Avances y limitaciones del diagnóstico precoz de las infecciones invasoras causadas por levaduras

Anti-Candida Antibodies of Patients with Invasive Candidiasis Inhibit Growth, Alter Cell Wall Structure, and Kill Candida albicans In Vitro

Invasive candidiasis (IC), caused by Candida yeasts, particularly Candida albicans, poses a significant threat with high mortality rates. Diagnosis is challenging due to Candida's common presence in human microbiota. To address this, our research group developed an immunofluorescence assay detecting Candida albicans Germ Tube Antibodies (CAGTA) in IC patients. CAGTA, indicative of invasive processes, is associated with a lower mortality rate in ICU patients. Based on this premise, this study aims to provide results regarding the lack of knowledge about the potential activity of CAGTA against invasive infections in humans caused by the fungus Candida albicans. Therefore, in order to characterize the activity of CAGTA produced by patients with IC, we used sera from 29 patients with IC caused by either C. albicans or non-albicans Candida species. Whole serum IgG antibodies were fractionated into anti-blastospores, CAGTA-enriched, and purified CAGTA and the assessments included XTT colorimetric assays for metabolic activity, CFU counts for viability, and microscopy for growth, viability, and morphological analysis. The CAGTA-enriched IgG fraction significantly reduced the metabolic activity and viability of C. albicans compared to anti-blastospores. Purified CAGTA altered germ tube cell wall surfaces, as revealed by electron microscopy, and exhibited fungicidal properties by DiBAC fluorescent staining. In conclusion, antibodies in response to invasive candidiasis have antifungal activity against Candida albicans, influencing metabolic activity, viability, and cell wall structure, leading to cell death. These findings suggest the potential utility of CAGTA as diagnostic markers and support the possibility of developing immunization protocols against Candida infections.

Combination of Candida biomarkers in patients receiving empirical antifungal therapy in a Spanish tertiary hospital: a potential role in reducing the duration of treatment

OBJECTIVES

Initiation of empirical antifungal therapy for invasive candidiasis (IC) is usually based on clinical suspicion. Serological biomarkers have not yet been studied as a means of ruling out IC. We evaluated the potential role of two combined biomarkers in stopping unnecessary antifungals in patients at risk of IC in the ICU and in other wards.

METHODS

This was a prospective observational study including adults starting empirical antifungal treatment for suspected IC, at Gregorio Marañón Hospital, Madrid (Spain). Patients were stratified according to admission department (ICU or other wards) and final diagnosis (no IC or proven or probable IC). Type of candidiasis (candidaemia or deep-seated candidiasis) was also considered. The Candida albicans germ tube antibody (CAGTA) test and the β-d-glucan (BDG) test were performed on serum samples collected by venepuncture on days 0, 3 and 5 after starting empirical antifungal therapy.

RESULTS

Sixty-three ICU patients and 37 non-ICU patients were included. High-risk gastrointestinal surgery and sepsis in non-surgical patients were the main indications for empirical treatment (30% each). Patients had no IC (58%), proven IC (30%) or probable IC (12%). Overall, sensitivity and negative predictive value of the combination of both the CAGTA test and the BDG test were 97% for the entire population. The best performance was observed in ICU patients (sensitivity and negative predictive value of 100%). Among patients without IC, all biomarkers were negative in 31 patients.

CONCLUSIONS

Serial determination of CAGTA/BDG during empirical antifungal therapy has a high sensitivity and negative predictive value. If properly confirmed, this strategy could be used to discontinue antifungal treatment in at least 31% of patients as a complementary tool in antifungal stewardship programmes.

Combined use of nonculture-based lab techniques in the diagnosis and management of critically ill patients with invasive fungal infections

Invasive fungal infections are associated with high morbidity and mortality in critically ill patients due, in part, to diagnostic difficulties in the early stages. Nonculture-based techniques such as (1,3)-β-d-glucan, galactomannan, mannan and antimannan antibodies, Candida albicans germ tube-specific antibodies or fungal DNA are required for earlier diagnosis, prognostic information and monitoring outcome. A decision-tree algorithm based on the combination of nonculture-based techniques is suggested to optimize the diagnosis and evolution of critically ill patients at risk of invasive mycoses. The use of (1,3)-β-d-glucan and blood cultures twice a week is proposed; if positive, treatment initiation is recommended alongside the performance of the nonculture-based microbiological tool depending on suspected mycoses and the availability of techniques.

Multidisciplinary approach to the treatment of invasive fungal infections in adult patients. Prophylaxis, empirical, preemptive or targeted therapy, which is the best in the different hosts?

The high morbidity, mortality, and health care costs associated with invasive fungal infections, especially in the critical care setting and immunocompromised host, have made it an excellent target for prophylactic, empiric, and preemptive therapy interventions principally based on early identification of risk factors. Early diagnosis and treatment are associated with a better prognosis. In the last years there have been important developments in antifungal pharmacotherapy. An approach to the new diagnosis tools in the clinical mycology laboratory and an analysis of the use new antifungal agents and its application in different clinical situations has been made. Furthermore, an attempt of developing a state of the art in each clinical scenario (critically ill, hematological, and solid organ transplant patients) has been performed, trying to choose the best strategy for each clinical situation (prophylaxis, pre-emptive, empirical, or targeted therapy). The high mortality rates in these settings make mandatory the application of early de-escalation therapy in critically ill patients with fungal infection. In addition, the possibility of antifungal combination therapy might be considered in solid organ transplant and hematological patients.

Fungal infections in severe acute pancreatitis

Severe acute pancreatitis (SAP) is associated with significant morbidity and mortality. The majority of deaths related to SAP are the result of infectious complications. Although bacterial infections are most commonly encountered, fungal infections are increasingly being recognized. Candida is the most common fungal infection. The occurrence of fungal infection in patients with acute pancreatitis adversely affects the clinical course, leading to a higher incidence of systemic complications, and possibly mortality as well. Important risk factors for fungal infection in patients with acute pancreatitis include broad-spectrum antibiotics, prolonged hospitalization and surgical/endoscopic interventions, use of total parenteral nutrition, and mechanical ventilation. Patients with higher severity of pancreatitis are at a greater risk. The pathogenesis of fungal infection in patients with acute pancreatitis is multifactorial. Translocation of microorganisms across the gut epithelium, lymphocyte dysfunction, and the virulence of the invading microorganisms play important roles. Histological demonstration of fungi remains the gold standard of diagnosis, but a positive biopsy is rarely obtained. The role of biomarkers in the diagnosis is being investigated. As early diagnosis and treatment can lead to improved outcome, a high index of suspicion is required for prompt diagnosis. Limiting the use of broad-spectrum antibiotics, early introduction of enteral nutrition, and timely change of vascular catheters are important preventive strategies. The role of antifungal prophylaxis remains controversial. Surgical necrosectomy with antifungal therapy is the most widely used treatment approach. Clinical trials on antifungal prophylaxis are needed, and indications for surgical intervention need to be clearly defined.

Current diagnostic approaches to invasive candidiasis in critical care settings

For the specialist, the management of invasive candidiasis infections, from diagnosis to selection of the therapeutic protocol, is often a challenge. Although early diagnosis and treatment are associated with a better prognosis, apart from cases with positive blood cultures or fluid/tissue biopsy, diagnosis is neither sensitive nor specific, relying on many different factors, clinical and laboratory findings but there is certainly a need for the specific markers in this disease. Recently, new serodiagnostic assays as Candida albicans germ-tube antibodies or (1,3)-beta-D-glucan detection and molecular techniques for the detection of fungal-specific DNA have been developed with controversial results in critical care setting. One of the main features in diagnosis is the evaluation of risk factor for infection, which will identify patients in need of preemptive or empirical treatment. Clinical scores were built from those risk factors. For these reasons, an approach to the new diagnosis tools in the clinical mycology laboratory and an analysis of the new prediction rules and its application situations has been made. Currently, the combination of prediction rules and non-culture microbiological tools could be the clue for improving the diagnosis and prognosis of invasive fungal infections in critically ill patients.

Candidemia in the critically ill patient

The frequency of invasive fungal infections caused by yeasts has increased in intensive care units. The most commonly isolated species is Candida albicans, although the number of non-albicans species isolated has increased, and associated mortality is greater in patients infected with these species. The factors that most frequently predispose to invasive candidiasis in the intensive care unit are alterations in skin and mucous barriers (catheters, surgery, intubation, etc.), renal insufficiency, parenteral nutrition, and therapy with corticosteroids or broad-spectrum antimicrobials. Early diagnosis of invasive fungal infections by detecting fungal DNA or invasiveness factors, such as (1-->3)-beta-D-glucan or antimycelial antibodies, and scores to predict and empirically treat invasive candidiasis, have proven very useful in reducing associated morbidity and mortality. In recent years there have been important advances in the development of antifungal agents, especially the new azoles and candins. The efficacy and safety profile of the candins make them the best option for treating invasive candidiasis in the critically ill patient.

Presente y futuro de voriconazol en el tratamiento de las micosis invasoras: el inseparable binomio diagnóstico-tratamiento

Two milestones have characterized the last decades in Medical Mycology: the continuous increase in incidence of invasive mycoses and the discovery of new antifungal drugs that have allowed the successful treatment of these severe infections. This monography presents the most relevant studies on the present situation of invasive mycoses, its diagnosis and treatment, as well as data confirming the important role of voriconazole in their treatment.