**1. Introduction**

14 Epidemiology Insights

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Tumbarello, M.; Posteraro, B.; Trecarichi, E.M.; Fiori, B.; Rossi, M.; Porta, R.; de Gaetano

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Donati, K.; La Sorda, M.; Spanu, T.; Fadda, G.; Cauda, R. & Sanguinetti, M. (2007). Biofilm production by Candida species and inadequate antifungal therapy as predictors of mortality for patients with candidemia. *Journal of Clinical Microbiology*,

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*Candida* bloodstream infections (BSI) have become a major healthcare problem, specially in tertiary- care hospitals worldwide (Al-Jasser & Elkhizzi, 2004, Almirante et al., 2005, Alonso-Valle et al., 2003, Atunes et al., 2004 Asmundsdottir et al., 2002, Costa et al., 2000, Fraser et al., 1992, Garbino et al., 2002, Luzzati et al. 2000, Marchetti et al., 2004, Pappas et al., 2003, Viudes et al., 2002). Several risk factor identified among patients hospitalized for long periods such as the exposition to broad spectrum antimicrobial and/or immunosuppressive chemotherapy, parenteral nutrition, and invasive medical procedures have contributed to this fact (Blumberg et al., 2001, Fraser et al., 1992). Despite some improvements in fungal BSI diagnosis during last years, candidemia diagnosis remains difficult. Besides, following the data appeared in the classical study from Berenguer and colleagues, only 50% of patients with disseminated candidiasis will have positive blood cultures and even fewer will have an antemortem diagnosis (15% to 40%) (Berenguer et al., 1993). Therefore, invasive candidemia is not easy to diagnose, has an expensive treatment and finally is a serious, often lifethreatening infection (Girmenia et al., 1996, Messer et al., 2009).

Although the incidence of candidemia has increased steadily among hospitalized patients during the eighties and nineties, recent series suggest that This increase has stabilized, but with great variations between different geographical locations with similar socio-economical development even in the same continent. For instance, in The Netherlands an increasing incidence of candidemia has been reported during the period between eighties and nineties (Voss et al., 1996) but on the other hand, in a neighbouring country such as Switzerland the incidence of *Candida* BSI infections remained unchanged during the same period (Marchetti et al., 2004). Therefore, it seems that there are some differences in the epidemiology of candidemia between different countries.

Besides, in recent years, a trend towards increasing resistance to both traditional and more recently introduced antifungal agents has been observed amongst invasive *Candida* infections, underscoring the need for continuous surveillance to monitor trends in incidence, species distribution, and antifungal drug susceptibility profiles.

Epidemiology of Bloodstream *Candida* spp. Infections

published by Nguyen *et al.* (Nguyen et al., 1998).

Stata 8.0 (Stata Corporation, Lenexa, TX).

**3. Distribution of Candida blodostream infections** 

**In vitro susceptibility testing** 

**Statistical analysis** 

admissions.

Observed During a Surveillance Study Conducted in Spain 17

*Incident case of candidemia:* The incident isolation of *Candida spp*. from a blood culture. *New incident case of candidemia:* An episode of candidemia occurring more than 30 days after the initial incident isolation. *Breakthrough candidemia:* The incident isolation of *Candida* spp. from a blood culture

*Fever*: Peripheral body temperature equal or higher than 37.8°C *Neutropenia*: An absolute neutrophil count of less than 500 cells / mm3.

Antifungal susceptibility tests were performed by using the broth microdilution assay according to the methodology recommended by the CLSI (formerly known as NCCLS), document M27-A2 (NCCLS, 2002) using a microtiter plate. Each isolate was tested against different antifungal drugs at the indicated concentration range suggested in the CLSI document. Quality control (QC) was ensured by testing the CLSI recommended QC strains, *C. krusei* ATCC 6258, and *C. parapsilosis* ATCC 22019.The MIC endpoint for amphotericin B, azoles and echinocandins and interpretative MIC breakpoints for azoles and echinocandins were those suggested by the CLSI document M27-A2, but for the definition of the amphotericin B MIC breakpoints we used the values suggested from a previous study

The numbers of admissions and patient-days were collected to calculate incidence rates. The incidence rate for each hospital was calculated as the number of candidemias per 1,000 admissions, whereas the overall incidence was determined using summed denominators of patient-days and admissions to calculate pooled mean rates. The data generated during the year of the surveillance on the different risk factors, underlying diseases, morbidity and mortality were recorded in a Microsoft Access 2003 (Microsoft Corporation, Redmond, WA) based case report database. Categorical data were analyzed using Chi-square or Fisher's exact tests as appropriate, and continuous variables were compared using the t-test or Wilcoxon test according to the significance of the normality test. Spearman rank-order correlation was used to measure the relationship between the MICs of fluconazole and voriconazole. We performed univariate and multivariate analysis of factors associated with candidemia caused by isolates with decreased susceptibility to fluconazole. Variables significant at *p-*values of less than 0.05 by univariate analysis were included in a multivariate model using a repeated measures logistic regression model (backward and forward). Data were analyzed using the SPSS 11.0.1 software (SPSS, Inc. Chicago, IL) and

During the 12-month study period a total of 984 Candida BSIs were reported. The calculated overall incidence was 1.09 cases per 1,000 admissions, however the incidence rate changed a lot between the 40 centers enrolled in this study and ranged from 0.76 to 1.49 cases per 1,000

any reason.

*Adult patients:* All patients whose age was over 14 years old. Table 1. Definitions according to NHSN (formerly NISS) used in this study

from a patient receiving systemic antifungal therapy for

The epidemiology of candidemia has been extensively studied in many countries and there are some large series published in this field (Alonso-Valle et al., 2003, Atunes et al., 2004, Banerjee et al., 1991, Colombo et al., 2006, Diekema et al., 2002, Kao et al., 1999, Messer et al., 2009, San Miguel et al., 2005, Silva et al., 2004, Tortorano et al., 2004, Trick et al., 2002). But, most of the data on candidemia in Spain until recent days are limited to retrospective reviews of medical records or observational studies conducted in a limited geographical area (Almirante et al., 2005, Alonso-Valle et al., 2003, Pemán et al., 2002, Pemán et al., 2011). Regarding the Spanish data available on antifungal resistance is often assessed by occasional surveys or reported in summaries of sporadically occurring cases of treatment failures. The purpose of such investigations is to monitor levels of susceptibility to different agents. However, long-term prospective studies of antifungal susceptibility have the advantage of eliminating a number of variable factors which may affect these assessments. Some of these factors include temporary changes in patterns of Invasive Candida infections (as stated before) and transient alterations in antifungal resistance due to special conditions (e.g. candidemia outbreaks in ICUs). Consequently, the epidemiological data about candidemia and its impact in the healthcare system is unknown, and no reliable nationwide data are available. In order to make a realistic global perspective of invasive Candida BSI, we designed a prospective laboratory-based surveillance study comprising 40 tertiary care hospitals across the country, to assess the incidence, species distribution, frequency of antifungal resistance, and risk factors for candidemia.
