Malassezia spp. yeasts are normal inhabitants of dog skin surface and are usually considered opportunistic pathogens. Malassezia dermatitis is a term used to describe skin diseases associated with Malassezia overgrowth (MO) in affected regions that shows a good clinical and cytological response to appropriate antifungal treatment. In dog M. pachydermatis is the main species of this genus [1]. The aim of this study is to identify and quantify Malassezia yeasts from dogs with or without dermatitis and/or otitis and to evaluate the correlation with clinical scores and previous treatments. Ninety-seven dogs were enrolled: 13 healthy (HD) and 84 with MO. Clinical history and previous treatments were recorded. After a complete physical and dermatological examination, CADESI-3 scores were calculated. Skin samples for cytological and mycological culture were obtained in all dogs from axillae, interdigital webs, ear pinnas and ear canals and from lesions where MO had been evidenced by cytology. Malassezia overgrowth was diagnosed by cytology when more than 2 and 10 yeasts with typical morphology were counted in 5 random fields at 40x magnification in skin and ear cytology, respectively [2]. Colonies were identified as Malassezia genus based on microscopic and macroscopic morphology and were suspected to belong to the non-lipid dependent M. pachydermatis species when grew on the SDA medium other than on DA medium. Final identification was confirmed with molecular biology methods. All count data were reported as a percentage and compared by chi-square test. Normal distribution of the data was tested using the Shapiro-Wilk test. A Global Score (GS) was calculated by taking into account numbers of yeasts counted in sampled regions. The association between the GS of Malassezia and the CADESI-03 scores among the dogs with MO was evaluated by the Spearman correlation index. Effect of pharmacological therapies on GS was tested with Mann-Whitney Test. The quantitative data (GS and CADESI-03) were analysed using ANOVA. P-value <0.05 was considered significant. Of the 419 examined slides a total of 124 (31 HD and 93 with MO) were positive on cytology to Malassezia yeasts. The greatest frequency (p < 0.001) of isolation of Malassezia spp. was for skin lesions. GSs obtained from HD and dogs with MO were significantly different (p=0.001). In dogs with MO, GS was significantly higher (p = 0.015) in the subgroup treated with antibiotics in the previous 3 months. GS was not significantly affected by treatment with steroids. From 142 swabs (from 52 animals; 39 with MO, 13 HD) 26 plates were considered positive (>70 UFC). All isolates were identified as Malassezia pachydermatis. The frequency of yeast isolation from diseased dogs in the present study was significantly higher (p=0.05) when compared with HD and the highest frequency of yeasts isolation in dogs with MO was found in areas with skin lesions. This study provides helpful insights into the occurrence of Malassezia in HD and in dogs with skin diagnosis of MO. Previous antibiotic treatments appear to be affecting the numbers of Malassezia yeasts.

Malassezia overgrowth in 97 dogs in northern Italy

Michele Berlanda
;
Barbara Contiero;Carlo Guglielmini;Helen Poser
2018

Abstract

Malassezia spp. yeasts are normal inhabitants of dog skin surface and are usually considered opportunistic pathogens. Malassezia dermatitis is a term used to describe skin diseases associated with Malassezia overgrowth (MO) in affected regions that shows a good clinical and cytological response to appropriate antifungal treatment. In dog M. pachydermatis is the main species of this genus [1]. The aim of this study is to identify and quantify Malassezia yeasts from dogs with or without dermatitis and/or otitis and to evaluate the correlation with clinical scores and previous treatments. Ninety-seven dogs were enrolled: 13 healthy (HD) and 84 with MO. Clinical history and previous treatments were recorded. After a complete physical and dermatological examination, CADESI-3 scores were calculated. Skin samples for cytological and mycological culture were obtained in all dogs from axillae, interdigital webs, ear pinnas and ear canals and from lesions where MO had been evidenced by cytology. Malassezia overgrowth was diagnosed by cytology when more than 2 and 10 yeasts with typical morphology were counted in 5 random fields at 40x magnification in skin and ear cytology, respectively [2]. Colonies were identified as Malassezia genus based on microscopic and macroscopic morphology and were suspected to belong to the non-lipid dependent M. pachydermatis species when grew on the SDA medium other than on DA medium. Final identification was confirmed with molecular biology methods. All count data were reported as a percentage and compared by chi-square test. Normal distribution of the data was tested using the Shapiro-Wilk test. A Global Score (GS) was calculated by taking into account numbers of yeasts counted in sampled regions. The association between the GS of Malassezia and the CADESI-03 scores among the dogs with MO was evaluated by the Spearman correlation index. Effect of pharmacological therapies on GS was tested with Mann-Whitney Test. The quantitative data (GS and CADESI-03) were analysed using ANOVA. P-value <0.05 was considered significant. Of the 419 examined slides a total of 124 (31 HD and 93 with MO) were positive on cytology to Malassezia yeasts. The greatest frequency (p < 0.001) of isolation of Malassezia spp. was for skin lesions. GSs obtained from HD and dogs with MO were significantly different (p=0.001). In dogs with MO, GS was significantly higher (p = 0.015) in the subgroup treated with antibiotics in the previous 3 months. GS was not significantly affected by treatment with steroids. From 142 swabs (from 52 animals; 39 with MO, 13 HD) 26 plates were considered positive (>70 UFC). All isolates were identified as Malassezia pachydermatis. The frequency of yeast isolation from diseased dogs in the present study was significantly higher (p=0.05) when compared with HD and the highest frequency of yeasts isolation in dogs with MO was found in areas with skin lesions. This study provides helpful insights into the occurrence of Malassezia in HD and in dogs with skin diagnosis of MO. Previous antibiotic treatments appear to be affecting the numbers of Malassezia yeasts.
2018
Atti 72° Convegno SISVET
978-8890909214
File in questo prodotto:
File Dimensione Formato  
doc00519320190606144122.pdf

accesso aperto

Tipologia: Published (publisher's version)
Licenza: Accesso gratuito
Dimensione 859.31 kB
Formato Adobe PDF
859.31 kB Adobe PDF Visualizza/Apri
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3331355
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact