Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/50822
標題: Toxin types, antibiogram, plasmid and PFGE analysis for methicillin-resistant Staphylococcus aureus strains isolated from clinical samples
Methicillin抗藥性金黃色葡萄球菌之毒素型分佈、抗生素型、質體圖譜 及脈衝式電場膠體電泳之分析
作者: 張玉芳
Chang, Yu-Fang
關鍵字: 質體圖譜
脫皮毒素
抗生素圖譜
脈衝式電場膠體電泳
聚合酉每鏈鎖反應
Methicillin抗藥性金黃色葡萄球菌
Methicillin-resistant Staphylococcus aureus
plasmid profile
exfoliative toxin
antibiogram
PFGE
PCR
出版社: 食品科學系
摘要: Methicillin抗藥性金黃色葡萄球菌(methicillin-resistant S.aureus, MRSA) 為醫院中主要的院內感染菌之一。在台灣地區,MRSA之分離率逐年 增加,因此本研究針對中部地區的醫院於1992-1998年分離出之198株MRSA 菌株,探討其抗藥性、產毒特性並配合質體圖譜及PFGE分析方法了解其感 染分佈情形。另外,亦對食品來源之金黃色葡萄球菌S. aureus產脫皮毒 素分佈加以調查,以了解此類毒素在食品病原菌之存在。利用聚合酉每 鏈鎖反應及免疫分析套組,分別針對MRSA菌株之腸毒素,脫皮毒素及中毒 性休克症候群毒素(TSST-1)基因及毒素之存在進行檢測。以腸毒素之PCR 檢測而言,198株MRSA中,有172株具腸毒素基因,其中有43株具A型腸毒 素基因,8株產B型,5株產D型,53株同時具A B型,26株具A D型,7株具 BD型,30株具A B D型,上述產毒菌在SET-RPLA的檢測中有59株產毒株, 其中有27株具A型腸毒素基因,5株產B型,3株產D型,12株同時具A B型 ,5株具A D型,1株具BD型,5株具A B D型,與PCR結果有明顯不符。在脫 皮毒素檢測方面,PCR結果顯示有22株具ETA基因,沒有菌株具ETB基因; 在RPLA結果方面,有4株產ETA毒素,只有2株與PCR結果相符,49株產ETB 毒素,23株同時產脫皮毒素A、B型,與PCR結果皆不相符。需要再設計實 驗確認之。至於TSST-1毒素,本研究中並未檢測出。而食品來源之150株 金黃色葡萄球菌脫皮毒素之PCR檢測,有38株帶有脫皮毒素基因,其中13 株具ETA型,4株具ETB型,21株同時具ETA、ETB型基因。在RPLA檢測方面 ,共有29株產毒株,產ETA有8株,ETB有8株,同時產ETA及ETB有13株。在 抗生素敏感性試驗方面,90%以上的MRSA菌株對clindamycin、 erythromycin、gentamycin、kanamycin、methicillin、oxacillin、 penicillin、streptomycin、trimethoprim及tetracycline具有抗性;沒 有對vancomycin產生抗藥性的菌株。兩醫院之間MRSA菌株之抗生素抗藥性 圖譜差異不大。本研究分離之MRSA菌株,大多帶有兩個或以上的質體,質 體大小為35.2Kb到1.1kb,只有19株菌不帶質體。可將MRSA分為27種質體 圖譜類型。兩醫院之間沒有完全相同的質體圖譜。因此可與其他分類方法 ,如PFGE,來調查MRSA菌株之間的相關性。在PFGE分析結果方面 ,1992-1993年MRSA菌株以type S 2居多,而type S 5則同為1996-1998年 分離自榮總及中山醫學院MRSA菌株之主要PFGE type。若配合抗生素圖譜 ,質體圖譜及PFGE分析,可將198株MRSA分成112個次分類型(subtype)。 其中有9個次分類型共同存在於1996-1997及1998年分離自榮總的MRSA菌株 中,此九個次分類型中有8株屬於PFGE type S5,1株屬於type S6,因此 這些MRSA菌株之間有高度種源相關性。而兩醫院之間並沒有發現完全相同 的次分類型。本研究結果可為MRSA提供流行病學研究之參考。 Methicillin-resistant Staphylococcus aureus (MRSA) is one of the major nosocomial pathogens in community hospitals. In Taiwan, the incidence of MRSA strains isolation is increasing by years. In this study, the antibiotic susceptibility and distributions of the toxin types for MRSA strains isolated from two hospitals, VGH and CSH, were investigated. In addition, the plasmid profile and PFGE analysis are used to trace the MRSA infection. Not only for MRSA, exfoliative toxins was also investigated for S. aureus strains isolated from food samples. The gene coding for staphylococcal enterotoxin , exfoliative toxin and TSST-1 toxin could be detected by PCR method. Results obtained from PCR were also compared with those from RPLA method. PCR assay showed that 172 of 198 MRSA strains possess enterotoxigenic gene, including 43 type A , 8 type B , 5 type D , 53 type AB , 26 type AD , 7 type BD and 30 type ABD strains. RPLA assay showed that only 59 strains are enterotoxigenic, including 27 type A, 5 type B, 3 type D, 12 type AB, 5 type AD, 1 type BD and 5 type ABD strains, although 172 strains indicate the possession of enterotoxigenic gene. On detection of exfoliative toxin , PCR assay showed that 22 strains pocess exfoliative toxin A (ETA) gene but none for the exfoliative toxin B (ETB) gene. In comparison with the results from RPLA assay which show that 5 strains produce ETA, 49 strains produce ETB and 23 strains produced ETA and ETB toxin, significant discrepancy was found, for the results from and PCR method. Therefore more experiments may be required to check the exfoliative toxin gene of MRSA strains isolated for this study. No TSST-1 toxin strain was found in this study by both the RPLA and the PCR method. ETA and ETB detection for S. aureus strains isolated from food sample by PCR method showed that 38 strains have exfoliative toxin gene, including 13 ETA strains, 4 ETB strains and 21 ETA and ETB strains. In comparison with the result from RPLA assay, 29 strains have positive result, including 8 ETA , 8 ETB, 13 ETA and ETB strains. The antibiotic susceptibility tests showed that no MRSA was resistant to vancomycin. The major antibiotic resistance type for all MRSA strain was resistant to clindamycin, erythromycin, gentamycin, kanamycin, methicillin, oxacillin, ofloxacin, penicillin, streptomycin, trimethoprim, and tetracycline ; There is no significant difference in the antibiogram of MRSA isolated from both hospitals. Plasmid analysis showed the 27 subtypes were found. Most of the MRSA strains bring 2-4 plasmids, the size range is 35.2-1.1Kb. Only 19 MRSA strains was without plasmid. No identical type between the two hospitals were observed.The plasmid profile can be combined for the investigation of the relatedness of MRSA isolates with other typing methods such as PFGE analysis. DNA fingerpriting analysis by PFGE revealed that the predominate PFGE type for MRSA strains isolated from VGH in 1992-1993 is type S2 . Type S5 is the major type for MRSA strains isolated from both hospitals in 1996-1998. When antibiograms , plasmid profiles and PFGE types were combined for subtyping, 112 subtypes were found for the 198 MRSA. Of these subtypes, 9 subtypes (8 in PFGE type S5, 1 in PFGE type S6) coexist between the two groups of MRSA strains isolated from VGH in two different periods (1996-1997 and 1998). These MRSA strains in PFGE type S5 and S6 are high clonally related. No identical subtype was found between VGH and CSH strains, ie, strains from these two hospitals. The results obtained may be used as the reference for epidemiology study of MRSA infection.
URI: http://hdl.handle.net/11455/50822
Appears in Collections:食品暨應用生物科技學系

文件中的檔案:

取得全文請前往華藝線上圖書館



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.