| 摘要: | 本研究收集 7 家醫學中心從 2003 年 3 月到 8 月共 281 株克雷白氏肺炎桿菌 (Klebsiella pneumoniae) 臨床菌株，這些菌株對第三代頭孢子菌素抗生素具有較高的抗性。本研究利用最小抑制濃度及紙錠擴散確認法等方法分析發現這些菌株中總共有 94.7% (266/281) 可產生超廣效性乙內醯胺酶，另外，利用 PCR 及 MIC 分析發現 281 株克雷白氏肺炎桿菌分離株中有 14.5% 擁有 plasmid-mediated AmpC 酵素。根據等電點電泳與 PCR 結果發現每一測試菌株中可能同時含有 2 或 3 種乙內醯胺酶已對廣效性頭孢子菌素具有抗性。281株克雷白氏肺炎桿菌分離株中具 TEM, CTX-M, SHV ESBLs及CMY-2與DHA-1相關性酵素基因分別佔 64.7, 55.0, 47.9, 3.5, 11.0%。利用核酸序列定序發現 blaCTX-M 基因存在 6 種subtypes，
blaCTX-M-3、blaCTX-M-13、blaCTX-M-14、blaCTX-M-17、blaCTX-M-19 和一種 novel blaCTX-M-38-related 基因。在克雷白氏肺炎桿菌 6 個 blaCTX-M subtypes 中， blaCTX-M-3 和 blaCTX-M-14 最為常見。而 blaCTX-M-17、blaCTX-M-19 和 novel blaCTX-M-38 基因則首次在台灣被發現。從不同醫院隨機選取具 blaCTX-M-3 或 blaCTX-M-14基因菌株，以 randomly amplified polymorphic DNA (RAPD) 分析可分別將其分為 17 種blaCTX-M-3 與 14 種 blaCTX-M-14 RAPD types。上述之測試菌株利用脈衝式電泳分析可將其分為18與14 種types。根據此結果發現，在不同醫院的分離株中 blaCTX-M-3 或 blaCTX-M-14 基因存在不同的現象。以異種接合實驗及質體分析發現該具有乙內醯胺酶質體可在不同種細菌間傳遞，且相似的抗藥性質體也可在不同醫院間傳播。
A total of 281 Klebsiella pneumoniae isolates were collected from seven medical center between March and August 2003. These isolates showed highly resistant to third generation of cephalosporins. The extended-spectrum β-lactamases (ESBLs) production was detected in 94.7% (266/281) of K. pneumoniae isolates by minimum inhibitory concentration (MIC) and disk diffusion confirmatory tests, and 14.5% of the K. pneumoniae isolates exhibited plasmid-mediated AmpC enzymes by PCR and MIC analysis. According the results of isoelectric focusing electrophoresis and PCR showed 281 K. pneumoniae isolates harbored two or three β-lactamases involved in resistance to extended-spectrum cephalosporins. In 281 isolates of K. pneumoniae, TEM (64.7%), CTX-M (55.0%), SHV ESBLs (47.9%), CMY-2-related enzymes (3.6%), and DHA-1-related enzymes (11.0%) were detected. Nucleotide sequencing of blaCTX-M genes revealed the presence of 6 subtypes, which were blaCTX-M-3, blaCTX-M-13, blaCTX-M-14, blaCTX-M-17, blaCTX-M-19, and a novel blaCTX-M-38-related genes. Among the seven blaCTX-M subtypes, blaCTX-M-3 and blaCTX-M-14 were predominant in K. penumoniae. The blaCTX-M-17, blaCTX-M-19, and the novel blaCTX-M-38 genes were firstly identified in Taiwan. The blaCTX-M-3- or blaCTX-M-14-positive strains were randomly selected from different hospitals, 17 types of blaCTX-M-3 and 14 types of blaCTX-M-14 were classified by randomly amplified polymorphic DNA (RAPD) analysis, 18 and 14 PFGE types were observed from these tested isolates, respectively. The results exhibited blaCTX-M-3 or blaCTX-M-14 genetic diversity among the isolates from different hospitals. The transconjugation experiments and plasmid analysis suggested these bla–positive plasmids could transfer to different species and interhospital spreading. |
