Trichophyton mentagrophytes of rabbit origin causing family incidence of kerion: an environmental study

First Terbinafine-Resistant Trichophyton indotineae Isolates with Phe397Leu and/or Thr414His Mutations in Turkey

Fungal infections of the skin, nails, and hair caused by dermatophyte species continue to be a worldwide concern. The increase in terbinafine-resistant superficial dermatophytosis has become a major concern over the last decade. In this report, we presented two cases of infection with terbinafine-resistant Trichophyton indotineae, the first diagnosis of this species in Turkey. One patient exhibited erythematous pruritic patches and plaques in the inguinal and gluteal regions, while the other patient showed annular erythematous scaly plaques in the bilateral posterior thigh and gluteal regions. One patient harbored a CD36 mutation. Both strains harbored the same amino acid substitution in the squalene epoxidase gene, whereas one isolate had another unknown mutation. Clinical improvement was observed with resveratrol treatment in the patient with the CD36 mutation but not in the other patient.

Descriptive epidemiology of dermatophytosis in rodents

INTRODUCTION

Dermatophytosis is a zoonotic disease caused by a group of keratinophilic fungi called dermatophytes.

OBJECTIVES

Since the epidemiology of diseases revolves over time, this research studies the incidence of dermatophytosis among rodents referred to mycology laboratory during 2019-2021.

METHODS

A total of 163 rodents including rabbits, guinea pigs, and hamsters suspecting having dermatophytosis were sampled by scraping lesions. Direct microscopic examination, culture, and polymerase chain reaction were done for diagnosis of dermatophytosis and identification of the etiologic agent.

RESULTS

The results of this study showed that 37.4% of rodents were involved with dermatophytosis, among which 41.13% of rabbits, 25% of guinea pigs, and 26.3% of hamsters were included. Microsporum canis (52.7%) was the most isolated agent. Incidence of dermatophytosis was higher in female in rabbits while in hamsters and guinea pigs male were mostly infected. Rodents less than 6 months were more susceptible for dermatophytosis except for hamsters in which 6-12 months animals had a higher prevalence.

CONCLUSION

In conclusion, it is significant to update our knowledge about the epidemiology of dermatophytosis in rodents and other animals every few years to define valid preventive strategies. Moreover, since dermatophytes are contagious and zoonotic, it is also a priority to apply preventing methods for dermatophytosis and treat infected rodents with appropriate antifungal agents to decrease the risk of infection.

Prevalence and Risk Factors of Zoonotic Dermatophyte Infection in Pet Rabbits in Northern Taiwan

Dermatophytes are the group of keratinophilic fungi that cause superficial cutaneous infection, which traditionally belong to the genera Trichophyton, Microsporum, and Epidermophyton. Dermatophyte infection is not only a threat to the health of small animals, but also an important zoonotic and public health issue because of the potential transmission from animals to humans. Rabbit dermatophytosis is often clinically identified; however, limited information was found in Asia. The aims of this study are to investigate the prevalence and to evaluate the risk factors of dermatophytosis in pet rabbits in Northern Taiwan. Between March 2016 and October 2018, dander samples of pet rabbits were collected for fungal infection examination by Wood’s lamp, microscopic examination (KOH preparation), fungal culture, and PCR assay (molecular identification). Z test and Fisher’s exact test were performed to evaluate the potential risk factors, and logistic regression analysis was then performed to build the model of risk factors related to dermatophyte infection. Of the collected 250 dander samples of pet rabbits, 29 (11.6%) samples were positive for dermatophytes by molecular identification. In those samples, 28 samples were identified as the T. mentagrophytes complex and 1 sample was identified as M. canis. Based on the results of the Firth’s bias reduction logistic analyses, animal source (rabbits purchased from pet shops) and number of rearing rabbits (three rabbits or more) were shown as the main risks for dermatophyte infection in the pet rabbits in Taiwan. The results of the present study elucidate the prevalence of rabbit dermatophyte infection, pathogens, and risk factors in Taiwan, and provide an important reference for the prevention and control of rabbit dermatophytosis.

Relationship Between Phenotypic and Genotypic Characteristics of Trichophyton mentagrophytes Strains Isolated from Patients with Dermatophytosis

According to epidemiological, clinical and mycological criteria, it has long been admitted that the Trichophyton mentagrophytes species includes two varieties: a zoophilic variety (var. mentagrophytes) and an anthropophilic variety (var. interdigitale) that involve the upper and the lower part of the body, respectively. The further application of molecular techniques to the characterization of dermatophyte strains showed that this classification is unreliable. The aim of our study was to assess the usefulness of PCR-RFLP (restriction fragment length polymorphism) and sequencing in the characterization of T. mentagrophytes strains taken from Tunisian patients. The study was carried out in 2008 in the laboratory of Parasitology-Mycology of Farhat Hached University Hospital, Sousse, Tunisia. A total of 133 strains were isolated from 133 patients addressed to the laboratory for dermatological lesions very evocative of dermatomycosis. Eighty strains were isolated from lesions located on the lower part of the body (onychomycosis, tinea pedis) and 53 strains from the upper part of the body (tinea capitis, tinea corporis). All strains were submitted to mycological examination (direct microscopic examination and culture on Sabouraud medium) and further investigated by using RFLP analysis of the PCR-amplified ITS1-5.8 s-ITS2 region of the ribosomal DNA and the MvaI restriction enzyme. In addition, 62 strains were further submitted to a sequencing of the ITS1-5.8 s-ITS2 region. On the basis of mycological criteria, all strains were diagnosed as T. mentagrophytes. All strains produced the same RFLP pattern and were identified as T. mentagrophytes interdigitale regardless of the location of lesions. Out of the 62 sequenced strains, 16 were found anthropophilic and 46 were zoophilic. In conclusion, all strains provisionally diagnosed as T. mentagrophytes on the basis of mycological criteria were shown to belong to T. interdigitale by using PCR-RFLP and sequencing irrespective of the site of lesions. The predominance of zoophilic strains needs further investigation.

Kerion and Tinea Corporis Caused by Rabbit-Derived Trichophyton interdigitale in Three Siblings and One Consulting Doctor Using β-Tubulin Gene to Identify the Pathogen

Trichophyton interdigitale is generally deemed as an anamorph of Arthroderma vanbreuseghemii based on internal transcribed spacer (ITS) sequencing, but recently their anamorph/teleomorph connection should be cautioned based on β-tubulin phylogeny. We report three siblings and one consulting doctor who developed kerion and tinea corporis after contact with domestic rabbits. Seven same strains were isolated from four patients and three regions of a sick rabbit. The ITS and D1/D2 sequences of our isolate were 99 % homologous to A. Vanbreuseghemii, while β-tubulin sequence was 100 % identical to T. interdigitale. Our isolate was identified as T. interdigitale based on maximum likelihood analysis of β-tubulin. Random amplified polymorphic DNA revealed that the band patterns of five isolated strains and another rabbit-derived strain WCH023 were identical for OPF-03 and OPF-12. Skin lesions of all patients resolved completely for 2- to 6-week therapy of oral terbinafine and topical 1 % bifonazole or 1 % terbinafine cream. This study demonstrates that T. interdigitale of rabbit origin can cause various types of human dermatophytosis by mild scratch. Terbinafine may be the first choice for dermatophytosis caused by T. interdigitale.

Zoonoses of rabbits and rodents

Millions of households in the US own rabbits or rodents, including hamsters, guinea pigs, and gerbils. Activities such as hunting and camping also involve human interactions with wild rabbits and rodents. In many environments, feral rabbits and rodents live in close proximity to humans, domesticated animals, and other wildlife. Education of rodent and rabbit owners and individuals with occupational or recreational exposures to these species is paramount to reduce the prevalence of zoonoses associated with rabbit and rodent exposure.

Molecular identification and phylogenesis of dermatophytes isolated from rabbit farms and rabbit farm workers

Little information is available on the molecular epidemiology of dermatophytoses in rabbit farms and farm workers. A total of 117 isolates belonging to the Trichophyton mentagrophytes complex and 21 isolates of Microsporum canis were collected from rabbits with or without skin lesions, air samples of farms known to harbour these pathogens, and from farm workers with skin lesions, and molecularly characterized. Sequencing of amplicons from the T. mentagrophytes complex and M. canis isolates revealed the presence of one sequence-type for both partial chitin synthase-1 gene (pchs-1) and ribosomal internal transcribed spacer (ITS+), respectively. On the basis of comparative sequence analyses, isolated representing the T. mentagrophytes complex were molecularly identified as Trichophyton interdigitale (zoophilic) Priestley. The M. canis and T. interdigitale pchs-1 sequences herein analysed were 100% homologous to known sequences from different hosts (i.e., cats, dogs, humans and rabbits). Conversely, the ITS+ sequences of T. interdigitale from dogs, pigs and mice were identical, but displayed up to 8.6% difference with those from humans, guinea pigs and rabbits. The results of this study suggest that environmental and clinical isolates of T. interdigitale (zoophilic) and M. canis might share a common origin. Interestingly, the close phylogenetic relationship between T. interdigitale (zoophilic) strains and isolates from dogs, pigs and mice might indicate that these animals represented a reservoir of dermatophyte infection in rabbit farms. These animal species should therefore be considered when setting up control protocols to prevent infections by dermatophytes and their zoonotic transmission.

Establishment of a novel model of onychomycosis in rabbits for evaluation of antifungal agents

We developed a novel model of onychomycosis in which we observed fungi in the deep layer of the nail, and we used the model to evaluate the efficacy of two topical antifungal drugs. To establish an experimental, in vivo model of onychomycosis, we applied Trichophyton mentagrophytes TIMM2789 to the nails of the hind limbs of rabbits that underwent steroid treatment. The nails were taken from the rabbits' feet at 0, 2, and 6 weeks after a 2-week infection. The localization of the fungi was evaluated histopathologically. Some fungi were seen to penetrate to the nail bed, and the infection rate in the sample at 0, 2, and 6 weeks after infection was 57, 87, and 93%, respectively. In addition, fungi proliferated and moved proximally into the nail plate in a manner that depended on the duration of infection. Second, using this model we evaluated antifungal efficacy both by the culture recovery method and histopathological examination. Two topical antifungal drugs, 8% ciclopirox nail lacquer and 5% amorolfine nail lacquer, were applied to the nail for 4 weeks in each group. On histopathological examination, two antifungal treatment groups showed no significant difference against the nontreated control group. However, there were a significantly low fungus-positive rate and intensity of the recovery of fungi on culture between antifungal treatment and nontreated control groups. We therefore suggest that we have established an in vivo model of onychomycosis that is useful for the evaluation of the efficacy of antifungal agents.

Epidemiology and risk factors for dermatophytoses in rabbit farms

While dermatophytoses of several animal species have been extensively investigated, information on their occurrence and epidemiology in rabbits is limited. We carried out a study from October 2006 to February 2007 of 23 rabbit farms in Apulia and Basilicata regions (southern Italy) in order to investigate the occurrence and risk factors associated with dermatophytoses in breeding rabbits. Dermatophytes were isolated from 86.9% (20/23) of the farms and from 51.8% (420/810) of the animals sampled. Trichophyton mentagrophytes (47.9%) and Microsporum canis (3.2%) were isolated from diseased (71.7%) and healthy (48.4%) animals as well from the surrounding environment (7.5%). The occurrence of lesions, the age of rabbits, and farm management (e.g., temperature, humidity and methods and frequency of disinfection practices) were identified as the most significant risk factors (P < 0.05) for the occurrence of dermatophytes. Animals in fattening and finishing stages were the most frequently infected (i.e., 58.2 and 61.6% respectively). Dermatophyte prevalence was significantly (P < 0.05) higher in areas with higher temperature (>20°C) and relative humidity ranging from 62-65%. The results of the present investigation suggest that zoonotic dermathophytes are present in rabbit farms and highlight the importance of correct management procedures for the control of the infections.