Mycology
Clinical significance of Candida colonization of intravascular catheters in the absence of documented candidemia,☆☆,

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Abstract

In order to assess the significance of Candida colonization of intravascular catheters (IVC) in patients without documented candidemia, we retrospectively reviewed all Candida-positive IVC tip cultures over a 4-year period. Cases were defined as those with a culture yielding ≥15 colony-forming units of Candida spp. that either did not have blood cultures (BC) taken or had concomitant BC negative for Candida. Patients were followed up until death or 8 months after discharge. Risk factors for poor outcome following IVC removal (death, candidemia, or Candida-related complication) were analyzed. We analyzed a total of 40 patients. Overall mortality was 40.0%, with no death directly attributed to Candida infection. Twenty-two patients received antifungal therapy at the time of IVC removal. Only 1 patient developed a metastatic complication (chorioretinitis) attributable to transient candidemia (2.5% of the global cohort and 3.7% among those with concomitant BC). There were no cases of subsequent candidemia. In the multivariate analysis, the use of antifungal therapy did not show any impact on the risk of poor outcome. The risk of invasive disease in patients with isolated IVC colonization by Candida seems to be low. Nevertheless, the initiation of systemic antifungal therapy should be carefully considered in such context.

Introduction

Candida species has emerged as the fourth leading cause of healthcare-associated bloodstream infections over the last few decades (Edmond et al., 1999), posing a major challenge as a result of the increased use of invasive procedures and immunosuppressive therapies. A population-based surveillance for Candida bloodstream infections performed in Barcelona (Spain) revealed an overall incidence of 0.53 cases per 1000 hospital discharges, with 89% of patients having a central venous catheter (CVC) at diagnosis (Almirante et al., 2005). The demonstration of intravascular catheter (IVC) tip colonization is one of the criteria required to establish the definitive diagnosis of catheter-related bloodstream infection (CRBSI) (Mermel et al., 2009). The Infectious Diseases Society of America (IDSA) guidelines for the diagnosis and management of IVC-related infection recommend, in their latest update, that tip cultures should be only done when a catheter is removed because of suspected CRBSI and advise against its routine processing (Mermel et al., 2009). However, it is not unusual in clinical practice to encounter a positive culture for Candida spp. from an IVC tip in patients with negative concomitant blood cultures taken at the time of removal, or for whom no blood cultures have been obtained. The significance in daily clinical practice of this finding remains difficult to interpret, with somewhat contradictory results in previous studies (Bach, 1995, Khatib et al., 1995, Park et al., 2010, Pérez-Parra et al., 2009). In fact, the IDSA guidelines identify this situation as an unresolved issue in the management of CRBSI (Mermel et al., 2009). Given these uncertainties, we conducted this retrospective study to evaluate the current therapeutic approaches and subsequent outcome in noncandidemic patients with isolated Candida spp. IVC tip cultures, paying specific attention on the impact of the administration of antifungal therapy in this subgroup.

Section snippets

Study population

This work was performed at the University Hospital “12 de Octubre” (Madrid, Spain), a 1300-bed tertiary-care center with a reference population of 590,000 inhabitants in 2007. It has 5 different adult intensive care units (medical, trauma, coronary, general surgery, and cardiac surgery). All types of solid organ and stem-cell transplantations are routinely performed at our institution. We retrospectively reviewed all IVC tip cultures positive for Candida spp. obtained between January 2005 and

Results

We identified 122 patients with IVC tip culture positive for Candida spp. during the study period. We excluded 66 (54.1%) patients with concomitant candidemia and 16 (13.1%) due to insufficient clinical data. The final cohort therefore consisted of 40 patients whose demographic and clinical characteristics are summarized in Table 1. Concomitant blood cultures were obtained in 27 patients (67.5%), yielding other microorganisms different from Candida spp. in 8 of them (coagulase-negative

Discussion

It is not exceptional that the isolation of Candida spp. from the tip of an IVC is not accompanied by simultaneous positive blood cultures. In the absence of specific, evidence-based recommendations for its therapeutic approach, such a scenario represents an area of uncertainty for the clinician and a potential source of unnecessary overuse of antifungals (Eggimann et al., 2009). In the present study, we have found a very low risk of metastatic complications potentially associated with an

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    A retrospective study of patients with CVC tips colonized with Candida spp. observed that the incidence of subsequent candidemia (SC) was only 1.7% and a multivariate analysis of risk factors for poor prognosis showed that antifungal therapy was not protective in this setting (OR = 0.82; 95% CI = 0.27–2.47).132 A more recent study showed that the incidence of SC was 2.5% and that administration of antifungals was not protective in 55% of patients.133 Another study however showed that the risk of infectious complications following catheter removal was higher when Candida spp. were involved (7.7%) than in the case of bacterial infection (1.8%) and initiating antifungal therapy was suggested for all patients with positive catheter tip cultures and negative blood cultures.134

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Funding sources: Francisco López-Medrano has received a grant from Fundación Mutua Madrileña. Mario Fernández-Ruiz holds a research training contract “Rio Hortega” (CM11/00187) from the Spanish Ministry of Economy and Competitiveness (Instituto de Salud Carlos III).

☆☆

This study was partially presented at the 15th Congress of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Málaga, Spain (June 1–4, 2011) [poster 266].

Transparency declaration: The authors have no conflicts of interest.

1

Both authors contributed equally to this work.

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