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.

Higher incidence of Malassezia pachydermatis in the eyes of dogs with corneal ulcer than in healthy dogs.

Malassezia pachydermatis is usually associated with otitis and dermatitis in dogs but it can also cause diseases in other species, including humans. In a human neonatal intensive care unit, M. pachydermatis was isolated from an infant's ocular discharge. Therefore, the aim of this study was to ascertain the presence of Malassezia spp. and its possible consequences in dogs' eyes. This research included 19 dogs with unilateral or bilateral corneal ulcers and 60 healthy dogs. A total of 158 clinical specimens from both the groups were obtained from the conjunctival sac of each eye by a calibrated platinum loop. The samples were placed on Dixon and blood agar, incubated at 35 degrees C, and examined daily for 15 days. Then, the strains were subcultured on Sabouraud agar. Of 22 clinical specimens collected from the eyes with corneal ulcers, five cultures (23%) were positive for M. pachydermatis. Of 16 samples collected from the contralateral healthy eye, cultures were positive in three samples (19%). Three animals had unilateral corneal ulcer and positive cultures for M. pachydermatis in both the eyes. Two dogs had unilateral corneal ulcer and positive cultures for M. pachydermatis in the same eye. However, from the 120 samples of 60 healthy dogs, only four clinical specimens (3%) had positive cultures for M. pachydermatis. The findings of M. pachydermatis, in a considerable percentage of clinical specimens from dogs with corneal ulcer, suggest its possible role at least as an aggravating factor in the pathophysiology of this disease.

Identification and antimicrobial susceptibility of bacteria isolated from corneal ulcers of dogs

A total of 22 clinical specimens were obtained from 19 dogs with corneal ulcer (16 unilateral and three bilateral) for isolation and antimicrobial susceptibility evaluation of the isolated bacteria. Bacterial growth was observed in 100 percent of the samples (n=22). Staphylococcus intermedius was the predominant species (35.5 percent), followed by Corynebacterium xerosis (19.3 percent). Gentamicin, ciprofloxacin, chloramphenicol and tobramycin had a high efficacy against all of the isolated bacteria. The results evidenced that 80.7 percent of the isolates were Gram positive cocci and Gram positive bacilli, and that those microorganisms were sensitive to gentamicin, ciprofloxacin, chloramphenicol and tobramycin.

Utilizaram-se 22 amostras de material, obtidas de 19 cães com úlcera de córnea, sendo 16 unilaterais e três bilaterais, para isolamento e avaliação da susceptibilidade antimicrobiana das bactérias isoladas. Observou-se crescimento bacteriano em 100 por cento das amostras (n=22). A espécie predominante foi Staphylococcus intermedius (35,5 por cento) seguido de Corynebacterium xerosis (19,3 por cento). Gentamicina, ciprofloxacina, cloranfenicol e tobramicina apresentaram alta eficácia contra todas as bactérias isoladas. Os resultados evidenciam que 80,7 por cento dos isolados foram cocos e bacilos Gram positivos e que estes microrganismos foram sensíveis à gentamicina, ciprofloxacina, cloranfenicol e tobramicina.