A fatal case of Exophiala dermatitidis meningoencephalitis in an immunocompetent host: A case report and literature review

Diversity and Antifungal Susceptibilities of Yeasts from Mangroves in Hong Kong, China-A One Health Aspect

While mangrove ecosystems are rich in biodiversity, they are increasingly impacted by climate change and urban pollutants. The current study provides first insights into the emergence of potentially pathogenic yeasts in Hong Kong's mangroves. Sediment and water samples were collected from ten urban and rural mangroves sites. Initial CHROMagarTM Candida Plus screening, representing the first application of this differential medium for water and soil samples collected from a non-clinical environment, enabled the rapid, preliminary phenotypic identification of yeast isolates from mangroves. Subsequent molecular profiling (ITS and/or 28S nrDNA sequencing) and antifungal drug susceptibility tests were conducted to further elucidate yeast diversity and drug resistance. A diversity of yeasts, including 45 isolates of 18 distinct species across 13 genera/clades, was isolated from sediments and waters from Hong Kong mangroves. Molecular profiling revealed a dominance of the Candida/Lodderomyces clade (44.4%), a group of notorious opportunistic pathogens. The findings also reveal a rich biodiversity of non-Candida/Lodderomyces yeasts in mangroves, including the first reported presence of Apiotrichum domesticum and Crinitomyces flavificans. A potentially novel Yamadazyma species was also discovered. Remarkably, 14.3% of the ubiquitous Candida parapsilosis isolates displayed resistance to multiple antifungal drugs, suggesting that mangroves may be reservoirs of multi-drug resistance. Wildlife, especially migratory birds, may disseminate these hidden threats. With significant knowledge gaps regarding the environmental origins, drug resistance, and public health impacts of pathogenic yeasts, urgent surveillance is needed from a One Health perspective. This study provides an early warning that unrestrained urbanization can unleash resistant pathogens from coastal ecosystems globally. It underscores the necessity for enhanced surveillance studies and interdisciplinary collaboration between clinicians, ornithologists, and environmental microbiologists to effectively monitor and manage this environmental health risk, ensuring the maintenance of 'One Health'.

Snakes as sentinel of zoonotic yeasts and bio-indicators of environmental quality

Reptiles in the wild or as pets may act as spreaders of bacteria, viruses, fungi and parasites. However, studies on the mycobiota of these animals are scanty. This study investigates the occurrence of yeasts from the cloacal swabs of snakes of different origins and the antifungal profile of the isolated strains. A total of 180 cloacal samples of snakes were collected from Morocco (Group I: n = 68) and Italy (Group II: n = 112). Yeast species were biochemically and molecularly identified. A total of 72 yeast strains belonging to 13 genera, 8 from snakes in Group I and five from snakes in Group II were identified. The most frequently isolated species were Trichosporon asahii (22.2%) and Candida tropicalis (15.3%) from snakes in Group I and Debaryomyces spp. (16.7%) and Metahyphopichia silvanorum (11.1%) from snakes in Group II. Multiple azole and amphotericin B (AmB) resistance phenomena were detected among isolated yeasts. Azole multi drug resistance phenomena were detected among yeasts from Group I and Rhodotorula mucilaginosa from Group II, whereas AmB resistance phenomena among those from Group II. Data suggest that snakes may harbor pathogenetic yeasts, being potential reservoirs and spreaders of these organisms in the environment. Since the yeast species community from different groups of animals as well as their antifungal profile reflects the epidemiology of human yeast infections in the same geographical areas, the results indicate that snakes may be considered as sentinels for human/animal pathogenic microorganisms and bio-indicators of environmental quality.

Multidisciplinary management of disseminated Exophiala dermatitidis mycosis in an infant with mixed phenotype acute leukemia: a case report

Background

Exophiala dermatitidis is a dematiaceous fungus isolated from various environmental sources. Systemic E. dermatitidis infections can lead to fatal outcomes, and treatment has not yet been standardized. Although E. dermatitidis is also known to cause cutaneous infection, it has not been previously reported to appear as ecthyma gangrenosum (EG), an uncommon cutaneous lesion in neutropenic patients that is mainly caused by Pseudomonas aeruginosa.

Case presentation

A 2-month-old male infant with mixed-phenotype acute leukemia presented with prolonged fever unresponsive to antibacterial and antifungal agents during myelosuppression due to remission induction therapy. He also presented with skin lesions on the left wrist and left lower quadrant of the abdomen. The abdominal lesion gradually turned black and necrotic, which was consistent with the findings of the EG. E. dermatitidis was isolated from the blood, stool, wrist skin, and endotracheal aspirate. During hematopoietic recovery, consolidation in both lungs was evident. Multiagent antifungal treatment failed to eliminate E. dermatitidis from blood. In order to salvage the central venous catheter, ethanol lock therapy (ELT) was adopted, following which the blood culture became negative. The abdominal lesion that evolved as a necrotic mass connecting the small intestine and subcutaneous tissue adjacent to the skin was surgically resected. After these interventions, the general condition improved.

Conclusion

Disseminated E. dermatitidis mycosis in the neutropenic infant was successfully managed with a multidisciplinary treatment consisting of multiagent antifungal treatment, ELT, and surgery.

Exophiala dermatitidis Central Line-Associated Bloodstream Infection in a Child with Ewing's Sarcoma: Case Report and Literature Review on Paediatric Infections

Exophiala dermatitidis is a dematiaceous, ubiquitous, dimorphic fungus, which can cause a wide range of invasive diseases in both immunocompromised and immunocompetent hosts. Bloodstream infections due to E. dermatitidis are rarely encountered in clinical practice, especially in pediatric patients. We describe a case of central line-associated bloodstream infection due to E. dermatitidis in a 4.5-year-old boy with Ewing's sarcoma. The fungus was isolated from blood specimens taken from the Hickman line. The isolate was identified by its phenotypic characteristics, by MALDI-TOF and by using molecular methods. The infection was successfully treated with voriconazole and catheter removal. The literature was also reviewed on pediatric infections caused by E. dermatitidis, focusing on clinical manifestations and challenges associated with diagnosis and management.

Distribution of Yeast Species and Risk Factors of Oral Colonization after Oral-Care Education among the Residents of Nursing Homes

Most yeasts causing infections in humans are part of commensal microflora and etiological agents of different infections when hosts become susceptible, usually due to becoming immunocompromised. The colonization of potentially pathogenic microbes in the oral cavity is increased by poor oral hygiene. This follow-up survey was conducted approximately two months after providing information on proper oral care at 10 nursing homes in Taiwan. Among the 117 of 165 residents colonized by yeasts, 67 were colonized by more than one yeast species. A total of 231 isolates comprising eight fungal genera and 25 species were identified. Candida albicans (44.6%) was the dominant species, followed by Candida glabrata (17.7%), Candida parapsilosis (8.7%), Candida tropicalis (7.8%), and Candida pararugosa (7.3%). Residents having a yeast colony-forming unit >10 (OR, 8.897; 95% CI 2.972−26.634; p < 0.001) or using a wheelchair (OR, 4.682; 95% CI 1.599−13.705; p = 0.005) were more likely to be colonized by multiple species. By comparing before and after oral-care education, dry mouth (OR, 3.199; 95% CI 1.448−7.068; p = 0.011) and having heart disease (OR, 2.681; 95% CI 1.068−6.732; p = 0.036) emerged as two independent risk factors for increased density of colonizing yeast.