Expressed Breast Milk as a Predictor of Neonatal Yeast Colonization in an Intensive Care Setting

Biochanin A Inhibits the Growth and Biofilm of Candida Species

The aim of this study was to investigate the antifungal activity of biochanin A (BCA) against planktonic growth and biofilms of six Candida species, including C. albicans, C. parapsilosis, C. glabrata, C. tropicalis, C. auris, and C. krusei. We applied various assays that determined (a) the antimicrobial effect on growth of Candida species, (b) the effect on formation of hyphae and biofilm, (c) the effect on the expression of genes related to hyphal growth and biofilm formation, (d) the influence on cell wall structure, and (e) the effect on cell membrane integrity and permeability. Moreover, disk diffusion tests were used to investigate the effect of a combination of BCA with fluconazole to assess their possible synergistic effect on drug-resistant C. albicans, C. glabrata, and C. auris. Our results showed that the BCA MIC50 values against Candida species ranged between 125 µg/mL and 500 µg/mL, and the MIC90 values were in a concentration range from 250 µg/mL to 1000 µg/mL. The treatment with BCA inhibited adhesion of cells, cell surface hydrophobicity (CSH), and biofilm formation and reduced hyphal growth in all the analyzed Candida species. Real-time qRT-PCR revealed that BCA down-regulated the expression of biofilm-specific genes in C. albicans. Furthermore, physical destruction of C. albicans cell membranes and cell walls as a result of the treatment with BCA was observed. The combination of BCA and fluconazole did not exert synergistic effects against fluconazole-resistant Candida.

"Molding" immunity-modulation of mucosal and systemic immunity by the intestinal mycobiome in health and disease

Fungi are important yet understudied contributors to the microbial communities of the gastrointestinal tract. Starting at birth, the intestinal mycobiome undergoes a period of dynamic maturation under the influence of microbial, host, and extrinsic influences, with profound functional implications for immune development in early life, and regulation of immune homeostasis throughout life. Candida albicans serves as a model organism for understanding the cross-talk between fungal colonization dynamics and immunity, and exemplifies unique mechanisms of fungal-immune interactions, including fungal dimorphism, though our understanding of other intestinal fungi is growing. Given the prominent role of the gut mycobiome in promoting immune homeostasis, emerging evidence points to fungal dysbiosis as an influential contributor to immune dysregulation in a variety of inflammatory and infectious diseases. Here we review current knowledge on the factors that govern host-fungi interactions in the intestinal tract and immunological outcomes in both mucosal and systemic compartments.

Pathogenesis and virulence of Candida albicans

Candida albicans is a commensal yeast fungus of the human oral, gastrointestinal, and genital mucosal surfaces, and skin. Antibiotic-induced dysbiosis, iatrogenic immunosuppression, and/or medical interventions that impair the integrity of the mucocutaneous barrier and/or perturb protective host defense mechanisms enable C. albicans to become an opportunistic pathogen and cause debilitating mucocutaneous disease and/or life-threatening systemic infections. In this review, we synthesize our current knowledge of the tissue-specific determinants of C. albicans pathogenicity and host immune defense mechanisms.

Dietary Supplementation With Medium-Chain Triglycerides Reduces Candida Gastrointestinal Colonization in Preterm Infants

BACKGROUND

Candida is an important cause of infections in premature infants. Gastrointestinal colonization with Candida is a common site of entry for disseminated disease. The objective of this study was to determine whether a dietary supplement of medium-chain triglycerides (MCTs) reduces Candida colonization in preterm infants.

METHODS

Preterm infants with Candida colonization (n = 12) receiving enteral feedings of either infant formula (n = 5) or breast milk (n = 7) were randomized to MCT supplementation (n = 8) or no supplementation (n = 4). Daily stool samples were collected to determine fungal burden during a 3-week study period. Infants in the MCT group received supplementation during 1 week of the study period. The primary outcome was fungal burden during the supplementation period as compared with the periods before and after supplementation.

RESULTS

Supplementation of MCT led to a marked increase in MCT intake relative to unsupplemented breast milk or formula as measured by capric acid content. In the treatment group, there was a significant reduction in fungal burden during the supplementation period as compared with the period before supplementation (rate ratio, 0.15; P = 0.02), with a significant increase after supplementation was stopped (rate ratio, 61; P < 0.001). Fungal burden in the control group did not show similar changes.

CONCLUSIONS

Dietary supplementation with MCT may be an effective method to reduce Candida colonization in preterm infants.

Host Defense Proteins in Breast Milk and Neonatal Yeast Colonization

BACKGROUND

Colonization increases risk for invasive candidiasis in neonates. Breast milk host defense proteins may affect yeast colonization of infants.

OBJECTIVE

This study aimed to evaluate breast milk host defense proteins relative to yeast colonization in infants.

METHODS

Infants admitted for longer than 72 hours to the neonatal intensive care unit at Women & Infants Hospital in Providence, Rhode Island, were eligible. After consent, expressed breast milk and swabs from oral, rectal, and inguinal sites from infants were cultured weekly for 12 weeks, or until discharge, transfer, or death. Breast milk was tested for levels of human lactoferrin, lysozyme, apolipoprotein J, mucin-1, dermcidin, and soluble CD14 using commercial ELISA. Concentrations of these components were compared in breast milk received by infants who were colonized or not colonized with yeast.

RESULTS

From an original cohort of 130, 61 infants had samples available for this subanalysis. A convenience sample of stored breast milk was analyzed. Median lactoferrin, apolipoprotein J, and mucin-1 did not differ between colonized and uncolonized groups. Soluble CD14 was higher in the surface-colonized group (1.8 μg/mL, n = 12) compared with the surface-uncolonized group (1.6 μg/mL, n = 12, P = .02). Median lysozyme levels were higher in the surface-uncolonized group (483.0 ng/mL, n = 12) versus the surface-colonized group (298.3 ng/mL, n = 12, P = .04). Median dermcidin levels were higher in the surface-uncolonized group (19.4 ng/mL, n = 12) versus the surface-colonized group (8.7 ng/mL, n = 12, P = .04).

CONCLUSION

This study shows an association between colonization with Candida in neonates and lower levels of lysozyme and dermcidin in received breast milk. Further study is needed to confirm these findings.

Neonatal Candidiasis: New Insights into an Old Problem at a Unique Host-Pathogen Interface

Candida species are the leading cause of invasive fungal infections in premature infants. Associated with substantial morbidity and mortality, these infections represent serious and sometimes catastrophic complications in the course of hospitalization of a preterm infant in the neonatal intensive care unit. Although virulence factors of Candida and the host defense mechanisms that are important in protection from candidiasis have been the subject of intensive study, considerably less is known about the features of this disease that are specific to premature neonates. As animal models for neonatal candidiasis have been developed, efforts to understand the similarities and differences of candidiasis in the neonatal host relative to other immunocompromised patients have begun to provide insights to these questions.