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

Polymicrobial candidemia

We conducted a retrospective review of the clinical data on patients with polymicrobial candidemia during a nine-year period (1992-2000) at our tertiary care University Hospital. Also, the clinical features of patients with polymicrobial vs monomicrobial candidemia were compared. There were 16 (5.2%) patients with multiple candidal species in blood among 303 patients with candidemia. Patients' age varied from 21-85 years (median 52 years); they had serious underlying co-morbidities with prolonged hospitalization (median duration 13 days); all had intravenous vascular catheters, had been exposed to multiple antibiotics and were heavily colonized with Candida. Concomitant serious bacterial infections were common (56%). Candida albicans was isolated from blood in 11 of 16 patients; other species were C. glabrata (7 patients), C. tropicalis (6 patients) and C. parapsilosis (4 patients). Sixty seven percent (8 of 12) patients had causative Candida species isolated from vascular catheter tip culture. Polymicrobial candidemia occurred in sicker, non-oncologic patients with frequent concomitant bacterial infections, as compared to those with monomicrobial candidemia. Crude mortality was 43%, a rate similar to that seen with monomicrobial candidemia. Polymicrobial candidemia is uncommon, seen in hospitalized patients with multiple co-morbidities and heavy candidal colonization; removal of vascular catheter and institution of antifungal therapy are important therapeutic maneuvers.

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

The incidence of fungal infections has been increasing for the last 3 decades, especially among neutropenic, cancer, and critically ill patients. These infections are associated with high mortality rates. We retrospectively reviewed medical charts of adult patients with fungemia from 1989 to 2000 at our institution. The characteristics of the population groups served by the hospital were described. Of 328 patients with fungemia, we reviewed 315 (96%) medical records, and focused on those with candidemia (n = 294). The species distribution in patients with candidemia showed that the most commonly identified species were Candida albicans (66%), followed by C. glabrata (17%), and C. parapsilosis (6%). The incidence of candidemia ranged from 0.2 to 0.46 per 10,000 patient-days with the highest incidence in 1993 and the lowest in 1997. Although most studies show an increased incidence of candidemia, we observed a reduction over the study period. Furthermore, we observed no shift from C. albicans to non-albicans Candida species despite a significant increase in the use of fluconazole. The overall mortality among patients with candidemia was 44%, with the highest rate in patients over 65 years (52%). Factors independently associated with higher mortality were patient age greater than 65 years, intensive care unit admission, and underlying cancer.

Secular trend of hospital-acquired candidemia among intensive care unit patients in the United States during 1989-1999

We describe the annual incidence of primary bloodstream infection (BSI) associated with Candida albicans and common non-albicans species of Candida among patients in intensive care units that participated in the National Nosocomial Infections Surveillance system from 1 January 1989 through 31 December 1999. During the study period, there was a significant decrease in the incidence of C. albicans BSI (P<.001) and a significant increase in the incidence of Candida glabrata BSI (P=.05).

Systemic candidiasis in intensive care units: A multicenter, matched-cohort study

OBJECTIVE

To determine the impact of systemic candidiasis on the mortality and length of hospital stay of intensive care unit (ICU) patients and the associated workload.

DESIGN

Multicenter, retrospective, matched-cohort study.

SETTING

Data were retrieved from a computerized database that prospectively collected clinical data submitted by 32 ICUs in the Paris, France area.

PATIENTS

A total of 149 stays with systemic candidiasis, including 104 candidemia, on ICU admission were identified in a 3-year period (1995-1997) among 49,063 admissions (3 per 1,000 admission). A total of 121 cases were matched with patients with no evidence of systemic Candida infection during the hospitalization period under study (same ICU, date of ICU admission, age, sex, simplified acute physiology score (SAPS II), location of the patient before admission, type of admission).

RESULTS

Patients with systemic candidiasis had longer ICU length of stays than controls (25 vs 10 d; P =.001) with a relative risk for death of 2.27 (95% confidence interval, 1.64-3.11; P =.001). There was no difference between patients with systemic candidiasis with or without positive blood culture.

CONCLUSIONS

Systemic Candida infections increased mortality and morbidity in severely ill patients. Optimizing management of such infections is imperative.

European Confederation of Medical Mycology (ECMM) prospective survey of candidaemia: report from one Italian region

An ECMM epidemiological prospective survey of candidaemia was performed in one Italian region (Lombardy; population: 8 924 870) by the National Society of Medical Mycology (FIMUA) from September 1997 to December 1999. In total, 569 episodes were reported with an overall rate of 0.38/1000 admissions, 4.4/100000 patient days. Predisposing factors included presence of an intravascular catheter (89%), antibiotic treatment (88%), surgery (56%), intensive care (45%), solid tumour (28%), steroid treatment (15%), haematological malignancy (7%), HIV infection (6%), fetal immaturity (4%). Mucous membrane colonization preceded candidaemia in 83% of patients. Candida albicans was identified in 58% of cases, followed by Candida parapsilosis (15%), Candida glabrata (13%), Candida tropicalis (6%). Septic shock occurred in 95 patients. Crude mortality was 35%, the highest in C. tropicalis fungaemia (44%), the elderly (64%) and solid tumour cancer patients (43%). Intravascular catheter removal was associated with higher survival rate (71 vs. 47%). This survey underscores the importance of candidaemia in hospital settings.

A review of nucleic acid-based diagnostic tests for systemic mycoses with an emphasis on polymerase chain reaction-based assays

Nucleic acid-based assays have good potential to complement and enhance the sensitivity and rapidity of conventional methods used in diagnostic mycology. The majority of molecular tests are polymerase chain reaction (PCR)-based assays focusing mainly on the detection of Candida and Aspergillus spp. from clinical samples. DNA extraction and purification procedures should be standardized and can be facilitated by using commercial extraction kits. In general, protocols that target multi-copy genes provide the greatest sensitivity. Objective endpoint assessments of PCR tests using enzyme-linked immunosorbent assays (ELISA) or commercial quantitative systems are capable of rapidly detecting and identifying Candida and Aspergillus spp. Sequencing of PCR products can be used to confirm the identity of amplicons. In cases of suspected invasive aspergillosis, PCR should be performed on both blood and bronchoalveolar lavage fluid to maximize test sensitivity and the positive predictive value. At least two blood specimens should be tested if PCR is undertaken on blood samples alone. In situ hybridization techniques have been used with success to identify fungi in tissue specimens. The wide application of PCR-based assays relies on the introduction of standardized protocols following their evaluation in multicentre, prospective studies.

Trends in the epidemiology of Candida bloodstream infections in Northern Ireland between January 1984 and December 2000

OBJECTIVE

To describe the epidemiology of Candida bloodstream infections (BSI) in Northern Ireland.

METHODS

Retrospective collation of data relating to all clinically significant BSI in a university teaching hospital, which had been recorded prospectively, between 1984 and 2000.

RESULTS

One hundred and forty five episodes of candidaemia occurred in 144 patients (of mean age 56.6 years). The contribution of Candida spp. towards all significant BSI increased from 2.0% to 2.5%. C. albicans was the most frequently isolated species, however, its incidence fell from 70% to 53% during the study period. The greatest increase in incidence was seen with C. glabrata which was the most common non-albicans species. Twenty-nine per cent of isolates occurred in patients from an intensive care unit and, surprisingly, a further 25.5% occurred in patients from a surgical service.

CONCLUSION

There appears to be several subtle differences in the epidemiology of candidal BSI between Northern Ireland and other countries.

Candidemia in French hospitals: incidence rates and characteristics

OBJECTIVE

To determine the incidence of candidemia in French hospitals.

MATERIALS AND METHODS

A representative sample of 25 French hospitals [nine teaching hospitals (TH), ten general hospitals (GH) and six cancer referral centers (CRC)] was randomly selected. The incidence rates of candidemia per number of admissions and per patient-days of hospitalization were determined and extrapolated to the national level.

RESULTS

From January 1, 1995 to December 31, 1995, the overall incidence rate per 1000 admissions was 0.29, ranging from 0.71/1000 in CRC, to 0.17/1000 in GH. The overall incidence for 1000 patient-days was 0.035 and the highest incidence was also observed in CRC (0.116/1000), followed by TH (0.052/1000). Candida albicans (53%) was the most common species isolated, a central venous catheter (26%) was the most common portal of entry and 50% of the candidaemic patients had a neoplasm.

CONCLUSION

This study should enable us to optimize surveillance, prevention and treatment of these potentially life-threatening infections.

Phospholipase and protease activities in clinical Candida isolates with reference to the sources of strains

The present study was aimed at determining in vitro phospholipase and protease activities in 95 clinical isolates of various Candida species (C. albicans, C. glabrata, C. guilliermondii,C.kefyr, C. krusei, C. lipolytica, C. lusitaniae, C. parapsilosis, C.rugosa and C. tropicalis). 59 (62.1%) of isolates examined were phospholipase positive and 75 (78.9.9%) were protease positive. 56 (93.3%) of C.albicans isolates tested were phospholipase producers - however only a few strains of C. glabrata and C. kefyr behaved in the same way. Protease activity was detected in 57 (95%) of C. albicans strains tested and in a few strains of C. kefyr, C.lipolytica, C. parapsilosis and C. tropicalis- the remaining isolates were negative. 56 strains of C.albicans and 2 strains of C. kefyr tested produced both phospholipase and protease.

Renewed increase in Candida albicans among yeast isolates from the Göttingen university hospital

We report on the recurrence of Candida albicans among yeast isolates from our university hospital. After a decline in occurrence which coincided with the onset of the use of fluconazole, the fraction of C. albicans recovered and at present has reached the pre-fluconazole level. No permanent rise of C. glabrata or C. krusei has been observed.

Non-albicans Candida spp. causing fungaemia: pathogenicity and antifungal resistance

Non-albicans Candida (NAC) species cause 35-65% of all candidaemias in the general patient population. They occur more frequently in cancer patients, mainly in those with haematological malignancies and bone marrow transplant (BMT) recipients (40-70%), but are less common among intensive care unit (ITU) and surgical patients (35-55%), children (1-35%) or HIV-positive patients (0-33%). The proportion of NAC species among Candida species is increasing: over the two decades to 1990, NAC represented 10-40% of all candidaemias. In contrast, in 1991-1998, they represented 35-65% of all candidaemias. The most common NAC species are C. parapsilosis (20-40% of all Candida species), C. tropicalis (10-30%), C. krusei (10-35%) and C. glabrata (5-40%). Although these four are the most common, at least two other species are emerging: C. lusitaniae causing 2-8% of infections, and C. guilliermondii causing 1-5%. Other NAC species, such as C. rugosa, C. kefyr, C. stellatoidea, C. norvegensis and C. famata are rare, accounting for less than 1% of fungaemias in man. In terms of virulence and pathogenicity, some NAC species appear to be of lower virulence in animal models, yet behave with equal or greater virulence in man, when comparison is made with C. albicans. Mortality due to NAC species is similar to C. albicans, ranging from 15% to 35%. However, there are differences in both overall and attributable mortality among species: the lowest mortality is associated with C. parapsilosis, the highest with C. tropicalis and C. glabrata (40-70%). Other NAC species including C. krusei are associated with similar overall mortality to C. albicans (20-40%). Mortality in NAC species appears to be highest in ITU and surgical patients, and somewhat lower in cancer patients, children and HIV-positive patients. There is no difference between overall and attributable mortality, with the exception of C. glabrata which tends to infect immunocompromised individuals. While the crude mortality is low, attributable mortality (fungaemia-associated mortality) is higher than with C. albicans. There are several specific risk factors for particular NAC species: C. parapsilosis is related to foreign body insertion, neonates and hyperalimentation; C. krusei to azole prophylaxis and along with C. tropicalis to neutropenia and BMT; C. glabrata to azole prophylaxis, surgery and urinary or vascular catheters; C. lusitaniae and C. guilliermondii to previous polyene (amphotericin B or nystatin) use; and C. rugosa to burns. Antifungal susceptibility varies significantly in contrast to C. albicans: some NAC species are inherently or secondarily resistant to fluconazole; for example, 75% of C. krusei isolates, 35% of C. glabrata, 10-25% of C. tropicalis and C. lusitaniae. Amphotericin B resistance is also seen in a small proportion: 5-20% of C. lusitaniae and C. rugosa, 10-15% of C. krusei and 5-10% of C. guilliermondii. Other NAC species are akin to C. albicans-susceptible to both azoles and polyenes (C. parapsilosis, the majority of C. guilliermondii strains and C. tropicalis). Therefore, 'species directed' therapy should be administered for fungaemia according to the species identified-amphotericin B for C. krusei and C. glabrata, fluconazole for other species, including polyene-resistant or tolerant Candida species (C. lusitaniae, C. guilliermondii). In vitro susceptibility testing should be performed for most species of NAC in addition to removal of any foreign body to optimize management.

Trends in species causing fungaemia in a tertiary care medical centre over 12 years

Trends in the species of yeast causing fungaemia over a 12-year period at a large tertiary care medical centre were reviewed. A total of 966 unique episodes of fungaemia occurred in 898 patients. There was an overall trend toward fewer fungaemic episodes due to Candida albicans and more due to Candida glabrata and Candida parapsilosis. However, C. albicans remained the predominant species causing fungaemia, and the proportion due to other species varied from year to year. Candida glabrata was disproportionately isolated from older adults, whereas C. parapsilosis was common among neonates and infants. The trends of increasing isolation of C. glabrata and decreasing isolation of C. albicans were associated with increasing usage of fluconazole, but changes in the proportion of fungaemias due to other species appeared to have no association with fluconazole usage.

[Candidiasis among non-neutropenic patients: from colonization to infection]

Invasive candidiasis is a dread complication in hospitalized patients, characterized by a mortality comparable to that of septic shock (40% to 60%). Its incidence in hospitalized patients is 0.5/1000 admissions, but it complicates about 10 per 1,000 admissions in critical care where it represents 10% to 15% of all nosocomial infections. Although a high proportion of hospitalized patients may become colonized with Candida spp, the clinical signs of infection manifest only late, rending it difficult to diagnose. A better knowledge of their pathophysiology and the availability of triazoles compounds, less toxic than amphotericin B, allowed the concept of early empirical or preemptive treatment. These strategies are based on the prompt identification of risk factors and require continuous attention from skilled physicians. However, the prescription of triazoles has to be restricted to carefully selected groups of patients to avoid the emergence and the dissemination of resistant strains.

Detection of Candida spp. in blood cultures using nucleic acid sequence-based amplification (NASBA)

Candida spp. are the main causes of fungal infections in immunocompromised patients. It is known, that the routinely used automated blood culture systems may fail to detect yeasts. We therefore investigated, whether Nucleic Acid Sequence-Based Amplification (NASBA) can be used to improve the detection rate of Candida spp. in blood cultures. Culture-positive as well as negative blood cultures from patients with a proven candidaemia were analyzed, and the results of BacT/Alert monitoring were compared with the results of NASBA-based detection of yeast RNA. With the NASBA-assay, the number of positive blood cultures increased from 21% to 34%. The NASBA-assay may confirm the diagnosis and demonstrate the need for prolonged treatment. In addition it may shorten the time to detection. In summary, using NASBA for the detection of yeast RNA in blood cultures, we have shown for the first time that it is possible to improve the detection rate of yeasts in blood cultures by using amplification technology.

Antifungal susceptibility of 262 bloodstream yeast isolates from a mixed cancer and non-cancer patient population: is there a correlation between in-vitro resistance to fluconazole and the outcome of fungemia?

The aim of this study was to test the antifungal susceptibility of 262 bloodstream yeast isolates (164 Candida albicans strain, 88 non-albicans Candida spp. and 10 non-Candida yeasts) recovered from 169 surgical, neonatal, critically ill intensive care unit patients (ICU), and cancer patients (mixed patient population) to amphotericin B (AmB), fluconazole (FLU), 5-flucytosine (5-FC), itraconazole (ITRA), ketoconazole (KETO), miconazole (MICO), and nystatin (NYS), in order to correlate in-vitro resistance to fluconazole with the outcome of fungemia. The agar disk diffusion test was used to assess the susceptibility of the 262 bloodstream yeasts isolates. In addition, 78 strains isolated from cancer patients were also tested with the E-test. There were no differences in the susceptibility of the various C. albicans strains tested, except in 40 isolates from surgery patients, which showed a somewhat lower susceptibility to KETO and MICO to (3.7-5.5% resistance). There were no C. albicans strains resistant to AmB, NYS, or FLU. There were slight differences in the susceptibility patterns of the 88 non-albicans Candida spp. (NAC) isolates. Resistance to AmB and NYS appeared in 1 strain of C. guillermondii (minimum inhibitory concentration; MIC to AmB; 4 microg/ml) and in 1 strain of C. parapsilosis (MIC to NYS, 8 microg/ml and MIC to AmB, 2 microg/ml). All other NACs were susceptible to both polyenes (AmB and NYS). Nine of the 11 strains of C. krusei were resistant to FLU (MIC >or= 64 microg/ml), the 2 exceptions showed, respectively, MICs for FLU of 6 and 32 microg/ml ("dose-dependent" susceptibility). However, only 2 of 29 C. glabrata strains were fully FLU-resistant (MIC >or= 64 microg/ml), 27 being susceptible with MIC values of 0.5-8 microg/ml. Apart from 9 C. krusei and 2 C. glabrata strains, 2 C. parapsilosis strains and 1 strain of C. tropicalis were also FLU-resistant. Among the 88 NACs, 17.04% were FLU-resistant and 3.7% were KETO- and ITRA-resistant. Resistance to 5-FC and AmB was minimal. We compared the outcomes of patients infected with FLU-resistant vs FLU-susceptible yeasts in 161 evaluable patients treated with FLU. Attributable mortality was significantly higher (19.0% vs 8.6%; P < 0.01) in patients infected with the FLU-resistant yeasts.

Management of Infections Caused by Candida glabrata

Candida glabrata infections undoubtedly have become more frequent, and are now common. They appear to be the consequence of widespread and often indiscriminate use of azoles, especially fluconazole. This species constitutes the Achilles heel of all available azoles, including newer ones in the pipeline. Even when amphotericin B is used, higher dosages are now required. Little is known about the epidemiology of and risk factors for this troublesome species; even less about its virulence factors. However, studying the resistance mechanisms of this haploid organism may provide answers in developing new fungicidal agents.

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.

Longitudinal 10-year prospective survey of fungaemia in Slovak Republic: trends in etiology in 310 episodes. Slovak Fungaemia study group

A 10-year prospective survey of fungaemia in the Slovak Republic, involving 31 microbiology laboratories and 71 hospitals, was conducted from 1989-1998 (10 years): 310 fungaemias were analyzed for etiology, clinical characteristics, therapy, and outcome. C. albicans was responsible for 191 (61.6%) fungaemias, non-albicans Candida spp. (NAC) for 97 (31.3%), non-Candida yeasts for 18 (5.8%) and moulds (Fulsarium spp.) for four fungaemias. The most frequent NAC isolated from blood cultures were C. parapsilosis--30 (9.7%), C. krusei--18 (5.8%), C. tropicalis--14 (4.5%), and C. glabrata--10 (3.2%). Secular trends in etiology showed a sustaining decrease of C. albicans (from 100% in 1989 to 50.7% in 1998) and increase of NAC (from 0% in 1989-1990 to 46.3% in 1998). Non-Candida yeasts and moulds showed a stable proportion during the investigated period. There were statistically significant differences in etiology of fungaemia various subgroups of patients: non-albicans Candida spp. was significantly more frequent observed among subgroups of patients with pancreatitis and coma (53.3% vs. 31.3%, p < or = 0.02) and less frequently in the subgroup of neonates (15.0% vs. 31.3%, p < or = 0.006). Vice versa, C. albicans appeared more frequently in neonates (85%).

Treatment of fungal infections in surgical patients using conventional antifungals

In surgical and intensive care units an alarming increase in the number of invasive fungal infections has been observed. This is partly due to temporal transferral of patients from hemato-oncological units or transplant units and partly to the enhanced use of corticosteroids and other immunosuppressants. Candida species have now become a common isolate in ill patients. Amphotericin B with or without flucytosine constituted the standard therapy for candidosis but similar response rates with less toxicity may be obtained with lipid and with fluconazole. Data on an improved outcome of candidemia if a central venous catheter is removed promptly are conflicting. Amphotericin B remains the standard therapy for other invasive mycoses; it is seldom possible to administer adequate doses and therefore the options and limitations of the triazoles and liposomal preparations should be explored.

Emerging Issues in Nosocomial Fungal Infections

Nosocomial fungal infections remain a serious cause of morbidity and mortality. As immunodeficient populations increase, the incidence of nosocomial fungal infections continues to rise. Although a wide variety of new and emerging fungi can cause nosocomial infections, Candida species remain the major etiologic agent. Candida species vary in their epidemiology and therapy. New diagnostic, epidemiologic, and therapeutic tools have been developed and are discussed in this review. They include the use of polymerase chain reaction-based diagnostic methods, recent advances in antifungal susceptibility testing, and comparative therapeutic and prophylactic trials. As advances in prevention, diagnosis, and therapy continue, nosocomial fungal infections and the morbidity and mortality associated with them can be reduced.

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.

High rate of non-albicans candidemia in Brazilian tertiary care hospitals

In order to evaluate the epidemiology of candidemia in Brazil, we performed a prospective multicenter study conducted in six general hospitals from São Paulo and Rio de Janeiro, We enrolled a total of 145 candidemic patients (85 males) with a median age of 32 years. Non-albicans species accounted for 63% of all episodes and the species most frequently causing candidemia were C. albicans (37%), C. parapsilosis (25%), C. tropicalis (24%), C. rugosa (5%), and C. glabrata (4%). Systemic azoles were used before the onset of candidemia in only six patients. There were no differences in the coexisting exposures or underlying diseases associated with the species most frequently causing candidemia. The overall crude mortality rate was 50%. Nosocomial candidemias in our tertiary hospitals are caused predominantly by non-albicans species, which are rarely fluconazole resistant. This predominance of non-albicans species could not be related to the previous use of azoles.

Nosocomial fungal infections: candidemia

Candida species are frequently encountered as part of the human commensal flora. Colonization mostly precedes candidemia and is an independent risk factor for the development of candidemia. Genotyping methods showed the similarity between colonizing and infecting strains, thus making endogenous origin likely, though exogenous sources like total parenteral nutrition also have been described. Health care workers (HCWs) play an important role in the transmission of yeasts. Candida species are frequently isolated from the hands of HCWs and can be transmitted from hands to patients. Granulocytopenia and damage of the mucosal lining resulting from intensive chemotherapy due to cancer, the increasing use of broad spectrum antibiotics, and the use of intravenous catheters are other important risk factors for the development of candidemia. Candidemia is associated with a high mortality and prolonged hospitalization. Therefore, and because of the high frequency of dissemination, all candidemias should be treated. Amphotericin B was considered the standard drug for the systemic treatment of candidemia. Fluconazole has been shown to be an effective and safe alternative in non-neutropenic patients. 5-Fluorocytosine has been used in combination with amphotericin B in the treatment of deep-seated infections. Liposomal formulations of amphotericin B and other new antifungal drugs currently are under investigation. C. albicans is the most frequently isolated Candida species, although the proportion of infections caused by non-C. albicans species is increasing. Also, there are reports of development of resistance to amphotericin B. C. lusitaniae is known for primary resistance and the development of resistance to amphotericin B. Development of resistance to fluconazole is mainly seen in AIDS patients with recurrent oropharyngeal candidiasis who receive longer courses of therapy.

New enzyme immunoassays for sensitive detection of circulating Candida albicans mannan and antimannan antibodies: useful combined test for diagnosis of systemic candidiasis

Two standardized enzyme immunoassays for the serological diagnosis of candidiasis were developed. The first one detects antimannan antibodies, while the second one detects mannan with a sensitivity of 0.1 ng/ml. These tests were applied to 162 serum samples retrospectively selected from 43 patients with mycologically and clinically proven candidiasis caused by Candida albicans. Forty-three serum samples were positive for mannan, and 63 had significant antibody levels. Strikingly, only five serum samples were simultaneously positive by both tests. When the results were analyzed per patient, 36 (84%) presented at least one serum positive by one test. For 30 of them, positivity by one test was always associated with negative results by the other test for any of the tested sera. For six patients whose sera were positive for either an antigen or an antibody response, a balance between positivity by each test was evidenced by kinetic analysis of sera drawn during the time course of the infection. Controls consisted of 98 serum samples from healthy individuals, 93 serum samples from patients hospitalized in intensive care units, and 39 serum samples from patients with deep mycoses. The sensitivities and specificities were 40 and 98% and 53 and 94% for mannanemia or antibody detection, respectively. These values reached 80 and 93%, respectively, when the results of both tests were combined. These observations, which clearly demonstrate a disparity between circulation of a given mannan catabolite and antimannan antibody response, suggest that use of both enzyme immunoassays may be useful for the routine diagnosis of candidiasis.

Comparison of the API Candida system with the AUXACOLOR system for identification of common yeast pathogens

Two commercial systems for the identification of yeasts were evaluated by using 159 clinical isolates that had also been identified by conventional biochemical and morphological methods. The API Candida system correctly identified 146 isolates (91.8%), and the AUXACOLOR system correctly identified 145 isolates (91.2%). However, of the 146 isolates identified by the API Candida system, 23 required supplemental biochemical tests or morphological assessment to obtain the correct identification. The AUXACOLOR system gave no identification in 13 cases (8.2%), while the API Candida system gave an unreadable profile in only one case. Incorrect identifications were more common with the API Candida system (12 isolates; 7.5%) than with the AUXACOLOR system (1 isolate; 0.6%).

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.

National surveillance of nosocomial blood stream infection due to Candida albicans: frequency of occurrence and antifungal susceptibility in the SCOPE Program

Surveillance of nosocomial blood stream infections (BSI) in the USA between April 1995 and June 1996 revealed that Candida was the fourth leading cause of nosocomial BSI, accounting for 8% of all infections. Fifty-two percent of 379 episodes of candidemia were due to Candida albicans. In vitro susceptibility studies using the 1997 National Committee for Clinical Laboratory Standards reference method demonstrated that 92% of C. albicans isolates were susceptible to 5-fluorocytosine and 90% were susceptible to fluconazole and itraconazole. Geographic variation in susceptibility of fluconazole and itraconazole was observed. Isolates from the Northwest and Southeast regions were more frequently resistant to fluconazole (13.3-15.5%) and to itraconazole (17.2-20.0%) than those from the Northeast and Southwest regions (2.9-5.5% resistant to fluconazole and itraconazole). Continued surveillance for infections caused by C. albicans and other species of Candida among hospitalized patients is recommended.

Rapid detection of Candida albicans in clinical samples by DNA amplification of common regions from C. albicans-secreted aspartic proteinase genes

Laboratory diagnosis based on genomic amplification methods such as PCR may provide an alternative and more sensitive method than conventional culture for the early detection of deep-seated candidiasis, an increasing cause of morbidity and mortality among immunocompromised patients. A novel method of DNA extraction from clinical samples based on treatment with proteinase K and isolation of DNA on a silica membrane was developed. The targets used for DNA amplification were the Candida albicans-secreted aspartic proteinase (SAP) genes, a multiple-gene family of at least seven members in C. albicans. A single pair of primers was designed in order to detect six of these SAP genes and, subsequently, to increase the sensitivity of the test. Detection of the PCR product by enzyme-linked immunosorbent assay was found to be as sensitive as Southern blotting with an SAP-labeled probe. The sensitivity of the assay was 1 cell/ml from serially diluted Candida cultures and 1 to 4 cells/ml from seeded blood specimens. The sensitivity and specificity of the present assay were tested in a retrospective study performed blindly with 156 clinical samples and were 100 and 98%, respectively, compared with the results of culture. For the subset of blood culture samples (n = 124), the sensitivity and the specificity were 100%. The two false-positive PCR samples came from patients treated with azole antifungal agents, indicating that PCR was probably able to detect damaged organisms that could not be recovered by culture.

Development and verification of fingerprinting probes for Candida glabrata

Since Candida glabrata has emerged as one of the most common Candida pathogens, DNA probes have been developed which fulfil the requirements for effective fingerprinting. Using a screen for complex genomic fragments containing moderately repetitive sequences, seven DNA probes were cloned which generate complex Southern blot hybridization patterns with EcoRI-digested C. glabrata DNA. All of the probes are species-specific and the majority cross-hybridize to varying degrees. The capacity of two of the probes, Cg6 and Cg12, to measure genetic distance between independent isolates is verified by comparing clustering in dendrograms based on similarity coefficients computed between all pairs of 39 independent isolates fingerprinted with Cg6, Cg12 and randomly amplified polymorphic DNA. The capacity of the probes Cg6 and Cg12 to assess microevolution in clonal populations of infecting C. glabrata over time is also demonstrated. These probes can now be used in large computer-assisted epidemiological studies.