Seminational surveillance of fungemia in Denmark: notably high rates of fungemia and numbers of isolates with reduced azole susceptibility

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.

A cluster of Candida krusei infections in a haematological unit

BACKGROUND

Candida krusei infections are associated with high mortality. In order to explore ways to prevent these infections, we investigated potential routes for nosocomial spread and possible clonality of C. krusei in a haematological unit which had experienced an unusually high incidence of cases.

METHODS

We searched for C. krusei contamination of the hospital environment and determined the level of colonization in patients and health care workers. We also analyzed the possible association between exposure to prophylactic antifungals or chemotherapeutic agents and occurrence of C. krusei. The C. krusei isolates found were genotyped by pulsed-field electrophoresis method in order to determine possible relatedness of the cases.

RESULTS

Twelve patients with invasive C. krusei infection and ten patients with potentially significant infection or mucosal colonization were documented within nine months. We were unable to identify any exogenic source of infection or colonization. Genetic analysis of the isolates showed little evidence of clonal transmission of C. krusei strains between the patients. Instead, each patient was colonized or infected by several different closely related genotypes. No association between medications and occurrence of C. krusei was found.

CONCLUSION

Little evidence of nosocomial spread of a single C. krusei clone was found. The outbreak may have been controlled by cessation of prophylactic antifungals and by intensifying infection control measures, e.g. hand hygiene and cohorting of the patients, although no clear association with these factors was demonstrated.

Fungemia at a tertiary care hospital: incidence, therapy, and distribution and antifungal susceptibility of causative species

The aim of this study was to review fungal bloodstream infections at a large tertiary care hospital to evaluate the incidence of fungemia and the distribution of causative species during the period 2001-2005. Another aim was to assess the extent of antifungal resistance. A review of all episodes of fungemia at the University Hospitals of Leuven (Belgium) was conducted between January 2001 and December 2005. For the first yeast isolate collected from each non-mould fungemic episode during a 1-year period (June 2004-June 2005), susceptibility to seven antifungal agents was determined using Sensititre YeastOne plates (Trek Diagnostic Systems, East Grinstead, UK), and the antifungal therapy was reviewed. The annual incidence of fungemia ranged between 1.30 and 1.68 episodes per 10,000 patient-days (on a total of 2,680,932 patient-days), with a decreasing trend observed over the 5-year study period. The most common species were Candida albicans (59%), Candida glabrata (22%), Candida parapsilosis (10%), and Candida tropicalis (4%). Overall, fluconazole resistance was rare (1.6%) and was detected only in C. glabrata and C. krusei. Voriconazole and caspofungin inhibited 100% of the isolates at a concentration of <or=1 microg/ml. Fluconazole was used to treat 75% of fungemic patients. Caspofungin was the second most commonly used antifungal agent (used to treat 11.7% of patients). The incidence of fungemia was higher than usually reported in other European countries. The low proportion of resistance supports the use of fluconazole as the treatment of first choice for candidemia in patients not previously exposed to this drug.

The use of caspofungin in HIV-infected individuals

Fungal infections are a significant cause of HIV-related morbidity and mortality, particularly in the developing world, but also in countries with access to highly active antiretroviral therapy. New agents are essential to improve present efficacy rates, particularly in cases of drug resistance. Caspofungin is a new antifungal from the echinocandin class and is licensed for the treatment of candidal infections and as a second-line therapy for invasive aspergillosis. In this paper, the pharmacology, interaction and susceptibility data for this agent are reviewed and studies supporting the use of this agent in HIV-infected individuals are examined. Finally, evidence for the use of caspofungin for the treatment of Pneumocystis jiroveci pneumonia, an unlicensed indication, including a case series from our own unit is explored.

Results from the ARTEMIS DISK Global Antifungal Surveillance study, 1997 to 2005: an 8.5-year analysis of susceptibilities of Candida species and other yeast species to fluconazole and voriconazole determined by CLSI standardized disk diffusion testing

Fluconazole in vitro susceptibility test results for 205,329 yeasts were collected from 134 study sites in 40 countries from June 1997 through December 2005. Data were collected for 147,776 yeast isolates tested with voriconazole from 2001 through 2005. All investigators tested clinical yeast isolates by the CLSI M44-A disk diffusion method. Test plates were automatically read and results recorded with a BIOMIC image analysis system. Species, drug, zone diameter, susceptibility category, and quality control results were collected quarterly. Duplicate (same patient, same species, and same susceptible-resistant biotype profile during any 7-day period) and uncontrolled test results were not analyzed. Overall, 90.1% of all Candida isolates tested were susceptible (S) to fluconazole; however, 10 of the 22 species identified exhibited decreased susceptibility (<75% S) on the order of that seen with the resistant (R) species C. glabrata and C. krusei. Among 137,487 isolates of Candida spp. tested against voriconazole, 94.8% were S and 3.1% were R. Less than 30% of fluconazole-resistant isolates of C. albicans, C. glabrata, C. tropicalis, and C. rugosa remained S to voriconazole. The non-Candida yeasts (8,821 isolates) were generally less susceptible to fluconazole than Candida spp. but, aside from Rhodotorula spp., remained susceptible to voriconazole. This survey demonstrates the broad spectrum of these azoles against the most common opportunistic yeast pathogens but identifies several less common yeast species with decreased susceptibility to antifungal agents. These organisms may pose a future threat to optimal antifungal therapy and emphasize the importance of prompt and accurate species identification.

Epidemiology of invasive candidiasis: a persistent public health problem

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

Trends in the Epidemiology of Invasive Fungal Infections

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

Role of antifungal susceptibility testing in patient management

PURPOSE OF REVIEW

The review focuses on the evolving role of antifungal susceptibility testing in the clinical management of patients with invasive fungal infections. It will clarify how to clinically interpret available susceptibility testing methods.

RECENT FINDINGS

Fluconazole susceptibility testing for yeasts has now shown a relationship between fluconazole resistance and therapeutic failure. Of increasing concern are the reported cases of fluconazole cross-resistance to the newer triazoles. The correlation between amphotericin B and echinocandin susceptibility testing for yeasts, resistance, and outcomes is unknown. Although there are reports of clinical failures with echinocandins, resistance is uncommon and susceptibility testing is unhelpful. There are standardized methods of testing for the triazoles and amphotericin B against molds; however, resistance has not been correlated with outcomes due to host and laboratory factors. Knowing the intrinsic resistance of molds to particular antifungals is of greater importance. Posaconazole is a potent new antifungal agent against many difficult-to-treat molds including fusariosis and zygomycosis.

SUMMARY

Antifungal susceptibility testing of yeasts can assist in treating patients with prior antifungal exposure in determining resistance or cross-resistance. Mold susceptibility testing is of limited clinical benefit, while posconazole is an exciting new agent for treating difficult invasive fungal infections.

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.

Anidulafungin pharmacokinetics and microbial response in neutropenic mice with disseminated candidiasis

Candidemia is often fatal, especially in patients with persistent neutropenia. New therapies are needed. We performed 24-h pharmacodynamic studies to compare the efficacies of anidulafungin, fluconazole, and amphotericin B in neutropenic mice with disseminated candidiasis caused by one of three strains of Candida glabrata. Anidulafungin produced a maximal fungal kill (E(max)) of 1.4 to 1.9 log(10) CFU/g in kidneys and was not influenced by resistance to either fluconazole or amphotericin B. Fluconazole produced an E(max) of 1.3 log(10) CFU/g in mice infected with fluconazole-susceptible C. glabrata, but the E(max) was 0 for mice infected with a C. glabrata strain that had a fluconazole MIC of >/=32 mg/liter. Amphotericin B achieved an E(max) of 4.2 log(10) CFU/g in mice infected with amphotericin B-susceptible C. glabrata, but the E(max) was 0 for mice infected with a C. glabrata strain with an amphotericin B MIC of 2 mg/liter. In all instances, anidulafungin's maximal microbial kill was superior to that of fluconazole. Next, we performed a 96-h anidulafungin pharmacokinetic-pharmacodynamic study. Anidulafungin exhibited delayed peak concentrations in kidneys compared to those in serum, after which the concentrations declined, with a serum terminal half-life of 21.6 (+/-4.6) h. This was accompanied by a persistent 96-h decrease in the kidney fungal burden after treatment with a single anidulafungin dose of >/=8 mg/kg of body weight. This pharmacokinetic-pharmacodynamic picture of anidulafungin persistence in tissues and the resultant persistent fungal decline should be exploited to improve the efficacy of anidulafungin therapy for candidemia.

Invasive Candidiasis

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

Epidemiological study of Candida infections in blood: susceptibilities of Candida spp. to antifungal agents, and clinical features associated with the candidemia

The purpose of this study was to evaluate the susceptibility to antifungal agents of Candida spp. isolated from blood samples from patients in our hospital, located in Osaka, Japan. We also examined the clinical background of these patients. We analyzed fungi isolated from clinical blood samples obtained in our hospital over a period of 10 years (1993 to 2002). Antifungal susceptibility testing was carried out for six agents, using the National Committee of Clinical Laboratory Standards (NCCLS) M-27-A2 method. The clinical backgrounds were reviewed using the medical records of 125 patients who were diagnosed as having candidemia. The major fungi isolated were Candida parapsilosis (39.2%) and C. albicans (30.1%), and both were sensitive to fluconazole. One strain of C. glabrata and six strains of C. krusei were resistant to fluconazole, and they constituted 4.4% of all Candida spp. isolated. With the exception of C. parapsilosis, most fungi were susceptible to micafungin, although there is no universally agreed breakpoint for this drug. Analysis of the patients' clinical backgrounds revealed that the major underlying disease was cancer (46.4% excluding hematological malignancies). C. krusei was detected almost exclusively in patients with hematological malignancies. Indwelling venous catheters had been responsible for infection in 93.6% of the infected patients. The clinical outcomes of the 125 patients were favorable in 52% and poor in 48%, and subsequent removal of the indwelling catheters was effective in about half of the patients in whom this was done, with good prognosis. To prevent mycosis and its complications, indwelling catheters should be avoided as much as possible. Attention must be paid to the possibility that resistant isolates of Candida spp. can be selected as a result of the use of antifungal agents.

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

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

Targeted short-term fluconazole prophylaxis among very low birth weight and extremely low birth weight infants

OBJECTIVES

To assess whether targeted short-term fluconazole prophylaxis reduces late-onset (>3 days of age) invasive fungal infection (IFI) among very low birth weight infants and extremely low birth weight (ELBW) infants and to assess mortality rates, toxicity, and costs associated with this intervention.

METHODS

An observational study of 2 subsequent epochs of inborn infants with birth weight of <1500 g or gestational age of <32 weeks, 1 before (control) and 1 after (fluconazole) initiation of routine targeted fluconazole prophylaxis in March 2003, was performed. Targeted fluconazole (3 mg/kg) prophylaxis was administered to infants for whom a decision was made to administer broad-spectrum antibiotics for >3 days.

RESULTS

IFI was observed for 13 (6.3%) of 206 infants in the control epoch and 2 (1.1%) of 178 in the fluconazole epoch, with a common odds ratio of 0.166. Logistic regression analysis taking into account all published factors (except for fungal colonization) showed that the fluconazole epoch was associated significantly with lower IFI rates. We observed no change in late (>3 days) mortality rates (11 of 206 infants in the control epoch vs 8 of 178 infants in the prophylaxis epoch). The mortality rate for ELBW infants with IFI was low (15%) in our study. Fluconazole was administered to 81% of ELBW infants, who received a median of 8 doses, and 41% of larger infants, who received a median of 5 doses. The intervention was cost-effective, and the effective number needed to treat to prevent 1 IFI was 10.

CONCLUSIONS

This study suggests that targeted short-course fluconazole prophylaxis in very low birth weight and ELBW infants may be efficacious and cost effective.

Amphotericin B and Caspofungin Resistance in Candida glabrata Isolates Recovered from a Critically Ill Patient

BACKGROUND

Consecutive Candida glabrata isolates recovered from a patient in an intensive care unit were resistant to amphotericin B (minimum inhibitory concentration, up to 32 mu g/mL; determined by Etest [AB Biodisk]). Analyses at the national reference laboratory showed that some isolates were also resistant to azoles and caspofungin. In this study, 4 isolates were studied thoroughly using susceptibility assays and a mouse model and to determine clonality.

METHODS

Different broth microdilution tests, Etests, and time-kill studies for antifungals were performed in different media. Three of the 4 isolates were examined in an in vivo experiment, in which mice were challenged intravenously with 1 of 3 isolates and treated daily with amphotericin B, caspofungin, or saline. For the clonality studies, arbitrarily primed polymerase chain reaction (PCR) was performed with the 4 isolates, 8 isolates obtained from nonrelated patients, and a reference strain.

RESULTS

The murine model indicated that 1 isolate was resistant to amphotericin B, 1 had intermediate susceptibility, and 1 was fully susceptible. Two of the 3 isolates were resistant to caspofungin. Microdilution methods did not reliably differentiate between amphotericin B-susceptible and -resistant isolates. All assays identified caspofungin-susceptible and -resistant isolates. Arbitrarily primed PCR showed that the 4 isolates probably were of clonal origin.

CONCLUSIONS

We have documented the emergence of amphotericin B-resistant and caspofungin-resistant C. glabrata isolates during treatment of a critically ill liver transplant recipient. Only the Etest predicted amphotericin B resistance in the isolates. We recommend that important fungal strains recovered from patients who are receiving antifungal therapy should be tested for susceptibility to the antifungal drug used, because resistance can be present initially or may occur during treatment.