Isolation,Identification And Drug Sensitivity Test Of Canine Skin Fungal Diseases

Objective: Fungal skin disease is the most common skin disease in dogs and has a high incidence in clinical practice.Due to the long course of disease,severe symptoms and recurrent episodes of fungal skin diseases,it has brought great difficulties to the treatment of this disease.Since most skin-causing fungi are zoonotic pathogens,the prevention and treatment of this disease are of great significance to public health.In-depth study of the pathogenesis,pathogen composition and drug resistance of canine fungal skin disease can provide effective theoretical support for the prevention,diagnosis and treatment of the disease.Method: Sample survey and disease collection were conducted at Xi'an Animal Hospital of Northwest A&F University.Using clinical epidemiological investigation methods,statistical investigations were carried out on the species,age,sex,main symptoms,and occurrence season of the diseased animals,and the pathogenesis of canine skin diseases was analyzed and summarized.The canine skin disease materials were collected for fungal isolation and culture,and the pathogenic strains were identified by PCR.The sensitivity of pathogenic fungi to nystatin,ketoconazole,and itraconazole was determined according to NCLLS' M38-A2 protocol and Rosco disk diffusion method.Result: The survey results showed that dogs with the first diagnosis of canine dermatology accounted for 13.62% of the total number of cases;The pathogen type of infection was mainly fungal(36.33%);July,August and September are the highest season of canine skin disease(36.89%);Dogs less than two years old are more susceptible to skin disease(53.95%);Most of the affected parts are limbs,ears and abdomen.During the experiment,58 skin materials of 32 dogs were randomly collected.The fungus was isolated and cultured,and 20 fungi were obtained.The amplified products are sequenced after PCR amplification of pathogenic fungi using the universal primers ITS1 and ITS4 sequences.The results obtained by clinical sampling are: 8 strains of Alternaria alternata;4 strains of microsporum canine;8 strains of conditional pathogens: 5 strains of Aspergillus(1 strain of Aspergillus flavus,2 strains of Aspergillus fumigatus,2 strains of Aspergillus niger)and 2 strains of Fusarium,1 strain of Mucor.The drug sensitivity of three drugs(nystatin NYS,ketoconazole KET,itraconazole ITC)to Microsporum canis and Alternaria was tested by M38-A2 microdilution methodand Rosco paper dilution method.Through the Rosco disk diffusion method susceptibility test,the sensitivity of Microsporum canis to three drugs was NYS>KET>ITC;the sensitivity of Alternaria to three drugs was NYS>ITC>KET.According to M38-A2 protocol,the MIC range of three drugs against M.canis was as follow: the MIC range of itraconazole was 0.0325~0.5 ?g/mL,the MIC range of ketoconazole was 0.25~1 ?g/mL,and the MIC range of nystatin was 0.0156~0.125 ?g/mL.The MIC range of three drugs against Alternaria was as follow: the MIC range of itraconazole was 0.0156~0.0625 ?g/mL,the MIC range of ketoconazole was 0.3125~2 ?g/mL,and the MIC range of nystatin was0.0625~0.25 ?g/mL.Conclusion: Canine dermatophytosis occurs mostly in July-September;The main pathogens are Alternaria and M.canis;Alternaria alternata is more sensitive to itraconazole,and M.canis is more sensitive to nystatin.