(1,3)-β-d-Glucan-based antifungal treatment in critically ill adults at high risk of candidaemia: an observational study

Combined use of serum (1,3)-β-D-glucan and procalcitonin for the early differential diagnosis between candidaemia and bacteraemia in intensive care units

Background

This study aimed to assess the combined performance of serum (1,3)-β-d-glucan (BDG) and procalcitonin (PCT) for the differential diagnosis between candidaemia and bacteraemia in three intensive care units (ICUs) in two large teaching hospitals in Italy.

Methods

From June 2014 to December 2015, all adult patients admitted to the ICU who had a culture-proven candidaemia or bacteraemia, as well as BDG and PCT measured closely to the time of the index culture, were included in the study. The diagnostic performance of BDG and PCT, used either separately or in combination, was assessed by calculating the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and positive and negative likelihood ratios (LR+ and LR–). Changes from pre-test probabilities to post-test probabilities of candidaemia and bacteraemia were inferred from Fagan’s nomograms.

Results

One hundred and sixty-six patients were included, 73 with candidaemia (44%) and 93 with bacteraemia (56%). When both markers indicated candidaemia (BDG ≥80 pg/ml and PCT <2 ng/ml) they showed higher PPV (96%) compared to 79% and 66% for BDG or PCT alone, respectively. When both markers indicated bacteraemia (BDG <80 pg/ml and PCT ≥2 ng/ml), their NPV for candidaemia was similar to that of BDG used alone (95% vs. 93%). Discordant BDG and PCT results (i.e. one indicating candidaemia and the other bacteraemia) only slightly altered the pre-test probabilities of the two diseases.

Conclusions

The combined use of PCT and BDG could be helpful in the diagnostic workflow for critically ill patients with suspected candidaemia.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1763-5) contains supplementary material, which is available to authorized users.

Antibodies against a β-glucan-protein complex of Candida albicans and its potential as indicator of protective immunity in candidemic patients

Sera from candidemic and non-candidemic subjects were examined for antibodies against the cell wall β1,3- and β1,6-glucans, as well as the β-glucan-associated protein MP65 of Candida species. Although antibodies against each of the above components were detected in all subjects, candidemic patients had lower antibody titers against β1,3-glucan, but higher antibody titers against β1,6-glucan and MP65, than non-candidemic subjects. The elevated levels of anti-β1,6-glucan and -MP65 antibodies found in candidemic patients were independent on the patient risk category, APACHE II score, presence of co-morbidities, β1,3-glucanemia level, Candida isolate, and antifungal treatment. Interestingly, however, the anti-MP65, but not the anti-β1,6-glucan antibodies, of candidemic patients had higher titers in survivors than in non-survivors, particularly in those subject categories with the highest mortality (>65-years old, diabetic, or septic shock patients). Thus, candidemic patients are capable of boosting anti-Candida immune responses upon infection, and some of these responses might be associated to the generation of protective immunity in patients with candidemia.

Intensive care medicine research agenda on invasive fungal infection in critically ill patients

PURPOSE

To describe concisely the current standards of care, major recent advances, common beliefs that have been contradicted by recent trials, areas of uncertainty, and clinical studies that need to be performed over the next decade and their expected outcomes with regard to Candida and Aspergillus infections in non-neutropenic patients in the ICU setting.

METHODS

A systematic review of the medical literature taking account of national and international guidelines and expert opinion.

RESULTS

Severe invasive fungal infections (IFIs) are becoming increasingly frequent in critically ill patients. Approximately 80% of IFIs are due to Candida spp. and 0.3-19% to Aspergillus spp. Recent observations emphasize the necessity of building a worldwide sentinel network to monitor the emergence of new fungal species and changes in susceptibility. Robust data on the attributable mortality are essential for the design of clinical studies with mortality endpoints. Although early antifungal therapy for Candida has been recommended in patients with risk factors, sepsis of unknown cause, and positive Candida serum biomarkers [β-1 → 3-D-glucan (BDG) and Candida albicans germ tube antibody (CAGTA)], its usefulness and influence on outcome need to be confirmed. Future studies may specifically address the optimal diagnostic and therapeutic strategies for patients with abdominal candidiasis. Better knowledge of the pharmacokinetics of antifungal molecules and tissue penetration is a key issue for intensivists. Regarding invasive aspergillosis, further investigation is needed to determine its incidence in the ICU, its relationship with influenza outbreaks, the clinical impact of rapid diagnosis, and the significance of combination treatment.

CONCLUSIONS

Fundamental questions regarding IFI have to be addressed over the next decade. The clinical studies described in this research agenda should provide a template and set priorities for the clinical investigations that need to be performed.