Infantile diarrhoea and malnutrition associated with Candida in a developing community

Repertory of eukaryotes (eukaryome) in the human gastrointestinal tract: taxonomy and detection methods

Eukaryotes are an important component of the human gut, and their relationship with the human host varies from parasitic to commensal. Understanding the diversity of human intestinal eukaryotes has important significance for human health. In the past few decades, most of the multitudes of techniques that are involved in the diagnosis of the eukaryotic population in the human intestinal tract were confined to pathological and parasitological aspects that mainly rely on traditionally based methods. However, development of culture-independent molecular techniques comprised of direct DNA extraction from faeces followed by sequencing, offer new opportunities to estimate the occurrence of eukaryotes in the human gut by providing data on the entire eukaryotic community, particularly not-yet-cultured or fastidious organisms. Further broad surveys of the eukaryotic communities in the gut based on high throughput tools such as next generation sequencing might lead to uncovering the real diversity of these ubiquitous organisms in the human intestinal tract and discovering the unrecognized roles of these eukaryotes in modulating the host immune system and inducing changes in host gut physiology and ecosystem.

Microbiota-Gut-Brain Axis: Yeast Species Isolated from Stool Samples of Children with Suspected or Diagnosed Autism Spectrum Disorders and In Vitro Susceptibility Against Nystatin and Fluconazole

Autism spectrum disorder (ASD) is a general term for a group of complex neurodevelopmental disorders of brain development that limits a person's ability to function normally. Etiology has not been clearly defined up to date. However, gut microbiota and the bidirectional communication between the gastrointestinal tract and brain, the so-called microbiota-gut-brain axis, are hypothesized, which may be involved in the etiology of several mental disorders. Recent reports suggest that Candida, particularly Candida albicans, growth in intestines may cause lower absorption of carbohydrates and minerals and higher toxin levels which are thought to contribute autistic behaviors. The aim of this study was to identify the 3-year deposited yeasts isolated from stool samples of children with diagnosed or suspected ASD and to determine in vitro activity of nystatin and fluconazole against these isolates using Clinical Laboratory Standards Institute M27-A3 guidelines. A 17-year retrospective assessment was also done using our laboratory records. Among the species identified, intrinsically fluconazole-resistant Candida krusei (19.8 %) and Candida glabrata (14.8 %) with elevated MICs were remarkable. Overall, C. albicans (57.4 %) was the most commonly isolated species in 17 years. The species identification and/or antifungal susceptibility tests have to be performed using the strain isolated from stool sample, to select the appropriate antifungal agent, if antimycotic therapy is needed.

Yeasts in the gut: from commensals to infectious agents

BACKGROUND

Controversy still surrounds the question whether yeasts found in the gut are causally related to disease, constitute a health hazard, or require treatment.

METHODS

The authors present the state of knowledge in this area on the basis of a selective review of articles retrieved by a PubMed search from 2005 onward. The therapeutic recommendations follow the current national and international guidelines.

RESULTS

Yeasts, mainly Candida species, are present in the gut of about 70% of healthy adults. Mucocutaneous Candida infections are due either to impaired host defenses or to altered gene expression in formerly commensal strains. The expression of virulence factors enables yeasts to form biofilms, destroy tissues, and escape the immunological attacks of the host. Yeast infections of the intestinal mucosa are of uncertain clinical significance, and their possible connection to irritable bowel syndrome, while plausible, remains unproved. Yeast colonization can trigger allergic reactions. Mucosal yeast infections are treated with topically active polyene antimycotic drugs. The adjuvant administration of probiotics is justified on the basis of positive results from controlled clinical trials.

CONCLUSION

The eradication of intestinal yeasts is advised only for certain clearly defined indications.

Fecal fungal flora of pediatric healthy volunteers and immunosuppressed patients

Most hematogenous candidiasis originates from endogeneous host flora. Fungal flora of gastrointestinal system are important source of infection especially in immunosupressed patients. The purpose of this study was to investigate the fecal fungal flora of pediatric patients with hematologic malignancy or disorders and to compare the results with healthy volunteers. For this purpose, fungal etiological agents were investigated retrospectively in stool samples of 80 patients followed in Bone marrow transplantation and Hematology-Oncology units. The diagnosis of patients were as follows: 26 acute myelogeneous leukemia, 19 acute lymphocytic leukemia, 5 lymphoma, 3 chronic myelogeneous leukemia, 2 solid tumor, 4 neuroblastoma and 21 hematologic disorders. In patients, totally 102 fungal growth was detected and 42 (41.2%) C. albicans and 51 (50%) non-albicans Candida species and 9 (8.8%) yeast other than Candida and mould was isolated. The results were compared prospectively with growth in stool samples of 61 healthy children. C. albicans was detected in 16 (43.2%) and non-albicans Candida species in 15 (40.5%) and yeasts other than Candida and mould in 6 (16.2%) of 37 fungal growth in controls. Non-albicans Candida species growth was found significantly higher and C. glabrata was more prevelant in patients than in controls (p < 0.001).

Faecal fungal flora in healthy volunteers and inpatients

The faecal fungal flora was analysed in healthy volunteers and inpatients. Self-obtained stool swabs from volunteers (n = 228) and inpatient stool-samples (n = 34) were cultured on Inhibitory-Mould-Agar plates. All yeast isolates were identified. Fungi were detected in 51.8% of volunteers; the majority (88.1%) had single species. The prevalence increased steadily with age. Candida albicans was detected in 62.7%, non-albicans Candida species in 22.0%, yeasts--other than Candida in 20.3% and moulds in 8.5% of volunteers with fungi. No gender-related differences were noted in the prevalence or types of yeast. Candida glabrata and C. krusei were detected in adults only. Intra-household species-similarity (excluding C. albicans) was noted in seven of 31 (22.6%) households with fungi in two or more members. Inpatients had higher prevalence of yeast (88.2%) with a single species in the majority (73.3%). Yeasts other than Candida were less common in inpatients (3.3%; P = 0.013) whereas C. glabrata was significantly more prevalent (33.3 versus 2.5%; P < 0.001). This study delineates the faecal fungal flora in volunteers and inpatients. Most subjects harbour a single species that may be shared with other households. The prevalence is somewhat higher in adults and the types of yeast may vary with age. Finally, C. glabrata appears to be acquired nosocomially.

Isolation of Candida rugosa from turkeys

The present study describes the isolation of Candida rugosa from young turkeys that died 10 days after the end of a therapeutic treatment for a recent outbreak of coccidiosis. Candida rugosa was isolated from the digestive tract of all the birds examined. This isolation is the first in turkeys and corroborates the fact that C. rugosa is an opportunistic yeast which circumvents host defences when other predisposing factors are present.

Methods for detection of an intestinal secretory immunoglobulin A response to Candida spp. and their preliminary application in human immunodeficiency virus-infected patients with chronic diarrhea

Six of 11 human immunodeficiency virus (HIV)-infected patients with chronic diarrhea, shedding only Candida spp. in their stools, elicited a Candida-specific secretory immunoglobulin A response. Similar responses were identified in only 1 of 10 HIV-positive patients with chronic diarrhea but without Candida spp. and in none of 10 HIV-negative subjects without diarrhea. Candida spp. may play a role in the etiology of chronic diarrhea associated with HIV infection.