Invasive fungal infections in neonates: a review

Neonatal innate immunity response in invasive candidiasis

Infections caused by Candida spp. are frequent in critically hospitalized patients, especially among premature neonates, representing one of the most common healthcare-related infections. Although there is considerable production of current knowledge about the mechanisms of immune response, aspects involved in the newborn's innate defense are not fully understood. The aim of this study was to describe the innate immune mechanisms involved in the defense of neonates against invasive candidiasis. This is an integrative literature review from the Scopus, Scifinder, Medline, Web of Science databases and the electronic libraries ScienceDirect and Scielo, in the period between 2002 and 2020, with rescue based on primary descriptor Immunity Innate plus secondary descriptors Candidiasis Invasive AND Infant Newborn. We have observed the involvement of various mechanisms in the neonatal response against invasive candidiasis, including the recognition, signaling, recruitment, and initiation of an effective immune response. These mechanisms encompass the presence of antimicrobial peptides, phagocytosis, synthesis of reactive oxygen species, inflammatory mediators, and complex cell signaling systems mediated by Pattern Recognition Receptors (PRRs). With this study, it is expected to contribute to the expansion of knowledge about the immunological mechanisms involved in the innate immune response of the newborn against disseminated infections caused by Candida species, and in the same sense, highlight the importance of this knowledge as a reflex in the decrease in mortality in the neonatal period.

End-organ damage from neonatal invasive fungal infection: a 14-year retrospective study from a tertiary center in China

BACKGROUND

Invasive fungal infection (IFI) has become an increasing problem in NICU neonates, and end-organ damage (EOD) from IFI is one of the leading causes of morbidity and mortality in neonates. This study was conducted to summarize clinical data on epidemiology, risk factors, causative pathogens, and clinical outcomes of IFI-associated EOD among neonates in a center in China for the sake of providing references for prevention and treatment of fungal infections in neonates in future.

METHODS

The clinical data of IFI neonates who received treatment in a tertiary NICU of China from January 2009 to December 2022 were retrospectively analyzed, including causative pathogens and the incidence of EOD. The neonates were divided into EOD group and non-EOD (NEOD) group. The general characteristics, risk factors and clinical outcomes of the two groups were compared.

RESULTS

Included in this study were 223 IFI neonates (137 male and 86 female) with a median gestational age (GA) of 30.71 (29,35) weeks and a median birth weight (BW) of 1470 (1120,2150) g. Of them, 79.4% were preterm infants and 50.2% were born at a GA of ≥ 28, <32 weeks, and 37.7% with BW of 1000-1499 g. Candida albicans (C. albicans) was the most common Candida spp. in these neonates, accounting for 41.3% of all cases, followed by C. parapsilosis (30.5%) and C. glabrata (7.2%). EOD occurred in 40 (17.9%) of the 223 cases. Fungal meningitis was the most common EOD, accounting for 13.5% of the 40 EOD cases. There was no significant difference in the premature birth rate, delivery mode, GA and BW between EOD and NEOD groups, but the proportion of male infants with EOD was higher than that without. There was no significant difference in antenatal corticosteroid use, endotracheal intubation, invasive procedures, use of antibiotics, total parenteral nutrition, blood transfusion, postnatal corticosteroid use, fungal prophylaxis and the incidence of necrotizing enterocolitis between the two groups, but the proportion of C. albicans infection cases in EOD group was higher than that in NEOD group (57.5% vs. 37.7%). Compared with NEOD group, the proportion of cured or improved infants in EOD group was significantly lower (P < 0.05), and the number of infants who died or withdrew from treatment was larger (P < 0.05).

CONCLUSIONS

Our retrospective study showed that preterm infants were prone to fungal infection, especially very preterm infants. C. albicans was the most common Candida spp. for IFI, and was a high-risk factor for EOD. EOD can occur in both full-term and premature infants, so the possibility of EOD should be considered in all infants with IFI.

A cluster of Candida parapsilosis displaying fluconazole-trailing in a neonatal intensive care unit successfully contained by multiple infection-control interventions

Objective

This study aimed to investigate and contain a cluster of invasive candidiasis cases caused by fluconazole-resistant Candida parapsilosis (FRC) in a neonatal intensive care unit.

Methods

Active surveillance was initiated. Direct observations of hand-hygiene compliance (HHC) among staff were conducted before and after the implementation of hand-hygiene (HH) education. Thirty-five environmental cultures were obtained. Phylogenetic analysis of FRC was performed using Fourier-transform infrared spectroscopy and microsatellite genotyping.

Results

A total of 14 patients (mean birth weight = 860 g, gestational age = 25 weeks) infected with FRC were identified using the fully automated analyzer, including 5 with clinical infection (three with catheter-related bloodstream infection, one with cutaneous infection, and one with fatal peritonitis) and 9 with colonization. The HHC rate in nurses before performing a sterile or aseptic procedure significantly improved after the HH education (P < .05). Sinks near the patients were contaminated with FRC. All FRC strains were confirmed to be susceptible to fluconazole using the CLSI method, and the microdilution procedure indicated a trailing effect. Phylogenetic analysis showed that all the fluconazole-trailing isolates from patients were clustered together and had the same genotype. Sinks were successfully decontaminated using accelerated hydrogen peroxide and drainage pipes were replaced. Ultraviolet-C decontamination was applied in the milk preparation room. No new cases were detected after the education and disinfection interventions.

Conclusions

Sinks are an important reservoir of C. parapsilosis. Active surveillance, environmental hygiene, and constant staff education on maintaining a high level of HHC are necessary to limit the spread of C. parapsilosis.

Epidemiological indicators and predictors of lethality associated with fungal infections in a NICU: a historical series

OBJECTIVES

Fungal infections (FI) pose a public health concern and significantly increase mortality rates, especially within Neonatal Intensive Care Units (NICU). Thus, this study aimed to investigate epidemiological indicators, risk factors, and lethality predictors associated with FI in a NICU.

METHODS

This study included 1,510 neonates admitted to the NICU of a reference hospital in Brazil between 2015 and 2022. Demographic data, such as sex, birth weight, gestational age, and use of invasive devices were analyzed.

RESULTS

Thirty neonates developed invasive FI, totaling 33 episodes and an incidence of 1.2 per 1,000 patient days. Candida albicans was the most frequent species (52.9 %), the bloodstream was the most affected site (78.9 %), and 72.7 % of infections occurred between 2015 and 2018. The lethality rate associated with FI was 33.3 %, and 90 % of deaths occurred within 30 days of diagnosis of infection. Weight < 750 g, prolonged hospital stay, use of parenteral nutrition, and broad-spectrum antimicrobials were independent risk factors for infection occurrence, especially glycopeptides and 4th generation cephalosporins, having a considerable role in the increase in fungal infections. Weight < 750 g was considered a significant predictor of lethality, and C. albicans had the highest lethality rate (40 %).

CONCLUSION

These findings highlight the elevated lethality rate associated with these infections, reinforcing the importance of developing strategies to control FI within NICU.

Overview of invasive fungal infections in children in South America - the threat of resistant Candida species and the role of climate change in the new geographic distribution of endemic systemic mycosis

PURPOSE OF REVIEW

Invasive fungal infection (IFI) in children is a growing problem with crescent morbidity and mortality, well recognized in developed countries, affecting mainly immunocompromised children, including neonates and children in intensive care units. The burden of IFI in South American children is less well comprehended. In addition, the current epidemiology of endemic systemic mycoses in children may have changed over time.

RECENT FINDINGS

Candida spp. infections are very prevalent in South America hospitalized children, especially in neonates, in a rate far superior compared to developed countries. C. auris, has already been responsible for outbreaks in neonates and children in Venezuela and Colombia. Sporotrichosis is well established as an urban zoonosis in impoverish families. Paracoccidioidomycosis and histoplasmosis are affecting new areas of Brazil, probably due to climate change, deforestation, and human migration.

SUMMARY

This review aims to unveil the real dimension of these infections in South American children. Hopefully, the awareness brought by this review will help healthcare professionals to recognize IFI more easily and it will provide support for getting more resources for IFI treatment and prevention.

Invasive candidiasis

Invasive candidiasis is an important fungal disease caused by Candida albicans and, increasingly, non-albicans Candida pathogens. Invasive Candida infections originate most frequently from endogenous human reservoirs and are triggered by impaired host defences. Signs and symptoms of invasive candidiasis are non-specific; candidaemia is the most diagnosed manifestation, with disseminated candidiasis affecting single or multiple organs. Diagnosis poses many challenges, and conventional culture techniques are frequently supplemented by non-culture-based assays. The attributable mortality from candidaemia and disseminated infections is ~30%. Fluconazole resistance is a concern for Nakaseomyces glabratus, Candida parapsilosis, and Candida auris and less so in Candida tropicalis infection; acquired echinocandin resistance remains uncommon. The epidemiology of invasive candidiasis varies in different geographical areas and within various patient populations. Risk factors include intensive care unit stay, central venous catheter use, broad-spectrum antibiotics use, abdominal surgery and immune suppression. Early antifungal treatment and central venous catheter removal form the cornerstones to decrease mortality. The landscape of novel therapeutics is growing; however, the application of new drugs requires careful selection of eligible patients as the spectrum of activity is limited to a few fungal species. Unanswered questions and knowledge gaps define future research priorities and a personalized approach to diagnosis and treatment of invasive candidiasis is of paramount importance.

Evaluation of the mannan antigen assay in neonates with or without Candida albicans colonization

Mannan antigen (MA) in neonates as a marker of invasive candidemia is not well studied, although 4% of all neonatal intensive care unit admissions are attributed to Candida spp. infections. The aim of this case-control study was to evaluate the performance of MA (Platelia™ Candida AgPluskit, Bio-Rad) in neonates who had rectal Candida colonization or in non-colonized controls. We cultured 340 rectal swabs of neonates and MA was negative in 24/25 C. albicans colonized (96% specificity) and in 30/30 non-colonized neonates (100% specificity). The results indicate a high specificity of the assay, which could be useful in neonates with possible candidemia.

Candida parapsilosis complex in the clinical setting

Representatives of the Candida parapsilosis complex are important yeast species causing human infections, including candidaemia as one of the leading diseases. This complex comprises C. parapsilosis, Candida orthopsilosis and Candida metapsilosis, and causes a wide range of clinical presentations from colonization to superficial and disseminated infections with a high prevalence in preterm-born infants and the potential to cause outbreaks in hospital settings. Compared with other Candida species, the C. parapsilosis complex shows high minimal inhibitory concentrations for echinocandin drugs due to a naturally occurring FKS1 polymorphism. The emergence of clonal outbreaks of strains with resistance to commonly used antifungals, such as fluconazole, is causing concern. In this Review, we present the latest medical data covering epidemiology, diagnosis, resistance and current treatment approaches for the C. parapsilosis complex. We describe its main clinical manifestations in adults and children and highlight new treatment options. We compare the three sister species, examining key elements of microbiology and clinical characteristics, including the population at risk, disease manifestation and colonization status. Finally, we provide a comprehensive resource for clinicians and researchers focusing on Candida species infections and the C. parapsilosis complex, aiming to bridge the emerging translational knowledge and future therapeutic challenges associated with this human pathogen.

Pharmacokinetic and Pharmacodynamic Considerations of Antibiotic Use in Neonates

The selection of an appropriate dose of a given antibiotic for a neonate not only requires knowledge of the drug's basic pharmacokinetic (PK) and pharmacodynamic (PD) properties but also the profound effects that organ development might have on the volume of distribution and clearance, both of which may affect the PK/PD of a drug. Interest has grown in alternative antibiotic dosing strategies that are better aligned with the antibiotic's PK and PD properties. These strategies should be used in conjunction with minimum inhibitory concentration measurements and therapeutic drug monitoring to measure their potential success. They can also guide the clinician in tailoring the delivery of antibiotics to suit an individual patient's needs. Model-informed precision dosing, such as Bayesian forecasting dosing software (which incorporates PK/PD population models), may be utilized to optimize antibiotic exposure in neonatal populations. Consequently, optimizing the antibiotic dose and exposure in each newborn requires expertise in different fields. It drives the collaboration of physicians together with lab technicians and quantitative clinical pharmacologists.

Neonatal fungemia caused by Lodderomyces elongisporus: first case report in Latin America

Premature hospitalized neonates have a greater risk for candidemia, however, fungemia due to rare opportunistic yeasts have been recently reported and is associated with high mortality rates. We herein report the first case in Latin America of Lodderomyces elongisporus fungemia in a premature neonate with a fatal outcome.

A novel diagnostic method for a rare fungus: FcMBL facilitates Wickerhamomyces anomalus identification in an immunocompromised neonate

Fungemia negatively impacts patient outcomes, current diagnostics lack sensitivity to identify emerging rare mycoses, and fungal infections are increasing in prevalence, variety, and resistance. We report a case of Wickerhamomyces anomalus in an immunocompromised neonate in which FcMBL bead-based matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) resulted in species identification roughly 30 hours before standard pathogen identification methods. Deploying FcMBL bead-based MALDI-TOF MS may improve the speed and accuracy of identification, and therefore treatment, of rare pathogens.

Trends in antifungal resistance in Candida from a multicenter study conducted in Madrid (CANDIMAD study): fluconazole-resistant C. parapsilosis spreading has gained traction in 2022

We previously conducted a multicenter surveillance study on Candida epidemiology and antifungal resistance in Madrid (CANDIMAD study; 2019-2021), detecting an increase in fluconazole-resistant Candida parapsilosis. We here present data on isolates collected in 2022. Furthermore, we report the epidemiology and antifungal resistance trends during the entire period, including an analysis per ward of admission. Candida spp. incident isolates from blood cultures and intra-abdominal samples from patients cared for at 16 hospitals in Madrid, Spain, were tested with the EUCAST E.Def 7.3.2 method against amphotericin B, azoles, micafungin, anidulafungin, and ibrexafungerp and were molecularly characterized. In 2022, we collected 766 Candida sp. isolates (686 patients; blood cultures, 48.8%). Candida albicans was the most common species found, and Candida auris was undetected. No resistance to amphotericin B was found. Overall, resistance to echinocandins was low (0.7%), whereas fluconazole resistance was 12.0%, being higher in blood cultures (16.0%) mainly due to fluconazole-resistant C. parapsilosis clones harboring the Y132F-R398I ERG11p substitutions. Ibrexafungerp showed in vitro activity against the isolates tested. Whereas C. albicans was the dominant species in most hospital wards, we observed increasing C. parapsilosis proportions in blood. During the entire period, echinocandin resistance rates remained steadily low, while fluconazole resistance increased in blood from 6.8% (2019) to 16% (2022), mainly due to fluconazole-resistant C. parapsilosis (2.6% in 2019 to 36.6% in 2022). Up to 7 out of 16 hospitals were affected by fluconazole-resistant C. parapsilosis. In conclusion, rampant clonal spreading of C. parapsilosis fluconazole-resistant genotypes is taking place in Madrid.

Clinical data analysis of 86 patients with invasive infections caused by Malassezia furfur from a tertiary medical center and 37 studies

Objective

Malassezia furfur (M. furfur) is a lipophilic, conditionally pathogenic yeast that mainly causes skin infections, but the reports of related invasive infections are increasing. The aim of this study is to provide clinical data to assist physicians in the management of patients with invasive infections caused by M. furfur.

Methods

A case of pulmonary infection caused by M. furfur in a hematopoietic stem cell transplant patient for aplastic anemia was reported. In addition, the literature on invasive infection by M. furfur published in PubMed and Web of Science in English until 31 July 2022 was reviewed.

Results

Clinical data analysis of 86 patients (from 37 studies and our case) revealed that most of them were preterm (44.2%), followed by adults (31.4%). M. furfur fungemia occurred in 79.1% of the 86 patients, and 45 of them were clearly obtained from catheter blood. Other patients developed catheter-related infections, pneumonia, peripheral thromboembolism, endocarditis, meningitis, peritonitis and disseminated infections. Thirty-eight preterm infants had underlying diseases such as very low birth weight and/or multiple organ hypoplasia. The remaining patients had compromised immunity or severe gastrointestinal diseases. 97.7% of patients underwent invasive procedures and 80.2% received total parenteral nutrition (TPN). Fever, thrombocytopenia and leukocytosis accounted for 55.8%, 38.4% and 24.4% of patients with M. furfur invasive infections, respectively. 69.8% of the patients received antifungal therapy, mainly amphotericin B (AmB) or azoles. Of 84 patients with indwelling catheters, 58.3% underwent the removal of catheters. TPN were discontinued in 30 of 69 patients. The all-cause mortality of 86 patients was 27.9%.

Conclusions

M. furfur can cause a variety of invasive infections. These patients mostly occur in premature infants, low immunity and severe gastrointestinal diseases. Indwelling catheters and TPN infusion are major risk factors. AmB, l-AmB and azoles are the most commonly used agents, and simultaneous removal of the catheter and termination of TPN infusion are important for the treatment of M. furfur invasive infections.

High-pressure pulses for Aspergillus niger spore inactivation in a model pharmaceutical lipid emulsion

High hydrostatic pressure (HHP) is a non-thermal process widely used in the food industry to reduce microbial populations. However, rarely its effect has been assessed in products with high oil content. This study evaluated the efficacy of HHP (200, 250, and 300 MPa) at different temperatures (25, 35, and 45 °C) by cycles (1, 2, or 3) of 10 min in the inactivation of Aspergillus niger spores in a lipid emulsion. After treatments at 300 MPa for 1 cycle at 35 or 45 °C, no surviving spores were recovered. All treatments were modeled by the linear and Weibull models. The presence of shoulders and tails in the treatments at 300 MPa at 35 or 45 °C resulted in sigmoidal curves which cannot be described by the linear model, hence the Weibull + Tail, Shoulder + Log-lin + Tail, and double Weibull models were evaluated to elucidate the inactivation kinetics. The tailing formation could be related to the presence of resistance subpopulations. The double Weibull model showed better goodness of fit (RMSE <0.2) to describe the inactivation kinetics of the treatments with the higher spore reductions. HHP at 200-300 MPa and 25 °C did not reduce the Aspergillus niger spores. The combined HHP and mild temperatures (35-45 °C) favored fungal spore inactivation. Spore inactivation in lipid emulsions by HHP did not follow a linear inactivation. HHP at mild temperatures is an alternative to the thermal process in lipid emulsions.

Updates in Laboratory Identification of Invasive Fungal Infection in Neonates

Invasive fungal infection (IFI) in immunocompromised neonates is significantly associated with high morbidity and mortality and has become the third most common infection in Neonatal Intensive Care Units. The early diagnosis of IFI for neonatal patients is difficult because of the lack of specific symptoms. The traditional blood culture remains the gold standard in clinical diagnosis for neonatal patients but it requires a long duration, which delays treatment initiation. Detections of fungal cell-wall components are developed for early diagnosis but the diagnostic accuracy in neonates needs to be improved. PCR-based laboratory methods, such as real-time PCR, droplet digital PCR, and the cationic conjugated polymer fluorescence resonance energy transfer (CCP-FRET) system, distinguish the infected fungal species by their specific nucleic acids and show a high sensitivity and specificity. Particularly, the CCP-FRET system, which contains a cationic conjugated polymer (CCP) fluorescent probe and pathogen-specific DNA labeled with fluorescent dyes, could identify multiple infections simultaneously. In the CCP-FRET system, the CCP and fungal DNA fragments can self-assemble into a complex with an electrostatic interaction and the CCP triggers the FRET effect under ultraviolet light to make the infection visible. Here, we summarize the recent laboratory methods for neonatal IFI identification and provide a new perspective for early clinical fungal diagnosis.

Adverse effects of antibiotics in children with cancer: are short-course antibiotics for febrile neutropenia part of the solution?

INTRODUCTION

Febrile neutropenia is a common complication experienced by children with cancer or those undergoing hematopoietic stem cell transplantation. Repeated episodes of febrile neutropenia result in cumulative exposure to broad-spectrum antibiotics with potential for a range of serious adverse effects. Short-course antibiotics, even in patients with high-risk febrile neutropenia, may offer a solution.

AREAS COVERED

This review addresses the known broad effects of antibiotics, highlights developments in understanding the relationship between cancer, antibiotics, and the gut microbiome, and discusses emerging evidence regarding long-term adverse antibiotic effects. The authors consider available evidence to guide the duration of empiric antibiotics in pediatric febrile neutropenia and directions for future research.

EXPERT OPINION

Broad-spectrum antibiotics are associated with antimicrobial resistance, Clostridioides difficile infection, invasive candidiasis, significant disturbance of the gut microbiome and may seriously impact outcomes in children with cancer or undergoing allogenic hematopoietic stem cell transplant. Short-course empiric antibiotics are likely safe in most children with febrile neutropenia and present a valuable opportunity to reduce the risks of antibiotic exposure.

[Recent research on pharmacological prevention strategies for invasive fungal infection in preterm infants]

There is a relatively high incidence rate of invasive fungal infection (IFI) in preterm infants admitted to the neonatal intensive care unit (NICU), and early diagnosis of IFI is difficult in clinical practice. The patients developing IFI tend to have severe conditions, a long course of treatment, high hospital costs, high mortality, and poor prognosis, and therefore, the prevention of IFI is of particular importance. At present, fluconazole is often used as the first-line drug for the prevention of IFI in preterm infants, but no consensus has been reached on the specific dose and course of treatment, and there are still controversies over the targeted population and prophylactic effect. This article reviews the recent research on the pharmacological prevention strategies for IFI in preterm infants in the NICU, so as to provide a reference for clinicians.

Antibiotic-induced depletion of Clostridium species increases the risk of secondary fungal infections in preterm infants

Preterm infants or those with low birth weight are highly susceptible to invasive fungal disease (IFD) and other microbial or viral infection due to immaturity of their immune system. Antibiotics are routinely administered in these vulnerable infants in treatment of sepsis and other infectious diseases, which might cause perturbation of gut microbiome and hence development of IFD. In this study, we compared clinical characteristics of fungal infection after antibiotic treatment in preterm infants. As determined by 16S rRNA sequencing, compared with non-IFD patients with or without antibiotics treatment, Clostridium species in the intestinal tracts of patients with IFD were almost completely eliminated, and Enterococcus were increased. We established a rat model of IFD by intraperitoneal inoculation of C. albicans in rats pretreated with meropenem and vancomycin. After pretreatment with antibiotics, the intestinal microbiomes of rats infected with C. albicans were disordered, as characterized by an increase of proinflammatory conditional pathogens and a sharp decrease of Clostridium species and Bacteroides. Immunofluorescence analysis showed that C. albicans-infected rats pretreated with antibiotics were deficient in IgA and IL10, while the number of Pro-inflammatory CD11c⁺ macrophages was increased. In conclusion, excessive use of antibiotics promoted the imbalance of intestinal microbiome, especially sharp decreases of short-chain fatty acids (SCFA)-producing Clostridium species, which exacerbated the symptoms of IFD, potentially through decreased mucosal immunomodulatory molecules. Our results suggest that inappropriate use of broad-spectrum antibiotics may promote the colonization of invasive fungi. The results of this study provide new insights into the prevention of IFD in preterm infants.

Paediatric and neonatal sepsis and inflammation

Sepsis has a huge impact on global mortality and has been declared as a priority by the World Health organisation the WHO.¹ Children have a high incidence of sepsis especially in the neonatal with an estimated 3 million babies affected worldwide and mortality ranges from 11 to 19%.² In addition, long-term neurodevelopmental outcomes are affected but this is largely unquantified. However, challenges remain in the early recognition, diagnosis and standardised management of sepsis. This series on Sepsis and inflammation in children reviews the conundrums of diagnostic criteria, biomarkers, management and future strategies to improve outcomes.