Early Treatment with Fluconazole in Adult ICU Patients at High Risk for Severe Candidiasis

This feature examines the impact of pharmacologic interventions on the treatment of the critically ill patient–an area of health care that has become increasingly complex. It will review recent advances (including evolving and controversial data) in drug therapy for adult ICU patients and assess these new modalities in terms of clinical, humanistic, and economic outcomes.

Clinical factors affecting costs in patients receiving systemic antifungal therapy in intensive care units in Greece: Results from the ESTIMATOR study

Invasive fungal infections are common in intensive care units (ICUs) but there is a great variability in factors affecting costs of different antifungal treatment strategies in clinical practice. To determine factors affecting treatment cost in adult ICU patients with or without documented invasive fungal infection receiving systemic antifungal therapy (SAT) we have performed a prospective, multicentre, observational study enrolling patients receiving SAT in participating ICUs in Greece. During the study period, 155 patients received SAT at 14 participating ICUs: 37 (23.9%) for proven fungal infection before treatment began, 10 (6.5%) prophylactically, 77 (49.7%) empirically and 31 (20.0%) pre-emptively; 66 patients receiving early SAT (55.9%) were subsequently confirmed to have proven infection with Candida spp. (eight while on treatment). The most frequently used antifungal drugs were echinocandins (89/155; 57.4%), fluconazole (31/155; 20%) and itraconazole (20/155; 12.9%). Mean total cost per patient by SAT strategy was €20 458 (proven), €15 054 (prophylaxis), €23 594 (empiric) and €22 184 (pre-emptive). Factors associated with significantly increased cost were initial treatment failure, length of stay (LOS) in ICU before starting SAT (i.e. from admission until treatment start), fever and proven candidaemia (all P≤.05).

CONCLUSION

Early administration of antifungal drugs was not a substantial component of total hospital costs. However, there was a significant adverse impact on costs with increasing LOS in febrile patients in ICU for whom diagnosis of fungaemia was delayed before starting SAT, and with initial treatment failure. Awareness of potential candidaemia and initiation of pre-emptive or empirical strategy as early appropriate treatment may improve ICU patient outcomes while reducing direct medical costs.

Prophylaxis, empirical and preemptive treatment of invasive candidiasis

PURPOSE OF REVIEW

Invasive candidiasis remains an important infection for ICU patients, associated with poor clinical outcomes. It has been increasingly recognized that the traditional paradigm of culture-directed antifungal treatment is unsatisfactory, and that earlier antifungal intervention strategies, such as prophylaxis, preemptive therapy, and empiric therapy, are required to improve patient outcomes. The purpose of this review is to summarize the recent supportive evidence for such strategies and to highlight the current challenges in their implementation.

RECENT FINDINGS

Despite new antifungal agents and classes, the mortality from invasive candidiasis remains high. Antifungal prophylaxis remains the best-studied early antifungal intervention strategy; however, unless targeted to patients at highest risk, is inefficient. Recent data suggests that although risk predictive models, using a combination of clinical risk factors and Candida colonization parameters, may be a relatively simple and practical approach to guide prophylaxis or preemptive therapy, further validation of these models is required. A single trial has demonstrated that empiric antifungal therapy is not of benefit when instituted to patients with antibiotic-refractory fever alone.

SUMMARY

On the basis of current knowledge, it is difficult to universally recommend antifungal prophylaxis, apart from patient groups with a known very high risk, such as those with necrotising pancreatitis or recurrent gastrointestinal perforations. Antifungal prophylaxis may also be reasonable where local incidence rates and epidemiology are compelling. Among stable patients with multifocal Candida colonization and/or a multitude of clinical-risk factors, preemptive therapy is currently not indicated, although the development of better risk predictive models may assist with such patients. Among patients with refractory fever despite broad-spectrum antibacterial therapy, empiric antifungal therapy may be reasonable where local incidence rates are high (e.g. >10%); however, a thorough search for alternate causes must be instituted.

Antifungal Activities of Ocimum sanctum Essential Oil and its Lead Molecules

Aqueous extracts and oils of five Indian medicinal plants, traditionally used for their antimicrobial activities, were evaluated against two of the most prevalent Candida species causing candidiasis, C. albicans and C. tropicalis. Of these plant materials, three showed varying degrees of antifungal activity against both species. Tulsi (Ocimum sanctum Linn.) essential oil (TEO) was found to be the most effective, followed by Peppermint essential oil, and Aloe vera aqueous leaf extract. The product with the lowest MIC was further studied along with its lead molecules to explore the possible mechanism of action of the most active constituents. Eugenol, methyl eugenol, linalool, and 1, 8-cineole, along with TEO were then evaluated at the same. The pattern and extent of inhibition was studied using growth and WST1 cytotoxicity assays. Proton pumps are important for growth and metabolism of Candida species and so H+ extrusion studies were performed to explore the possible mechanism of the test compounds. Linalool was the most active constituent of TEO, whereas inhibition of H+ extrusion appeared to be a synergistic function of the lead molecules.

Recommendations for the treatment of established fungal infections

Evidence-based guidelines for the treatment of established fungal infections in the adult haematology/oncology setting were developed by a national consensus working group representing clinicians, pharmacists and microbiologists. These updated guidelines replace the previous guidelines published in the Internal Medicine Journal by Slavin et al. in 2004. The guidelines are pathogen-specific and cover the treatment of the most common fungal infections including candidiasis, aspergillosis, cryptococcosis, zygomycosis, fusariosis, scedosporiosis, and dermatophytosis. Recommendations are provided for management of refractory disease or salvage therapies, and special sites of infections such as the cerebral nervous system and the eye. Because of the widespread use newer broad-spectrum triazoles in prophylaxis and empiric therapy, these guidelines should be implemented in concert with the updated prophylaxis and empiric therapy guidelines published by this group.

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.

Interpretive breakpoints for fluconazole and Candida revisited: a blueprint for the future of antifungal susceptibility testing

Developing interpretive breakpoints for any given organism-drug combination requires integration of the MIC distribution, pharmacokinetic and pharmacodynamic parameters, and the relationship between in vitro activity and outcome from both in vivo and clinical studies. Previously, the Subcommittee for Antifungal Testing of the Clinical and Laboratory Standards Institute (CLSI [formerly National Committee for Clinical Laboratory Standards]) proposed MIC interpretive breakpoints for fluconazole and Candida spp. These breakpoints were considered to be somewhat weak, because the clinical data supporting them came largely from mucosal infections and there were very few infections involving strains with elevated fluconazole MICs. We readdress the issue of fluconazole breakpoints for Candida by using published clinical and microbiologic data to provide further validation of the breakpoints proposed by the CLSI in 1997. We also address interpretive breakpoints for agar disk diffusion testing of fluconazole. The MIC distribution for fluconazole was determined with a collection of 13,338 clinical isolates. The overall MIC at which 90% of the isolates were inhibited was 8 microg/ml: 91% were susceptible (S) at a MIC of or= 64 microg/ml). Similar results were obtained for 2,190 isolates from randomized clinical trials. Analysis of available data for 1,295 patient-episode-isolate events (692 represented mucosal infections and 603 represented invasive infections) from 12 published clinical studies demonstrated an overall success rate of 77%, including 85% for those episodes in which the fluconazole MIC was or= 64 microg/ml) isolates. Pharmacodynamic analysis demonstrated a strong relationship between MIC, fluconazole dose, and outcome. A dose/MIC ratio of approximately 25 was supportive of the following susceptibility breakpoints for fluconazole and Candida spp.: S, MIC or= 64 microg/ml. The corresponding disk test breakpoints are as follows: S, >or=19 mm; SDD, 15 to 18 mm; R, Collapse

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MESH Headings

• Antifungal Agents/administration & dosage
• Antifungal Agents/pharmacology
• Antifungal Agents/therapeutic use
• Candida/drug effects
• Candidiasis/drug therapy
• Clinical Trials as Topic
• Dose-Response Relationship, Drug
• Drug Resistance, Fungal
• Fluconazole/pharmacokinetics
• Fluconazole/pharmacology
• Fluconazole/therapeutic use
• Humans
• Microbial Sensitivity Tests/standards
• Treatment Outcome

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Affiliation(s)

M A Pfaller Department of Pathology, Medical Microbiology Division, C606 GH, University of Iowa College of Medicine, Iowa City, 52242, USA.
D J Diekema
D J Sheehan

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Antifungal agents for preventing fungal infections in non-neutropenic critically ill and surgical patients: systematic review and meta-analysis of randomized clinical trials

OBJECTIVES

This study aims to systematically identify and summarize the effects of antifungal prophylaxis in non-neutropenic critically ill adult patients on all-cause mortality and the incidence of invasive fungal infections.

METHODS

Systematic review and meta-analysis of randomized controlled trials in all languages comparing the prophylactic use of any antifungal agent or regimen with placebo, no antifungal or another antifungal agent or regimen in non-neutropenic critically ill adult patients. We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2005), MEDLINE (1966 to 2 September 2005) and EMBASE (1980 to week 36, 2005). We also hand-searched reference lists, abstracts of conference proceedings and scientific meetings (1998-2004) and contacted authors of included studies and pharmaceutical manufacturers. The primary outcomes assessed were all-cause mortality and proven invasive fungal infections. Two reviewers independently applied selection criteria, performed quality assessment and extracted data using an intention-to-treat approach. Data were synthesized using the random effects model and expressed as relative risk with 95% confidence intervals.

RESULTS

Twelve unique trials (eight comparing fluconazole and four ketoconazole with no antifungal or a non-absorbable agent) involving 1606 randomized patients were included. For both outcomes of total mortality and invasive fungal infections, almost all trials of fluconazole and ketoconazole separately showed a non-significant risk reduction with prophylaxis. When combined, fluconazole/ketoconazole reduced total mortality by one-quarter (relative risk 0.76, 95% confidence interval 0.59-0.97) and invasive fungal infections by about one-half (relative risk 0.46, 95% confidence interval 0.31-0.68). No significant increase in the incidence of infection or colonization with the azole-resistant fungal pathogens Candida glabrata or Candida krusei was demonstrated, although the confidence intervals of the summary effect measures were wide. Adverse effects requiring treatment discontinuation were not more common amongst patients receiving prophylaxis. Results across all trials were homogeneous despite considerable heterogeneity in clinical and methodological characteristics.

CONCLUSIONS

Prophylaxis with fluconazole or ketoconazole in critically ill patients reduces invasive fungal infections by one-half and total mortality by one-quarter. Although no significant increase in azole-resistant Candida species associated with prophylaxis was demonstrated, trials were not powered to exclude such an effect. In patients at increased risk of invasive fungal infections, antifungal prophylaxis with fluconazole should be considered.

Antifungal agents for preventing fungal infections in non-neutropenic critically ill patients

BACKGROUND

Invasive fungal infections, important causes of morbidity and mortality in critically ill patients, may be preventable with the prophylactic administration of antifungal agents.

OBJECTIVES

This study aims to systematically identify and summarize the effects of antifungal prophylaxis in non-neutropenic critically ill adult patients on all-cause mortality and the incidence of invasive fungal infections.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), (The Cochrane Library, Issue 3, 2005), MEDLINE (1966 to 2 September 2005), and EMBASE (1980 to week 36, 2005). We also handsearched reference lists, abstracts of conference proceedings and scientific meetings (1998 to 2004), and contacted authors of included studies and pharmaceutical manufacturers.

SELECTION CRITERIA

We included randomized controlled trials in all languages comparing the prophylactic use of any antifungal agent or regimen with placebo, no antifungal, or another antifungal agent or regimen in non-neutropenic critically ill adult patients.

DATA COLLECTION AND ANALYSIS

Two authors independently applied selection criteria, performed quality assessment, and extracted data using an intention-to-treat approach. We resolved differences by discussion. We synthesized data using the random effects model and expressed results as relative risk with 95% confidence intervals.

MAIN RESULTS

We included 12 unique trials (eight comparing fluconazole and four ketoconazole with no antifungal or a nonabsorbable agent) involving 1606 randomized patients. For both outcomes of total mortality and invasive fungal infections, almost all trials of fluconazole and ketoconazole separately showed a non-significant risk reduction with prophylaxis. When combined, fluconazole/ketoconazole reduced total mortality by about 25% (relative risk 0.76, 95% confidence interval 0.59 to 0.97) and invasive fungal infections by about 50% (relative risk 0.46, 95% confidence interval 0.31 to 0.68). We identified no significant increase in the incidence of infection or colonization with the azole-resistant fungal pathogens Candida glabrata or C. krusei, although the confidence intervals of the summary effect measures were wide. Adverse effects were not more common amongst patients receiving prophylaxis. Results across all trials were homogeneous despite considerable heterogeneity in clinical and methodological characteristics.

AUTHORS' CONCLUSIONS

Prophylaxis with fluconazole or ketoconazole in critically ill patients reduces invasive fungal infections by one half and total mortality by one quarter. Although no significant increase in azole-resistant Candida species associated with prophylaxis was demonstrated, trials were not powered to exclude such an effect. In patients at increased risk of invasive fungal infections, antifungal prophylaxis with fluconazole should be considered.

Clinical trials of antifungal prophylaxis among patients in surgical intensive care units: concepts and considerations

BACKGROUND

Fungal infections are important clinical infections in patients in surgical intensive care units. In some institutions, antifungal prophylaxis has become commonplace, and increasing resistance has been reported. However, trials of antifungal prophylaxis are hampered by difficulties in trial design, and the findings may not be generalizable.

METHODS

Issues in clinical trial design are reviewed from existing and theoretical perspectives.

RESULTS

Identification of a primary hypothesis with a sound epidemiological basis is essential. The study must include institutions where fungal infections have a high and well-studied incidence. A high-risk patient population should be identified and enrolled. The agent selected should have an appropriate spectrum, be easily delivered to the population selected, and be cost effective with few adverse events. At present, fluconazole appears to be the best agent for targeted prophylaxis. The primary end point of the study should be based on an easily measured outcome, for example, days free from fungal infection rather than death due to fungal infection.

CONCLUSIONS

Trials of antifungal prophylaxis for patients in surgical intensive care units have had problems in design, and several issues in the conceptual basis of future clinical trials must be addressed.

Epidemiology and antifungal susceptibility of Candida species isolated from blood: results of a 2-year multicentre study in Spain

This study, included in the prospective survey of candidaemia in Europe supported by the European Confederation of Medical Mycology, presents the epidemiological and antifungal susceptibility results of 290 cases of candidaemia (80 in children <15 years old) reported from September 1997 to August 1999 by 19 Spanish hospitals. Presence of an intravenous catheter and previous antibiotic therapy were the most frequent risk factors. The percentages of the four most common species isolated (adults/children) were as follows: Candida albicans (46/36.2), C. parapsilosis (21.9/50), C. tropicalis (12.8/3.75), and C. glabrata (10.1/5). As initial therapy, fluconazole was preferred in adults (54%) and liposomal amphotericin B in children (58%). The 30-day mortality rate was 40.6%, and the species most frequently associated with a fatal outcome was C. krusei (60%). The rates of susceptibility to antifungal agents were as follows: amphotericin B, 91%; flucytosine, 99%; fluconazole, 93.6%; itraconazole, 87.4%; and voriconazole, 92%. These results provide baseline data for future epidemiological and susceptibility studies and for evaluating the impact of new antifungal agents on the distribution of species and the mortality rates associated with candidaemia in Spain.