| Summary: | 博士 === 義守大學 === 化學工程學系暨生物技術與化學工程研究所 === 107 === The problem of antibiotic-resistant strains has become a global public issue; antibiotic resistance not only limits the choice of treatments but also increases the morbidity, mortality and treatment costs. The multi-drug resistant Acinetobacter baumannii is occurring simultaneously in hospital and has become a major public health issue worldwide. Antimicrobial-resistant strains of Acinetobacter baumannii, including multidrug-resistant Acinetobacter baumannii (MDRAB), carbapenem resistant Acinetobacter baumannii (CRAB), extended-spectrum β-lactamases producing gram-negative bacteria (ESBL producing GNB), extensively drug-resistant Acinetobacter baumannii (XDRAB) and pandrug resistant Acinetobacter baumannii (PDRAB) strains, endanger the efficacy of antibiotics and threaten with millions of lives of the world. Although many medical units have begun to control the use of antibiotics and paid attention to the issue of drug resistance, understanding of the transmission pathways of clinical drug-resistant bacteria and drug-resistant mechanisms can be effective to real-time control and prevent the outbreak of antibiotic resistant pathogens. In this study, a total of 154 isolates of Acinetobacter baumannii obtained from Chia-Yi Christian hospital were collected for antibiotic-susceptibility assay, specific resistance genotyping and biofilm formation analysis. The statistical analysis was used to determine the interaction between antibiotic-susceptibility, specific resistance genotype combinations and biofilm formation. Antibiotic-susceptibility assays were conducted with disc diffusion method and minimum inhibitory concentration determination; a total of 11 antibiotics included cephalexin, ceftazidime, imipenem, gentamycin, amikacin, streptomycin, piperacillin, ticarcillin, carbenicillin, tetracyline and sulfamethoxazole-triethoprim were used for the assays. Nine genes related to drug resistance, including blaOXA-51-like , blaOXA-23-like, blaOXA-58-like, blaOXA-24-like, blaOXA-143-like, tnpA, ISAba1, blaNDM and blaADC were selected for genotyping analysis. In addition, Carba NP test was used to rapidly analyze the resistant genes. The analysis of biofilm formation was determined by spectrophotometry and scanning electron microscope observation, and the biofilm related genes, including bap, blaPER, ompA and csuE, were analyzed. The results showed that most of the tested strains possessed multiple drug resistance against most of the test antibiotics. Among the carbapenem resistant strains of Acinetobacter baumannii, 93% of the strains carried ISAba1 gene and 68% of the highly multidrug-resistant strains carried tnpA and ISAba1 genes. In the biofilm formation analysis, it was found that the multiple drug resistant isolates usually provided a higher biofilm formation. The experimental results indicated that the antibiotic resistance, the formation of biofilm and the resistant genotype were significantly related. The results of this study can effectively help to understand the correlation between drug resistance, biofilm formation and its resistant genotype. The analysis on the antibiotic resistant mechanism provides the valuable information to the screening, identification, diagnosis, treatment and control of clinical antibiotic-resistant pathogens, and an important reference pointer to prevent strains from producing resistance.
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