Dissertation > Medicine, health > Clinical > Diagnostics > Laboratory diagnosis > Microbiological examination of

Studies on the Drug Tolerance of One Pathogenic Bacteria Strain of "Skin Fester" Disease in Koi (Cyprinus Carpio) against Disinfectants and Eight Chinese Herbal Medicines

Author XinWeiTao
Tutor YangGuang
School Tianjin Agricultural
Course Aquaculture
Keywords Cryprinus carpiod skin fester disease Sphingomonas paucimobilis disinfectant Chinese herbal medicine drug tolerance
CLC R446.5
Type Master's thesis
Year 2012
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With the development of aquaculture, the use of aquacultural drugs is wider. Because of the low degradated rate the aquaculture water contains the drugs with a certain concentration. With long-term contact with the drugs, the drug tolerance of pathogenic bacteria will come out, and bring about some difficulties in preventing and treating diseases in aquaculture. There are two kinds of fish, edible-type and ornamental-type. And Koi is an Ornamental fish. Skin fester disease which is a familiar disease in Koi culture can reduce the enjoyment, so prevention and cure the skin fester disease of Koi are very important. The pathogenic bacteria strain which is isolated and purified from the liver, spleen and kidney of koi with skin fester disease, and identified as Sphingomonas paucimobilis by VITEK-2automated microbiology system in this study firstly.The drug tolerance of S. paucimobilis against methanal, potassium hypermanganate and trichloroiminocyanuric acid is studied. It subcultures the S. paucimobilis living in the culture medium which contains the minimal inhibitory bacteria concentration of disinfectants. After24h, the MIC and MBC are determined again. Repeating this process to the15th generation, the study compares the change of MIC and MBC, and tests the drug tolerance. Then the bacteria is cultivated in ordinary nutrient broth medium to the the15th generation continuously. The result shows that the MIC and MBC change by the contact with the sublethal concentration’s disinfectant for long time. The MIC of methanal, potassium hypermanganate and trichloroiminocyanuric acid rose from13.6μl/L、3.11mg/L、12mg/L to17.5μl/L、5.12mg/L、16mg/L respectively, and the MBC rose from27μl/L、14.1mg/L、36mg/L to30.1μl/L、18.8mg/L、43mg/L; The MIC and MBC of three disinfectants reduce to14.9μl/L、3.26mg/L、15mg/L and26.9μl/L、17.1mg/L、39mg/L respectively in the recovery of resistance test.The drug tolerance of extract of Coptis chinensis Franch, Scutellaria baicalensis Georgi, Forsythia suspense Vahl, Rhubarb, Cortex Phellodendri Chinensis, Chinese nutgall, Pulsatilla chinensis, and Fructus Mume are studied with the similar method of disinfectants. The result shows that the MIC of8kinds of Chinese herbal medicine against S. paucimobi-lis are3.84mg/ml、3.96mg/ml、39.5mg/ml、6.56mg/ml、4.38mg/ml、5.11mg/ml、0.11mg/mL、1.08mg/mL, and the MBC are4.28mg/mL、4.38mg/mL、41.3mg/mL、7.08 mg/mL、4.69mg/mL、5.73mg/mL、0.12mg/mL、1.1mg/mL. It confirms that the bacteria is difficult to produce drug resistance against the eight kinds of Chinese herb medicine.By the research of the bacterias drug resistance against disinfectants, it shows that the bacteria produces drug resistance generating in culture medium containing disinfectants at sub-lethal concentration after a a period of time,and it dose not in the research of Chinese herb medicine. So the disinfectants should be used reasonably, but they should not be used in a low level for long time. And Chinese herbal medicine should be used preferentially.

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