Breakthrough candidaemia caused by phenotypically susceptible Candida spp. in patients with haematological malignancies does not correlate with established interpretive breakpoints

Update on therapeutic approaches for invasive fungal infections in adults

Invasive fungal infections are increasingly encountered with the expansion of iatrogenic immunosuppression, including not only solid organ and hematopoietic stem cell transplant recipients but also patients with malignancies or autoimmune diseases receiving immunomodulatory therapies, such as Bruton Tyrosine Kinase (BTK) inhibitor. Their attributable mortality remains elevated, part of which is a contribution from globally emerging resistance in both molds and yeasts. Because antifungal susceptibility test results are often unavailable or delayed, empiric and tailored antifungal approaches including choice of agent(s) and use of combination therapy are heterogeneous and often based on clinician experience with knowledge of host's net state of immunosuppression, prior antifungal exposure, antifungal side effects and interaction profile, clinical severity of disease including site(s) of infection and local resistance data. In this review, we aim to summarize previous recommendations and most recent literature on treatment of invasive mold and yeast infections in adults to guide optimal evidence-based therapeutic approaches. We review the recent data that support use of available antifungal agents, including the different triazoles that have now been studied in comparison to previously preferred agents. We discuss management of complex infections with specific emerging fungi such as Scedosporium spp., Fusarium spp., Trichosporon asahii, and Candida auris. We briefly explore newer antifungal agents or formulations that are now being investigated to overcome therapeutic pitfalls, including but not limited to olorofim, rezafungin, fosmanogepix, and encochleated Amphotericin B. We discuss the role of surgical resection or debridement, duration of treatment, follow-up modalities, and need for secondary prophylaxis, all of which remain challenging, especially in patients chronically immunocompromised or awaiting more immunosuppressive therapies.

In Vitro Susceptibility Tests in the Context of Antifungal Resistance: Beyond Minimum Inhibitory Concentration in Candida spp

Antimicrobial resistance is a matter of rising concern, especially in fungal diseases. Multiple reports all over the world are highlighting a worrisome increase in azole- and echinocandin-resistance among fungal pathogens, especially in Candida species, as reported in the recently published fungal pathogens priority list made by WHO. Despite continuous efforts and advances in infection control, development of new antifungal molecules, and research on molecular mechanisms of antifungal resistance made by the scientific community, trends in invasive fungal diseases and associated antifungal resistance are on the rise, hindering therapeutic options and clinical cures. In this context, in vitro susceptibility testing aimed at evaluating minimum inhibitory concentrations, is still a milestone in the management of fungal diseases. However, such testing is not the only type at a microbiologist's disposal. There are other adjunctive in vitro tests aimed at evaluating fungicidal activity of antifungal molecules and also exploring tolerance to antifungals. This plethora of in vitro tests are still left behind and performed only for research purposes, but their role in the context of invasive fungal diseases associated with antifungal resistance might add resourceful information to the clinical management of patients. The aim of this review was therefore to revise and explore all other in vitro tests that could be potentially implemented in current clinical practice in resistant and difficult-to-treat cases.

Comparison of amphotericin B lipid complex, deoxycholate amphotericin B, fluconazole, and anidulafungin activity against Candida albicans biofilm isolated from breakthrough candidemia

INTRODUCTION

Biofilm formation causes virulence and resistance in Candida albicans. However, little is known about breakthrough candidemia isolates. We evaluated the antifungal activity of fluconazole, anidulafungin, deoxycholate amphotericin B (dAMB), and amphotericin B lipid complex (ABLC) against biofilms of C. albicans isolated from patients with breakthrough candidemia.

METHODS

The present study used strains of C. albicans isolated from breakthrough and non-breakthrough candidemia patients (control group). The susceptibility of planktonic cells to amphotericin B, anidulafungin, and fluconazole was determined by broth microdilution. Antifungal activity in sessile cells was evaluated using the minimum biofilm eradication concentration (MBEC), metabolic activity was estimated by reducing MTT, and biomass was estimated using crystal violet retention.

RESULTS

The planktonic strains were susceptible to amphotericin B, anidulafungin, and fluconazole, with minimum inhibitory concentrations of 1, ≤0.03, and 2mg/L, respectively. However, fluconazole and anidulafungin did not exert an antifungal effect on biofilms. Additionally, dAMB and ABCL reduced the metabolic activity and biomass. However, eradication was only achieved using 16mg/L dAMB. C. albicans isolates of breakthrough candidemia exhibited strong biofilm production, and the in vitro activity of available therapeutic options was poor.

CONCLUSION

In the present study, only dAMB and ABCL exhibited antibiofilm effects against sessile breakthrough candidemia isolates.

Clinical Characteristics and Outcomes of Breakthrough Candidemia in 71 Hematologic Malignancy Patients and/or Allogeneic Hematopoietic Stem Cell Transplant Recipients: A Single-center Retrospective Study From China, 2011-2018

BACKGROUND

Antifungal prophylaxis may result in breakthrough infections in hematology patients with severe agranulocytosis, with few studies assessing risk factors and clinical outcomes of breakthrough candidemia. We described the distribution of Candida species, assessed risk factors for mortality in such patients, and determined differences in the incidence and mortality of breakthrough candidemia between patients who did or did not receive an allogeneic hematopoietic stem cell transplant.

METHODS

We collected clinical and microbiological data of patients with hematologic malignancies and breakthrough candidemia from a single center. Seven-day and 30-day follow-up outcomes were recorded; the incidence and mortality of breakthrough candidemia between patients who did or did not undergo an allogeneic transplant were compared. Kaplan-Meier survival estimates were used to generate survival curves, and predictors were identified using Cox regression analyses.

RESULTS

Of 71 enrolled patients, 17 received allogeneic transplants. Incidences of breakthrough candidemia were 17 of 2924 (0.58%) and 54 of 12 015 (0.45%) in the transplant and nontransplant groups, respectively (P = .35). The most common isolate was Candida tropicalis, and antifungal agent combinations were the most common first-line treatment. Cumulative mortality rates of patients were 21.1% and 31.0% at days 7 and 30, respectively, and they significantly differed between both groups. Septic shock, central venous catheter removal, and granulocyte recovery were significantly associated with 7-day mortality; the latter 2 remained independent predictors of 30-day mortality.

CONCLUSIONS

Breakthrough candidemia-related mortality was higher in the allogeneic transplant group, although the incidence was not significantly different between the groups. Prompt and adequate antifungal treatment with catheter removal may reduce mortality.

Treatment Failure of Isavuconazole in a Patient with Cryptococcosis

Isavuconazole is a broad-spectrum azole that is FDA-approved for the treatment of aspergillosis and mucormycosis; data on the use of isavuconazole for the treatment and prevention of other invasive fungal infections are limited. Here, we report a patient with pulmonary cryptococcosis treated with isavuconazole who experienced progression to disseminated infection with Cryptococcus while on isavuconazole. Caution is advised when using isavuconazole in situations where there is a paucity of data to recommend its use.

Breakthrough bloodstream infections in critically ill non-neutropenic patients: higher incidence and better survival than non-breakthrough infections

Introduction. Breakthrough bloodstream infections (BSIs) are rare among non-neutropenic patients.Aim. Our goal was to determine the risk factors associated with development of breakthrough BSIs among critically ill non-neutropenic patients and its role in mortality.Methodology. During a 24-month period (August 2016 to July 2018), all BSIs among non-neutropenic patients hospitalized at the University General Hospital of Patras, Greece, were included. Antimicrobial resistance of isolates was interpreted according to EUCAST guidelines. BSIs were considered as breakthrough when blood cultures yielded a pathogen in a patient who, for at least the previous 72 h, had been receiving at least one antibiotic to which the isolated microorganism was susceptible.Results. Among 217 episodes of BSI, 118 (54.4 %) developed a breakthrough infection. Primary BSIs predominated (101; 46.5 %), followed by catheter-related BSIs (56; 25.8 %). Gram-negative bacteria represented the most common pathogens isolated (157; 72.4 %), followed by Gram-positive bacteria (36; 16.6 %) and fungi (36; 16.6 %). Factors independently associated with the development of breakthrough BSIs were immunosuppressive therapy, obesity (body mass index ≥30 kg m^{- 2}), infection by Gram-positive bacteria, noradrenaline dose during 24 h from BSI onset, prior use of colistin and antifungal treatment. Overall 14-day mortality was 23.0 % (50 patients). Multivariate analysis revealed noradrenaline dose during 24 h from BSI onset as an independent predictor of mortality, while appropriate empiric antimicrobial treatment and breakthrough BSI were identified as predictors of good prognosis.Conclusion. Breakthrough BSIs were common among critically ill non-neutropenic patients and these patients were associated with better survival because they were de facto receiving appropriate antibiotics.

Integrated Analysis of Clinical and Microbiome Risk Factors Associated with the Development of Oral Candidiasis during Cancer Chemotherapy

Oral candidiasis is a common side effect of cancer chemotherapy. To better understand predisposing factors, we followed forty-five subjects who received 5-fluorouracil- or doxorubicin-based treatment, during one chemotherapy cycle. Subjects were evaluated at baseline, prior to the first infusion, and at three additional visits within a two-week window. We assessed the demographic, medical and oral health parameters, neutrophil surveillance, and characterized the salivary bacteriome and mycobiome communities through amplicon high throughput sequencing. Twenty percent of all subjects developed oral candidiasis. Using multivariate statistics, we identified smoking, amount of dental plaque, low bacteriome and mycobiome alpha-diversity, and the proportions of specific bacterial and fungal taxa as baseline predictors of oral candidiasis development during the treatment cycle. All subjects who developed oral candidiasis had baseline microbiome communities dominated by Candida and enriched in aciduric bacteria. Longitudinally, oral candidiasis was associated with a decrease in salivary flow prior to lesion development, and occurred simultaneously or before oral mucositis. Candidiasis was also longitudinally associated with a decrease in peripheral neutrophils but increased the neutrophil killing capacity of Candida albicans. Oral candidiasis was not found to be associated with mycobiome structure shifts during the cycle but was the result of an increase in Candida load, with C. albicans and Candida dubliniensis being the most abundant species comprising the salivary mycobiome of the affected subjects. In conclusion, we identified a set of clinical and microbiome baseline factors associated with susceptibility to oral candidiasis, which might be useful tools in identifying at risk individuals, prior to chemotherapy.

Risk Factors and Outcomes of Recurrent Candidemia in Children: Relapse or Re-Infection?

In this paper, our aim was to investigate the incidence, clinical characteristics, risk factors, and outcomes of recurrent candidemia in children. We retrospectively reviewed all children with candidemia from a medical center in Taiwan between 2004 and 2015. Two episodes of candidemia ≥30 days apart with clinical and microbiological resolution in the interim were defined as "late recurrence", and those that had 8⁻29 days apart from previous episodes were defined as "early recurrence". 45 patients (17.2%) had 57 episodes of recurrent candidemia, and 24 had 28 episodes of late recurrent candidemia. The median time between recurrences was 1.8 months (range: <1 month to 13 months). Of those, 29 had relapsed candidemia and 28 were re-infected by different Candida species (n = 24) or by different strains (n = 4). Recurrent candidemia patients were more likely to require echinocandins treatment, had a longer duration of candidemia, and higher rate of treatment failure (p = 0.001, 0.014, and 0.012, respectively). Underlying gastrointestinal diseases (Odds ratio (OR) 3.84; 95% Confidence interval (CI) 1.81⁻8.12) and neurological sequelae (OR 2.32; 95% CI 1.15⁻4.69) were independently associated with the development of recurrent candidemia. 17.2% of pediatric patients with candidemia developed recurrent candidemia, and approximately half were re-infected. Underlying gastrointestinal diseases and neurological sequelae were the independent risk factors for recurrent candidemia.

Risk factors and clinical outcomes of breakthrough yeast bloodstream infections in patients with hematological malignancies in the era of newer antifungal agents

Although yeast bloodstream infections (BSIs) are increasingly being reported in patients with hematological malignancies undergoing antifungal therapy, clinical information regarding breakthrough infections is scarce. The aim of this study was to determine the risk factors for and clinical outcomes of breakthrough yeast BSIs in patients with hematological malignancies in the era of newer antifungal agents. Between 2011 and 2014, all consecutive patients with hematological malignancies who developed yeast BSIs were included in a case-control study wherein breakthrough infections (cases) and de novo infections (controls) were compared. Of 49 patients with yeast BSIs, 21 (43%) met the criteria for breakthrough infections. The proportions of Candida krusei and Candida tropicalis in the cases and controls were significantly different (32% [7/22] vs. 3% [1/29], P = .015; 5% [1/22] vs. 38% [11/29], P = .007, respectively). Acute leukemia, presence of a central venous catheter and neutropenia in the 3 days prior to BSI were significant risk factors for breakthrough infections. Six-week mortality rates was 33% [7/21] in the cases and 43% [12/28] in the controls (P = .564). Refractory neutropenia and the Pitt bacteremia score were independent predictors of 6-week mortality. In conclusion, breakthrough infections accounted for a significant proportion of yeast BSIs in patients with hematological malignancies. However, these infections did not increase the risk of death by themselves. Our results suggest that current clinical management of breakthrough yeast BSIs, which includes switching to a different antifungal class and prompt catheter removal is reasonable.

Management of Invasive Fungal Infections in Adult Patients with Hematological Malignancies in Greece during the Financial Crisis: Challenges and Recommendations

There are concerns that the financial crisis in Greece negatively affected the management of invasive fungal infections (IFIs) among patients with hematological malignancies (HM). A working group (WG) was formed to explore the situation and make recommendations. A questionnaire was created and distributed to physicians caring for patients with HM, to gather information in a standardized manner on prescribing physicians, patient characteristics, availability of diagnostics, antifungal treatment practices and the conditions and particularities of Greek hospitals. A total of 141 physicians from 36 hematology units and laboratories located in 26 Greek hospitals participated. Regarding hospitalization conditions, only 56% reported that their patients were treated in isolated single or double bed rooms, 22% reported availability of HEPA filters, 47% reported construction works in progress, and an alarming 18% reported the presence of birds on open windows. Regarding diagnosis, only 31% reported availability of biomarkers for diagnosis of IFIs, 76% reported that CT scans were performed in a timely fashion, 42% reported prompt availability of broncho-alveolar lavage, and only 6% availability of therapeutic drug monitoring. Of concern, 26% of the responders reported non-availability of some antifungals. In conclusion, significant challenges exist for the optimal management of IFIs in patients with HM in Greece.

Micafungin Breakthrough Fungemia in Patients with Hematological Disorders

Limited data are available on micafungin breakthrough fungemia (MBF), fungemia that develops on administration of micafungin, in patients with hematological disorders. We reviewed medical and microbiological records of patients with hematological disorders who developed MBF between January 2008 and June 2015. A total of 39 patients with MBF were identified, and Candida (30 strains) and non-Candida (9 strains) fungal species were recognized as causative strains. Among 35 stored strains, Candida parapsilosis (14 strains), Trichosporon asahii (7 strains), Candida glabrata (5 strains), and other fungal species (9 strains) were identified by sequencing. Neutropenia was identified as an independent predictor of non-Candida fungemia (P = 0.023). T. asahii was the most common causative strain (7/19) during neutropenia. The 14-day crude mortality rate of patients treated with early micafungin change (EMC) to other antifungal agents was lower than that of the patients not treated with EMC (14% versus 43%, P = 0.044). Most of the stored causative Candida strains were susceptible (80%) or showed wild-type susceptibility (72%) to micafungin. The MICs of voriconazole for T. asahii were low (range, 0.015 to 0.12 μg/ml), whereas the MICs of amphotericin B for T. asahii were high (range, 2 to 4 μg/ml). MBF caused by non-Candida fungus should be considered, especially in patients with neutropenia. EMC could improve early mortality. Based on epidemiology and drug susceptibility profiling, empirical voriconazole-containing therapy might be suitable for treating MBF during neutropenia to cover for T. asahii.

Efficacy of micafungin for the treatment of invasive candidiasis and candidaemia in patients with neutropenia

Neutropenia is linked to the development of invasive candidiasis/candidaemia, for which micafungin has demonstrated efficacy, but evidence in patients with neutropenia is limited. The aim of this study was to evaluate the efficacy of micafungin for the treatment of invasive candidiasis/candidaemia in patients with neutropenia (<500 neutrophils/μL) and without neutropenia. This pooled, post hoc analysis of 2 Phase 3 trials compared micafungin 100 mg/d (adults) and 2 mg/kg/d (paediatrics) with L-AmB 3 mg/kg/d (NCT00106288) and micafungin 100 mg/d and 150 mg/d with caspofungin 70 mg/d followed by 50 mg/d (adults) (NCT00105144); treatment duration 2-4 weeks (≤8 weeks for chronic disseminated candidiasis). Effects of neutropenia duration and Candida spp. on efficacy outcomes (treatment success, clinical and mycological response) were examined. Of 685 patients, 77 had neutropenia. The most common infection in patients with/without neutropenia was due to C. tropicalis (31/77) and C. albicans (295/608) respectively. Overall success was numerically lower in patients with vs without neutropenia (63.6% vs 72.9%). Clinical and mycological response was similar between groups. Neutropenia duration or Candida spp. did not impact micafungin's overall success rate. This analysis supports evidence that micafungin is effective against invasive candidiasis/candidaemia in patients with neutropenia, irrespective of neutropenia duration or Candida spp., although overall success may be lower than in patients without neutropenia.

Invasive Fungal Infections in Patients with Hematological Malignancies: Emergence of Resistant Pathogens and New Antifungal Therapies

Invasive fungal infections caused by drug-resistant organisms are an emerging threat to heavily immunosuppressed patients with hematological malignancies. Modern early antifungal treatment strategies, such as prophylaxis and empirical and preemptive therapy, result in long-term exposure to antifungal agents, which is a major driving force for the development of resistance. The extended use of central venous catheters, the nonlinear pharmacokinetics of certain antifungal agents, neutropenia, other forms of intense immunosuppression, and drug toxicities are other contributing factors. The widespread use of agricultural and industrial fungicides with similar chemical structures and mechanisms of action has resulted in the development of environmental reservoirs for some drug-resistant fungi, especially azole-resistant Aspergillus species, which have been reported from four continents. The majority of resistant strains have the mutation TR34/L98H, a finding suggesting that the source of resistance is the environment. The global emergence of new fungal pathogens with inherent resistance, such as Candida auris, is a new public health threat. The most common mechanism of antifungal drug resistance is the induction of efflux pumps, which decrease intracellular drug concentrations. Overexpression, depletion, and alteration of the drug target are other mechanisms of resistance. Mutations in the ERG11 gene alter the protein structure of C-demethylase, reducing the efficacy of antifungal triazoles. Candida species become echinocandin-resistant by mutations in FKS genes. A shift in the epidemiology of Candida towards resistant non-albicans Candida spp. has emerged among patients with hematological malignancies. There is no definite association between antifungal resistance, as defined by elevated minimum inhibitory concentrations, and clinical outcomes in this population. Detection of genes or mutations conferring resistance with the use of molecular methods may offer better predictive values in certain cases. Treatment options for resistant fungal infections are limited and new drugs with novel mechanisms of actions are needed. Prevention of resistance through antifungal stewardship programs is of paramount importance.

Clinical and Microbiological Characteristics of Breakthrough Candidemia in Allogeneic Hematopoietic Stem Cell Transplant Recipients in a Japanese Hospital

Few data on breakthrough candidemia (BC), defined as candidemia that develops on administration of antifungal agents (AFAs), in allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients are available. The medical and microbiological records of recipients of an allo-HSCT obtained between December 2008 and December 2014 were reviewed. Of 768 allo-HSCT cases, 26 developed BC. Among the 26 causative strains, 22 strains were stored and identified by sequencing. The following species were isolated: Candida parapsilosis (9 strains), C. glabrata (4 strains), C. guilliermondii (3 strains), and other Candida species (6 strains). The AFAs being used when BC developed were micafungin (17 cases), liposomal amphotericin B (5 cases), itraconazole (2 cases), and voriconazole (2 cases). All 17 cases who developed BC during micafungin administration were administered 150 mg/day of micafungin. The susceptibilities of the causative Candida species to the administered AFAs when breakthrough occurred ranged from susceptible to resistant. Especially, 85% of the Candida species that caused BC during micafungin administration were susceptible to micafungin. Additionally, 75% of the strains were wild type for susceptibility to the administered AFAs when breakthrough occurred. Systemic steroid administration and a longer severe neutropenic phase (≥5 days) were independent risk factors for BC (P = 0.016 and P = 0.015, respectively). BC developed in allo-HSCT recipients even when they received a sufficient dose of AFA, including micafungin, to which the causative Candida species were susceptible and/or had wild-type susceptibility in vitro Systemic steroid administration and a longer severe neutropenic phase were host-based factors associated with BC.

Breakthrough candidemia in children: clinical and microbiological characteristics, therapeutic strategies and impact on outcomes

AIM

To assess the characteristics, treatments, risk factors and outcomes of breakthrough candidemia in children.

MATERIALS & METHODS

Episodes of breakthrough candidemia in children were compared with the remaining episodes in a 13-year cohort study.

RESULTS

Out of 319 episodes, 45 (14.1%) were breakthrough candidemia. Breakthrough candidemia occurred in patients with more acutely ill conditions, and the majority was caused by non-albicans Candida species (73.3%; 33 episodes). A total of 79.1% of breakthrough candidemia were caused by antifungal-susceptible Candida isolates and emergence of resistance was the mechanism in five cases of patients receiving fluconazole. Episodes of breakthrough candidemia had significantly higher illness severity and higher rates of fungemia-attributable mortality.

CONCLUSION

Breakthrough candidemia independently contributed to unfavorable outcomes, and more aggressive treatment strategies are warranted when breakthrough candidemia is encountered.