Malassezia pachydermatis with special reference to canine skin disease

Malassezia: Zoonotic Implications, Parallels and Differences in Colonization and Disease in Humans and Animals

Malassezia spp. are commensals of the skin, oral/sinonasal cavity, lower respiratory and gastrointestinal tract. Eighteen species have been recovered from humans, other mammals and birds. They can also be isolated from diverse environments, suggesting an evolutionary trajectory of adaption from an ecological niche in plants and soil to the mucocutaneous ecosystem of warm-blooded vertebrates. In humans, dogs and cats, Malassezia-associated dermatological conditions share some commonalities. Otomycosis is common in companion animals but is rare in humans. Systemic infections, which are increasingly reported in humans, have yet to be recognized in animals. Malassezia species have also been identified as pathogenetic contributors to some chronic human diseases. While Malassezia species are host-adapted, some species are zoophilic and can cause fungemia, with outbreaks in neonatal intensive care wards associated with temporary colonization of healthcare worker’s hands from contact with their pets. Although standardization is lacking, susceptibility testing is usually performed using a modified broth microdilution method. Antifungal susceptibility can vary depending on Malassezia species, body location, infection type, disease duration, presence of co-morbidities and immunosuppression. Antifungal resistance mechanisms include biofilm formation, mutations or overexpression of ERG11, overexpression of efflux pumps and gene rearrangements or overexpression in chromosome 4.

Effect of an anti-inflammatory pomegranate otic treatment on the clinical evolution and microbiota profile of dogs with otitis externa

BACKGROUND

Canine otitis externa (OE) is a common disease characterised by inflammation of the epithelial tissue of the external ear canal. Secondary infections are frequent, and Malassezia pachydermatis and Staphylococcus pseudintermedius are routinely isolated and treated with antifungal and antibiotic compounds.

HYPOTHESIS/OBJECTIVES

To analyse the otitis ear microbiome before and after a treatment with prednisolone plus pomegranate or antimicrobial drugs ANIMALS: 15 dogs with nonpurulent OE.

METHODS AND MATERIALS

A 30 day, double-blinded, multicentre, randomized and controlled parallel-group (1:1) trial was conducted in 15 dogs with nonpurulent OE, following two different topical treatments (prednisolone plus pomegranate versus prednisolone plus antibiotic and antifungal drugs). On days (D)0, D15 and D30, serum and skin otic samples were collected, and clinical examination and microbiome analysis (bacteria and fungi) were performed. Results were compared with validated otitis clinical scores to assess the effectiveness of both treatments.

RESULTS

Nine bacterial and four fungal families were detected during the three time-points tested. An increase in fungal diversity (Shannon index) and composition was the most significant change observed after both treatments. At treatment D15 and D30, the reduction in clinical signs was statistically significant in both treatment groups (P ≤ 0.05). Prednisolone plus pomegranate cleanser treatment was able to control the clinical signs of otitis as well as the bacterial and fungal overgrowth.

CONCLUSIONS AND CLINICAL IMPORTANCE

Mild otitis cases associated with microbial overgrowth may be managed with topical antiseptic and anti-inflammatory agents without the need for antibiotic and/or antifungal compounds.

Antifungal agent susceptibilities and interpretation of Malassezia pachydermatis and Candida parapsilosis isolated from dogs with and without seborrheic dermatitis skin

Malassezia pachydermatis and Candida parapsilosis are recognized as commensal yeasts on the skin of healthy dogs but also causative agents of eborrheic dermatitis, especially in atopic dogs. We determined and compared the susceptibility levels of yeasts isolated from dogs with and without seborrheic dermatitis (SD) using the disk diffusion method (DD) for itraconazole (ITZ), ketoconazole (KTZ), nystatin (NYS), terbinafine (TERB) and 5-fluorocytosine (5-FC) and the broth microdilution method (BMD) for ITZ and KTZ. The reliability between the methods was assessed using an agreement analysis and linear regression. Forty-five M. pachydermatis and 28 C. parapsilosis isolates were identified based on physiological characteristics and an approved molecular analysis. By DD, all tested M. pachydermatis isolates were susceptible to ITZ, KTZ, NYS and TERB but resistant to 5-FC. Only 46 - 60% of the tested C. parapsilosis isolates were susceptible to KTZ, TERB and 5-FC, but ITZ and NYS were effective against all. By BMD, over 95% of M. pachydermatis isolates were susceptible to KTZ and ITZ with an MIC90 < 0.03 and 0.12 μg/ml, respectively. The frequency of KTZ- and ITZ-resistant C. parapsilosis was 29% and 7%, and the MIC90 values were 1 μg/ml and 0.5-1 μg/ml, respectively. Regarding the agreement analysis, 2.2% of minor errors were observed in M. pachydermatis and 0.2-1% of very major errors occurred among C. parapsilosis. There were no significant differences in the yeast resistance rates between dogs with and without SD. KTZ and ITZ were still efficacious for M. pachydermatis but a high rate of KTZ resistant was reported in C. parapsilosis.

Immune response to fungal infections

The immune mechanisms of defence against fungal infections are numerous, and range from protective mechanisms that were present early in evolution (innate immunity) to sophisticated adaptive mechanisms that are induced specifically during infection and disease (adaptive immunity). The first-line innate mechanism is the presence of physical barriers in the form of skin and mucous membranes, which is complemented by cell membranes, cellular receptors and humoral factors. There has been a debate about the relative contribution of humoral and cellular immunity to host defence against fungal infections. For a long time it was considered that cell-mediated immunity (CMI) was important, but humoral immunity had little or no role. However, it is accepted now that CMI is the main mechanism of defence, but that certain types of antibody response are protective. In general, Th1-type CMI is required for clearance of a fungal infection, while Th2 immunity usually results in susceptibility to infection. Aspergillosis, which is a disease caused by the fungus Aspergillus, has been the subject of many studies, including details of the immune response. Attempts to relate aspergillosis to some form of immunosuppression in animals, as is the case with humans, have not been successful to date. The defence against Aspergillus is based on recognition of the pathogen, a rapidly deployed and highly effective innate effector phase, and a delayed but robust adaptive effector phase. Candida albicans, part of the normal microbial flora associated with mucous surfaces, can be present as congenital candidiasis or as acquired defects of cell-mediated immunity. Resistance to this yeast is associated with Th1 CMI, whereas Th2 immunity is associated with susceptibility to systemic infection. Dermatophytes produce skin alterations in humans and other animals, and the essential role of the CMI response is to destroy the fungi and produce an immunoprotective status against re-infection. The resolution of the disease is associated with a delayed hypersensitive response. There are many effective veterinary vaccines against dermatophytoses. Malassezia pachydermatis is an opportunistic yeast that needs predisposing factors to cause disease, often related to an atopic status in the animal. Two species can be differentiated within the genus Cryptococcus with immunologic consequences: C. neoformans infects predominantly immunocompromised hosts, and C. gattii infects non-immunocompromised hosts. Pneumocystis is a fungus that infects only immunosupressed individuals, inducing a host defence mechanism similar to that induced by other fungal pathogens, such as Aspergillus.

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.

Malassezia pachydermatis carriage in dog owners

Malassezia pachydermatis is commonly carried on the hands of dog owners and may cause disease in immunocompromised persons.

Yeasts of the genus Malassezia serve as both commensal microorganisms and pathogens on the skin of humans and domestic animals. Although rare, cases of life-threatening fungemia in people have been attributed to Malassezia pachydermatis, for which dogs are a natural host. Zoonotic transfer has been documented from dogs to immunocompromised patients by healthcare workers who own dogs. We investigated the role of pet dogs as risk factors for mechanical carriage of M. pachydermatis on human hands. Dogs and their owners were sampled as pairs, by fungal culture and nested polymerase chain reaction (PCR). Although fungal culture was not a reliable means by which to detect carriage of the yeast on human hands, PCR identified M. pachydermatis on most (≈93%) human participants. Human carriage of ubiquitous opportunistic pathogens such as M. pachydermatis underscores the importance of good hand hygiene by healthcare professionals.

Effects of .BETA.-Thujaplicin on Anti-Malassezia pachydermatis Remedy for Canine Otitis Externa

The antifungal activity of beta-thujaplicin was evaluated against 51 Malassezia pachydermatis strains isolated from canine ear canals with or without otitis externa. For comparison, sensitivity tests were performed on M. pachydermatis isolates for nystatin, ketoconazole, and terbinafine HCl, all clinically available antifungal agents. The minimal inhibition concentrations over 50% of the tested isolates (MIC50) were 3.13 microg/ml for beta-thujaplicin and nystatin, 0.016 microg/ml for ketoconazole, and 1.56 microg/ml for terbinafine HCl. The antifungal effect for M. pachydermatis of beta-thujaplicin compared favorably with commercial antifungal agents. None of the 51 M. pachydermatis isolates showed resistance against any of the tested antibiotics investigated in this study. Ten representative isolates of M. pachydermatis were subcultured for 30 generations at concentrations close to the MIC levels of beta-thujaplicin, nystatin, ketoconazole, and terbinafine HCl, and examined to determine whether they had acquired resistance to each drug. As a result, M. pachydermatis was found to achieve resistance more easily for ketoconazole and terbinafine HCl than for beta-thujaplicin or nystatin. The MIC50 of beta-thujaplicin did not change during the course of subculture, and it is thought that the potential development of a resistant strain is low, even with continuous infusion for otitis externa therapy. beta-Thujaplicin is an inexpensive and safe treatment with anti-inflammatory and deodorant effects that can be recommended as an effective remedy for canine otitis externa.

Correlations of Fatty Acid Supplementation, Aeroallergens, Shampoo, and Ear Cleanser With Multiple Parameters in Pruritic Dogs

Seventy-two pruritic dogs were fed one of four diets controlled for n-6:n-3 fatty acid ratios and total dietary intake of fatty acids. Multiple parameters were evaluated, including clinical and cytological findings, aeroallergen testing, microbial sampling techniques, and effects of an anti-fungal/antibacterial shampoo and ear cleanser. Significant correlations were observed between many clinical parameters, anatomical sampling sites, and microbial counts when data from the diet groups was combined. There were no statistically significant differences between individual diets for any of the clinical parameters. The importance of total clinical management in the control of pruritus was demonstrated.

Description of a new yeast species, Malassezia japonica, and its detection in patients with atopic dermatitis and healthy subjects

Lipophilic yeasts of the genus Malassezia are part of the normal cutaneous microflora and are considered one of the factors that trigger atopic dermatitis (AD). We isolated two strains of Malassezia from a healthy Japanese female. Analysis of the D1/D2 26S ribosomal DNA and internal transcribed spacer region sequences of the isolates suggested that they are new members of the genus Malassezia. We propose the name Malassezia japonica sp. nov. for the isolates. M. japonica is easily distinguished from the seven known lipophilic species by its ability to assimilate Tween 40 and Tween 60 and its inability to assimilate Tween 20 and Tween 80 and to grow at 40 degrees C. Furthermore, by applying transparent dressings to the skin lesions of 36 patients with AD and the skin of 22 healthy subjects, M. japonica DNA was detected by a non-culture-based method consisting of nested PCR with M. japonica species-specific primers. M. japonica DNA was detected from 12 of the 36 patients (33.3%) and 3 of the 22 healthy subjects (13.6%). Although it is not known whether M. japonica plays a role in AD, this species was part of the microflora in both patients with AD and healthy subjects.

Factors associated with the prevalence of Malassezia species in the external ears of cattle from the state of Minas Gerais, Brazil

Swabs collected from the external ears of 942 cattle, including both European and zebu breeds, were used to evaluate the epidemiology of Malassezia species. High numbers of Malassezia isolates were significantly associated with maturity of the animals and with diagnosed otitis. In healthy animals, a particularly low prevalence of the genus was found in Holstein cows, especially in the summer months, a finding perhaps correlating with the open, air-exposed ears of this breed. Pendutlous-eared zebu breeds and hybrids had higher levels of colonization, although this effect was more pronounced in humid regions, and was least in the dry north and west of the state. The most common species seen was M. sympodialis, which accounted for 47.1% of isolates from healthy cattle and 39.1% from cattle with otitis. In cattle with otitis sampled in summer, we found that the relatively thermotolerant M. sympodialis made up 80.8% of isolates. By contrast, during the winter the less thermotolerant M. globosa was the most common species from otitis, making up 56% of the isolates. Humidity and temperature may be the main factors explaining the epidemiology of Malassezia diseases and colonizations in both animals and humans.

Evaluation of serum obtained from atopic dogs with dermatitis attributable to Malassezia pachydermatis for passive transfer of immediate hypersensitivity to that organism

OBJECTIVE

To determine the functionality of canine anti-Malassezia IgE via the passive transfer of immediate hypersensitivity localized to the skin (ie, cutaneous anaphylaxis) from atopic dogs with dermatitis attributable to overgrowth of Malassezia pachydermatis (Malassezia dermatitis [MD]) to healthy recipient dogs by use of the Prausnitz-Küstner (P-K) technique.

ANIMALS

7 clinically normal dogs, 32 atopic dogs with MD, serum from 11 atopic dogs with MD, and 3 healthy dogs without prior sensitization to M pachydermatis.

PROCEDURE

Serum from atopic dogs with MD was used for P-K tests in 3 clinically normal recipient dogs. Serial dilutions of untreated, heat-inactivated, IgE-absorbed, and bovine serum albumin (BSA)-absorbed (control) aliquots of serum were injected ID in triplicate for dermal sensitization. Twenty-four, 48, and 72 hours later, a crude extract of M pachydermatis was injected ID into the sites used for sensitization injections, and immediate hypersensitivity reactions were graded on a 4-point scale.

RESULTS

Untreated serum caused P-K reactivity beginning 24 hours after passive sensitization and persisting through 72 hours (titers, 1:32 to 1:64). Heat inactivation and IgE-absorption of serum eliminated P-K reactivity, whereas treatment of serum with BSA did not.

CONCLUSIONS AND CLINICAL RELEVANCE

Analysis of P-K test results supports the passive transfer of cutaneous anaphylaxis by anti-Malassezia IgE and indicates it is functional in type-1 hypersensitivity reactions of atopic dogs with MD. Reduction or blockade of anti-Malassezia IgE in atopic dogs with MD may provide better clinical control of the disease.

Comparison of pulse administration versus once daily administration of itraconazole for the treatment of Malassezia pachydermatis dermatitis and otitis in dogs

OBJECTIVE To compare clinical efficacy of pulse administration with itraconazole versus once daily administration for the treatment of cutaneous and otic M pachydermatis infection in dogs.

DESIGN

Randomized controlled trial.

ANIMALS

20 dogs.

PROCEDURE

Dogs were treated with itraconazole orally (n = 10/group), using a pulse administration regimen (5 mg/kg [2.3 mg/lb], PO, q 24 h for 2 consecutive days per week for 3 weeks) or once daily administration (5 mg/kg, PO, q 24 h for 21 days). No other treatment was permitted. On days 0 and 21, clinical severity of cutaneous and otic disease was assessed, and samples were collected for cytologic examination and yeast culture. Cytology (sum of the mean number of yeast organisms per oil immersion field for affected sites) and culture (mean of the score for extent of yeast growth for samples from affected sites) scores were calculated.

RESULTS

For dogs in both treatment groups, clinical severity of cutaneous and otic disease was significantly decreased by day 21, but decrease in severity was not significantly different between groups. Similarly, skin cytology, skin culture, and ear culture scores were significantly decreased on day 21, compared with day 0, for both groups, but decreases were not significantly different between groups except that dogs in the pulse administration group had a significantly greater decrease in ear culture scores than did dogs in the daily administration group. However, when cytology scores only for ear samples were analyzed, day 21 score was not significantly decreased, compared with day 0 score, for either group.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that both pulse administration and once daily administration of itraconazole were efficacious in the treatment of M pachydermatis cutaneous infection in dogs. However, adjunctive treatment may be needed in dogs with M pachydermatis otitis.

Canine atopic dermatitis: a retrospective study of 266 cases examined at the University of California, Davis, 1992-1998. Part I. Clinical features and allergy testing results

The medical records of 266 dogs diagnosed as having atopic dermatitis were reviewed. Statistical data were evaluated referable to breed predilections, clinical signs and positive reactions to allergens. Positive reactions were most common to house dust mites (more common with clinical signs in the fall) followed by moulds (more common with clinical signs in the fall and spring). Dogs with positive reactions to moulds, trees or cultivated plants were more likely to have skin and ear yeast infections. Dogs with positive reactions to cultivated plants were more likely to have otitis externa and pedal lesions. Positive reactions to house dust were more common in dogs with early onset of signs and in those tested early in the disease. Dogs had more positive reactions to weeds when allergy tests were performed in the summer and fall. Positive reactions to flea antigen were highly correlated with the clinical diagnosis of flea allergy dermatitis.

Response to Malassezia pachydermatis by peripheral blood mononuclear cells from clinically normal and atopic dogs

OBJECTIVE

To investigate the potential cell-mediated immune response of atopic dogs to the yeast Malassezia pachydermatis and to correlate it with the type-1 hypersensitivity (humoral) response of the same population of dogs.

ANIMALS

16 clinically normal dogs, 15 atopic dogs with Malassezia dermatitis, 5 atopic dogs with Malassezia otitis, and 7 atopic control (ie, without Malassezia dermatitis or otitis) dogs.

PROCEDURE

A crude extract of M pachydermatis was extracted for use as an intradermal allergy testing reagent and for stimulation of isolated peripheral blood mononuclear cells in vitro. Flow cytometry was also used to assess cell surface antigenic determinants (CD3, CD4, CD8, CD14, CD21, CD45RA, surface immunoglobulin) on peripheral blood mononuclear cells.

RESULTS

Atopic dogs with cytologic evidence of Malassezia dermatitis had an increased lymphocyte blastogenic response to crude M pachydermatis extract, compared with clinically normal dogs and dogs with Malassezia otitis. Atopic control dogs did not differ significantly in their responses from atopic dogs with Malassezia dermatitis or otitis. A significant correlation was not found between the lymphocyte blastogenic response and the type-1 hypersensitivity response to M pachydermatis within any of the groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Cell-mediated and humoral reactivities to M pachydermatis contribute to the pathogenesis of atopic dermatitis in dogs but are not directly correlated. Modification of the dysregulated immune response toward M pachydermatis may assist in the reduction of pathologic changes associated with an atopic dermatitis phenotype in dogs.

Retrospective study: the presence of Malassezia in feline skin biopsies. A clinicopathological study

Malassezia spp. dermatitis, a rare disorder in cats, has previously been associated with immune suppression and internal malignancies. This study evaluates the presence and importance of Malassezia spp. in feline biopsy specimens submitted for histopathological examination. Five hundred and fifty haematoxylin and eosin-stained skin biopsy specimens received for histopathological examination between January 1999 and November 2000 were reviewed. Fifteen (2.7%) submissions contained Malassezia organisms in the stratum corneum of the epidermis or follicular infundibulum. Eleven of 15 cats presented with an acute onset of multifocal to generalized skin lesions. All 11 cats were euthanized or died within 2 months of the onset of clinical signs. Seven cats had dermatopathological changes and clinical signs supportive of paraneoplastic alopecia, and three cats had an interface dermatitis suggestive of erythema multiforme or thymoma-associated dermatosis. Histopathological changes were nonspecific in one cat that was euthanized 2 weeks following onset of severe pruritus and alopecia. In three cats, Malassezia spp. were found in localized sites (two chin, one footpads) and appeared inconsequential to their overall health status. One cat had Malassezia spp. in association with cutaneous demodicosis. These findings suggest that Malassezia yeast in dermatopathological specimens from multifocal or generalized lesions should prompt a thorough clinical work-up for internal neoplasia.

Serum antibodies to Malassezia yeasts in canine atopic dermatitis

Significant numbers of humans with atopic dermatitis develop Malassezia-specific IgE. Immediate skin-test reactivity to Malassezia has been demonstrated in atopic dogs. The aim of this study was to compare the serum IgG and IgE response to Malassezia in atopic dogs with and without clinical evidence of Malassezia dermatitis and/or otitis, nonatopic dogs with clinical evidence of Malassezia dermatitis and/or otitis and healthy dogs. Cytology was used to diagnose clinically significant Malassezia dermatitis and otitis. Contact plate cultures confirmed the validity of this technique. Reproducible enzyme-linked immunosorbent assays for Malassezia-specific IgG and IgE in canine serum were established. Atopic dogs had significantly higher serum IgG and IgE levels than either healthy dogs or nonatopic dogs with clinical evidence of Malassezia dermatitis and/or otitis. There was no significant difference in IgG and IgE levels between atopic dogs with and without clinical evidence of Malassezia dermatitis and/or otitis. The implications of these findings in the pathogenesis and management of canine atopic dermatitis are discussed.

Epidermal dysplasia and Malassezia infection in two West Highland White Terrier siblings: an inherited skin disorder or reaction to severe Malassezia infection?

Two 9-month-old West Highland White Terrier siblings were referred to our clinic with pruritus, alopecia and lichenification. Cytological examination of Scotch tape strippings revealed Malassezia organisms and cocci. Skin biopsy specimens showed epidermal dysplasia. Treatment included bathing with a 2% miconazole/chlorhexidine-containing shampoo, orally administered ketoconazole (5 mg kg-1, every 12 h) and cloxacillin (25 mg kg-1 every 8 h). Six weeks later, the dermal infection had resolved and there was hair regrowth. However, the dogs were still moderately pruritic. Intradermal allergy testing was positive for house dust mites, storage mites and Malassezia. Immunotherapy was initiated, and treatment with ketoconazole and cloxacillin was stopped. Skin biopsies, which were performed in both dogs 4 months after the first presentation, revealed mild superficial perivascular dermatitis. The remaining mild facial pruritus was easily controlled with topical treatment. These two cases indicate that epidermal dysplasia might be an inflammatory or hypersensitivity reaction to the Malassezia infection or a result of excessive self-trauma, rather than a congenital keratinization disorder.

The ACVD task force on canine atopic dermatitis (XII): the relationship of cutaneous infections to the pathogenesis and clinical course of canine atopic dermatitis

Dogs and human beings with atopic dermatitis (AD) frequently exhibit concurrent skin infections with Staphylococcus sp. bacteria or Malassezia yeast, and treatment of such infections is an important facet of managing these patients. Staphylococci appear to colonize atopic skin readily, and bacterial products on the skin could augment cutaneous inflammation via immediate hypersensitivity responses to the bacteria, by superantigen-mediated lymphocyte activation, or other non-specific mechanisms. Similarly, skin colonization by Malassezia yeast could contribute to clinical signs of AD; yeast components could induce inflammation via non-specific mechanisms, such as alteration in mediator release, or via antigen-specific hypersensitivity reactions. Clinical and experimental evidence exists that secondary microbial infections can both initiate and perpetuate episodes of AD in dogs and humans, and could even participate in promotion of pro-allergic immunologic responses. Mechanistic details of these complex interactions are under extensive investigation in human beings; only a few observations have been extended to include dog with AD.

Extracellular enzymatic activity of Malassezia spp. isolates

Extracellular enzymatic activity of different species of Malassezia spp was evaluated. Thirty-three isolates of animal origin (dogs and cats) and stock culture samples were studied. Twenty isolates of M. pachydermatis, 8 of M. furfur, 2 of M. sympodialis and M. globosa and one of M. restricta, M. obtusa and M. slooffiae were examined. The enzymatic activity was investigated using Api Zym system. The enzymatic patterns showed light differences. Esterase lipase, Phosphatase acid and Naphtol-AS-BI-phosphohydrolase were produced in significant amounts from most isolates excepted for M. restricta, confirming the limited enzymatic activity of this species. Data obtained from the other new species described after the revision of the genus, appear to be quite homogeneous. Dixon's broth appeared to be a valid medium for the growth of all Malassezia spp.

Optimum incubation conditions for the isolation of yeasts from canine otitis externa

Samples from otitis externa in the dog were cultured on a variety of media under different conditions of incubation in order to assess the most suitable conditions, especially for the isolation of Malassezia pachydermatis. Columbia blood and MacConkey agar at 37 degrees C for 24 h with air and Sabouraud glucose agar under microaerophilic conditions for 48 h at 37 degrees C were considered the ideal combination.

Malassezia pachydermatis isolated from a South American sea lion (Otaria byronia) with dermatitis

A fungus was isolated from the skin of an Otaria byronia and from the water of the pool in which the animal was kept. It formed creamy colonies with soft texture on Dixon agar and grew well without supplements of long-chain fatty acids. Cells were ovoid to cylindrical in shape, budded from a broad base, and budded and divided at the same location. Thus, the isolate was identified as M. pachydermatis. We compared this very rare isolate from a marine mammal with four strains of M. pachydermatis using the freeze-etching electron-microscopy technique. The cells showed the same characteristic ring-swellings on the protoplasmic membrane on the neck site between the mother and the daughter parts, and the same accumulation of circumvallate bulgings in a small area near the straight sections of spiral grooves as four reference strains. Thus, in terms of morphology and ultrastructure, the isolate could be regarded as a typical M. pachydermatis.

Demonstration of Malassezia furfur and M. sympodialis together with M. pachydermatis in veterinary specimens

In the present study, 47 wild-type isolates of the genus Malassezia were isolated from dog and cat specimens by means of a simple differentiating system recently published. The purpose was to determine whether any of the other seven Malassezia spp. apart from M. pachydermatis occur in carnivores. Of the 47 isolates, three had been obtained from cats (ear 2, skin 1) and 44 from dogs (ear 37, skin 3, faeces 2, claw and paw 2). After primary isolation, they were subcultured on mDixon agar and then purified and differentiated by means of assimilation of Cremophor EL, splitting of esculin, growth on lipid-free medium and formation of tryptophan-dependent pigments and fluorochromes. Thus, a total of 100 strains could be obtained from the 47 primary isolates. Referring to the source material, M. pachydermatis was found in 83%, M. furfur in 45% and M. sympodialis in 75%. More than 80% of cultures were mixed, comprising two or all three species; a single species was isolated in only nine cases. This shows that animals are not colonized by M. pachydermatis alone, as has been thought until now, but in nearly all cases by mixed cultures. Thus, (domestic) animals could well be a reservoir for other Malassezia species such as M. furfur and M. sympodialis. Surprisingly, Malassezia yeasts were also isolated from dog faeces, indicating that they apparently pass through the gastrointestinal tract in unchanged form after having been taken up by licking colonized areas. The survivability of Malassezia yeasts in highly acid milieu was also demonstrated in vitro. The study confirms the usefulness of the new test procedures and allows new statements concerning the epidemiology of Malassezia yeasts.