Candida parapsilosis is a significant neonatal pathogen: a systematic review and meta-analysis

Draft genome sequence of a non-human primate-derived isolate of Candida parapsilosis

Candida parapsilosis is a common human commensal and opportunistic fungal pathogen that is also found in non-human primates (NHPs). Here, we report the first draft sequence of C. parapsilosis NCYC 4418, a fecal isolate from an adult cynomolgus macaque.

Inter-Institutional Dynamics and Impact of Fluconazole-Resistant Candida parapsilosis

BACKGROUND

Infections with fluconazole-resistant Candida parapsilosis have been increasing in Israeli hospitals with unclear implications for patient outcomes.

OBJECTIVES

To determine the frequency, mechanisms, molecular epidemiology, and outcomes of azole-resistant C. parapsilosis bloodstream infections in four hospitals in Israel.

PATIENTS/METHODS

C. parapsilosis bloodstream isolates were collected at four hospitals in central Israel during varying periods from 2005 to 2022. Antifungal susceptibility testing was done using CLSI broth microdilution. Risk factors for fluconazole resistance were investigated using logistic regression. ERG11 gene sequencing was performed on all isolates. Genetic relatedness was determined using multilocus microsatellite genotyping. Clinical cure, microbiological eradication, and mortality rates were compared between fluconazole-susceptible and resistant isolates.

RESULTS

A total of 192 patient-specific C. parapsilosis isolates were analysed. Resistance to fluconazole and voriconazole was detected in 80 (41%) and 14 (7.2%) isolates, respectively. The ERG11 Y132F substitution was found in 91% of fluconazole-resistant and 1% of fluconazole-susceptible isolates. Increasing age, intensive care hospitalisation, haemodialysis, and recent exposure to antibiotics were risk factors for fluconazole-resistant C. parapsilosis. Distinct but related genotypes predominated at each centre, indicating extensive dissemination within hospitals and limited transmission among them. Fluconazole resistance was associated with increased likelihood of microbiological failure but no significant difference in clinical cure and mortality.

CONCLUSIONS

We found high rates of fluconazole resistance in C. parapsilosis, attributable to nosocomial spread of hospital-specific clones bearing the Y132F substitution. Fluconazole resistance was associated with a higher risk of microbiological but not clinical failure. Strategies to limit nosocomial transmission of C. parapsilosis are needed.

Role of ERG11 and MDR1 genes in cycloheximide and multidrug resistance in Candida species

Candida species are amongst the commensals of the mucosal surfaces of the human body which include the oral cavity, vagina, and intestinal mucosa. Fungal infections are on the rise worldwide. The overall burden of infections due to fungi is difficult to estimate because the majority of them remain undiagnosed. The present study aims to determine the burden of antifungal resistance in low socioeconomic country, Pakistan and the frequency of ERG11 and MDR1 genes involved. A total of 636 Candida isolates were obtained from various tertiary care institutions in Lahore in the form of culture on various culture plates. Sabouraud agar culture plates were used to culture the Candida spp. Antifungal resistance was determined against Fluconazole, Itraconazole, Ketoconazole, and Nystatin via disk diffusion technique. Most resistance was observed against Fluconazole followed by Itraconazole, Ketoconazole, and Nystatin. The Candida isolates recovering from CVP tip and tissue have a high resistance profile. Candida species resistant to at least two antifungals were chosen for further ERG11 and MDR1 detection through real-time PCR. Among 255 Candida isolates, 240 contained ERG11 gene while MDR1 gene is present in 149 Candida isolates. The isolates carrying both genes were tested by the broth microdilution technique for the susceptibility against cycloheximide, all of them were able to grow in cycloheximide. The genetic determinants of antifungal resistance such as ERG11 and MDR1 are as important in the multidrug resistance against a variety of compounds and antifungal drugs.

Early- and late-onset candidemia in very low birth weight infants in the Korean neonatal network, 2013-2017

BACKGROUND

Candidiasis is a critical infection that is associated with very low birth weight (VLBW; <1500 g). This study investigated the characteristics and clinical presentation of candidiasis in Korean VLBW infants according to the onset of candidemia.

METHODS

All VLBW infants with candidemia, defined as blood culture-positive candidiasis and registered in a multicenter database with data from 70 neonatal units of the Korean Neonatal Network between 2013 and 2017, were included in this study. Early-onset candidemia (EOC; ≤10 days) and late-onset candidemia (LOC; >10 days) were analyzed. The demographic characteristics, clinical presentations, and outcomes of candidemia were also determined.

RESULTS

The overall incidence of candidemia was 2% (209/10,397) and 4% (173/3934) in VLBW and extremely very low birth weight (ELBW; <1000 g) infants, respectively. In ELBW infants, gestational age was significantly younger at EOC than at LOC (P = 0.015). Cesarean section, respiratory distress syndrome, severe bronchopulmonary disease, pulmonary hemorrhage, prior-bacteremia, neonatal seizures, and periventricular leukomalacia were significantly more common in the LOC group than in the EOC group (P < 0.05). The duration of invasive ventilation, total parenteral nutrition, and hospital stay were significantly longer in the LOC group than in the EOC group (P < 0.05). Most infections were caused by Candida spp. (91.8%). The mortality rate of ELBW infants with candidemia was 41%, which was higher than that of those without candidemia (29%) (P < 0.001). Mortality due to infection was also higher in infants with candidemia (55%) than in those without candidemia (15%) (P < 0.001); however, there were no significant differences between the EOC and LOC groups.

CONCLUSIONS

LOC was more common than EOC in VLBW infants. Considering the risk factors of LOC, active weaning from invasive ventilators and aggressive enteral feeding are required to decrease LOC. Furthermore, preventing candidemia is necessary to reduce mortality in VLBW infants.

Analysis of clinical Candida parapsilosis isolates reveals copy number variation in key fluconazole resistance genes

We used whole-genome sequencing to analyze a collection of 35 fluconazole-resistant and 7 susceptible Candida parapsilosis isolates together with coverage analysis and GWAS techniques to identify new mechanisms of fluconazole resistance. Phylogenetic analysis shows that although the collection is diverse, two persistent clinical lineages were identified. We identified copy number variation (CNV) of two genes, ERG11 and CDR1B, in resistant isolates. Two strains have a CNV at the ERG11 locus; the entire ORF is amplified in one, and only the promoter region is amplified in the other. We show that the annotated telomeric gene CDR1B is actually an artifactual in silico fusion of two highly similar neighboring CDR genes due to an assembly error in the C. parapsilosis CDC317 reference genome. We report highly variable copy numbers of the CDR1B region across the collection. Several strains have increased the expansion of the two genes into a tandem array of new chimeric genes. Other strains have experienced a deletion between the two genes creating a single gene with a reciprocal chimerism. We find translocations, duplications, and gene conversion across the CDR gene family in the C. parapsilosis species complex, showing that it is a highly dynamic family.

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.

Antifungal drug resistance in Candida: a special emphasis on amphotericin B

Invasive fungal infections in humans caused by several Candida species, increased considerably in immunocompromised or critically ill patients, resulting in substantial morbidity and mortality. Candida albicans is the most prevalent species, although the frequency of these organisms varies greatly according to geographic region. Infections with C. albicans and non-albicans Candida species have become more common, especially in the past 20 years, as a result of aging, immunosuppressive medication use, endocrine disorders, malnourishment, extended use of medical equipment, and an increase in immunogenic diseases. Despite C. albicans being the species most frequently associated with human infections, C. glabrata, C. parapsilosis, C. tropicalis, and C. krusei also have been identified. Several antifungal drugs with different modes of action are approved for use in clinical settings to treat fungal infections. However, due to the common eukaryotic structure of humans and fungi, only a limited number of antifungal drugs are available for therapeutic use. Furthermore, drug resistance in Candida species has emerged as a result of the growing use of currently available antifungal drugs against fungal infections. Amphotericin B (AmB), a polyene class of antifungal drugs, is mainly used for the treatment of serious systemic fungal infections. AmB interacts with fungal plasma membrane ergosterol, triggering cellular ion leakage via pore formation, or extracting the ergosterol from the plasma membrane inducing cellular death. AmB resistance is primarily caused by changes in the content or structure of ergosterol. This review summarizes the antifungal drug resistance exhibited by Candida species, with a special focus on AmB.

Evaluation of Biofilm Production and Antifungal Susceptibility to Fluconazole in Clinical Isolates of Candida spp. in Both Planktonic and Biofilm Form

Candida spp. are an important opportunistic pathogen that can represent a possible cause of severe infections, especially in immunocompromised individuals. The clinical impact of Candida spp. depends, in part, on the ability to form biofilms, communities of nestled cells into the extracellular matrix. In this study, we compared the biofilm formation ability of 83 strains of Candida spp. isolated from blood cultures and other materials, such as respiratory samples, urine, and exudate, and their sensitivity to fluconazole (FLZ). Strains were divided into tertiles to establish cut-offs to classify isolates as low, moderate, or high biofilm producers (<0.26, 0.266-0.839, >0.839) and biofilms with low, moderate, or high metabolic activity (<0.053, 0.053-0.183, >0.183). A non-linear relationship between biofilm production and metabolic activity was found in C. glabrata and C. tropicalis. In addition, the increase in minimum biofilm eradication concentrations (MBEC50) compared to the Minor Inhibitory Concentration (PMIC) of the planktonic form in Candida spp. confirms the role of biofilm in the induction of resistance to FLZ.

Analysis of clinical Candida parapsilosis isolates reveals copy number variation in key fluconazole resistance genes

We used whole-genome sequencing to analyse a collection of 35 fluconazole resistant and 7 susceptible Candida parapsilosis isolates together with coverage analysis and GWAS techniques to identify new mechanisms of fluconazole resistance. Phylogenetic analysis shows that although the collection is diverse, two probable outbreak groups were identified. We identified copy number variation of two genes, ERG11 and CDR1B, in resistant isolates. Two strains have a CNV at the ERG11 locus; the entire ORF is amplified in one, and only the promoter region is amplified in the other. We show the annotated telomeric gene CDR1B is actually an artefactual in silico fusion of two highly similar neighbouring CDR genes due to an assembly error in the C. parapsilosis CDC317 reference genome. We report highly variable copy numbers of the CDR1B region across the collection. Several strains have increased expansion of the two genes into a tandem array of new chimeric genes. Other strains have experienced a deletion between the two genes creating a single gene with a reciprocal chimerism. We find translocations, duplications, and gene conversion across the CDR gene family in the C. parapsilosis species complex, showing that it is a highly dynamic family.

Candida spp. in Human Intestinal Health and Disease: More than a Gut Feeling

Fungi are an essential part of the normal collection of intestinal microorganisms, even though their collective abundance comprises only 0.1-1% of all fecal microbes. The composition and role of the fungal population is often studied in relation to early-life microbial colonization and development of the (mucosal) immune system. The genus Candida is frequently described as one of the most abundant genera, and altered fungal compositions (including elevated abundance of Candida spp.) have been linked with intestinal diseases such as inflammatory bowel disease and irritable bowel syndrome. These studies are performed using both culture-dependent and genomic (metabarcoding) techniques. In this review, we aimed to summarize existing data on intestinal Candida spp. colonization in relation to intestinal disease and provide a brief overview of the biological and technical challenges in this field, including the recently described role of sub-species strain variation of intestinal Candida albicans. Together, the evidence for a contributing role of Candida spp. in pediatric and adult intestinal disease is quickly expanding, even though technical and biological challenges may limit full understanding of host-microbe interactions.

Congenital staphylococcal scalded skin syndrome in a preterm infant

Staphylococcal scalded skin syndrome (SSSS) is a rare condition in premature infants. We report a case of SSSS in a preterm neonate who displayed all clinical manifestations at birth, leading to a fatal outcome from Candida parapsilosis fungemia. The clinical presentation was challenging to differential diagnosis. SSSS diagnosis was confirmed by skin biopsy. This case emphasizes the significance of early recognition and diagnosis of SSSS promptly for clinicians. Congenital SSSS in premature infants can be fatal, but with early recognition and appropriate supportive and antimicrobial therapy, outcomes can be improved and lives can be saved.

Candida auris-macrophage cellular interactions and transcriptional response

The pathogenic yeast Candida auris represents a global threat of the utmost clinical relevance. This emerging fungal species is remarkable in its resistance to commonly used antifungal agents and its persistence in the nosocomial settings. The innate immune system is one the first lines of defense preventing the dissemination of pathogens in the host. C. auris is susceptible to circulating phagocytes, and understanding the molecular details of these interactions may suggest routes to improved therapies. In this work, we examined the interactions of this yeast with macrophages. We found that macrophages avidly phagocytose C. auris; however, intracellular replication is not inhibited, indicating that C. auris resists the killing mechanisms imposed by the phagocyte. Unlike Candida albicans, phagocytosis of C. auris does not induce macrophage lysis. The transcriptional response of C. auris to macrophage phagocytosis is very similar to other members of the CUG clade (C. albicans, C. tropicalis, C. parapsilosis, C. lusitaniae), i.e., downregulation of transcription/translation and upregulation of alternative carbon metabolism pathways, transporters, and induction of oxidative stress response and proteolysis. Gene family expansions are common in this yeast, and we found that many of these genes are induced in response to macrophage co-incubation. Among these, amino acid and oligopeptide transporters, as well as lipases and proteases, are upregulated. Thus, C. auris shares key transcriptional signatures shared with other fungal pathogens and capitalizes on the expansion of gene families coding for potential virulence attributes that allow its survival, persistence, and evasion of the innate immune system.

Fluconazole and echinocandin resistance of Candida species in invasive candidiasis at a university hospital during pre-COVID-19 and the COVID-19 outbreak

Antifungal susceptibility of Candida species is decreasing. Successful treatment for antifungal-resistant candida infection is challenging and associated with significant mortality. We performed a prospective observational study to identify the species and antifungal susceptibilities of invasive isolates of Candida species over a 5-year period at a university hospital in southern Thailand. Between 2017 and 2021, the species distribution was 39.1% Candida tropicalis, 24.8% Candida albicans, 20.3% Candida parapsilosis complex, 10.5% Candida glabrata, and 5.2% miscellaneous Candida spp. Notable observations include elevated minimal inhibitory concentration (MIC) and decrease susceptibility of C. tropicalis and C. glabrata to echinocandin and all tested triazoles. A shift of MIC90 value in the COVID-19 era was seen in C. albicans and C. tropicalis with azoles and echinocandins. Azole resistance increased among C. tropicalis isolates, and echinocandin resistance also increased among C. parapsilosis and C. glabrata isolates. Novel alterations in FKS1 HS1 and HS2 were detected in both isolates of anidulafungin-resistant C. parapsilosis. As Candida species have become more resistant to azoles and less susceptible to echinocandin development, the need arose to observe the emergence of resistance to both antifungal classes in candida clinical isolates, for a more effective infection control in the hospital.

Candida parapsilosis cell wall proteins-CPAR2_404800 and CPAR2_404780-Are adhesins that bind to human epithelial and endothelial cells and extracellular matrix proteins

One of the initial steps necessary for the development of Candida infections is the adherence to the host tissues and cells. Recent transcriptomic studies suggest that, in Candida parapsilosis-a fungal infectious agent that causes systemic candidiasis in immunosuppressed individuals-the adhesion is mediated by pathogen cell-exposed proteins belonging to the agglutinin-like sequence (Als) family. However, to date, the actual interactions of individual members of this family with human cells and extracellular matrix (ECM) have not been characterized in detail. In the current study, we focused attention on two of these C. parapsilosis Als proteins-CPAR2_404800 and CPAR2_404780-that were proteomically identified in the fungal cell wall of yeasts grown in the media suitable for culturing human epithelial and endothelial cells. Both proteins were extracted from the cell wall and purified, and using a microplate binding assay and a fluorescence microscopic analysis were shown to adhere to human cells of A431 (epithelial) and HMEC-1 (endothelial) lines. The human extracellular matrix components that are also plasma proteins-fibronectin and vitronectin-enhanced these interactions, and also could directly bind to CPAR2_404800 and CPAR2_404780 proteins, with a high affinity (KD in a range of 10-7 to 10-8  M) as determined by surface plasmon resonance measurements. Our findings highlight the role of proteins CPAR2_404800 and CPAR2_404780 in adhesion to host cells and proteins, contributing to the knowledge of the mechanisms of host-pathogen interactions during C. parapsilosis-caused infections.

Comparative Analysis of Two Candida parapsilosis Isolates Originating from the Same Patient Harbouring the Y132F and R398I Mutations in the ERG11 Gene

This work presents a comparative analysis of two clinical isolates of C. parapsilosis, isolated from haemoculture (HC) and central venous catheter (CVC). Both strains harboured Y132F and R398I mutations in the gene ERG11 associated with resistance to fluconazole (FLC). Differences between the HC and CVC isolates were addressed in terms of virulence, resistance to FLC, and lipid distribution. Expression of the ERG6 and ERG9 genes, lipid analysis, fatty acid composition, and lipase activity were assessed via qPCR, thin-layer chromatography/high-performance liquid chromatography, gas chromatography, and spectrophotometry, respectively. Regulation of the ERG6 and ERG9 genes did not prove any impact on FLC resistance. Analysis of lipid metabolism showed a higher accumulation of lanosterol in both the isolates regardless of FLC presence. Additionally, a decreased level of triacylglycerols (TAG) with an impact on the composition of total fatty acids (FA) was observed for both isolates. The direct impact of the ERG11 mutations on lipid/FA analysis has not been confirmed. The higher lipase activity observed for C. parapsilosis HC isolate could be correlated with the significantly decreased level of TAG. The very close relatedness between both the isolates suggests that one isolate was derived from another after the initial infection of the host.

Candidemia in Brazilian neonatal intensive care units: risk factors, epidemiology, and antifungal resistance

Candidemia is responsible for substantial morbidity and mortality in neonatal intensive care units and represents a challenge due to the complexity of hospitalized neonates, the deficiency in approved and precise diagnostic techniques, and the increasing number of species resistant to antifungal agents. Thus, the objective of this study was to detect candidemia among neonates evaluating the risk factors, epidemiology, and antifungal susceptibility. Blood samples were obtained from neonates with suspected septicemia, and the mycological diagnosis was based on yeast growth in culture. The fungal taxonomy was based on classic identification, automated system, and proteomic, when necessary molecular tools were used. The in vitro susceptibility tests were performed according to the broth microdilution method from Clinical and Laboratory Standards Institute. Statistical analysis was performed using the R software version R-4.2.2. The prevalence of neonatal candidemia was 10.97%. The major risk factors involved were previous use of parenteral nutrition, exposure to broad-spectrum antibiotics, prematurity, and prior use central venous catheter, but only this last was statistically associated with mortality risk. Species from Candida parapsilosis complex and C. albicans were the most frequent. All isolates were susceptible to amphotericin B, except C. haemulonii that also exhibited elevated MICs to fluconazole. C. parapsilosis complex and C. glabrata exhibit the highest MICs to echinocandins. Considering these data, we emphasize that an effective management strategy to reduce the impact of neonatal candidemia should involve the knowledge of risk factors, rapid and precise mycological diagnostic, and tests of antifungal susceptibility to help in the selection of an appropriate treatment.

Neonatal Brain Abscess with Serratia marcescens after Intrauterine Infection: A Case Report

Brain abscesses are a possible complication of bacterial sepsis or central nervous system infection but are uncommon in the neonatal period. Gram-negative organisms often cause them, but Serratia marcescens is an unusual cause of sepsis and meningitis in this age group. This pathogen is opportunistic and frequently responsible for nosocomial infections. Despite the existing antibiotics and modern radiological tools, mortality and morbidity remain significant in this group of patients. We report an unusual unilocular brain abscess in a preterm neonate caused by Serratia marcescens. The infection had an intrauterine onset. The pregnancy was achieved through assisted human reproduction techniques. It was a high-risk pregnancy, with pregnancy-induced hypertension, imminent abortion, and required prolonged hospitalization of the pregnant woman with multiple vaginal examinations. The infant was treated with multiple antibiotic cures and percutaneous drainage of the brain abscess associated with local antibiotic treatment. Despite treatment, evolution was unfavorable, complicated by fungal sepsis (Candida parapsilosis) and multiple organ dysfunction syndrome.

Draft Genome Sequence of a Preterm Infant-Derived Isolate of Candida parapsilosis

Candida parapsilosis is a human fungal pathogen of increasing incidence and causes invasive candidiasis, notably in preterm or low-birthweight neonates. Here, we present the genome sequence of C. parapsilosis NCYC 4289, a fecal isolate from a preterm male infant.

Vertical Transmission and Antifungal Susceptibility Profile of Yeast Isolates from the Oral Cavity, Gut, and Breastmilk of Mother-Child Pairs in Early Life

Yeast acquisition begins at birth; however, the contribution of the mother on yeast transmission to the offspring and associated resistance is yet to be clarified. The aim of this study was to explore the vertical transmission of yeasts and their antifungal susceptibility profile in early life. Oral, fecal, and breastmilk samples were collected from 73 mother-child pairs four to twelve weeks after delivery and cultured on Sabouraud dextrose agar with chloramphenicol. The isolates were identified by MALDI-TOF MS. The vertical transmission was studied by microsatellite genotyping. Antifungal susceptibility was determined for fluconazole, voriconazole, miconazole, anidulafungin, and nystatin by broth microdilution assay, following CLSI-M60 guidelines. A total of 129 isolates were identified from 53% mother-child pairs. We verified the vertical transmission of Candida albicans (n = three mother-child pairs) and Candida parapsilosis (n = one mother-child pair) strains, including an antifungal resistant strain transmitted from breastmilk to the gut of a child. Most isolates were susceptible to the tested antifungals, with the exception of four C. albicans isolates and one R. mucilaginosa isolate. The vertical transmission of yeasts happens in early life. This is the first work that demonstrated the role of the mother as a source of transmission of antifungal-resistant yeasts to the child.

Candida parapsilosis Virulence and Antifungal Resistance Mechanisms: A Comprehensive Review of Key Determinants

Candida parapsilosis is the second most common Candida species isolated in Asia, Southern Europe, and Latin America and is often involved in invasive infections that seriously impact human health. This pathogen is part of the psilosis complex, which also includes Candida orthopsilosis and Candida metapsilosis. C. parapsilosis infections are particularly prevalent among neonates with low birth weights, individuals who are immunocompromised, and patients who require prolonged use of a central venous catheter or other indwelling devices, whose surfaces C. parapsilosis exhibits an enhanced capacity to adhere to and form biofilms. Despite this well-acknowledged prevalence, the biology of C. parapsilosis has not been as extensively explored as that of Candida albicans. In this paper, we describe the molecular mechanistic pathways of virulence in C. parapsilosis and show how they differ from those of C. albicans. We also describe the mode of action of antifungal drugs used for the treatment of Candida infections, namely, polyenes, echinocandins, and azoles, as well as the resistance mechanisms developed by C. parapsilosis to overcome them. Finally, we stress the importance of the ongoing search for species-specific features that may aid the development of effective control strategies and thus reduce the burden on patients and healthcare costs.

Candidiasis and Other Emerging Yeasts

Purpose of Review

The review presents a comprehensive and updated information on the contemporary status of invasive candidiasis (IC), other emerging yeast infections, and the challenges they present in terms of at-risk population, specific virulence attributes, and antifungal susceptibility profile.

Recent Findings

With the advancement in medical field, there has been parallel expansion of vulnerable populations over the past two decades. This had led to the emergence of a variety of rare yeasts in healthcare settings, both Candida and non-Candida yeast causing sporadic cases and outbreaks. The advancements in diagnostic modalities have enabled accurate identification of rare Candida species and non-Candida yeast (NCY) of clinical importance. Their distribution and susceptibility profile vary across different geographical regions, thus necessitating surveillance of local epidemiology of these infections to improve patient outcomes.

Summary

The challenges in management of IC have been complicated with emergence of newer species and resistance traits. C. tropicalis has already overtaken C. albicans in many Asian ICUs, while C. auris is rising rapidly worldwide. Recent genomic research has reclassified several yeasts into newer genera, and an updated version of MALDI-TOF MS or ITS sequencing is necessary for accurate identification. Having a knowledge of the differences in predisposing factors, epidemiology and susceptibility profile of already established pathogenic yeasts, as well as new emerging yeasts, are imperative for better patient management.

Incidence and factors associated with invasive candidiasis in a neonatal intensive care unit in Mexico

INTRODUCTION

Neonatal Candida spp. infections are serious events due to their morbidity and mortality, however, epidemiological information is insufficient in developing countries. The objective of this study was to describe the incidence and factors associated with invasive infection by Candida spp. in a Neonatal Intensive Care Unit in Mexico.

METHODS

Case-control study nested in a cohort and matched for birth weight. We estimated the incidence of invasive neonatal infection by Candida spp. For the bivariate analysis of the studied factors, McNemar's test was used to contrast hypotheses and multivariate analysis was made with logistic regression.

RESULTS

The incidence of infection was 2.27 events/1000 live newborns. The species identified were C. albicans 35.3% (n 30), C. parapsilosis 30.6% (n 26), C. glabrata 31.8% (n 27) and two events with C. lipolytica. The factors associated with a higher risk were mechanical ventilation (OR 3.04, 95% CI 1.13-8.14), systemic antibiotics (OR 7.48, 95% CI 1.30-42.9), number of antimicrobial regimens (OR 2.02, 95% CI 1.01-4.03), and days with total parenteral nutrition (OR 1.14, 95% CI 1.04-1.25) or with venous catheter central (OR 1.11, 95% CI 1.02-1.20). Fluconazole prophylaxis decreased the risk (OR 0.32, 95% CI 0.12-0.84).

CONCLUSIONS

Invasive interventions (central catheter, mechanical ventilation, and parenteral nutrition) and the use of antimicrobials increase the risk of neonatal Candida spp. Infection, while prophylactic fluconazole is protective.

Characteristics of Biofilms Formed by C. parapsilosis Causing an Outbreak in a Neonatal Intensive Care Unit

Background: We dealt with the occurrence of an outbreak of Candida parapsilosis in a neonatal intensive care unit (NICU) in September 2020. There have been several reports of C. parapsilosis outbreaks in NICUs. In this study we describe our investigation into both the transmission route and the biofilm of C. parapsilosis. Methods: C. parapsilosis strains were detected in three inpatients and in two environmental cultures in our NICU. One environmental culture was isolated from the incubator used by a fungemia patient, and another was isolated from the humidifier of an incubator that had been used by a nonfungemia patient. To prove their identities, we tested them by micro satellite analysis. We used two methods, dry weight measurements and observation by electron microscopy, to confirm biofilm. Results: Microsatellite analysis showed the five C. parapsilosis cultures were of the same strain. Dry weight measurements and electron microscopy showed C. parapsilosis formed biofilms that amounted to clumps of fungal cells. Conclusions: We concluded that the outbreak happened due to horizontal transfer through the humidifier of the incubator and that the C. parapsilosis had produced biofilm, which promoted an invasive and infectious outbreak. Additionally, biofilm is closely associated with pathogenicity.

Clinical Laboratory Features of Microbes That Cause Neonatal Sepsis: An 8-Year Retrospective Study

Purpose

To determine the distribution and antibiotic resistance patterns among pathogens that cause neonatal sepsis (NS) and to assess trends in antibiotic resistance.

Patients and methods

A total of 864 patients with sepsis admitted to a neonatal intensive care unit (NICU) between 2014 and 2021 were enrolled. Data on neonate age and sex, pathogenic microbes, and antimicrobial susceptibility were collected. Univariate and linear regression analyses were performed to determine the differences and trends in antibiotic resistance rates.

Results

The overall incidence rate of NS was 4.59 cases per 1000 live births. Of these cases, 255 (29.5%) were early-onset neonatal sepsis (EONS) and 609 (70.5%) were late-onset neonatal sepsis (LONS). A total of 670 (70.5%) gram-positive cocci and 171 (19.8%) gram-negative bacilli were identified. Among the 552 coagulase-negative Staphylococcus (CoNS) strains, the rate of oxacillin resistance was 70.6%, but no strains were resistant to linezolid, vancomycin or tigecycline. Among the antibiotic resistance patterns of the top three gram-negative pathogens, K. pneumoniae showed the highest rates of resistance, with resistance rates of 37.9% and 39.4% to ertapenem and imipenem, respectively, while E. coli and Enterobacter cloacae showed high levels of susceptibility to both. With regard to the trends in resistance among important pathogens, the rates of resistance to rifampicin, ciprofloxacin, levofloxacin, moxifloxacin and clindamycin by Staphylococcus epidermidis significantly decreased (p<0.05) during the study period. E. coli strains exhibited a significant increase in ceftriaxone resistance during the study period (p<0.05).

Conclusion

CoNS was the main microbe that caused NS, followed by E. coli. The bacterial isolates showed varying levels of resistance to the antimicrobial drugs tested. Thus, periodic surveillance in hospital settings to monitor changes in pathogens and antibiotic resistance is important.

Multi-Strain and -Species Investigation of Volatile Metabolites Emitted from Planktonic and Biofilm Candida Cultures

Candida parapsiliosis is a prevalent neonatal pathogen that attains its virulence through its strain-specific ability to form biofilms. The use of volatilomics, the profiling of volatile metabolites from microbes is a non-invasive, simple way to identify and classify microbes; it has shown great potential for pathogen identification. Although C. parapsiliosis is one of the most common clinical fungal pathogens, its volatilome has never been characterised. In this study, planktonic volatilomes of ten clinical strains of C. parapsilosis were analysed, along with a single strain of Candida albicans. Headspace-solid-phase microextraction coupled with gas chromatography-mass spectrometry were employed to analyse the samples. Species-, strain-, and media- influences on the fungal volatilomes were investigated. Twenty-four unique metabolites from the examined Candida spp. (22 from C. albicans; 18 from C. parapsilosis) were included in this study. Chemical classes detected across the samples included alcohols, fatty acid esters, acetates, thiols, sesquiterpenes, and nitrogen-containing compounds. C. albicans volatilomes were most clearly discriminated from C. parapsilosis based on the detection of unique sesquiterpene compounds. The effect of biofilm formation on the C. parapsilosis volatilomes was investigated for the first time by comparing volatilomes of a biofilm-positive strain and a biofilm-negative strain over time (0–48 h) using a novel sampling approach. Volatilomic shifts in the profiles of alcohols, ketones, acids, and acetates were observed specifically in the biofilm-forming samples and attributed to biofilm maturation. This study highlights species-specificity of Candida volatilomes, and also marks the clinical potential for volatilomics for non-invasively detecting fungal pathogens. Additionally, the range of biofilm-specificity across microbial volatilomes is potentially far-reaching, and therefore characterising these volatilomic changes in pathogenic fungal and bacterial biofilms could lead to novel opportunities for detecting severe infections early.

The Pathogenic Yeast Candida parapsilosis Forms Pseudohyphae through Different Signaling Pathways Depending on the Available Carbon Source

Candida parapsilosis is an emerging fungal pathogen that primarily affects immunocompromised patients in hospitals. A significant risk factor is the use of implanted medical devices, which support the growth of biofilms composed of a mixture of individual yeast cells and chains of elongated pseudohyphal cells. The morphological switch between these two forms is triggered by cues from the environment, including nutrient availability and temperature. We examined how different nutrient sources affect the balance between yeast and pseudohyphae and found that cells grown in the presence of five- or six-carbon sugars form more pseudohyphae at 30°C than at 37°C. Conversely, cells grown on glycerol, a three-carbon polyalcohol, form more pseudohyphae at 37°C. Furthermore, we found that different regulators influence pseudohyphal growth on glucose at 30°C compared with those on glycerol at 37°C. In particular, cAMP signaling and the sirtuin deacetylase Hst1 were required for pseudohyphal growth on glycerol at 37°C but not on glucose at 30°C. Finally, we found that the carbon source on which C. parapsilosis is grown can influence its ability to establish an infection in a wax moth model. Overall, this study reveals that environmental conditions affect not only the extent of pseudohyphal growth but also which pathways and regulators govern pseudohyphal formation.

IMPORTANCECandida parapsilosis is one of the leading causes of hospital-acquired yeast infections and poses a significant risk to immunocompromised people. Two of its properties that contribute to infection are metabolic flexibility, to use a range of nutrients available in the host, and cellular dimorphism, to switch between round yeast cells and chains of elongated pseudohyphal cells. Uncovering the molecular mechanisms that regulate these processes could reveal new targets for antifungal drugs. We found that for C. parapsilosis, the balance between yeast and pseudohyphal cells depends on the nutrients available and the growth temperature. Moreover, these environmental changes can affect its ability to cause infections. Finally, we found that a potential sensor of the cell’s metabolic state, the sirtuin Hst1, contributes to pseudohyphal growth for cells grown on glycerol. These findings indicate that the shape and virulence of C. parapsilosis likely vary depending on its location in the host.

Prevalence of biofilms in Candida spp. bloodstream infections: A meta-analysis

CONTEXT

Candida-related infections are nowadays a serious Public Health Problem emerging multidrug-resistant strains. Candida biofilm also leads bloodstream infections to invasive systemic infections.

OBJECTIVE

The present meta-analysis aimed to analyze Candida biofilm rate, type, and antifungal resistance among hospitalized patients between 1995 and 2020.

DATA SOURCES

Web of Science, Scopus, PubMed, and Google Scholar databases were searched for English papers using the following medical subject heading terms (MESH): "invasive candidiasis"; "bloodstream infections"; "biofilm formation"; "biofilm-related infections"; "mortality"; and "prevalence".

STUDY SELECTION

The major inclusion criteria included reporting the rate of biofilm formation and the prevalence of biofilm-related to Candida species, including observational studies (more exactly, cohort, retrospective, and case-control studies). Furthermore, data regarding the mortality rate, the geographical location of the study set, and the use of anti-fungal agents in clinical isolates were also extracted from the studies.

DATA EXTRACTION

Independent extraction of articles by 2 authors using predefined data fields, including study quality indicators.

DATA SYNTHESIS

A total of 31 studies from publicly available databases met our inclusion criteria. The biofilm formation in the data set varied greatly from 16 to 100% in blood samples. Most of the studies belonged to Europe (17/31) and Asia (9/31). Forest plot showed a pooled rate of biofilm formation of 80.0% (CI: 67-90), with high heterogeneity (Q = 2567.45, I2 = 98.83, τ2 = 0.150) in random effects model (p < 0.001). The funnel plot and Egger's linear regression test failed to find publication bias (p = 0.896). The mortality rate in Candida-related bloodstream infections was 37.9% of which 70.0% were from biofilm-associated infections. Furthermore, Candida isolates were also characterized in low, intermediate, or high biofilm formers through their level of biofilm mass (crystal violet staining or XTT assays) after a 24h growth. When comparing between countries, statistical differences were obtained (p = 0.0074), showing the lower and higher biofilm prevalence values in Italy and Spain, respectively. The prevalence of low, intermediate, and high biofilms were 36.2, 18.9, and 35.0% (p < 0.0001), respectively. C. tropicalis was the prevalent species in high biofilm formation (67.5%) showing statistically significant differences when compared to other Candida species, except for C. krusei and C. glabrata. Finally, the rates of antifungal resistance to fluconazole, voriconazole, and caspofungin related to biofilm were 70.5, 67.9 and 72.8% (p < 0.001), respectively.

CONCLUSIONS

Early detection of biofilms and a better characterization of Candida spp. bloodstream infections should be considered, which eventually will help preserve public health resources and ultimately diminish mortality among patients.

WMR Peptide as Antifungal and Antibiofilm against Albicans and Non-Albicans Candida Species: Shreds of Evidence on the Mechanism of Action

Candida species are the most common fungal pathogens infecting humans and can cause severe illnesses in immunocompromised individuals. The increased resistance of Candida to traditional antifungal drugs represents a great challenge in clinical settings. Therefore, novel approaches to overcome antifungal resistance are desired. Here, we investigated the use of an antimicrobial peptide WMR against Candida albicans and non-albicans Candida species in vitro and in vivo. Results showed a WMR antifungal activity on all Candida planktonic cells at concentrations between 25 μM to >50 μM and exhibited activity at sub-MIC concentrations to inhibit biofilm formation and eradicate mature biofilm. Furthermore, in vitro antifungal effects of WMR were confirmed in vivo as demonstrated by a prolonged survival rate of larvae infected by Candida species when the peptide was administered before or after infection. Additional experiments to unravel the antifungal mechanism were performed on C. albicans and C. parapsilosis. The time-killing curves showed their antifungal activity, which was further confirmed by the induced intracellular and mitochondrial reactive oxygen species accumulation; WMR significantly suppressed drug efflux, down-regulating the drug transporter encoding genes CDR1. Moreover, the ability of WMR to penetrate within the cells was demonstrated by confocal laser scanning microscopy. These findings provide novel insights for the antifungal mechanism of WMR against Candida albicans and non-albicans, providing fascinating scenarios for the identification of new potential antifungal targets.

Characterisation of Candida parapsilosis CYP51 as a Drug Target Using Saccharomyces cerevisiae as Host

The fungal cytochrome P450 lanosterol 14α-demethylase (CYP51) is required for the biosynthesis of fungal-specific ergosterol and is the target of azole antifungal drugs. Despite proven success as a clinical target for azole antifungals, there is an urgent need to develop next-generation antifungals that target CYP51 to overcome the resistance of pathogenic fungi to existing azole drugs, toxic adverse reactions and drug interactions due to human drug-metabolizing CYPs. Candida parapsilosis is a readily transmitted opportunistic fungal pathogen that causes candidiasis in health care environments. In this study, we have characterised wild type C. parapsilosis CYP51 and its clinically significant, resistance-causing point mutation Y132F by expressing these enzymes in a Saccharomyces cerevisiae host system. In some cases, the enzymes were co-expressed with their cognate NADPH-cytochrome P450 reductase (CPR). Constitutive expression of CpCYP51 Y132F conferred a 10- to 12-fold resistance to fluconazole and voriconazole, reduced to ~6-fold resistance for the tetrazoles VT-1161 and VT-1129, but did not confer resistance to the long-tailed triazoles. Susceptibilities were unchanged in the case of CpCPR co-expression. Type II binding spectra showed tight triazole and tetrazole binding by affinity-purified recombinant CpCYP51. We report the X-ray crystal structure of ScCYP51 in complex with VT-1129 obtained at a resolution of 2.1 Å. Structural analysis of azole—enzyme interactions and functional studies of recombinant CYP51 from C. parapsilosis have improved understanding of their susceptibility to azole drugs and will help advance structure-directed antifungal discovery.

Hsp90 interaction networks in fungi-tools and techniques

Heat-shock protein 90 (Hsp90) is a central regulator of cellular proteostasis. It stabilizes numerous proteins that are involved in fundamental processes of life, including cell growth, cell-cycle progression and the environmental response. In addition to stabilizing proteins, Hsp90 governs gene expression and controls the release of cryptic genetic variation. Given its central role in evolution and development, it is important to identify proteins and genes that interact with Hsp90. This requires sophisticated genetic and biochemical tools, including extensive mutant collections, suitable epitope tags, proteomics approaches and Hsp90-specific pharmacological inhibitors for chemogenomic screens. These usually only exist in model organisms, such as the yeast Saccharomyces cerevisiae. Yet, the importance of other fungal species, such as Candida albicans and Cryptococcus neoformans, as serious human pathogens accelerated the development of genetic tools to study their virulence and stress response pathways. These tools can also be exploited to map Hsp90 interaction networks. Here, we review tools and techniques for Hsp90 network mapping available in different fungi and provide a summary of existing mapping efforts. Mapping Hsp90 networks in fungal species spanning >500 million years of evolution provides a unique vantage point, allowing tracking of the evolutionary history of eukaryotic Hsp90 networks.

Characteristics, Risk Factors and Predictors for Candidemia in the Pediatric Intensive Care Unit at the University Hospital Centre Zagreb in Croatia: A 9-Year Retrospective Study

BACKGROUND

Candidemia is one of the leading causes of bloodstream infections in the pediatric intensive care unit (PICU). The aim of this study was to define characteristics and risk factors for candidemia in the PICU setting and propose a predictive model to identify the patients at risk.

METHODS

This was a retrospective matched case-control study in the PICU during a 9-year period. Patients with candidemia were studied and matched with control patients without candidemia. Univariate analysis was performed for potential risk factors and multivariate analysis was conducted to determine the prediction score for candidemia.

RESULTS

Forty-two cases of candidemia were matched with 84 control patients. Candida parapsilosis was the most common (71.4%) species. Risk factors independently associated with candidemia were: the use of >2 antibiotics in a maximum period of 4 weeks before the candidemia (odds ratio [OR]: 10.59; 95% confidence interval [CI]: 2.05-54.83), a previous bacterial infection in a maximum period of 4 weeks before the candidemia (OR: 5.56; 95% CI: 1.44-21.5) and the duration of PICU stay of >10 days (OR: 4.22; 95% CI: 1.02-17.41). The proposed predictive scoring system has a sensitivity of 95.24%, specificity of 76.12%, OR 64.0, 95% CI 14.2-288.6, the positive predictive value of 66.67% and the negative predictive value of 96.97%.

CONCLUSIONS

Previously reported risk factors for candidemia have been confirmed and some new have been detected. The presented scoring system can help identify patients who would benefit from prophylactic antifungal therapy.

Epidemiology of Candidemia in Children over 7 Years in a Medical Center in Turkey

The aims of the study were to describe Candida species in children with candidemia, to determine the changing epidemiology of candidemia over time in our tertiary care hospital, and to examine the demographic and clinical characteristics of patients with candidemia caused by parapsilosis and nonparapsilosis Candida spp. From 2012 to 2018, we identified a total of 126 cases of candidemia. The most commonly isolated Candida sp. was C. parapsilosis (n = 71, 56.3%), followed by C. albicans (n = 34, 26.9%). A total of 21 candidemia episodes (16.6%) were caused by other Candida species. Patients were divided into two groups (parapsilosis and nonparapsilosis) to identify any potential differences between the groups in terms of risk factors, mortality, and antifungal resistance. The median age of the patients, the median durations of the hospital and pediatric intensive care unit stay, receipt of immunosuppressive therapy within 2 weeks of developing candidemia, the rate of using total parenteral nutrition, need for mechanical ventilation, and receipt of carbapenems were statistically significantly higher in the parapsilosis group than in the nonparapsilosis group (P = 0.020, P = 0.001, P = 0.011, P = 0.036, P = 0.002, P = 0.038, and P = 0.004, respectively). The overall 30-day mortality rates (4.2% versus 3.6%) and resistance to fluconazole (33.8% versus 32.7%) were similar between the groups (P = 0.790 and P = 0.860, respectively). The distribution of Candida strains isolated in this study was consistent with the global trend, with C. parapsilosis being the most commonly identified species. Determining local epidemiologic data at regular intervals in candidemia cases is important in terms of determining both the changing epidemiology and empirical antifungal agents.

IMPORTANCE In our study, the changing epidemiology of Candida species in candidemia in children was evaluated. The dominance of Candida parapsilosis species in the changing epidemiology was remarkable. We found that fluconazole resistance was high in both parapsilosis and nonparapsilosis groups. Updating local epidemiologic data at certain intervals in candidemia cases is important in determining both the changing epidemiology and empirical antifungal agents.

Deciphering of Candida parapsilosis induced immune response in Drosophila melanogaster

Candida infections are the most prevalent cause of serious human mycoses and are the third most common pathogens isolated from bloodstream infections in hospitalized patients. C. parapsilosis is a member of the non-albicans spp., which have a predilection for causing life-threatening disease in neonates and hospitalized pediatric patients. In this study, we utilized a Drosophila melanogaster infection model to analyze the immunological responses to C. parapsilosis. Our results demonstrate that the Toll pathway in Drosophila controls C. parapsilosis proliferation as the Toll signaling mutant MyD88^-/- flies are highly susceptible to C. parapsilosis. We also confirmed that the MyD88^-/- fly is a convenient invertebrate animal model to analyze virulence properties of different species and strains from the C. parapsilosis sensu lato complex as C. orthopsilosis, C. metapsilosis proved to be less virulent than C. parapsilosis sensu stricto and the N-mannan deficient C. parapsilosis och1Δ/Δ strain showed attenuated pathogenicity in this immunodeficient Drosophila background. We also found that Persephone protease is not required for detection and activation of Toll pathway during C. parapsilosis infection. Furthermore, we observed that Drosophila β-glucan receptor deficient flies where more sensitive to C. parapsilosis compared to wild-type flies; however, we could not find a clear dependence on the recognition of this receptor and the cell wall β-glucan exposure-induced host response. These studies establish this D. melanogaster infection model as an efficient tool in deciphering immune responses to C. parapsilosis as well as for assessing virulence factors produced by this emerging fungal predator.

Spectrum and Antifungal Resistance of Candidemia in Neonates With Early- and Late-Onset Sepsis in Pakistan

BACKGROUND

Neonatal candidemia leads to high morbidity and mortality in developing countries. We studied the trends, spectrum and antifungal resistance in neonatal candidemia isolates from the year 2014 to 2019.

METHODS

This was a cross-sectional study conducted at the Aga Khan University, Pakistan. Neonates with positive blood cultures with Candida species were retrospectively identified from the laboratory database (2014-2018) and prospectively in 2019 where clinical information was also collected as part of routine laboratory reporting.

RESULTS

We identified 669 neonates with Candida species in blood cultures. Three hundred forty-six neonates had early-onset disease (EOD age ≤7 days) and 323 had late-onset disease (LOD age >7 days). Non-albicans Candida species (86.7%) were predominant versus C. albicans (13.3%; P-value 0.024) with Candida tropicalis being most common in both EOD and LOD. Candida pelliculosa and Candida guilliermondii were associated with EOD and C. albicans with LOD. Isolation of fluconazole nonsusceptible non-albicans Candida species was significantly higher in early-onset (5.9%) versus late-onset (2%) neonatal candidemia (P-value 0.005; crude odds ratio [COR] 2.73, 95% CI: 1.34-5.53). LOD in neonates was more likely associated with the use of vancomycin (COR 3.89, 95% CI: 1.39-10.89). EOD was more likely seen in patients with vaginal delivery (COR 4.16, 95% CI: 1.42-12.23) and in neonates with respiratory distress leading to intensive care unit admission (COR 3.31, 95% CI: 1.05-10.42).

CONCLUSIONS

Non-albicans Candida species were increasingly isolated from neonates with candidemia during recent years from Pakistan. Amphotericin remains first-line option for neonatal candidemia in our setting as fluconazole nonsusceptible Candida species are commonly isolated.

Epidemiology of Candidemia in Kuwait: A Nationwide, Population-Based Study

The Candida species cause a majority of invasive fungal infections. In this article, we describe the nationwide epidemiology of candidemia in Kuwait in 2018. Yeast bloodstream isolates submitted from all major hospitals and identified by phenotypic MALDI-TOF MS and/or by molecular methods were studied. Susceptibility testing was performed by Etest. Out of 313 bloodstream yeasts, 239 Candida spp. isolates (excluding duplicate isolates) were obtained during 234 candidemic episodes among 223 patients. Mixed-species candidemia and re-infection occurred in 5 and 11 patients, respectively. C. albicans (n = 74), C. parapsilosis (n = 54), C. tropicalis (n = 35), C. auris (n = 33), C. glabrata (n = 32), other Candida spp. (n = 11), and other yeasts (n = 9) caused fungemia. Nearly 50% of patients were in intensive care units. Candida spp. isolates (except C. glabrata) were susceptible to caspofungin and 27% of C. auris were amphotericin B-resistant. Resistance to fluconazole was 100% in C. auris, 17% in C. parapsilosis, 12% in C. glabrata, and 1% in C. albicans. Mortality was 47% for other Candida/yeast infections. Nationwide candidemia incidence in 2018 was 5.29 cases/100,000 inhabitants. Changes in species spectrum, increasing fluconazole resistance in C. parapsilosis, and the emergence of C. auris as a major pathogen in Kuwait are noteworthy findings. The data could be of help in informing decisions regarding planning, in the allocation of resources, and in antimicrobial stewardship.

Epidemiology of Culture-confirmed Candidemia Among Hospitalized Children in South Africa, 2012-2017

BACKGROUND

We aimed to describe the epidemiology of candidemia among children in South Africa.

METHODS

We conducted laboratory-based surveillance among neonates (≤28 days), infants (29 days to <1 year), children (1-11 years) and adolescents (12-17 years) with Candida species cultured from blood during 2012-2017. Identification and antifungal susceptibility of viable isolates were performed at a reference laboratory. We used multivariable logistic regression to determine the association between Candida parapsilosis candidemia and 30-day mortality among neonates.

RESULTS

Of 2996 cases, neonates accounted for 49% (n = 1478), infants for 27% (n = 806), children for 20% (n = 589) and adolescents for 4% (n = 123). The incidence risk at tertiary public sector hospitals was 5.3 cases per 1000 pediatric admissions (range 0.39-119.1). Among 2943 cases with single-species infections, C. parapsilosis (42%) and Candida albicans (36%) were most common. Candida auris was among the 5 common species with an overall prevalence of 3% (n = 47). Fluconazole resistance was more common among C. parapsilosis (55% [724/1324]) versus other species (19% [334/1737]) (P < 0.001). Of those with known treatment (n = 1666), 35% received amphotericin B deoxycholate alone, 32% fluconazole alone and 30% amphotericin B deoxycholate with fluconazole. The overall 30-day in-hospital mortality was 38% (n = 586) and was highest among neonates (43% [323/752]) and adolescents (43% [28/65]). Compared with infection with other species, C. parapsilosis infection was associated with a reduced mortality among neonates (adjusted odds ratio 0.41, 95% confidence interval: 0.22-0.75, P = 0.004).

CONCLUSIONS

Candidemia in this setting mainly affected neonates and infants and was characterized by fluconazole-resistant C. parapsilosis with no increased risk of death.

[Incidence and factors associated with invasive candidiasis in a neonatal intensive care unit in Mexico]

INTRODUCTION

Neonatal Candida spp. infections are serious events due to their morbidity and mortality, however, epidemiological information is insufficient in developing countries. The objective of this study was to describe the incidence and factors associated with invasive infection by Candida spp. in a Neonatal Intensive Care Unit in Mexico.

METHODS

Case-control study nested in a cohort and matched for birth weight. We estimate the incidence of invasive neonatal infection by Candida spp. For the bivariate analysis of the studied factors, McNemar's test was used to contrast hypotheses and multivariate analysis was made with logistic regression.

RESULTS

The incidence of infection was 2.27 events/1000 live newborns. The species identified were C. albicans 35.3% (n 30), C. parapsilosis 30.6% (n 26), C. glabrata 31.8% (n 27) and two events with C. lipolytica. The factors associated with a higher risk were mechanical ventilation (OR 3.04; 95% CI 1.13-8.14), systemic antibiotics (OR 7.48; 95% CI 1.30-42.9), number of antimicrobial regimens (OR 2.02; 95% CI 1.01-4.03), and days with total parenteral nutrition (OR 1.14; 95% CI 1.04-1.25) or with venous catheter central (OR 1.11; 95% CI 1.02-1.20). Fluconazole prophylaxis decreased the risk (OR 0.32; 95% CI 0.12-0.84).

CONCLUSIONS

Invasive interventions (central catheter, mechanical ventilation, and parenteral nutrition) and the use of antimicrobials increase the risk of neonatal Candida spp. Infection, while prophylactic fluconazole is protective.

Treatment with Micafungin in a Preterm Neonate with an Invasive Candida parapsilosis Infection after a Severe Terlipressin-Induced Skin Necrosis

Candida parapsilosis infections are increasingly reported in preterm neonates, but the optimal treatment remains uncertain. We report the clinical history of an extremely preterm neonate, who developed a devastating skin necrosis due to terlipressin administration, with subsequent superinfection by Candida parapsilosis. The infant underwent multiple curettages and skin grafts to resolve skin lesions and was treated with systemic micafungin administration at a high dose (8 mg/kg/day), with resolution of the fungal infection.

The antifungal activity of caspofungin in combination with antifungals or non-antifungals against Candida species in vitro and in clinical therapy

Introduction: Candida species have been regarded as global health threats due to their ability to cause invasive infections. It is challenging to treat Candida bloodstream infections, which are associated with high mortality levels. Monotherapy with antifungals is sometimes not effective against severe Candida infections, and combination therapy is needed in clinical practice.Areas covered: This review was undertaken based on data from a PubMed search for English language reports published before March 2021 by using the terms 'caspofungin,' 'Candida species,' 'combination therapy,' 'antifungal effect,' and 'novel antifungal agent.'Expert opinion: Combination therapy is an empirical strategy for treating refractory Candida infections. Caspofungin has been recommended to treat candidaemia. Caspofungin in combination therapy has some applications, while the efficacy of combination therapy in the treatment of refractory Candida infections needs more study, such as randomized controlled trials. In addition, novel compounds or drugs with potential antifungal activities have been examined, and some of them exhibit synergistic interactions with caspofungin. Thus, the antifungal activity of caspofungin in combination with antifungals or non-antifungals against Candida species in vitro and in clinical therapy is summarized.

Candida Bloodstream Infections: Changes in Epidemiology and Increase in Drug Resistance

The literature on bloodstream infections (BSIs) have predominantly been biased towards bacteria, given their superior clinical significance in comparison with the other types of microorganisms. Fungal pathogens have epidemiologically received relatively less attention, although they constitute an important proportion of BSI aetiologies. In this review, the authors discuss the clinical relevance of fungal BSIs in the context of Candida species, as well as treatment options for the infections, emphasizing the compelling need to develop newer antifungals and strengthen antimicrobial stewardship programmes in the wake of the rapid spread of antifungal resistance.

Genetic Manipulation as a Tool to Unravel Candida parapsilosis Species Complex Virulence and Drug Resistance: State of the Art

An increase in the rate of isolation of Candida parapsilosis in the past decade, as well as increased identification of azole-resistant strains are concerning, and require better understanding of virulence-like factors and drug-resistant traits of these species. In this regard, the present review “draws a line” on the information acquired, thus far, on virulence determinants and molecular mechanisms of antifungal resistance in these opportunistic pathogens, mainly derived from genetic manipulation studies. This will provide better focus on where we stand in our understanding of the C. parapsilosis species complex–host interaction, and how far we are from defining potential novel targets or therapeutic strategies—key factors to pave the way for a more tailored management of fungal infections caused by these fungal pathogens.

Oral Epithelial Cells Distinguish between Candida Species with High or Low Pathogenic Potential through MicroRNA Regulation

Oral epithelial cells monitor microbiome composition and initiate immune response upon dysbiosis, as in the case of Candida imbalances. Candida species, such as C. albicans and C. parapsilosis, are the most prevalent yeasts in the oral cavity. Comparison of healthy oral epithelial cell responses revealed that while C. albicans infection robustly activated inflammation cascades, C. parapsilosis primarily activated various inflammation-independent pathways. In posttranscriptional regulatory processes, several miRNAs were altered by both species. For C. parapsilosis, the dose of yeast cells directly correlated with changes in transcriptomic responses with higher fungal burdens inducing significantly different and broader changes. MicroRNAs (miRNAs) associated with carbohydrate metabolism-, hypoxia-, and vascular development-related responses dominated with C. parapsilosis infection, whereas C. albicans altered miRNAs linked to inflammatory responses. Subsequent analyses of hypoxia-inducible factor 1α (HIF1-α) and hepatic stellate cell (HSC) activation pathways predicted target genes through which miRNA-dependent regulation of yeast-specific functions may occur, which also supported the observed species-specific responses. Our findings suggest that C. parapsilosis is recognized as a commensal at low doses by the oral epithelium; however, increased fungal burden activates different pathways, some of which overlap with the inflammatory processes robustly induced by C. albicans IMPORTANCE A relatively new topic within the field of immunology involves the role of miRNAs in innate as well as adaptive immune response regulation. In recent years, posttranscriptional regulation of host-pathogenic fungal interactions through miRNAs was also suggested. Our study reveals that the distinct nature of human oral epithelial cell responses toward C. parapsilosis and C. albicans is possibly due to species-specific fine-tuning of host miRNA regulatory processes. The findings of this study also shed new light on the nature of early host cell transcriptional responses to the presence of C. parapsilosis and highlight the species' potential inflammation-independent host activation processes. These findings contribute to our better understanding of how miRNA deregulation at the oral immunological barrier, in noncanonical immune cells, may discriminate between fungal species, particularly Candida species with high or low pathogenic potential.

The impact of the Fungus-Host-Microbiota interplay upon Candida albicans infections: current knowledge and new perspectives

Candida albicans is a major fungal pathogen of humans. It exists as a commensal in the oral cavity, gut or genital tract of most individuals, constrained by the local microbiota, epithelial barriers and immune defences. Their perturbation can lead to fungal outgrowth and the development of mucosal infections such as oropharyngeal or vulvovaginal candidiasis, and patients with compromised immunity are susceptible to life-threatening systemic infections. The importance of the interplay between fungus, host and microbiota in driving the transition from C. albicans commensalism to pathogenicity is widely appreciated. However, the complexity of these interactions, and the significant impact of fungal, host and microbiota variability upon disease severity and outcome, are less well understood. Therefore, we summarise the features of the fungus that promote infection, and how genetic variation between clinical isolates influences pathogenicity. We discuss antifungal immunity, how this differs between mucosae, and how individual variation influences a person's susceptibility to infection. Also, we describe factors that influence the composition of gut, oral and vaginal microbiotas, and how these affect fungal colonisation and antifungal immunity. We argue that a detailed understanding of these variables, which underlie fungal-host-microbiota interactions, will present opportunities for directed antifungal therapies that benefit vulnerable patients.

Antimicrobial Peptides Pom-1 and Pom-2 from Pomacea poeyana Are Active against Candidaauris, C. parapsilosis and C. albicans Biofilms

Recently two peptides isolated from the Cuban freshwater snail Pomacea poeyana (Pilsbry, 1927) were described to have antimicrobial activity against bacterial pathogens. Here we show considerable activities of Pom-1 and Pom-2 to reduce the viability of C. albicans, C. parapsilosis and the less common species C. auris measured as the decrease of metabolic activity in the resazurin reduction assay for planktonic cells. Although these activities were low, Pom-1 and Pom-2 turned out to be highly potent inhibitors of biofilm formation for the three Candida species tested. Whereas Pom-1 was slightly more active against C. albicans and C. parapsilosis as representatives of the more common Candida species Pom-2 showed no preference and was fully active also against biofilms of the more uncommon species C. auris. Pom-1 and Pom-2 may represent promising lead structures for the development of a classical peptide optimization strategy with the realistic aim to further increase antibiofilm properties and other pharmacologic parameters and to generate finally the first antifungal drug with a pronounced dedication against Candida biofilms.

High Biofilm Formation of Non-Smooth Candida parapsilosis Correlates with Increased Incorporation of GPI-Modified Wall Adhesins

Candida parapsilosis is among the most frequent causes of candidiasis. Clinical isolates of this species show large variations in colony morphotype, ranging from round and smooth to a variety of non-smooth irregular colony shapes. A non-smooth appearance is related to increased formation of pseudohyphae, higher capacity to form biofilms on abiotic surfaces, and invading agar. Here, we present a comprehensive study of the cell wall proteome of C. parapsilosis reference strain CDC317 and seven clinical isolates under planktonic and sessile conditions. This analysis resulted in the identification of 40 wall proteins, most of them homologs of known Candida albicans cell wall proteins, such as Gas, Crh, Bgl2, Cht2, Ecm33, Sap, Sod, Plb, Pir, Pga30, Pga59, and adhesin family members. Comparative analysis of exponentially growing and stationary phase planktonic cultures of CDC317 at 30 °C and 37 °C revealed only minor variations. However, comparison of smooth isolates to non-smooth isolates with high biofilm formation capacity showed an increase in abundance and diversity of putative wall adhesins from Als, Iff/Hyr, and Hwp families in the latter. This difference depended more strongly on strain phenotype than on the growth conditions, as it was observed in planktonic as well as biofilm cells. Thus, in the set of isolates analyzed, the high biofilm formation capacity of non-smooth C. parapsilosis isolates with elongated cellular phenotypes correlates with the increased surface expression of putative wall adhesins in accordance with their proposed cellular function.

In vitro activities of Traganum nudatum and Mentha pulegium extracts combined with amphotericin B against Candida albicans in production of hydrolytic enzymes

Background and Purpose :

Candida albicans is an important microorganism in the normal flora of a healthy subject; however, it has an expedient pathogenic character that induces hydrolytic virulence. Regarding this, the present study aimed to find an in vitro alternative that could reduce the virulence of this yeast.

Materials and Methods:

For the purpose of the study, the effect of amphotericin B (AmB) combined with the extract of Traganum nudatum (E1) or Mentha pulegium (E2) was evaluated against the hydrolytic activities of esterase, protease, and phospholipase. This effect was determined by calculating the minimum inhibitory concentration (MIC), used to adjust the extract/AmB mixtures in culture media.

Results:

The evaluated Pz values, which corresponded to the different enzymatic activities, showed a decrease in the hydrolytic activities of C. albicans strains after the addition of E1/AmB and E2/AmB combinations at descending concentrations (lower than the obtained MICs).

Conclusion:

Based on the findings, it would be possible to reduce the pathogenesis of this species without destabilizing the balance of the flora.

Fluconazole prophylaxis against invasive candidiasis in very low and extremely low birth weight preterm neonates: a systematic review and meta-analysis

BACKGROUND

Evidence shows that fluconazole prophylaxis is an effective treatment against invasive fungal infections in preterm neonates, however, the most efficient schedule of fluconazole prophylaxis for the colonization and mortality of invasive candidiasis (IC) is unknown.

PURPOSE

This systematic review and meta-analysis aimed to assess the efficiency of different prophylactic fluconazole schedules in controlling IC colonization, infection, and mortality in very low birth weight (VLBW) and extremely low birth weight (ELBW) infants in neonatal intensive care units.

METHODS

We searched the PubMed, Scopus, Embase, and Cochrane databases using the keywords "candida," "invasive candidiasis," "IC," "fluconazole prophylaxis," "preterm infants," "very low birth weight infants," "VLBW," "extremely low birth weight," and "ELBW."

RESULTS

Mortality was significantly decreased in a metaanalysis of studies using different fluconazole prophylaxis regimens. The meta-analysis also indicated a significant decrease in the incidence of IC-associated mortality in ELBW infants using the same fluconazole prophylaxis schedules.

CONCLUSION

Future studies should explore the effectiveness of other different fluconazole prophylaxis schedules on IC colonization, infection, and mortality.

Epidemiology and risk factors of candidemia due to Candida parapsilosis in an intensive care unit

We analyzed the clinical features and risk factors of candidemia due to C. parapsilosis (n=104) in the intensive care unit of a tertiary hospital over six years. This was a monocentric, retrospective study of candidemia, conducted from January 2013 to March 2019. Epidemiological characteristics, clinical features, invasive procedures, laboratory data and outcomes of 267 patients with candidemia were analyzed to determine risk factors of candidemia due to C. parapsilosis. Sixty-three cases of C. albicans and 204 cases of non-C. albicans Candida (NCAC) species were included, the latter was composed of 104 cases of C. parapsilosis and 100 cases of non-C. albicans species (46 cases of C. tropicalis, 22 cases of C. glabrata, 23 cases of C. guilliermondii, 5 cases of C. krusei and 4 cases of C. lusitaniae), suggesting that C. parapsilosis was the predominant Candida species isolated from cases of candidemia. A binary multivariate logistic regression analysis showed that APACHE II scores, central venous catheterization and the use of broad-spectrum antibiotics were closely related to C. parapsilosis candidemia, with OR values of 1.159, 3.913 and 2.217, respectively. In conclusion, we found that C. parapsilosis was the main pathogen among the NCAC candidemia in the ICU patients. APACHE II scores, central venous catheterization and the use of broad-spectrum antibiotics were independent risk factors for the occurrence of C. parapsilosis candidemia, which may provide data to support the early introduction of anti-fungal therapy.