Gastrointestinal translocation as a possible source of candidemia in an AIDS patient

Trichosporon asahii Infective Endocarditis of Prosthetic Valve: A Case Report and Literature Review

Trichosporon spp. endocarditis is a severe and hard-to-treat infection. Immunosuppressed subjects and carriers of prosthetic valves or intracardiac devices are at risk. This article presents the case of an immunocompetent 74-year-old man affected by endocarditis of the prosthetic aortic valve. After Bentall surgery, cultures of the removed valve demonstrated Trichosporon ashaii as the etiological agent. The patient was treated with amphotericin B at first and subsequently with fluconazole. Given the fragility of the patient and the aggressiveness of the pathogen, life-long prophylactic therapy with fluconazole was prescribed. After 5 years follow-up, no drug-related toxicities were reported and the patient never showed any signs of recurrence. The review of the literature illustrates that Trichosporon spp. endocarditis may present even many years after heart surgery, and it is often associated with massive valve vegetations, severe embolic complications, and unfavorable outcome. Due to the absence of international guidelines, there is no unanimous therapeutic approach, but amphotericin B and azoles are usually prescribed. Additionally, a prompt surgical intervention seems to be of paramount importance. When dealing with a life-threatening disease, such as mycotic endocarditis of prosthetic valves, it is essential to consider and treat even rare etiological agents such as Trichosporon spp.

Characterization of the Intestinal Fungal Microbiome in HIV and HCV Mono-Infected or Co-Infected Patients

Intestinal mycobiome dysbiosis plays an important role in the advancement of HIV- and HCV-infected patients. Co-infection with HCV is an important risk factor for exacerbating immune activation in HIV-infected patients, and gut fungal microbial dysbiosis plays an important role. However, no systematic study has been conducted on the intestinal fungal microbiome of HIV/HCV co-infected patients to date. Patients infected with HIV and HCV, either alone or in combination, and healthy volunteers were included. Stool samples were collected for fungal ITS sequencing and for further mycobiome statistical analysis. We found that the abundance of fungal species significantly decreased in the HIV/HCV co-infection group compared to in the healthy control group, while no significant differences were found in the mono-infection groups. Low-CD4 + T-cell patients in the HIV group and high-ALT-level patients in the HCV group were discovered to have a more chaotic fungal community. Furthermore, the opportunistic pathogenic fungal profiles and fungal inter-correlations in the co-infection group became less characteristic but more complicated than those in the mono-infection groups. Intestinal fungal dysregulation occurs in HIV- and HCV-infected patients, and this dysregulation is further complicated in HIV/HCV co-infected patients.

Current knowledge of Trichosporon spp. and Trichosporonosis

Trichosporon spp. are basidiomycetous yeast-like fungi found widely in nature. Clinical isolates are generally related to superficial infections. However, this fungus has been recognized as an opportunistic agent of invasive infections, mostly in cancer patients and those exposed to invasive medical procedures. It is possible that the ability of Trichosporon strains to form biofilms on implanted devices, the presence of glucuronoxylomannan in their cell walls, and the ability to produce proteases and lipases are all factors likely related to the virulence of this genus and therefore may account for the progress of invasive trichosporonosis. Disseminated trichosporonosis has been increasingly reported worldwide and represents a challenge for both diagnosis and species identification. Phenotypic identification methods are useful for Trichosporon sp. screening, but only molecular methods, such as IGS region sequencing, allow the complete identification of Trichosporon isolates at the species level. Methods for the diagnosis of invasive trichosporonosis include PCR-based methods, Luminex xMAP technology, and, more recently, proteomics. Treating patients with trichosporonosis remains a challenge because of limited data on the in vitro and in vivo activities of antifungal drugs against clinically relevant species of the genus. Despite the mentioned limitations, the use of antifungal regimens containing triazoles appears to be the best therapeutic approach.

Candida colonisation as a source for candidaemia

Candida spp. are important healthcare-associated pathogens. Identifying the source of infection is important for prevention and control strategies. The objective of this study was to evaluate candida colonisation sites as potential sources for candidaemia. Sixty-three consecutive patients with a positive blood culture for candida were included. Surveillance cultures were collected from urine, rectum, oropharynx, skin, intravascular catheter tip and skin around catheter. Molecular typing was performed when the same species of candida was isolated from blood and surveillance sites of a patient. C. albicans was associated with 42% of candidaemias, C. parapsilosis 33%, C. tropicalis 16% and C. guilliermondii, C. krusei, C. glabrata, C. holmii and C. metapsilosis were all 2% each. Six of 10 C. parapsilosis catheter tip isolates were indistinguishable from corresponding blood isolates (all in neonates). C. albicans isolates from blood were indistinguishable from corresponding gastrointestinal tract isolates in 13 of 26 patients and from catheter tip isolates in two patients. In conclusion, the results suggest that gastrointestinal colonisation is the probable source of C. albicans candidaemia and C. parapsilosis is exogenous.

Preventive strategy for Candida gut translocation during ischemia-reperfusion injury supervening on protein-calorie malnutrition

OBJECTIVE

The aim of the present study was to test the hypothesis that protein-calorie malnutrition aggravates the gut translocation of Candida albicans triggered by mesenteric ischemia-reperfusion (IR) injury in an experimental model while testing a natural product containing the antifungal anethole/polygodial mixture (Kolorex).

METHODS

MFI strain white mice (n = 90) were randomly allocated to a 4-week dietary regimen: (1) standard pellet diet containing 25% casein; (2) low-protein (2.5%) casein diet; (3) as group 2 plus oral supplementation with 20 microL of a 5% solution of Kolorex during the last 4 days. Twenty rats from each of these groups (termed 1a, 2a and 3a) were orally inoculated with Candida suspension 6 h prior to mesenteric IR injury. Animals of each group but without Candida inoculation (termed 1b, 2b and 3b) served as control. A colon permeability study was carried out as well. Rats were killed prior to the IR injury and 3 h afterwards. Control rats were killed at the same time.

RESULTS

Over 60% of the mesenteric lymph nodes and 30% of kidney samples were positive for C. albicans in the low-protein-fed rats after IR injury. Kolorex significantly decreased that rate of positivity and also significantly reduced the concentration of C. albicans per gram of each positive tissue sample examined. Protein-calorie malnourished animals showed a statistically significant increase in colon permeability and this phenomenon further increased after IR injury. The groups of rats treated with Kolorex compound showed a partial, although significant, improvement of this parameter.

CONCLUSIONS

These results suggest that Kolorex might exert a competitive effect against with C. albicans colonization. The present study represents the first experimental in vivo investigation of the anethole/polygodial-containing compound under the specific conditions of calorie-protein malnutrition and the results have potential clinical interest.

Revisiting the source of candidemia: skin or gut?

The source of candidemia has been the subject of considerable debate, with some suggesting a origin in the gastrointestinal tract and others suggesting a skin origin. To evaluate the potential sources of candidemia, we performed a computerized search of the MEDLINE database for studies published from January 1966 through September 2000 and we identified relevant abstracts presented at national meetings. We reviewed the literature with special emphasis on studies that used appropriate definitions, evaluated both gut and skin as sources, and conducted molecular-relatedness studies. Among 203 candidemia studies published, we identified 21 that evaluated a specific source for candidemia and only 5 that performed molecular typing. Those studies and additional experimental, epidemiologic, and molecular-relatedness studies strongly suggested that the gut is an important source of candidemia, and studies that supported the skin as a source for this infection were surprisingly incomplete.

Limited effect of refined carbohydrate dietary supplementation on colonization of the gastrointestinal tract of healthy subjects by Candida albicans

BACKGROUND

Infections due to Candida albicans occur readily in situations in which ample glucose is available. In mice, dietary refined carbohydrate supplementation leads to higher rates of Candida growth in the gastrointestinal tract and favors mucosal invasion.

OBJECTIVE

The modulating properties of dietary carbohydrate supplementation on colonization of the human gastrointestinal tract by C. albicans were evaluated.

DESIGN

A 2-step study was conducted in 28 healthy volunteers. First, we determined the subjects' habitual uptake of refined carbohydrates and correlated these data with the C. albicans blastoconidia concentration in the mouth washes and feces of subjects with no intervention. Second, we compared C. albicans counts in the specimens before, during, and after a high-sugar diet.

RESULTS

No correlation between C. albicans counts in the specimens and the habitual uptake of refined carbohydrates was observed. A high-sugar diet did not increase the frequency of C. albicans-positive samples, the number of subjects positive for C. albicans in the mouth washes, or the concentration of candidal blastoconidia in the samples of the 28 subjects. However, in selected subjects with elevated counts of oral C. albicans, we observed an increase in fecal C. albicans counts in response to the diet.

CONCLUSIONS

The effect of adding a high amount of refined carbohydrates to the diet of healthy human subjects has a limited influence on Candida colonization. Follow-up studies should define whether selected patient groups might benefit from dietary restriction of refined carbohydrates.