| Summary: | 碩士 === 元培科技大學 === 醫學檢驗生物技術研究所 === 99 === Acinetobacter baumannii (AB) is an aerobic, non-fermenting, Gram-negative bacillus and distributed widespread in the natural environment, could survival in a dry environment for up to 13 days, even longer than 2 weeks. AB can persistently living in dry or moist hospital environment in this special characteristic become an important opportunistic pathogenic bacteria. AB is easily produced a new antibiotic resistant strain in recent years and many multiple-resistant strains are emerged, and the only treatment method is antibiotics combination therapy. The past researches for opportunistic infection of AB were focused on the infections from lung or wound. However, our experimental design is in mouse model: multi-resistant strains (MDRAB) isolated from the hospital patients. 109 CFU of bacteria are injected by intra-peritoneal, mice were sacrificed after 3 hours then blood smear staining and bacterial cultures were all positive. The bacterial cultures of homogeneous liquids from liver, spleen or kidney were also positive. These results indicated that the production of bacteremia was in early stages to induce systemic infection and the mortality rate reached 100% after 24 hours. The blood smear staining and bacterial culture were two-thirds positive under the injection of 107 CFU after 12 hours, but the results were negative after 24 hours. The bacterial cultures of homogeneous liquids from liver, spleen or kidney were negative in any periods, indicating the inoculation of 107 CFU required longer duration to produce bacteremia, and the death was 0 % after 24 hrs showed would not form the systemic infection. The WBC counts were less than 2000/mm3 (normal 4000-5000/mm3) after 3 hours MDRAB injection. However, the ratios of neutrophils were significantly increased above 30%. The ratio of lymphocytes decreased to below 80% in low concentrations treatment. Usage of tissue biopsy stain, the liver, spleen and kidneys were infiltrated by large number of neutrophils, liver and spleen was congested after 6-12 hours and liver and spleen displayed abscess (abscess) phenomenon under high bacteria concentration treatment. In particular, some of variations for tissue biopsy are not mentioned by other mice model studies. We also measured the production of the cytokine TNF-α and IL-1β from blood after bacteria infection. The productions of TNF-α and IL-1β showed a positive relationship to the dose of injection. However, the productions were beginning decline after injection for 12 hours. The results also showed that multi-drug resistant Acinetobacter baumannii lead to diarrhea and nasal bleeding. Thus, mice injected MDRAB by intraperitoneal actually induced bacteremia, change the amount of WBC in blood. The organs infiltrated by bacteria and WBC. The productions of cytokines were also increased significantly. Therefore, the injection of MDRAB in mice model could benefit for future investigation and research on the infection mechanism.
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