Fungemia: An increasing problem in a Danish university hospital 1989 to 1994

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

The aim of this study was to present the first set of comprehensive data on fungemia in Denmark including the distribution of species and range of susceptibility to major antifungal compounds based on a seminational surveillance study initiated in 2003. The catchment area of the participating hospitals had a population of 2.8 million, or 53% of the Danish population. A total of 303 episodes of fungemia were registered (annual rate, 11 of 100,000 people or 0.49 of 1,000 hospital discharges). Candida species accounted for 97.4% of the fungal pathogens. C. albicans was the predominant species (63%), but the proportion varied from 57% to 72% among participating departments of clinical microbiology. C. glabrata was the second most frequent species (20%; range, 8% to 32%). C. krusei was a rare isolate (3%) and occurred only at two of the participating hospitals. Retrospective data retrieved from the Danish laboratory systems documented a continuous increase of candidemia cases since the early 1990s. For the 272 susceptibility-tested isolates, MICs of amphotericin B and caspofungin were within the limits expected for the species or genus. However, decreased azole susceptibility, defined as a fluconazole MIC of >8 microg/ml and/or itraconazole MIC of >0.125 microg/ml, was detected for 11 Candida isolates that were neither C. glabrata nor C. krusei. Including intrinsically resistant fungi, we detected decreased susceptibility to fluconazole and/or itraconazole in 87 (32%) current Danish bloodstream fungal isolates. We showed a continuous increase of fungemia in Denmark and an annual rate in 2003 to 2004 higher than in most other countries. The proportion of bloodstream fungal isolates with reduced susceptibility to fluconazole and/or itraconazole was also notably high.

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.

Evaluation of the VITEK 2 system for rapid identification of yeasts and yeast-like organisms

The new VITEK 2 system is a fully automated system dedicated to the identification and susceptibility testing of microorganisms. In conjunction with the VITEK ID-YST card the VITEK 2 system allows the identification of clinically important yeasts and yeast-like organisms in 15 h due to a sensitive fluorescence-based technology. The ID-YST card consists of 47 biochemical reactions. The database comprises 51 taxa, including newly described species. In this study we evaluated the reliability of the VITEK ID-YST card for the identification of yeasts and yeast-like organisms encountered in a clinical microbiology laboratory. A total of 241 strains representing 21 species were studied. The strains were isolated from clinical samples within a period of 60 days prior to the identification. The tests were performed using 24-h to 55-h subcultures on Sabouraud-gentamicin-chloramphenicol agar. Each strain was tested in parallel using the ID 32C strip as a comparison method combined with microscopic morphology and an agglutination test for C. krusei. Overall, 222 strains (92.1%) were unequivocally identified including 11 isolates (4.6%) identified with low discrimination resolved by simple additional tests. Ten strains (4. 1%) for which results were given with low discrimination could not be unequivocally identified with supplemental tests, 4 strains (1. 7%) were misidentified and 5 strains (2.1%) could not be identified. In conclusion, we found that the VITEK 2 system is a rapid and accurate method for the identification of medically important yeasts and yeast-like organisms.

Bloodstream infections due to Candida species: SENTRY antimicrobial surveillance program in North America and Latin America, 1997-1998

An international program of surveillance of bloodstream infections (BSI) in the United States, Canada, and Latin America detected 306 episodes of candidemia in 34 medical centers (22 in the United States, 6 in Canada, and 6 in Latin America) in 1997 and 328 episodes in 34 medical centers (22 in the United States, 5 in Canada, and 7 in Latin America) in 1998. Of the 634 BSI, 54.3% were due to Candida albicans, 16.4% were due to C. glabrata, 14.9% were due to C. parapsilosis, 8.2% were due to C. tropicalis, 1.6% were due to C. krusei, and 4.6% were due to other Candida spp. The percentage of BSI due to C. albicans decreased very slightly in the United States between 1997 and 1998 (56.2 to 54.4%; P = 0.68) and increased in both Canada (52.6 to 70.1%; P = 0.05) and Latin America (40.5 to 44. 6%; P = 0.67). C. glabrata was the second most common species observed overall, and the percentage of BSI due to C. glabrata increased in all three geographic areas between 1997 and 1998. C. parapsilosis was the third most prevalent BSI isolate in both Canada and Latin America, accounting for 7.0 and 18.5% of BSI, respectively. Resistance to fluconazole (MIC, >/=64 microgram/ml) and itraconazole (MIC, >/=1.0 microgram/ml) was observed infrequently in both 1997 (2.3 and 8.5%, respectively) and 1998 (1.5 and 7.6%, respectively). Among the different species of Candida, resistance to fluconazole and itraconazole was observed in C. glabrata and C. krusei, whereas isolates of C. albicans, C. parapsilosis, and C. tropicalis were all highly susceptible to both fluconazole (98.9 to 100% susceptible) and itraconazole (96.4 to 100% susceptible). Isolates from Canada and Latin America were generally more susceptible to both triazoles than U.S. isolates were. Continued surveillance appears necessary to detect these important changes.

[Candidiasis in cancer patients: Epidemiology, diagnosis, prophylaxis and therapy]

New approaches in successful treatment of cancer patients are impaired by increasing incidence of fungal infections with high mortality. Relevant prognostic factors could be identified by numerous trials, such as age, kind and status of disease, intensity of previous chemotherapy, bone marrow transplantation, advanced fungal colonization of gastrointestinal tract. In clinical practice options for prompt and sensitive diagnostics are limited despite of new PCR-techniques. Prophylactic efficiency of polyenes or azoles is proven in high risk patients. Amphotericin B is established for treatment in case of documented or assumed invasive fungal infection. Liposomal preparations are less toxic and at least as effective as conventional amphotericin B in randomized trials.

Detection of fluconazole-resistant Candida strains by a disc diffusion screening test

A commercial disc diffusion test has been evaluated as a screening method for the detection of Candida species with decreased susceptibility to fluconazole. A total of 1,407 Candida strains of different species were tested, and the results were compared with the MIC results. The recently published National Committee for Clinical Laboratory Standards breakpoint criteria have been used. Isolates were classified as susceptible if the MIC for the isolates was </=8 microg/ml, susceptible-dose dependent (S-DD) if the MIC was 16 to 32 microg/ml, and resistant if the MIC was >/=64 microg/ml. All 77 resistant strains and 121 of 122 S-DD strains had fluconazole zone diameters of </=21 mm, and most of the strains (91%) had zone diameters of </=15 mm. It was not possible to distinguish between resistant and S-DD strains by the disc test. Among a total of 1,208 strains found to be susceptible by the microdilution method, 49 (4. 1%) yielded fluconazole zone sizes of </=21 mm and would have been misclassified as resistant or S-DD strains on the basis of the disc test. For the majority (86%) of these 49 strains the fluconazole MIC was 8 microg/ml. The fluconazole disc test is recommended as a simple and reliable screening test for the detection of Candida strains with decreased susceptibility to fluconazole. Fluconazole MICs should be determined for strains found to be resistant by the disc test. The reason for confirmatory testing is twofold: to determine if isolates are resistant or S-DD, since the disc test does not make this distinction, and to identify fluconazole-susceptible strains that are found to be falsely resistant by the fluconazole disc test.

International surveillance of blood stream infections due to Candida species in the European SENTRY Program: species distribution and antifungal susceptibility including the investigational triazole and echinocandin agents. SENTRY Participant Group (Europe)

The SENTRY Antimicrobial Surveillance Program, an international study of blood stream infections (BSIs), detected 170 episodes of candidemia in 20 European medical centers (13 nations) between January and December, 1997. Twenty-three percent of the candidal BSI occurred in patients hospitalized in an intensive care unit, 21% in patients in an internal medicine service, 13% in patients in a surgical service, and 9% in patients in an oncology service. Overall, 53% of the BSI were attributable to Candida albicans followed in prevalence by C. parapsilosis (21%), C. glabrata (12%), C. tropicalis (6%), C. famata (2%), C. krusei (1%), and C. inconspicua (1%). As observed previously in Canada and Latin America, C. parapsilosis and not C. glabrata, was the most common non-albicans species causing yeast BSI in Europe. The proportion of these candidemias attributable to C. albicans varied widely from 0-100% among the 20 European centers. Among the different species of Candida, resistance to fluconazole (MIC, > or = 64 micrograms/mL) and itraconazole (MIC, > or = 1.0 microgram/mL) was observed with C. glabrata and C. krusei and was observed more rarely among other species (e.g., C. inconspicua). Isolates of C. albicans, C. parapsilosis, C. tropicalis, and C. guilliermondii were all highly susceptible to both fluconazole and itraconazole. Furthermore, the investigational triazoles (BMS-207147, Sch 56592, and voriconazole) and an echinocandin (MK-0991) all demonstrated potent in vitro activity (MIC90s, 0.5, 0.5, 1.0, and 2.0 micrograms/mL, respectively) against these isolates. Continued surveillance at an international level will be important to monitor trends in species distribution and antifungal susceptibility among invasive strains of Candida.

Constant low rate of fungemia in norway, 1991 to 1996. The Norwegian Yeast Study Group

Since 1991 information on yeast isolates from blood cultures has been recorded prospectively from all microbiological laboratories (5 university and 16 county or local hospital laboratories) in Norway (population, 4.3 million). From 1991 to 1996 a total of 571 episodes of fungemia in 552 patients occurred (1991, 109 episodes; 1992, 81 episodes; 1993, 93 episodes; 1994, 89 episodes; 1995, 98 episodes; and 1996, 101 episodes). The fungemia rates per 10,000 patient days were 0.29 in 1991 and 0.27 in 1996. The average rates for the years 1991 to 1996 were 0.37 for the university laboratories and 0.20 for the other laboratories. These rates are low compared to the rate (0. 76) in five Dutch university hospitals in 1995 and the rate (2.0) in Iowa in 1991. The four most frequently isolated species were Candida albicans (66%), Candida glabrata (12.5%), Candida parapsilosis (7.6%), and Candida tropicalis (6.4%). The incidences of both C. albicans (range, 63 to 73%) and C. glabrata (range, 8.4 to 15.7%) varied somewhat throughout this period, but no significant increase or decrease was noted. MICs of amphotericin B, flucytosine, and fluconazole were determined for 89% of the isolates. All were susceptible to amphotericin B, and only 29 (5.6%) strains had decreased susceptibility to flucytosine. All C. albicans isolates were susceptible to fluconazole. The percentage of yeast isolates with decreased susceptibility to fluconazole (MICs, >/=16 microgram/ml) did increase, from 9.6% in 1991 and 1992 to 12.2% in 1994, 16.1% in 1995, and 18.6% in 1996. This was largely due to increases in the percentages of resistant C. glabrata and Candida krusei strains in the last 2 years. Compared to the incidence in other countries, it is remarkable that Norway has such a low and constant incidence of fungemia. A possible reason for this difference might be a restricted antibiotic use policy in Norway.

International surveillance of bloodstream infections due to Candida species: frequency of occurrence and antifungal susceptibilities of isolates collected in 1997 in the United States, Canada, and South America for the SENTRY Program. The SENTRY Participant Group

An international program of surveillance of bloodstream infections (BSIs) in the United States, Canada, and South America between January and December 1997 detected 306 episodes of candidemia in 34 medical centers (22 in the United States, 6 in Canada, and 6 in South America). Eighty percent of the BSIs were nosocomial and 50% occurred in patients hospitalized in an intensive care unit. Overall, 53.3% of the BSIs were due to Candida albicans, 15.7% were due to C. parapsilosis, 15.0% were due to C. glabrata, 7.8% were due to C. tropicalis, 2.0% were due to C. krusei, 0.7% were due to C. guilliermondii, and 5.8% were due to Candida spp. However, the distribution of species varied markedly by country. In the United States, 43.8% of BSIs were due to non-C. albicans species. C. glabrata was the most common non-C. albicans species in the United States. The proportion of non-C. albicans BSIs was slightly higher in Canada (47.5%), where C. parapsilosis, not C. glabrata, was the most common non-C. albicans species. C. albicans accounted for 40.5% of all BSIs in South America, followed by C. parapsilosis (38.1%) and C. tropicalis (11.9%). Only one BSI due to C. glabrata was observed in South American hospitals. Among the different species of Candida, resistance to fluconazole (MIC, > or = 64 microg/ml) and itraconazole (MIC, > or = 1.0 microg/ml) was observed with C. glabrata and C. krusei and was observed more rarely among other species. Isolates of C. albicans, C. parapsilosis, C. tropicalis, and C. guilliermondii were all highly susceptible to both fluconazole (99.4 to 100% susceptibility) and itraconazole (95.8 to 100% susceptibility). In contrast, 8.7% of C. glabrata isolates (MIC at which 90% of isolates are inhibited [MIC90], 32 microg/ml) and 100% of C. krusei isolates were resistant to fluconazole, and 36.9% of C. glabrata isolates (MIC90, 2.0 microg/ml) and 66.6% of C. krusei isolates were resistant to itraconazole. Within each species there were no geographic differences in susceptibility to fluconazole or itraconazole.

Occurrence of yeast bloodstream infections between 1987 and 1995 in five Dutch university hospitals

The aim of this study was to identify retrospectively trends in fungal bloodstream infections in The Netherlands in the period from 1987 to 1995. Results of over 395,000 blood cultures from five Dutch university hospitals were evaluated. Overall, there were more than 12 million patient days of care during the nine-year study period. The rate of candidemia doubled in the study period, reaching an incidence of 0.71 episodes per 10,000 patient days in 1995. The general increase in candidemia was paralleled by an increase in non-Candida albicans bloodstream infections, mainly due to Candida glabrata. However, more than 60% of the infections were caused by Candida albicans. Fluconazole-resistant species such as Candida krusei did not emerge during the study period. The increasing rate of candidemia found in Dutch university hospitals is similar to the trend observed in the USA, but the rate is lower and the increase is less pronounced.

Clinical and laboratory diagnosis of invasive candida infection in neutropenic patients

Cancer patients, especially those with acute leukaemia, represent a group that has the greatest risk for deep fungal infection. Almost no cases were seen before the advent of modern chemotherapy, and prior to the availability of antibacterial agents, less than 5% of patients with acute leukaemia died of fungal infection. These infections are now responsible for 40% or more of the deaths at some institutions. Candida species continues to be the most common fungal pathogen. Rapid and specific diagnosis of invasive candiosis enabling early effective therapy is therefore an important measure for reducing mortality in patients. Here the current status of clinical and laboratory diagnosis of invasive candida infection in neutropenic patients is discussed and recommendations made as to future development programmes.

Evaluation of the ATB 32 C system for identification of clinical yeast isolates

OBJECTIVE: To compare the ATB 32 C system for routine identification of clinical yeast isolates in a clinical microbiology laboratory with identification carried out by conventional methods in a mycology reference laboratory. METHODS: A total of 113 strains initially isolated at our hospital and identified in the reference laboratory were returned in duplicate, under separate code numbers, to the microbiology laboratory where the ATB 32 C system was used for identification by: 1) visual assessment of turbidity at 72 h with use of identification table; 2) visual assessment at 72 h with use of ATB 32 C analytical profile index; and 3) automatic readings with the ATB reader at 48 h and 72 h with results of growth assessments transmitted to a computer and interpreted by the ATB 32 C software. RESULTS: Visual assessment plus identification table and visual assessment plus profile index provided correct identification in 98% and 91% of strains, respectively. Visual assessment was, however, sometimes difficult and required more experience than is usually available in a routine clinical microbiology laboratory. Automatic readings with computer identification plus supplementary tests correctly identified 87% and 86% after 48 h and 72 h, respectively. CONCLUSIONS: The ATB 32 C system with automatic readings and computer identification is a satisfactory system for identification of clinical yeast isolates in a routine clinical microbiology laboratory.