Pathological and clinical aspects of the diseases caused by Malassezia species

Advances in Microbiology, Infectious Diseases and Public Health: Fungal Occurrence in the Hair and Skin of Symptomatic Pets in Turin, Italy

Companion animals, often asymptomatic reservoir of fungi, can be important sources of infection in humans, due to the close contact with their owners. The present study was aimed to assess the occurrence of dermatophytes and other fungi isolated from pet dermatological lesions in Turin, Italy. Dermatological specimens were examined for fungal elements by direct microscopy and cultured to detect dermatophytes, other filamentous fungi and yeasts: 247 pets (118 cats, 111 dogs and 18 dwarf rabbits) were positive for fungal detection in culture. Microsporum canis was the most frequent dermatophyte in cats and dogs, whereas Trichophyton mentagrophytes was the most common in rabbits. Among the other fungi, for all examined pets, dematiaceous fungi were the most isolated, followed by Mucorales, penicilli, yeasts and yeast-like fungi, and aspergilli. No gender predisposition was detected for dermatophyte growth; on the contrary, for the other fungi male cats were more susceptible than female. The highest fungal occurrence was recorded in <1-year-old cats for dermatophytes, and in <5-year-old cats and dogs for the other fungi. Autumn was the period associated with a relevant incidence of fungal infection. Finally, fungi were more frequent in non pure-breed cats and in pure-breed dogs. These data underline the importance to timely inform pet owners about the potential health risk of infection caused not only by dermatophytes but also by non-dermatophyte fungi, routinely considered to be contaminants or harmless colonizers, since their role as source of zoonotic infections is not to be excluded.

Prevalence of Malassezia pachydermatis in dogs with suspected Malassezia dermatitis or otitis in Slovakia

The aim of the study was to evaluate the prevalence of yeast Malassezia pachydermatis in dogs from Slovakia in relation to different predisposition factors (sex, age, body localisation, hair type, and season). Samples of ear swabs (58) and dermal swabs (131) from 147 dogs with clinical symptoms of suspected yeast dermatitis and/or otitis, were examined between June 2005 to June 2007. Relatively higher prevalence of M. pachydermatis was found in samples taken from males (45.2%) than in females (35.2%), and in geriatric dogs (63.6%) than in young (42.5%) or adult (38.5%) dogs. Malassezia pachydermatis was isolated more often from ear swabs (44.8%) than from skin swabs (38.9%). Prevalence of M. pachydermatis was significantly higher (p < 0.05) in samples from the trunk area (60.3%) than in samples from other skin areas. Significantly higher prevalence was found in samples from long-haired (51.5%) and short-haired (45.9%) dogs compared to smooth-haired (21.4%) dogs. The prevalence was relatively higher in the samples taken in autumn (52.6%), than the other seasons: spring (36.1%), summer (27.3%), winter (45.7%); those differences were not significant. Malassezia pachydermatis is one of the most frequent yeasts isolated in dogs. Knowledge of factors predisposing to development of infection is valuable attribute of the correct diagnostic approach and case management.

Acupuncture Prevents Relapses of Recurrent Otitis in Dogs: A 1-Year Follow-Up of a Randomised Controlled Trial

Background

Recurrent infections within a particular, well-localised body location are often seen in veterinary and medical practice. This condition could represent a localised or segmental immune deficiency. Recurrent canine otitis seems to be one example of this problem. It has been reported that acupuncture increased the efficacy of conventional treatment for canine otitis by >50%.

Objective

To assess whether the relapse rate of recurrent canine otitis over 1 year can be modified by acupuncture in adult dogs.

Methods

One-year follow-up of a randomised controlled trial. 31 dogs with a history of recurring otitis were randomised into two groups. In addition to conventional treatment, each group received four sessions of either real acupuncture, group A (n=16), or sham acupuncture, group B (n=15). The main outcome for the follow-up was the rate of acute otitis episodes in each group over 1 year, with blinded evaluation. A χ2 test was used for statistical analysis.

Results

There was one dropout in each group. Fourteen (93%) dogs in group A: were free of otitis relapses, compared with 7 (50%) in group B (p<0.01).

Conclusion

Acupuncture seems effective for preventing relapses in cases of recurrent canine otitis. This result suggests that acupuncture could be tested as a treatment of other recurrent localised infections. Given the ability of acupuncture to modulate neurotransmitters and opioid peptides, which can in turn modulate the immune system, the immune response to acupuncture also seems worth exploring.

Comparative study of the activity and kinetic properties of malate dehydrogenase and pyruvate decarboxylase from Candida albicans, Malassezia pachydermatis, and Saccharomyces cerevisiae

Candida albicans and Malassezia pachydermatis cause human and animal infections of the skin and internal organs. We compare the properties of two enzymes, pyruvate decarboxylase (PDC) and malate dehydrogenase (MDH), from these species and from Saccharomyces cerevisiae cultivated under aerobic and anaerobic conditions to find differences between the enzymes that adapt pathogens for virulence and help us in searching for new antifungal agents. Malassezia pachydermatis did not show any growth under anaerobic conditions, as opposed to C. albicans and S. cerevisiae. Under aerobic conditions, C. albicans showed the highest growth rate. Malassezia pachydermatis, contrary to the others, did not show any PDC activity, simultaneously showing the highest MDH activity under aerobic conditions and a Km value for oxaloacetate lower than S. cerevisiae. Candida albicans and S. cerevisiae showed a strong decrease in MDH activity under anaerobic conditions. Candida albicans shows four different isoforms of MDH, while M. pachydermatis and S. cerevisiae are characterized by two and three isoforms. Candida albicans shows about a twofold lower activity of PDC but, simultaneously, almost a threefold lower Km value for pyruvate in comparison with S. cerevisiae. The PDC apoform share under aerobic conditions in C. albicans was 47%, while in S. cerevisiae was only 26%; under anaerobic conditions, the PDC apoform decreased to 12% and 8%, respectively. The properties of enzymes from C. albicans show its high metabolic flexibility (contrary to M. pachydermatis) and cause easy switching between fermentative and oxidative metabolism. This feature allows C. albicans to cause both surface and deep infections. We take into consideration the use of thiamin antimetabolites as antifungal factors that can affect both oxidative and fermentative metabolism.

Molecular analysis of fungal microbiota in samples from healthy human skin and psoriatic lesions

Psoriasis, a common cutaneous disease of unknown etiology, may be triggered by infections, including those due to fungi. Since the fungal community of human skin is poorly characterized, we aimed to analyze the mycological microbiota in healthy skin and psoriatic lesions. Twenty-five skin samples from five healthy subjects (flexor forearm) and three patients with psoriasis were analyzed using broad-range 18S ribosomal DNA (rDNA) and 5.8S rDNA/internal transcribed spacer 2 (ITS2) Malassezia-specific PCR primers. Broad-range PCR analysis indicated that most organisms resembled Malassezia. Malassezia-specific 5.8S/ITS2 analysis of 1,374 clones identified five species and four unknown phylotypes, potentially representing new species. The species distribution appears largely host specific and conserved in different sites of healthy skin. In three subjects, the Malassezia microbiota composition appeared relatively stable over time. Samples of Malassezia microbiota from healthy skin and psoriatic lesions were similar in one patient but substantially different in two others. These data indicate the predominance of Malassezia organisms in healthy human skin, host-specific variation, stability over time, and as yet, no consistent patterns differentiating psoriatic skin from healthy skin.

Malassezia pachydermatis isolated from normal and diseased external ear canals in dogs: A comparative analysis

To investigate the role of Malassezia pachydermatis as a pathogenic agent in canine otitis, a comparative analysis of isolates from normal and diseased external ear canals in dogs was undertaken. Specimens were collected from the ears of dogs with unilateral or bilateral otitis and from healthy dogs. Mycological analysis was by direct microscopy and fungal culture on Sabouraud's dextrose agar and Dixon's agar. Of the otitis specimens, 63.7% showed typical Malassezia cells on cytological examination. In samples taken from the healthy ears of dogs with unilateral otitis, only 21.43% (P<0.05) showed evidence of Malassezia. M. pachydermatis was identified cytologically and culturally in 57.53% (P<0.05), 14.29% and 30.0% of samples from the ears of dogs with otitis, from the healthy ears of dogs with unilateral otitis and from the ears of healthy dogs with no otitis. In the group with otitis associated with M. pachydermatis, the poodle was the most common breed (39.29%; P<0.05), whereas in the group without otitis, the German Shepherd breed was prominent (although this observation was not statistically significant). In both groups, the majority of dogs with M. pachydermatis were aged between 1 and 3 years (P<0.05). The higher incidence of M. pachydermatis isolated from the ears of dogs with otitis externa suggests a putative pathogenic role of this yeast in this condition.

Therapeutic Effects of .BETA.-Thujaplicin Eardrops on Canine Malassezia-Related Otitis Externa

An eardrop solution of beta-thujaplicin was examined for therapeutic effects on canine Malassezia-related otitis externa. Half to one ml of beta-thujaplicin solution of 100 microg/ml including DMSO 2% was injected everyday into both external ear canals of 31 cases for test-of-cure agreement. Fifteen score phases were established from the symptoms and cerumen smear biopsy findings, and score changes were recorded at least once a week. The means of the second and the third inspection day scores decreased significantly more than the previous value of each. In addition, the numbers of yeast-like organisms clearly decreased. These results suggest that beta-thujaplicin eardrops are effective for Malassezia-related otitis externa in dogs.