Isolation Of Canine Pyoderma Pathogen And Establishment Of Mouse Skin Infection Model Induced By Staphylococcus

Canine pyoderma is one of the common skin diseases in dogs of all ages,which seriously affects the living quality of dogs.The disease is mainly caused by bacterial infection,which has the characteristics of long course and easy recurrence,complicated etiology and difficult to control.At present,the main treatment method for canine pyoderma is using antibacterial drugs and topical disinfectants.However,due to the increasing resistance of pathogenic bacteria gradually year by year,it is often tough to reach the desired therapeutic effect.Therefore,it is very vital to detect the antimicrobial susceptibility and disinfectant resistance of canine pyoderma.The research and development of new drug is the main direction for the treatment of canine pyoderma.The research and development of drug is inseparable from animal experiments.Dogs are expensive and dangerous for experimental animals.Mice are commonly used disease research model animals.The murine skin infection model can be used for pathological research and treatment experiments of canine pyoderma.This study collects canine pyoderma disease materials from pet hospitals in Xi’an and its surrounding areas,isolates and identifies pathogens,detects the sensitivity of the main pathogens to commonly used antibacterial drugs and resistance to chlorhexidine acetate,and establishes that the main pathogens cause skin infections in mice model and perform model evaluation.The following results were obtained:1.In this experiment,43 samples of canine pyoderma were collected from Xi’an and its surrounding areas,and 9 kinds of bacteria were isolated,a total of 56 strains,22 strains of S.aureus,9 strains of S.pseudointermediate,and 8 strains of Bacillus,4 strains of P.mirabilis,3 strains of P.vulgaris,3 strains of E.coli,2 strains of S.epidermidis,2 strains of S.plodding,2 strains of S.schleiferi,1 strain of S.saprophytica.The identification results showed that the main pathogens of canine pyoderma in this area were S.aureus and S.pseudointermediate.2.The results of the pathogenic bacteria drug sensitivity test showed that vancomycin,ceftriaxone,gentamycin,amoxicillin and ampicillin were the most sensitive in common clinical antibiotics,followed by doxycycline,clindamycin,enrofloxacin,and levofloxacin.TMP,compound trimethoprim and penicillin are highly resistant,and pathogens resistant to multiple antimicrobials account for more than 40%.3.The MIC test results of chlorhexidine acetate against S.pseudointermediate and S.aureus showed that the MIC of chlorhexidine acetate against 9 strains of S.pseudointermediate was 0.5μg/m L,and the MIC for 14 strains of S.aureus was 0.5μg/m L.The MIC was 8μg/m L,the MIC for 4 strains of S.aureus was 4μg/m L,and the MIC for 4 strains of S.aureus was 1μg/m L,both of which exceed chlorhexidine acetate for S.aureus ATCC 25923 MIC(0.25μg/m L).The resistance gene test showed that 9 strains of S.pseudointermediate all carried the qac A/B resistance gene,and 6 strains carried the qac H gene(sp-2,sp-4,sp-5,sp-6,sp-8,sp-9);Only two strains(sp-2,sp-9)carrying the qac G gene,qac J and Smr genes were not detected.None of the above resistance genes were detected in all S.aureus.4.The conditions for establishing a mouse infectious skin disease model caused by S.aureus and S.pseudointermediate which were as follows:using sandpaper to polish the buttocks with at least the amount of blood oozing,and maintain a living environment with60%relative humidity.Different bacterial counts(1×10~6 CFU,1×10~7 CFU and 1×10~8 CFU)can be successfully applied to the model,and the model with high bacterial count(1×10~8CFU)is better.5.Both S.pseudointermediate and S.aureus can be successfully modeled,but the model created by S.pseudointermediate was easier to form abscesses,and most of the inflammatory cells in the model made by S.aureus were diffusely distributed.