Clinical Relevance and Prognostic Value of Persistently Negative (1,3)-β-D-Glucan in Adults With Candidemia: A 5-year Experience in a Tertiary Hospital

Duration of systemic antifungal therapy for patients with invasive fungal diseases: A reassessment

Invasive fungal diseases are associated with significant morbidity and mortality, especially among immunocompromised patients, and often prompt for rapid and aggressive treatment aiming cure. Due to the expanding magnitude of patients burdened by chronic immunosuppression and affected by fungal diseases, the diversity of clinical settings has risen. This often results in prolonged therapy (induction, consolidation and maintenance) associated with potentially severe side effects, and clinicians face the challenging decisions of when and how to stop anti-fungal therapy. Adequate duration of therapy is poorly defined, hampered by the lack of dedicated trials to the question, the heterogeneity of cases (type of fungal pathogen, localization of infection, underlying host conditions) and various confounding factors that may influence the clinical response (e.g. persistence vs recovery of immunosuppression, impact of surgery). In this review, we aim to evaluate the existing data underlying the guidelines and recommendations of treatment duration for the most frequent invasive fungal diseases (cryptococcal meningitis, Pneumocystis pneumonia, invasive aspergillosis, invasive candidiasis and mucormycosis), as well as specific localizations of deep-seated diseases (osteo-articular or central nervous system diseases and endocarditis) and emerging considerations and strategies.

The Diagnostic Sensitivity of Beta-D-Glucan Assay in Patients with Chronic Disseminated Candidiasis

Objectives: Chronic disseminated candidiasis (CDC) is a specific syndrome in patients with hematologic malignancies which usually occurs after the recovery of neutrophils due to previous chemotherapy. The beta-D-glucan (BDG) assay has been proposed as an adjunct test for diagnosing invasive fungal infection. However, data on BDG assay in patients with CDC are scarce. We aimed to investigate the diagnostic sensitivity of BDG assay in patients with CDC. Methods: All adult patients who were diagnosed as CDC in a tertiary hospital in Seoul, South Korea, from January 2017 to December 2019 and underwent BDG assay (Gold Mountain River Tech Development, Beijing, China) were retrospectively reviewed. CDC was defined by the demonstration of small, target-like abscesses in the liver or spleen (bull’s-eye lesions) or in the brain at the time of neutrophil recovery after a prolonged phase of neutropenia. The values for BDG over 80 pg/mL were classified as positive. Results: A total of 20 patients were enrolled. The median age was 51 years (IQR 39 – 64). Of these, 13 patients had AML, 3 ALL, 2 MDS, and 1 aplastic anemia. Candida spp. were isolated in 6 patients; 3 were C. tropicalis, 2 C. glabrata, and 1 C. krusei. Of the 20 patients, 10 (50%) revealed positive BDG results. The median BDG value was 174 pg/dL (IQR 137–402). More CDC patients with previous candidemia had positive BDG assay than those without candidemia, but with no statistical significance (4/5 (80%) vs. 6/15 (40%), P = 0.30). In the 7 patients with BDG assay-positive CDC, for whom follow-up BDG results were available, the BDG remained high in 6 patients (86%) for more than 4 weeks after adequate antifungal therapy. All 4 patients who died had a positive BDG assay, and 3 of them showed an increasing trend of BDG values during treatment. Conclusions: Negative BDG assay appears to be not useful to rule out CDC. BDG assay decreased slowly during the adequate treatment of CDC.

The added value of (1,3)-β-D-glucan for the diagnosis of Invasive Candidiasis in ICU patients: a prospective cohort study

PURPOSE

Beta-D-Glucan (BDG) testing has been suggested to support the diagnosis of candidemia and invasive candidiasis. The actual benefit in critically ill high-risk patients in intensive care units (ICU) has not been verified so far.

METHODS

In ICU patients receiving empirical echinocandin treatment for suspected invasive candidiasis (IC), serial BDG testing using the Fujifilm Wako Beta-Glucan Test was performed, starting on the first day of echinocandin administration and every 24-48 h afterwards. Diagnostic accuracy was determined for single testing and serial testing strategies using a range of cut-off values. In addition, we compared the added value of these testing strategies when their results were introduced as additional predictors into a multivariable logistic regression model controlling for established risk factors of IC.

RESULTS

A total of 174 ICU patients, forty-six of which (25.7%) classified as cases of IC, were included in our study. Initial BDG testing showed moderate sensitivity (74%, 95%CI 59-86%) and poor specificity (45%, 95% CI 36-54%) for IC which could hardly be improved by follow-up testing. While raw BDG values or test results obtained with very high thresholds improved the predictive performance of our multivariable logistic regression model for IC, neither single nor serial testing with the manufacturer-proposed low-level cut-off showed substantial benefit.

CONCLUSIONS

In our study of critically ill intensive care patients at high risk for candidemia or invasive candidiasis, diagnostic accuracy of BDG testing was insufficient to inform treatment decisions. Improved classification was only achieved for cases with very high BDG values.

Novel evidence on sepsis-inducing pathogens: from laboratory to bedside

Sepsis is a life-threatening condition and a significant cause of preventable morbidity and mortality globally. Among the leading causative agents of sepsis are bacterial pathogens Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus pyogenes, along with fungal pathogens of the Candida species. Here, we focus on evidence from human studies but also include in vitro and in vivo cellular and molecular evidence, exploring how bacterial and fungal pathogens are associated with bloodstream infection and sepsis. This review presents a narrative update on pathogen epidemiology, virulence factors, host factors of susceptibility, mechanisms of immunomodulation, current therapies, antibiotic resistance, and opportunities for diagnosis, prognosis, and therapeutics, through the perspective of bloodstream infection and sepsis. A list of curated novel host and pathogen factors, diagnostic and prognostic markers, and potential therapeutical targets to tackle sepsis from the research laboratory is presented. Further, we discuss the complex nature of sepsis depending on the sepsis-inducing pathogen and host susceptibility, the more common strains associated with severe pathology and how these aspects may impact in the management of the clinical presentation of sepsis.

Incidence of Candidemia Is Higher in COVID-19 versus Non-COVID-19 Patients, but Not Driven by Intrahospital Transmission

There is scarce information on the actual incidence of candidemia in COVID-19 patients. In addition, comparative studies of candidemia episodes in COVID-19 and non-COVID-19 patients are heterogeneous. Here, we assessed the real incidence, epidemiology, and etiology of candidemia in COVID-19 patients, and compared them with those without COVID-19 (2020 vs. 2019 and 2020, respectively). We also genotyped all C. albicans, C. parapsilosis, and C. tropicalis isolates (n = 88), causing candidemia in both groups, providing for the first time a genotypic characterization of isolates gathered in patients with either COVID-19 or non-COVID-19. Incidence of candidemia was higher in patients with COVID-19 than non-COVID-19 (4.73 vs. 0.85 per 1000 admissions; 3.22 vs. 1.14 per 10,000 days of stay). No substantial intergroup differences were found, including mortality. Genotyping proved the presence of a low number of patients involved in clusters, allowing us to rule out rampant patient-to-patient Candida transmission. The four patients, involved in two clusters, had catheter-related candidemia diagnosed in the first COVID-19 wave, which demonstrates breaches in catheter management policies occurring in such an overwhelming situation. In conclusion, the incidence of candidemia in patients with COVID-19 is significantly higher than in those without COVID-19. However, genotyping shows that this increase is not due to uncontrolled intrahospital transmission.

Update on Non-Culture-Based Diagnostics for Invasive Fungal Disease

Diagnostic tests for fungi provide the mycological evidence to strengthen diagnosis of invasive fungal disease. Conventional microbiology and histopathology have their limitations. Recognizing this, there have been attempts at developing new methods to improve yield of diagnosing invasive fungal disease (IFD). The recent focus has been on non-culture-based antigen detection and molecular methods. The use of antigen detection of IFD through 1,3-β-D-glucan and galactomannan assay have been expanded, followed by development of lateral flow assays, and in combination with other diagnostic modalities to further increase diagnostic yield. The molecular diagnostic front has seen initiatives to standardize polymerase chain reaction methodologies to detect fungi and anti-fungal resistance, new platforms such as the T2Candida Biosystems and foray into fungal metagenomics. As these newer assays undergo stringent validation before incorporation into the diagnostic algorithm, the clinician needs to be mindful of their bedside utility as well as their limitation.

Protocol for the pBDG2 Study: Prospective Evaluation of 1.3-β-D-Glucan in the Peritoneal Fluid for the Diagnosis of Intra-Abdominal Candidiasis in Critically Ill Patients

Background: The delayed diagnosis of the presence of Candida in severe intra-abdominal infections exposes patients to an increased risk of mortality. The prevalence of intra-abdominal candidiasis (IAC) varies with the type of intra-abdominal infection, the underlying conditions and the presence of risk factors for Candida infection. This study aims to evaluate the interest of the measure of 1.3-β-D-glucan (BDG) in the peritoneal fluid for the early diagnosis of IAC. Methods and analysis: This is a prospective multicenter (n = 5) non-interventional study, focusing on all critically ill patients with an intra-abdominal infection requiring intra-abdominal surgery. The primary objective is to assess the diagnostic performance of the BDG measured in the peritoneal fluid for the early detection of IAC using the Candida culture as the gold standard. The secondary objective is to report the prevalence of IAC in the selected population. This study aims to enroll 200 patients within 48 months. By estimating the prevalence of IAC in the selected population at 30%, 50 patients with IAC (cases) are expected. These 50 IAC cases will be matched with 50 non-IAC patients (as a control group). The peritoneal BDG will be measured a posteriori in all of these 100 selected patients. This article presents the protocol and the current status of the study. Only the prevalence of IAC is reported as preliminary result.

Adequate duration of therapy in severe fungal infections

PURPOSE OF REVIEW

To highlight recent findings on the adequate duration of antifungal therapy in patients with invasive fungal disease (IFD).

RECENT FINDINGS

Plenty of published data available suggest that there is no additional clinical benefit at a certain point after initiation of antifungal treatment in patients with confirmed IFD. Moreover, the prolonged antifungal exposure can be associated with an increased risk of side effects and toxicity as well as striking risk for developing antifungal resistance or rising unnecessary healthcare costs. Recent data suggest that, in the presence of an adequate initial antifungal therapy and adequate source control of the infection, new stratified approaches integrating clinical judgment, biomarkers and microbiological eradication, should be considered as an alternative to the 'one-size-fits-all' treatment duration currently used worldwide.

SUMMARY

The optimal duration of antifungal therapy is still an unresolved issue that depends by many key elements including the host; the pathogen and its microbiological eradication, the adequateness of initial antifungal therapy and the promptness of source control of the infection. In general, many patients with invasive candidiasis can be treated with a 2 weeks course of antifungal therapy. Longer antifungal course (6 weeks or more) is generally required for patients with invasive aspergilosis.

Recent Advances and Novel Approaches in Laboratory-Based Diagnostic Mycology

What was once just culture and microscopy the field of diagnostic mycology has significantly advanced in recent years and continues to incorporate novel assays and strategies to meet the changes in clinical demand. The emergence of widespread resistance to antifungal therapy has led to the development of a range of molecular tests that target mutations associated with phenotypic resistance, to complement classical susceptibility testing and initial applications of next-generation sequencing are being described. Lateral flow assays provide rapid results, with simplicity allowing the test to be performed outside specialist centres, potentially as point-of-care tests. Mycology has responded positively to an ever-diversifying patient population by rapidly identifying risk and developing diagnostic strategies to improve patient management. Nowadays, the diagnostic repertoire of the mycology laboratory employs classical, molecular and serological tests and should be keen to embrace diagnostic advancements that can improve diagnosis in this notoriously difficult field.

Clinical Profile of Non-neutropenic Patients with Invasive Candidiasis: A Retrospective Study in a Tertiary Care Center

Introduction: Invasive candidiasis (IC) is a major cause of morbidity and mortality in critically ill patients in the intensive care unit (ICU). In this study, we aim to analyze the clinical profile, species distribution, and susceptibility pattern of patients with IC. Methods: Case records of non-neutropenic patients ≥18 years of age with IC between January 2016 and June 2019 at a tertiary care referral hospital were analyzed. IC was defined as either candidemia or isolation of Candida species from a sterile site (such as CSF; ascitic, pleural, or pericardial fluid; or pus or tissue from an intraoperative sample) in a patient with clinical signs and symptoms of infection. Results: A total of 114 patients were analyzed, out of which 105 (92.1%) patients had bloodstream infection (BSI) due to Candida and 9 (7.9%) had IC identified from a sterile site. Central line-associated blood stream infection (27 patients, 23.6%) and a gastrointestinal source (30 patients, 26.3%) were the most common presumed sources for candidemia. The commonest species was Candida tropicalis 42 (36.8%), followed by Candida glabrata 20 (17.5%). Serum beta-D-glucan (BDG) was done only in 32 patients of the 114 (35.3%); among those who were tested, 5 (15.6%) had a BDG value of less than 80 pg/mL despite having Candida BSI. Fluconazole sensitivity was 69.5% overall. At 14 days after diagnosis of IC, 49.1% had recovered, with the remainder having an unfavorable outcome (32.4% had died and 18.4% had left against medical advice). Clinical significance: IC is a major concern in Indian ICUs, with a satisfactory outcome in only half of our patients. Serum BDG is a valuable test to diagnose blood culture-negative IC, but more studies are needed to determine its role in the exclusion of IC, as we had a small minority of patients with negative tests despite proven IC. Conclusion: We recommend sending two sets of blood cultures and serum BDG assay for all suspected patients. Initiating empiric antifungal therapy with an echinocandin is advisable, in view of increasing azole resistance and the emergence of Candida auris, with de-escalation to fluconazole for sensitive isolates after clinical stability and blood culture clearance. How to cite this article: Sridharan S, Gopalakrishnan R, Nambi PS, Kumar S, Sethuraman N, Ramasubramanian V. Indian J Crit Care Med 2021;25(3):267-272.

(1,3)-β-D-glucan is able to predict therapeutic failure of patients with candidemia and not only mortality

BACKGROUND

Candidemia is a major cause of bloodstream infection in tertiary hospitals worldwide and fungal biomarkers may provide early diagnosis.

OBJECTIVES

To evaluate the performance of (1-3)-β-D-glucan (BDG) in the diagnosis of candidemia and its ability to predict therapeutic failure.

PATIENTS AND METHODS

This was a prospective, multi-centre study conducted in 3 Brazilian hospitals. Clinical outcome was evaluated along 2 weeks of treatment, and therapeutic failure was defined as the occurrence of persistent candidemia, Candida deep-seated infection or death. Baseline BDG detection was performed with the Fungitell^® assay (Associates of Cape Cod, Falmouth-USA).

RESULTS

We enrolled a total of 71 patients with candidemia and a control group with 110 healthy volunteers. The sensitivity and specificity of BDG for diagnosing candidemia were as follows: 71.8% (95% confidence interval [95% CI] 59.7% - 81.5%) and 98.2% (95% CI 92.9% - 99.7%), respectively. The only predictor of therapeutic failure was a higher BDG value at diagnosis of candidemia; a value > 226 pg/mL predicted failure with sensitivity and specificity of 75% and 78%, respectively.

CONCLUSIONS

A high baseline serum BDG value was associated with therapeutic failure.

Invasive candidiasis in critical care: challenges and future directions

Invasive candidiasis is the most common critical care-associated fungal infection with a crude mortality of ~ 40-55%. Important factors contributing to risk of invasive candidiasis in ICU include use of broad-spectrum antimicrobials, immunosuppressive drugs, and total parenteral nutrition alongside iatrogenic interventions which breach natural barriers to infection [vascular catheters, renal replacement therapy, extracorporeal membrane oxygenation (ECMO), surgery]. This review discusses three key challenges in this field. The first is the shift in Candida epidemiology across the globe to more resistant non-albicans species, in particular, the emergence of multi-resistant Candida glabrata and Candida auris, which pose significant treatment and infection control challenges in critical care. The second challenge lies in the timely and appropriate initiation and discontinuation of antifungal therapy. Early antifungal strategies (prophylaxis, empirical and pre-emptive) using tools such as the Candida colonisation index, clinical prediction rules and fungal non-culture-based tests have been developed: we review the evidence on implementation of these tools in critical care to aid clinical decision-making around the prescribing and cessation of antifungal therapy. The third challenge is selection of the most appropriate antifungal to use in critical care patients. While guidelines exist to aid choice, this heterogenous and complex patient group require a more tailored approach, particularly in cases of acute kidney injury, liver impairment and for patients supported by extracorporeal membrane oxygenation. We highlight key research priorities to overcome these challenges in the future.

The Presence of (1→3)-β-D-Glucan as Prognostic Marker in Patients After Major Abdominal Surgery

BACKGROUND

While the serological detection of (1→3)-β-D-glucan (BDG) can indicate invasive fungal disease (IFD), false positivity occurs. Nevertheless, the presence of BDG can still be recognized by the host's innate immune system and persistent BDG antigenemia, in the absence of IFD, can result in deleterious proinflammatory immune responses.

METHODS

During the XXX (INTENSE) study into the preemptive use of micafungin to prevent invasive candidiasis (IC) after abdominal surgery, the serum burden of BDG was determined to aid diagnosis of IC. Data from the INTENSE study were analyzed to determine whether BDG was associated with organ failure and patient mortality, while accounting for the influences of IC and antifungal therapy.

RESULTS

A BDG concentration >100 pg/mL was associated with a significantly increased Sequential Organ Failure Assessment score (≤100 pg/mL: 2 vs >100 pg/mL: 5; P < .0001) and increased rates of mortality (≤100 pg/mL: 13.7% vs >100 pg/mL: 39.0%; P = .0002). Multiple (≥2) positive results >100 pg/mL or a BDG concentration increasing >100 pg/mL increased mortality (48.1%). The mortality rate in patients with IC and a BDG concentration >100 pg/mL and ≤100 pg/mL was 42.3% and 25.0%, respectively. The mortality rate in patients without IC but a BDG concentration >100 pg/mL was 37.3%. The use of micafungin did not affect the findings.

CONCLUSIONS

The presence of persistent or increasing BDG in the patient's circulation is associated with significant morbidity and mortality after abdominal surgery, irrespective of IC. The potential lack of a specific therapeutic focus has consequences when trying to manage these patients, and when designing clinical trials involving patients where host-associated BDG concentrations may be elevated.

CLINICAL TRIALS REGISTRATION

NCT01122368.