Skin microbiome changes in patients with interdigital tinea pedis

Clinical Features and Skin Microbiome of Tinea Scrotum: An Observational Study of 113 Cases in China

BACKGROUND

The scrotum is considered as an uncommon site for tinea, hence there is a lack of knowledge about the clinical characteristics, pathogenic agents and the skin microbiome changes of tinea scrotum.

OBJECTIVE

We sought to analyze the clinical features, pathogenic agents and skin microbiome of tinea scrotum.

METHODS

A two-center prospective observational study was carried out in outpatient dermatology clinics in Zhejiang, China, from September 2017 to September 2019. The diagnosis of tinea scrotum was confirmed by direct microscopy. Clinical and mycological data were collected. The composition of microbial communities of patients with tinea scrotum was analyzed and compared with healthy controls.

RESULTS

A total of 113 patients with tinea scrotum were included. Tinea scrotum was either presented with isolated lesions (9/113, 8.0%) or accompanied by tinea of other sites (104/113, 92.0%). Tinea cruris was detected in 101 cases (89.38%). Fungal culture was positive in 63 cases, among which Trichophyton rubrum was grown in 60 cases (95.2%) and Nannizzia gypsea was cultured in 3 cases (4.8%). The skin microbiome in scrotum lesions from 18 patients showed increased abundance of Trichophyton compared with 18 healthy individuals, while Malassezia was decreased. No significant difference in bacterial diversity was found.

CONCLUSIONS

Tinea scrotum was often companied by superficial fungal infections of other skin sites, with tinea cruris being the most common condition. Instead of N. gypsea, T. rubrum was the most frequently identified pathogen for tinea scrotum. In general, tinea scrotum exhibited changes in the fungal communities of the skin with increased Trichophyton and decreased Malassezia abundance.

Altered skin fungal and bacterial community compositions in tinea capitis

BACKGROUND

Tinea capitis is an infection of the scalp and hair shaft caused by dermatophytes that predominantly occurs in children. Skin fungal infections have been found to be associated with alterations in the overall bacterial and fungal communities. However, the scalp microbiome in tinea capitis have not been fully investigated.

OBJECTIVES

To investigate and compare the scalp bacterial and fungal microbiomes between children with tinea capitis and healthy children and between children and adults.

METHODS

Skin samples were collected from the scalp. Bacterial and fungal community compositions were analysed by amplification sequencing of the V3-V4 of 16S rDNA and ITS1-5F, respectively.

RESULTS

The predominant fungi detected using amplicon sequencing were consistent with the culture- or real-time PCR-positive pathogens in most samples. Children with tinea capitis had lower fungal and higher bacterial Shannon diversity than healthy children. A higher relative abundance of pathogenic fungi and significant alterations in the bacterial community in the lesional sites of tinea capitis than healthy scalps. Compared with adults, healthy children were characterised by higher Shannon diversities with significantly lower relative abundances of Malassezia and Cutibacterium and higher relative abundances of Candida and Streptococcus.

CONCLUSIONS

We demonstrated that tinea capitis was characterised by significant alterations in both fungal and bacterial communities and amplicon sequencing could be a complementary method for pathogen identification.

Tinea Imbricata among the Indigenous Communities: Current Global Epidemiology and Research Gaps Associated with Host Genetics and Skin Microbiota

Tinea imbricata is a unique fungal skin disease that mostly affects indigenous populations in Southeast Asia, Oceania, and Central and South America. The control and management of this disease among these communities are challenging given their remote locations, certain traditional practices, and severe malnutrition status. To date, there are only a handful of reports published globally, which highlights the need for a more holistic approach in addressing this skin disease. Several bodies of evidence and reports have shown that host genetic factors have a profound influence on the pathogenesis of tinea imbricata, while skin microbiota is touted to have a role in the pathogenesis of the disease. However, there are limited studies of how host genetics and skin microbiota impact disease susceptibility in the host. To improve the understanding of this disease and to find possible long-term effective treatment among the affected indigenous communities, a comprehensive literature review is needed. Hence, this review paper aims to present the current status of tinea imbricata among the indigenous communities, together with published findings on the possible underlying reasons for its specific distribution among these communities, particularly on the ways in which host skin microbiota and host genetics affect occurrence and disease patterns. This information provides valuable insights for future research by highlighting the current knowledge gaps in these areas.

Characterisation of the nail microbiome in psoriatic and nonpsoriatic patients with onychomycosis

BACKGROUND

Onychomycosis (OM) is the most common infectious nail disease, and it occurs frequently in patients with psoriasis. Microbial community shifts have been suggested to play a role in psoriasis and fungal infection occurrence.

OBJECTIVES

To investigate and compare nail microbial community compositions in psoriatic and nonpsoriatic patients with OM.

METHODS

Toenail samples were collected from nonpsoriatic patients with OM, psoriatic patients with nail psoriasis (NP) and OM, patients with only NP and healthy controls. Bacterial and fungal community compositions were analysed by amplicon sequencing of the V3-V4 regions of the 16S rDNA gene and the ITS1 region, respectively.

RESULTS

Psoriatic OM patients had higher bacterial and fungal alpha diversities. Taxonomic analysis revealed a significantly lower relative abundance of Trichophyton rubrum (32.88% vs 82.18%, p < .001) and an increased trend of the abundance of Candida in psoriatic patients with OM than in nonpsoriatic patients. Nonpsoriatic patients with OM had a higher abundance of Staphylococcus than healthy controls (59.66% vs 45.76%, p < .05). Trichophyton, Alternaria and Malassezia could accurately differentiate psoriatic and nonpsoriatic patients with OM, with an area under the curve (AUC) of 0.86. The severity of OM was positively correlated with the relative abundance of Trichophyton rubrum. Further, Trichophyton was positively correlated with Staphylococcus and negatively correlated with Corynebacterium, Anaerococcus, Malassezia and Alternaria.

CONCLUSIONS

The nail microbiome in psoriatic patients with OM has distinct bacterial and fungal signatures, suggesting that different dysbiosis is associated with the pathogenesis of OM in psoriatic and nonpsoriatic patients.

Characterization of the cutaneous mycobiota in Persian cats with severe dermatophytosis

BACKGROUND

Persian cats are predisposed to chronic and severe dermatophytosis. Alterations to the cutaneous microbiota are one potential contributor to this predisposition.

OBJECTIVES

To characterise the cutaneous and environmental fungal microbiota of Persian cats with chronic, severe dermatophytosis, and to compare the fungal microbiota of cats with and without dermatophytosis.

ANIMALS

Thirty-six client-owned cats, including 26 Persian cats and 10 domestic long hair (DLH) cats.

METHODS AND MATERIALS

Skin and home environment swabs were collected from Persian cats with severe, chronic dermatophytosis as well as groups of healthy control cats (Persian and DLH). Sequencing of the internal transcribed spacer 1 (ITS1) region was performed in addition to ITS1 quantitative PCR and fungal culture.

RESULTS

Next-generation sequencing (NGS) targeting the fungal ITS region detected Microsporum sp. DNA from all Persian cats diagnosed with dermatophytosis and from environmental samples of their homes. A significant difference in community structure was identified between cases and controls, largely resulting from the Microsporum spp. DNA in samples from affected cats. Persian cats with dermatophytosis do not exhibit decreased fungal diversity. NGS failed to identify dermatophyte DNA on two culture-positive asymptomatic Persian controls and identified Trichophyton rubrum DNA from a culture-negative asymptomatic Persian control.

CONCLUSIONS

Aside from M. canis, our results indicate that an underlying fungal dysbiosis is not likely to play a role in development of dermatophytosis in Persian cats. Other explanations for predisposition to this disease, such as a primary immunodeficiency, ineffective grooming or unique features of Persian cat hair should be investigated.

Expression of epidermal antimicrobial peptides is increased in tinea pedis

BACKGROUND

Tinea pedis is often chronic or recurrent, but not all individuals are equally susceptible to this infection. Dermatophytes are able to induce the expression of antimicrobial peptides and proteins (AMPs) in human keratinocytes and certain AMPs can inhibit the growth of dermatophytes.

OBJECTIVE

The focus of this study was to analyse the secretion of relevant AMPs, especially RNase 7, human beta-defensin-2 (hBD-2) and the S-100 protein psoriasin (S100A7), in patients with confirmed tinea pedis.

METHODS

To verify the diagnosis, skin scales were obtained from all patients (n = 13) and the dermatophytes were identified by potassium hydroxide mount, culture and molecular analysis. To determine the AMP concentrations, the lesional skin area of the foot was rinsed with a buffer that was subsequently analysed by ELISA. The corresponding area of the other unaffected foot as well as defined healthy skin areas of the forearm and forehead and samples from age and gender-matched healthy volunteers served as controls.

RESULTS

In tinea pedis patients the AMP concentrations were higher in lesional skin than in non-lesional skin and in healthy skin of controls. In particular, concentrations of hBD-2 and psoriasin were significantly elevated.

CONCLUSIONS

The induction of AMPs in tinea pedis might be triggered directly by the dermatophytes; furthermore, attendant inflammation and/or differentiation processes may play a role. Our results indicate that there is no defect in the constitutive expression and induction of the analysed AMPs by dermatophytes in the epidermis of affected patients. However, it is not known why the elevated AMP concentrations fail to efficiently combat dermatophyte growth.

Application of laser capture microdissection and polymerase chain reaction in the diagnosis of Trichoderma longibrachiatum infection: a promising diagnostic tool for 'fungal contaminants' infection

Although Trichoderma species are usually considered to be culture contaminants, an increasing number of case reports have demonstrated their pathogenicity. Current diagnostic tools, including fungal culture, radiology, histopathology, and direct microscopy examination, are often unable to differentiate the pathogenicity of 'fungal contaminants' such as Trichoderma species in patients. Accurate diagnostic tools for 'fungal contaminants' infection have become the urgent needs. To that end, we applicated laser capture microdissection (LCM) and polymerase chain reaction (PCR) to confirm T. longibrachiatum infection for the first time. A 57-year-old man presented with a cough and hemoptysis lasting for more than 40 days. Computed tomography scan revealed a mass at the left hilum. In addition to pulmonary spindle cell carcinoma, fungal hyphae were also detected in histopathological examination. The cultured fungus was identified as T. longibrachiatum using molecular procedures. The results from DNA sequencing of DNA obtained by LCM revealed the identical result. Antifungal susceptibility testing revealed resistance to itraconazole, fluconazole and flucytosine. The patient was managed with oral voriconazole for 4 months. No relapse of Trichoderma infection was observed at a year follow-up visit. Although there are potential disadvantages, LCM-based molecular biology technology is a promising diagnostic tool for 'fungal contaminants' infection.

Differences in foot skin microbiomes between patients with type 2 diabetes and healthy individuals

Impaired immunity and changes in the microenvironment in patients with diabetes might influence the composition of the cutaneous microbiome. However, data on the cutaneous microbiome of these patients are scarce. This study compared the fungal and bacterial components of the skin microbiome between patients with type 2 diabetes mellitus (DM) and healthy individuals. We obtained skin swab samples from the plantar forefoot of 17 patients with DM and 18 healthy individuals to conduct a cross-sectional study. The samples were profiled with culture-independent sequencing of the V3 to V4 regions of the bacterial 16S rRNA gene and the fungal ITS2 region, followed by direct DNA extraction and molecular polymerase chain reaction (PCR). We observed a differential cutaneous microbiome, especially for fungi, in patients with type 2 diabetes compared to that in healthy controls. Trichophyton rubrum was more abundant in DM samples. The Shannon diversity index for fungi was lower in the DM patients. Principal coordinate analysis plots and permutational multivariate analysis of variance (PERMANOVA) tests based on Bray-Curtis distances between samples supported the association of the fungal microbiome with DM at the species level. The results suggest that clinicians should pay attention to both fungi and bacteria and provide appropriate prevention and therapeutic strategies for diabetic cutaneous complications including diabetic foot ulcers. These data also contribute to future research associated with diabetes and cutaneous microbiomes.

Characterization of Skin Microbiome in Tinea Pedis

Tinea pedis has been associated with Trichophyton rubrum infection. However, it's not clear whether other microbes were implicated in disease pathogenesis. The composition of microbial communities of patients with tinea pedis and healthy controls were analyzed to identify the characteristics of tinea pedis and differences associated with clinical patterns. We found that microbial community structures were different in patients with tinea pedis compared with healthy controls. Moreover, skin microbiome varied in different forms of tinea pedis. Healthy controls exhibited greater fungal diversity than patients with tinea pedis. In patients with tinea pedis, the dominant bacterial and fungal genera were Staphylococcus and Trichophyton. Compared with healthy controls, Corynebacterium tuberculostearicum was decreased and T. rubrum was increased. C. tuberculostearicum was more abundant in vesicular tinea pedis than in hyperkeratotic and interdigital tinea pedis. Interdigital tinea pedis had a higher detection rate of Corynebacterium minutissimum and T. rubrum than the other forms. These results indicated that bacterial microbes may take part in the development of tinea pedis.