| Summary: | 碩士 === 國立嘉義大學 === 獸醫學系研究所 === 104 === Brachyspira species cause swine dysentery (SD) and porcine intestinal spirochetosis (PIS/PCS). The major pathogens are Brachyspira hyodysenteriae and Brachyspira pilosicoli, these diseases usually occur in growing to finishing pigs, the most important period of weight gaining. Severe economical losses caused by decrease of feed input and feed conversion ratio, costs of treatment and death. Using antibacterial agents can control the epidemic, but Brachyspira have been reported having high level resistance to commonly used first-line antibiotics such as tylosin and lincomycin in most international research. Moreover, the susceptibility of second-line antibiotics such as tiamulin has been decline in some countries. There isn’t any antimicrobial susceptibility and isolation information of swine Brachyspira in Taiwan at present and reluctantly blind dosing often make the epidemic situation worse.
This study was aimed to find out the optimal isolation method of Brachyspira in Taiwan. Using 4 different medium from references, with or without pre-treatment, and culture under 37℃ or 42℃ respectively. Total 16 different isolation methods were used to isolate Brachyspira from 14 PCR positive samples of Brachyspira hyodysenteriae. All of these methods, CVSR medium culture under 42℃ seems to be the best method which the isolative rate is 100%. Isolation after pre-treatment could reduce the probability of mistake, but may cause the false negative of some low bacterial quantity samples.
55 Brachyspira hyodysenteriae and 19 other species of Brachyspira be isolated, and 56 of them were used for antimicrobial susceptibility test. 21 antimicrobial agents were used in antimicrobial minimal inhibitory concentration test with agar dilution method. According to the result, using lincomycin and tiamulin as the first-line antibiotic to treat SD recommendly. If the treatment failed, administration of oxytetracycline, doxycycline, gentamicin and ionophores may be effective.
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