Advances in the Treatment of Mycoses in Pediatric Patients

Antifungal agents and the kidney: pharmacokinetics, clinical nephrotoxicity, and interactions

INTRODUCTION

Invasive fungal infections continue to be important causes of morbidity and mortality in severely ill and immunocompromised patient populations. The past three decades have seen a considerable expansion in antifungal drug research, resulting in the clinical development of different classes of antifungal agents with different pharmacologic properties. Among drug-specific characteristics of antifungal agents, renal disposition and nephrotoxicity are important clinical considerations as many patients requiring antifungal therapy have compromised organ functions or are receiving other potentially nephrotoxic medications.

AREAS COVERED

The present article reviews incidence, severity and mechanisms of nephrotoxicity associated with antifungal agents used for prevention and treatment of invasive fungal diseases by discussing distribution, metabolism, elimination and drug-related adverse events in the context of safety data from phase II and III clinical studies.

EXPERT OPINION

Based on the available data amphotericin B deoxycholate has the highest relative potential for nephrotoxicity, followed by the lipid formulations of amphotericin B, and, to a much lesser extent and by indirect mechanisms, the antifungal triazoles.

Invasive fungal infections in a pediatric hematology-oncology department: A 16-year retrospective study

Background and Purpose

Invasive fungal infections (IFIs) are a major cause of morbidity and mortality in immunocompromised children. The purpose of our study was to evaluate the incidence of IFIs in pediatric patients with underlying hematologic malignancies and determine the patient characteristics, predisposing factors, diagnosis, treatment efficacy, and outcome of IFIs.

Materials and Methods

For the purpose of the study, a retrospective analysis was performed on cases with proven and probable fungal infections from January 2001 to December 2016 (16 years).

Results

During this period, 297 children with hematologic malignancies were admitted to the 2nd Pediatric Department of Aristotle University of Thessaloniki, Greece, and 24 cases of IFIs were registered. The most common underlying diseases were acute lymphoblastic leukemia (ALL; n=19,79%), followed by acute myeloid leukemia (AML; n=4, 17%) and non-Hodgkin lymphoma (NHL; n=1,4%). The crude incidence rates of IFIs in ALL, AML, and NHL were 10.5%, 18.2%, and 2.8% respectively. Based on the results, 25% (n=6) and 75% (n=18) of the patients were diagnosed as proven and probable IFI cases, respectively. The lung was the most common site of involvement in 16 (66.7%) cases. Furthermore, Aspergillus and Candida species represented 58.3% and 29.1% of the identified species, respectively. Regarding antifungal treatment, liposomal amphotericin B was the most commonly prescribed therapeutic agent (n=21), followed by voriconazole (n=9), caspofungin (n=3), posaconazole (n=3), micafungin (n=1), and fluconazole (n=1). In addition, 12 children received combined antifungal treatment. The crude mortality rate was obtained as 33.3%.

Conclusion

As the findings of the present study indicated, despite the progress in the diagnosis and treatment of IFIs with the use of new antifungal agents, the mortality rate of these infections still remains high.

A comparative proteomic analysis of Candida species in response to the oxidizing agent cumene hydroperoxide

Candida genus comprises several species that can be found in the oral cavity and the gastrointestinal and genitourinary tracts of healthy individuals. Under certain conditions, however, they behave as opportunistic pathogens that colonize these tissues, most frequently when the immune system is compromised by a disease or under certain medical treatments. To colonize the human host, these organisms require to express cell wall proteins (CWP) that allowed them to adhere and adapt to the reactive oxygen (ROS) and nitrogen (RNS) species produced in the macrophage during the respiratory burst. The aim of this study was to determine how four Candida species respond to the oxidative stress imposed by cumene hydroperoxide (CHP). To this purpose, C. albicans, C. glabrata, C. krusei and C. parapsilosis were exposed to this oxidant which is known to generate ROS in the membrane phospholipids. Accordingly, both mock and CHP-exposed cells were used to extract and analyze CWP and also to measure catalase activity and the levels of protein carbonylation. Results indicated that all four species express different CWP to neutralize ROS. Most relevant among these proteins were the glycolytic enzymes enolase and glyceraldehyde-3-phosphate dehydrogenase, known as moonlight proteins because in addition to participate in glycolysis they play an important role in the cell response to ROS. In addition, a thiol-specific antioxidant enzyme (Tsa) was also found to counteract ROS.

An Overview of the Management of the Most Important Invasive Fungal Infections in Patients with Blood Malignancies

In patients with hematologic malignancies due to immune system disorders, especially persistent febrile neutropenia, invasive fungal infections (IFI) occur with high mortality. Aspergillosis, candidiasis, fusariosis, mucormycosis, cryptococcosis and trichosporonosis are the most important infections reported in patients with hematologic malignancies that undergo hematopoietic stem cell transplantation. These infections are caused by opportunistic fungal pathogens that do not cause severe issues in healthy individuals, but in patients with hematologic malignancies lead to disseminated infection with different clinical manifestations. Prophylaxis and creating a safe environment with proper filters and air pressure for patients to avoid contact with the pathogens in the surrounding environment can prevent IFI. Furthermore, due to the absence of specific symptoms in IFI, rapid and accurate diagnosis reduces the mortality rate of these infections and using molecular techniques along with standard mycological methods will improve the diagnosis of disseminated fungal infection in patients with hematologic disorders. Amphotericin B products, extended-spectrum azoles, and echinocandins are the essential drugs to control invasive fungal infections in patients with hematologic malignancies, and according to various conditions of patients, different results of treatment with these drugs have been reported in different studies. On the other hand, drug resistance in recent years has led to therapeutic failures and deaths in patients with blood malignancies, which indicates the need for antifungal susceptibility tests to use appropriate therapies. Life-threatening fungal infections have become more prevalent in patients with hematologic malignancies in recent years due to the emergence of new risk factors, new species, and increased drug resistance. Therefore, in this review, we discuss the different dimensions of the most critical invasive fungal infections in patients with hematologic malignancies and present a list of these infections with different clinical manifestations, treatment, and outcomes.

MIC distributions for amphotericin B, fluconazole, itraconazole, voriconazole, flucytosine and anidulafungin and 35 uncommon pathogenic yeast species from the UK determined using the CLSI broth microdilution method

Background

Epidemiological cut-off values and clinical interpretive breakpoints have been developed for a number of antifungal agents with the most common Candida species that account for the majority of infections due to pathogenic yeasts species. However, less-common species, for which susceptibility data are limited, are increasingly reported in high-risk patients and breakthrough infections.

Methods

The UK National Mycology Reference Laboratory performs routine antifungal susceptibility testing of clinical yeast isolates submitted from across the UK. Between 2002 and 2016, >32 000 isolates representing 94 different yeast species were referred to the laboratory. Here we present antifungal susceptibility profiles generated over this period for amphotericin B, fluconazole, voriconazole, itraconazole, anidulafungin and flucytosine against 35 species of uncommon yeast using CLSI methodologies. MIC data were interpreted against epidemiological cut-off values and clinical breakpoints developed with Candida albicans, in order to identify species with unusually skewed MIC distributions that potentially indicate resistance.

Results

Potential resistance to at least one antifungal agent (>10% of isolates with MICs greater than the epidemiological cut-off or clinical breakpoint) was evidenced for 29/35 species examined here. Four species exhibited elevated MICs with all of the triazole antifungal drugs against which they were tested, and 21 species exhibited antifungal resistance to agents from at least two different classes of antifungal agent.

Conclusions

This study highlights a number of yeast species with unusual MIC distributions and provides data to aid clinicians in deciding which antifungal regimens may be appropriate when confronted with infections with rarer yeasts.

Pharmacological prophylaxis of infection in pediatric acute myeloid leukemia patients

Introduction: Pediatric patients treated for acute myeloid leukemia (AML) are at high risk of developing severe infectious complications. The choice of an optimum supportive treatment should be based on local epidemiology, as well as intensity and toxicity of the anti-leukemic therapy applied.Areas covered: This review presents an overview of recently published studies focusing on the prevention of infection in pediatric AML patients. PubMed has been systematically searched for clinical trials, reviews, and meta-analyses published in the last 10 years. The focus of this article will be limited to primary prophylaxis only, while secondary prophylaxis is beyond the scope of the current review.Expert opinion: Although anti-bacterial agents may decrease the bacterial infection burden, there is no consensus regarding prophylactic use. To that end, there is a need for further randomized controlled trials to establish the precise role of anti-bacterial prophylaxis in pediatric AML patients. The prophylactic use of anti-fungal agents is strongly recommended for all AML patients. Since the contribution of hematopoietic growth factors to improved survival has not been demonstrated, they should not be routinely applied. Decisions regarding an appropriate prophylactic strategy should be taken in collaboration with the infectious disease experts and pharmacology team.

Fluconazole Resistance in Isolates of Uncommon Pathogenic Yeast Species from the United Kingdom

The triazole drug fluconazole remains one of the most commonly prescribed antifungal drugs, both for prophylaxis in high-risk patients and also as a second-line treatment option for invasive Candida infections. Established susceptibility profiles and clinical interpretive breakpoints are available for fluconazole with Candida albicans, Candida glabrata, Candida tropicalis, and Candida parapsilosis, which account for the majority of infections due to pathogenic yeast species. However, less common species for which only limited susceptibility data are available are increasingly reported in high-risk patients and from breakthrough infections. The UK National Mycology Reference Laboratory performs routine antifungal susceptibility testing of clinical isolates of pathogenic yeast submitted from across the United Kingdom. Between 2002 and 2016, ∼32,000 isolates were referred, encompassing 94 different yeast species. Here, we present fluconazole antifungal susceptibility data generated using a CLSI methodology over this 15-year period for 82 species (2,004 isolates) of less common yeast and yeast-like fungi, and amphotericin B, fluconazole, itraconazole, voriconazole, posaconazole, and anidulafungin, with members of the Nakaseomyces clade (C. glabrata, Candida nivariensis, and Candida bracarensis). At least 22 different teleomorph genera, comprising 45 species, exhibited high MICs when tested with fluconazole (>20% of isolates with MICs higher than the clinical breakpoint [≥8 mg/liter] proposed for C. albicans). Since several of these species have been reported anecdotally from breakthrough infections and therapeutic failures in patients receiving fluconazole, the current study underscores the importance of rapid and accurate yeast identification and may aid clinicians dealing with infections with rarer yeasts to decide whether fluconazole would be appropriate.

Rational Use of Medicine in Children-The Conflict of Interests Story. A Review

BACKGROUND

United States (US) and European Union (EU) legislation attempts to counterbalance the presumed discrimination in pediatric drug treatment and development.

METHODS

We analyzed the history of drug development, US/EU pediatric laws, and pediatric studies required by US/EU regulatory authorities and reviewed relevant literature.

RESULTS

The US and EU definitions of a child are defined administratively (rather than physiologically) as being aged <17 years and <18 years, respectively. However, children mature physiologically well before their seventeenth or eighteenth birthdays. The semantic blur for these differing definitions may indicate certain conflicts of interest.

CONCLUSIONS

Pediatric healthcare today is better than ever. Regulatory-related requirements for "pediatric" studies focus on labeling. Most of these studies lack medical usefulness and may even harm "pediatric" patients through administration of placebo and/or substandard treatment, despite the resultant publications, networking, patent extensions, and strengthened regulatory standing. Clinicians, parents, and ethics committees should be aware of these issues. New rules are needed to determine new pharmaceutical dose estimates in prepubescent patients, and when/how to clinically confirm them. Internet-based structures to divulge this information should be established between drug developers, clinicians, and regulatory authorities. A prerequisite for the rational use of pharmaceuticals in children would be to correct the flawed concept that children are discriminated against in drug treatment and development, and to abandon separate "pediatric" drug approval processes.

Invasive Aspergillosis in Pediatric Leukemia Patients: Prevention and Treatment

The purpose of this article is to review and update the strategies for prevention and treatment of invasive aspergillosis (IA) in pediatric patients with leukemia and in patients with hematopoietic stem cell transplantation. The major risk factors associated with IA will be described since their recognition constitutes the first step of prevention. The latter is further analyzed into chemoprophylaxis and non-pharmacologic approaches. Triazoles are the mainstay of anti-fungal prophylaxis while the other measures revolve around reducing exposure to mold spores. Three levels of treatment have been identified: (a) empiric, (b) pre-emptive, and (c) targeted treatment. Empiric is initiated in febrile neutropenic patients and uses mainly caspofungin and liposomal amphotericin B (LAMB). Pre-emptive is a diagnostic driven approach attempting to reduce unnecessary use of anti-fungals. Treatment targeted at proven or probable IA is age-dependent, with voriconazole and LAMB being the cornerstones in >2yrs and <2yrs age groups, respectively.