there has been an important increase in the incidence of fungal infections. These infections are common in the setting of Intensive Care Units (ICU), where the prevalence of high-risk patients is important. In this review we discuss the incidence of candidemia in ICUs, as well as the mortality and economic impact. The participation of non-Candida albicans Candida species in the etiology of these infections is currently increasing.

Secular trends in nosocomial candidaemia in non-neutropenic patients in an Italian tertiary hospital

A retrospective study was performed in an Italian tertiary hospital to evaluate trends in candidaemia between 1992 and 2001, and to compare the characteristics of episodes of fungaemia between 1992--1997 and 1998--2001. In total, 370 episodes of candidaemia were identified, with an average incidence of 0.99 episodes/10 000 patient-days/year (range 0.49--1.29 episodes). On an annual trend basis, the overall incidence was essentially stable in surgical and medical wards, but decreased in intensive care units (ICUs) (p 0.0065). The average use of fluconazole was 37.9 g/10 000 patient-days/year (range 21.4--56.1 g), and did not change significantly during the 10-year period. Nearly two-thirds of patients were in ICUs at the onset of candidaemia, but none was neutropenic in either study period. Candida albicans remained the predominant species isolated (53.8% vs. 48.1%), followed by Candida parapsilosis, Candida glabrata and Candida tropicalis, the distribution of which did not change significantly. The 30-day crude mortality rate was essentially similar (44% vs. 35%) in both study periods. Thus the incidence of nosocomial candidaemia, although high in this institution, decreased among critically-ill patients during the 10-year period. This finding seemed to be related to an improvement in infection control practices, particularly regarding the prevention of intravascular catheter-related infections in ICUs. Although the overall use of fluconazole was considerable, no increase in azole-resistant non-albicans Candida spp. was detected.

Global trends in candidemia: Review of reports from 1995–2005

Candida species are an important cause of health care-related bloodstream infections (BSI). Understanding the current Candida BSI incidence trends, the dominant species causing disease, and the mortality associated with this infection are important to help guide therapeutic and prophylaxis measures. In this review, trends in the incidence of Candida BSI are assessed using data extracted from reports published worldwide during 1995 to 2005. The incidence trend of Candida BSI was found to be stable for most of the reports reviewed, and Candida albicans remains the most common species causing Candida BSIs. Surveillance to monitor the burden of disease and emergence of resistance, among the general patient population and among high risk patient populations, should be continued.

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.

Rapid identification of Candida species and other clinically important yeast species by flow cytometry

Two rapid diagnostic assays, utilizing two different Luminex flow cytometry methods, were developed for identification of clinically important ascomycetous yeast species. Direct hybridization and allele-specific primer extension methods were both successful in establishing a DNA-based assay that can rapidly and accurately identify Candida albicans, Candida krusei, Candida parapsilosis, Candida glabrata, and Candida tropicalis as well as other clinical species. The direct hybridization assay was designed to identify a total of 19 ascomycetous yeast species, and the allele-specific primer extension assay was designed to identify a total of 34 species. Probes were validated against 438 strains representing 303 species. From culture to identification, the allele-specific primer extension method takes 8 h and the direct hybridization method takes less than 5 h to complete. These assays represent comprehensive, rapid tests that are well suited for the clinical laboratory.

Characteristics of candidaemia with Candida-albicans compared with non-albicans Candida species and predictors of mortality

Candidaemia due to non-albicans Candida species is increasing in frequency. We describe 272 episodes of candidaemia, define parameters associated with Candida albicans and other Candida species, and analyse predictors associated with mortality. Patients with C. albicans (55%) had the highest fatality rate and frequently received immunosuppressive therapy, while patients with Candida parapsilosis (16%) had the lowest fatality and complication rates. Candida tropicalis (16%) was associated with youth, severe neutropenia, acute leukaemia or bone marrow transplantation, Candida glabrata (10%) was associated with old age and chronic disease, and Candida krusei (2%) was associated with prior fluconazole therapy. The overall fatality rate was 36%, and predictors of death by multi-variate analysis were shock, impaired performance status, low serum albumin and congestive heart failure. Isolation of non-albicans Candida species, prior surgery and catheter removal were protective factors. When shock was excluded from analysis, antifungal therapy was shown to be protective. Unlike previous concerns, infection with Candida species other than C. albicans has not been shown to result in an increased fatality rate.

Candida glabrata Fungemia: Experience in a Tertiary Care Center

BACKGROUND

During the past decade, Candida glabrata has emerged as an important cause of fungemia. We reviewed demographic data, risk factors, treatment, and outcomes associated with C. glabrata fungemia from 1995-2002 and performed susceptibility testing of isolates.

METHODS

Data on all episodes of fungemia were prospectively recorded, and the associated isolates were saved. Medical records were reviewed retrospectively. Susceptibility testing was performed for fluconazole, itraconazole, and voriconazole.

RESULTS

C. glabrata caused 103 (17%) of 609 fungemic episodes during the 8-year period that we studied. Medical records and isolates were available for 94 episodes that occurred in 91 patients. The patients included 42 men and 49 women. The mean age was 51 years. Thirty-four episodes (36%) occurred in patients >60 years old; only 3 episodes occurred in patients <1 year old. The most common predisposing factors were use of broad-spectrum antibiotics (in 86% of episodes), use of central venous catheters (77%), stay in an intensive care unit (48%), renal failure (46%), and receipt of parenteral nutrition (45%). Of the 94 episodes, 83 were treated with antifungal agents. The overall mortality rate at day 30 was 29%. For the 11 episodes that were not treated, the mortality rate was 64% (7 of 11 episodes). Outcome appeared to be unrelated to whether fluconazole or amphotericin B was administered. In vitro, 60% of isolates were resistant to fluconazole, 83% to itraconazole, and 44% to voriconazole. Susceptibility to these azoles did not change over the 8 years of the study.

CONCLUSION

C. glabrata fungemia was most often seen in older adults and was associated with a mortality rate of 29%. Outcomes appeared to be unrelated to in vitro susceptibility results and to the antifungal agent used.

Strains and strategies for large-scale gene deletion studies of the diploid human fungal pathogen Candida albicans

Candida albicans is the most common human fungal pathogen and causes significant morbidity and mortality worldwide. Nevertheless, the basic principles of C. albicans pathogenesis remain poorly understood. Of central importance to the study of this organism is the ability to generate homozygous knockout mutants and to analyze them in a mammalian model of pathogenesis. C. albicans is diploid, and current strategies for gene deletion typically involve repeated use of the URA3 selectable marker. These procedures are often time-consuming and inefficient. Moreover, URA3 expression levels-which are susceptible to chromosome position effects-can themselves affect virulence, thereby complicating analysis of strains constructed with URA3 as a selectable marker. Here, we describe a set of newly developed reference strains (leu2Delta/leu2Delta, his1Delta/his1Delta; arg4Delta/arg4Delta, his1Delta/his1Delta; and arg4Delta/arg4Delta, leu2Delta/leu2Delta, his1Delta/his1Delta) that exhibit wild-type or nearly wild-type virulence in a mouse model. We also describe new disruption marker cassettes and a fusion PCR protocol that permit rapid and highly efficient generation of homozygous knockout mutations in the new C. albicans strains. We demonstrate these procedures for two well-studied genes, TUP1 and EFG1, as well as a novel gene, RBD1. These tools should permit large-scale genetic analysis of this important human pathogen.

Management of invasive candidiasis in critically ill patients

Candida species have become predominant pathogens in critically ill patients. In this population, invasive candidiasis is associated with a poor prognosis but adequate management can limit the attributable mortality. Adequate management, however, is hampered by a problematic diagnosis as the clinical picture of invasive disease is non-specific and blood cultures have a low sensitivity. Moreover, it is often hard to differentiate colonisation from infection and many critically ill patients are heavily colonised with Candida species, especially when receiving broad-spectrum antibacterials. The question of which antifungal agent to choose has become more complex as the development of new drugs raises promising expectations. Until the 1980s therapy for invasive candidiasis was limited to amphotericin B, but with the advent of new antifungal agents, such as azoles and echinocandins, less toxic therapeutic options are possible and doors have opened towards prevention and optimised therapy in the case of documented candidiasis. Through the arrival of these new antifungal agents, a range of therapeutic strategies for the management of invasive candidiasis has been developed: antifungal prophylaxis, pre-emptive therapy, and empirical and definitive antifungal therapy. Each of these strategies has a specific target population, as defined by specific underlying conditions and/or individual risk factors. Antifungal prophylaxis, in order to prevent candidal infection, is based on the type of underlying diseases with a high risk for invasive candidiasis. Individual risk factors are not taken into account. Potential indications are bone marrow transplantation, liver transplantation, recurrent gastrointestinal perforations or leakages, and surgery for acute necrotising pancreatitis. Pre-emptive therapy is also a preventive strategy. It can be recommended on the basis of an individual risk profile including overt candidal colonisation. Empirical therapy is started in patients with a risk profile for invasive candidiasis. It is recommended in the presence of clinical signs of infection, deteriorating clinical parameters, or a clinical picture of infection not responding to antibacterials but in the absence of a clear causative pathogen. Definitive antifungal therapy is defined as therapy in patients with documented invasive infection. The main goal is to maintain a balance between optimal prevention and timely initiation of therapy on one hand, and to minimise selection pressure in order to avoid a shift towards less susceptible Candida species on the other hand.

Invasive Candida species infections: a 5 year population-based assessment

OBJECTIVES

Candida species have emerged as important causes of invasive infections and rates of resistance to standard antifungal therapies are rising. The objective of this study was to define the occurrence of, risk factors for, and antifungal susceptibilities of invasive Candida species infections in a large Canadian health region.

METHODS

Population-based surveillance was conducted for invasive Candida species infections in the Calgary Health Region during a 5 year period and susceptibility testing was performed.

RESULTS

The annual incidence of invasive Candida species infection was 2.9 per 100,000 population (0.2 and 2.8 per 100,000 for central nervous system and bloodstream infection, respectively). The very young and elderly were at highest risk for invasive Candida species infections. Several risk factors for developing invasive Candida species infection were identified with chronic haemodialysis, organ transplant recipient, and cancer patients at highest risk. Thirty percent (56/184; 43 susceptible, dose-dependent and 13 resistant) of isolates demonstrated reduced susceptibility to fluconazole. Only one (1%) isolate had reduced susceptibility to amphotericin B and six (3%) and three (2%) isolates had minimum inhibitory concentrations of >or=1 mg/L to voriconazole and caspofungin, respectively. Overall, 40% of patients died in-hospital for an annual mortality rate of 1.2 per 100,000.

CONCLUSIONS

Candida species are an important cause of invasive infection and patients with co-morbidities and extremes of age are at highest risk. Alternatives to fluconazole should be considered for initial empiric therapy in patients with severe invasive Candida species infections.

Genotype distribution of Candida albicans isolates by 25S intron analysis with regard to invasiveness

The aim of this study was to genotype Candida albicans strains isolated from patients with invasive and non-invasive deep-seated infections. For this purpose, 301 C. albicans isolates (81 invasive and 220 non-invasive) were genotyped by using specific PCR primers designed to span the transposable group I intron of the 25S rDNA gene. Fifty-three of the 81 invasive isolates were genotype A (65.4%), eight were genotype B (9.9%) and 20 were genotype C (24.7%), while 98 of the 220 non-invasive isolates were genotype A (44.6%), 46 were genotype B (20.9%) and 76 were genotype C (34.5%). Genotype A was more prevalent among invasive isolates and genotypes B and C were more prevalent among non-invasive isolates (P = 0.0046). Genotypes D and E which represent C. dubliniensis were not found. These results indicate that there may be a relationship between C. albicans genotypes and invasiveness; genotype A being more invasive than others. The presence or absence of the transposable group I intron in the 25S rDNA gene may be important in determining the invasiveness of C. albicans.

Distribution of gentamicin from a Gentacoll sponge measured by in vivo microdialysis

Microdialysis has produced valuable information concerning the distribution of antibiotics in peripheral tissue. The aim of this study was to measure the local distribution of gentamicin in cancellous bone tissue after the application of a Gentacoll sponge. Two microdialysis catheters were inserted into the cancellous bone of 9 pigs. After calibration of the microdialysis, a Gentacoll sponge was implanted, either dry or wet, into the bone marrow of the tibia. Serum and microdialysates were obtained over a period of 6 h. Data presented are median (range). A rank sum test was performed for statistical analysis. The peak concentration was 120 mg/l (33-585) (wet group) and 178 mg/l (60-1294) (dry group) (p=0.31). The AUC6 of the catheters placed 1 cm away from the implant was 24,431 mg*min/l (5155-152,855) and the AUC6 of the catheter placed 2 cm away from the implant was 13,759 mg*min/l (6351-74,573) (p=0.25). The study showed that peak concentrations and AUC6 did not differ between the wet- and dry-application group; neither did the distance from the sponge to the catheter have a significant impact on the distribution of gentamicin. It seems that microdialysis is capable to measure concentrations of locally applied antibiotics.

Epidemiology and predictors of mortality in cases of Candida bloodstream infection: results from population-based surveillance, barcelona, Spain, from 2002 to 2003

We conducted population-based surveillance for Candida bloodstream infections in Spain to determine its incidence, the extent of antifungal resistance, and risk factors for mortality. A case was defined as the first positive blood culture for any Candida spp. in a resident of Barcelona, from 1 January 2002 to 31 December 2003. We defined early mortality as occurring between days 3 to 7 after candidemia and late mortality as occurring between days 8 to 30. We detected 345 cases of candidemia, for an average annual incidence of 4.3 cases/100,000 population, 0.53 cases/1,000 hospital discharges, and 0.73 cases/10,000 patient-days. Outpatients comprised 11% of the cases, and 89% had a central venous catheter (CVC) at diagnosis. Overall mortality was 44%. Candida albicans was the most frequent species (51% of cases), followed by Candida parapsilosis (23%), Candida tropicalis (10%), Candida glabrata (8%), Candida krusei (4%), and other species (3%). Twenty-four isolates (7%) had decreased susceptibility to fluconazole (MIC > or = 16 microg/ml). On multivariable analysis, early death was independently associated with hematological malignancy (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.1 to 10.4). Treatment with antifungals (OR, 0.05; 95% CI, 0.01 to 0.2) and removal of CVCs (OR, 0.3; 95% CI, 0.1 to 0.9) were protective factors for early death. Receiving adequate treatment, defined as having CVCs removed and administration of an antifungal medication (OR, 0.2; 95% CI, 0.08 to 0.8), was associated with lower odds of late mortality; intubation (OR, 7.5; 95% CI, 2.6 to 21.1) was associated with higher odds. The incidence of candidemia and prevalence of fluconazole resistance are similar to other European countries, indicating that routine antifungal susceptibility testing is not warranted. Antifungal medication and catheter removal are critical in preventing mortality.

Excess mortality, length of stay, and costs associated with serious fungal infections among elderly cancer patients: findings from linked SEER-Medicare data

OBJECTIVE

To calculate the excess mortality, length of stay, and costs attributable to serious fungal infections in hospitalized elderly patients with selected cancers.

METHODS

This study involved a retrospective cohort analysis using linked data from the Surveillance, Epidemiology and End Results Program of the National Cancer Institute (SEER) and Medicare claims data. Study cohorts included patients aged 65 years and older who newly received a diagnosis of a selected cancer (acute myeloid leukemia [AML] or squamous cell carcinoma of the head and neck [SCCHN]) in a SEER registry between 1991 and 1996 and who had a subsequent diagnosis of a serious fungal infection during an inpatient hospitalization, and hospitalized controls without a fungal infection matched 1:1 by age, geographic region, receipt of recent chemotherapy, concomitant bacterial infection, timing of the index hospitalization, and cancer stage at diagnosis (for SCCHN patients only).

RESULTS

Eighty AML patients and 52 SCCHN patients experienced a serious fungal infection involving hospitalization. Relative to matched controls, SCCHN patients with fungal infections had significantly higher all-cause mortality (40% vs. 14%, P = 0.002), while mortality rates did not differ between AML cohorts. Patients with fungal infections had significantly longer index hospitalizations regardless of cancer type (mean: 30 days vs. 19 days for AML patients; 20 days vs. 9 days for SCCHN patients), and correspondingly higher Medicare payments (mean +/- SD: 34,268 dollars +/- 31,811 dollars vs. 21,416 dollars +/- 22,449 dollars among AML patients, P < 0.0001; 25,942 dollars +/- 29,122 dollars vs. 10,131 dollars +/- 10,686 dollars among SCCHN patients, P < 0.0001).

CONCLUSIONS

Efforts to prevent these infections and/or initiate early treatment may yield both clinical and economic benefits.

Prophylaxis and treatment of invasive candidiasis in the intensive care setting

The term "invasive candidiasis" encompasses a group of infections of increasing relevance in the intensive care setting. Prophylaxis is an attractive strategy when dealing with diseases of high prevalence, morbidity, and mortality. The success of prophylaxis is determined by the selection of a population at high risk and the use of the safest and most effective drug. Although risk factors for this disease are known, risk assessment strategies need to be developed to predict a high likelihood of disease so that targeted prophylaxis can be offered. Recent advances in antifungal therapy, such as development of the azoles and echinocandins, have resulted in excellent prophylactic and therapeutic choices for the management of this problem.

Hospital-acquired candidemia in HIV-infected patients. Incidence, risk factors and predictors of outcome

A retrospective case-control study was performed to analyze hospital-acquired candidemia in HIV-positive patients. To understand the impact of Highly Active Antiretroviral Therapy (HAART) on the incidence of nosocomial candidemia, two time periods were compared: A (1992-1996) and B (1997-2001). 32 out of 38 (84%) cases of candidemia were hospital-related. A significant reduction in the incidence of all cases of hospital-acquired candidemia has been observed in the post-HAART in respect to pre-HAART period (0.09 episodes vs. 1.1 per 100/py). Multivariate analysis showed that the presence of central venous catheter was the only variable independently associated with the development of nosocomial candidemia. The overall mortality rate was 59%. Univariate analysis indicated three prognostic indicators: presence of concomitant opportunistic infections, isolation of non-albicans Candida species; neutropenia. Multivariate analysis of prognostic indicators showed that isolation of non-albicans Candida species is the only independent variable. Despite the use of HAART, this disease still represents a severe complication of advanced stage of AIDS.

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

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

Incidence of bloodstream infections due to Candida species and in vitro susceptibilities of isolates collected from 1998 to 2000 in a population-based active surveillance program

To determine the incidence of Candida bloodstream infections (BSI) and antifungal drug resistance, population-based active laboratory surveillance was conducted from October 1998 through September 2000 in two areas of the United States (Baltimore, Md., and the state of Connecticut; combined population, 4.7 million). A total of 1,143 cases were detected, for an average adjusted annual incidence of 10 per 100,000 population or 1.5 per 10,000 hospital days. In 28% of patients, Candida BSI developed prior to or on the day of admission; only 36% of patients were in an intensive care unit at the time of diagnosis. No fewer than 78% of patients had a central catheter in place at the time of diagnosis, and 50% had undergone surgery within the previous 3 months. Candida albicans comprised 45% of the isolates, followed by C. glabrata (24%), C. parapsilosis (13%), and C. tropicalis (12%). Only 1.2% of C. albicans isolates were resistant to fluconazole (MIC, > or = 64 microg/ml), compared to 7% of C. glabrata isolates and 6% of C. tropicalis isolates. Only 0.9% of C. albicans isolates were resistant to itraconazole (MIC, > or = 1 micro g/ml), compared to 19.5% of C. glabrata isolates and 6% of C. tropicalis isolates. Only 4.3% of C. albicans isolates were resistant to flucytosine (MIC, > or = 32 microg/ml), compared to < 1% of C. parapsilosis and C. tropicalis isolates and no C. glabrata isolates. As determined by E-test, the MICs of amphotericin B were > or = 0.38 microg/ml for 10% of Candida isolates, > or =1 microg/ml for 1.7% of isolates, and > or = 2 microg/ml for 0.4% of isolates. Our findings highlight changes in the epidemiology of Candida BSI in the 1990s and provide a basis upon which to conduct further studies of selected high-risk subpopulations.

Epidemiology of candidemia in Swiss tertiary care hospitals: secular trends, 1991-2000

Candida species are among the most common bloodstream pathogens in the United States, where the emergence of azole-resistant Candida glabrata and Candida krusei are major concerns. Recent comprehensive longitudinal data from Europe are lacking. We conducted a nationwide survey of candidemia during 1991-2000 in 17 university and university-affiliated hospitals representing 79% of all tertiary care hospital beds in Switzerland. The number of transplantations and bloodstream infections increased significantly (P<.001). A total of 1137 episodes of candidemia were observed: Candida species ranked seventh among etiologic agents (2.9% of all bloodstream isolates). The incidence of candidemia was stable over a 10-year period. C. albicans remained the predominant Candida species recovered (66%), followed by C. glabrata (15%). Candida tropicalis emerged (9%), the incidence of Candida parapsilosis decreased (1%), and recovery of C. krusei remained rare (2%). Fluconazole consumption increased significantly (P<.001). Despite increasing high-risk activities, the incidence of candidemia remained unchanged, and no shift to resistant species occurred.

Candidemia: The Impact of Antifungal Prophylaxis in a Surgical Intensive Care Unit

BACKGROUND

Candidemia is fourfold more common in 1990 compared to 1980. In addition, a shift to non-albicans species has occurred in some institutions. Antifungal prophylaxis (AP) is effective in high-risk patients including critically ill surgical patients, but its use has been attributed to a resultant shift to non-albicans candida species. We hypothesized that the use of fluconazole prophylaxis would lead to a decreased incidence of candidemia but a possible increased incidence of resistant species of Candida, especially Candida glabrata (CG).

METHODS

From 1990 to 2002, all patients with candidemia (C) in the surgical intensive care unit (SICU) of a large tertiary care hospital were identified and reviewed retrospectively. Antifungal prophylaxis began in 2000 for high-risk patients. The periods were separated into PRE (1990-2000), and POST prophylaxis (2000-2002).

RESULTS

Excluding the year of the trial studying prophylaxis, (1998; five cases of C) a total of 83 patients developed candidemia: 69 PRE (83%) (1.94/1000 patient days) and 14 POST (17%) (0.76/1000 patient days) (OR 0.44; 95% CI 0.25, 0.78; p = 0.004). In the PRE period C. albicans (45%) and CG (30%) were predominant, whereas in the POST period, CG (9/14, 64%) (p = 0.05), and C. albicans (3/14, 21%) were common. Non-albicans species were 38/69 (55%) PRE and 11/14 (79%) POST, p = 0.14. Mortality in the group was 43/83 (52%) and did not differ PRE/POST or based on treatment. Predictors of SICU mortality (model r2 = 0.61) included hospital length of stay (LOS) (OR 1.14, CI 1.04, 1.25), fever (OR 51.2, CI 2.46, 1064), and broad-spectrum antibiotics (OR 69.7, CI 2.08, 2351), whereas post-transplantation status (OR 0.005, CI 0.00, 0.56), blood sugar <180 mg/dL (OR 0.03, CI 0.01, 0.81), and fungal prophylaxis (OR 0.03, CI 0.01, 0.58) were associated with a decreased risk of mortality.

CONCLUSIONS

Unfortunately, the mortality of candidemia remains high in SICU patients (52%). In the SICU, risk factors for candidemia and mortality are common. However, antifungal prophylaxis has significantly decreased the annual incidence of candidemia without a statistically significant shift to non-albicans pathogens.

New approaches to the risk of Candida in the intensive care unit

PURPOSE OF REVIEW

Candidemia is the fourth most common bloodstream infection in the United States with similar trends reported worldwide. This infection is particularly relevant in the intensive care setting, and is independently associated with increased morbidity and mortality. Identification of patients at risk and developing new prophylactic strategies is a priority area of research. This review focuses on recent advances in risk identification and the groundwork for prophylaxis of invasive candidiasis in the intensive care setting.

RECENT FINDINGS

Although risk factors for invasive candidiasis have been clearly identified (such as colonization, length of stay, use of parenteral nutrition, antibiotics, central lines, and abdominal surgery), there are few risk assessment strategies that clearly define or predict a population at high risk of getting this disease. Currently available risk assessment strategies are yet to be validated in multiple centers and settings. Geographically limited or population specific clinical trials (such as surgical patients) have shown early indications that antifungal prophylaxis is useful in reducing the incidence of invasive candidiasis by more than 50% in units with high incidence of infection, or in carefully selected high-risk patients. Interesting advances in non-culture diagnostic methods and surrogate markers of infection may also have an impact in early identification of infection and preemptive treatment.

SUMMARY

Invasive candidiasis is a relevant problem in the intensive care setting. Better risk assessment strategies will permit identification of the subpopulations of patients that would benefit from prophylactic antifungal therapy the most, having the potential to save millions of lives and dollars.

Epidemiology of Candida species infections in critically ill non-immunosuppressed patients

A substantial proportion of patients become colonised with Candida spp during hospital stay, but only few subsequently develop severe infection. Clinical signs of severe infection manifest early but lack specificity until late in the course of the disease, thus representing a particular challenge for diagnosis. Mostly nosocomial, invasive candidiasis occurs in only 1-8% of patients admitted to hospitals, but in around 10% of patients housed in intensive care units where it can represent up to 15% of all nosocomial infections. We review the epidemiology of invasive candidiasis in non-immunocompromised, critically ill patients with special emphasis on disease trends over time, pathophysiology, diagnostic approach, risk factors, and impact. Recent epidemiological data suggesting that the emergence of non-albicans candida strains with reduced susceptibility to azoles, previously linked to the use of new antifungals for empiric and prophylactic therapy in immunocompromised patients, may not have occurred in the critically ill. Management of invasive candidiasis in these patients will be addressed in the December issue of The Lancet Infectious Diseases.

The global epidemiology of invasive Candida infections—is the tide turning?

Invasive candidiasis is a condition of major medical importance. Its incidence has increased dramatically over the last 50 years, reflecting increasingly interventional standards of medical care. Candida spp. are regularly reported to be the fourth commonest cause of bloodstream infection, and it is perceived that the incidence of invasive Candida spp. infections continues to increase. The global disease burden of invasive Candida spp. infections is difficult to quantify because of wide geographic variation. Data originating from the United States indicate that mortality from candidiasis has been falling since 1989. Data from several locations have shown that the dramatic increases in Candida spp. bloodstream infections seen during the 1980s were not sustained through the 1990s. Some authors have reported a decreasing incidence. The contribution of non-albicans Candida spp. to invasive infection is rising. Invasive infections with Candida spp. continue to represent a major economic burden, increasing both mortality and morbidity in an already expensive group of hospital patients. There remains much scope for ongoing and future research into the epidemiology and basic disease processes underlying these infections.