由臺灣中南部地區下痢仔豬分離之廣效性乙內醯胺酶大腸桿菌之特性分析

Characteristics of Extended Spectrum β-lactamase-producing Escherichia coli from the Piglets with Diarrhea in Central and Southern Taiwan

李婉甄(Wan-Chen Lee)

指導教授 ： 葉光勝

國立臺灣大學/獸醫專業學院/獸醫學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201600230

摘要

廣效性乙內醯胺酶 (Extended spectrum β-lactamases, ESBLs) 是一種可水解 β-lactams 類抗生素，包括第三代頭孢子素的酵素。雖然 ESBLs 在全球興起和散布成為嚴重的抗藥性問題，但在臺灣，對於家畜 ESBLs 監控的相關研究仍有限。本研究的目的在於研究分析 2015 年間臺灣中南部地區，由下痢仔豬糞便所分離之具有廣效性乙內醯胺酶之大腸桿菌。275 個糞便棉棒拭子來自於台中、南投、彰化、雲林、嘉義、台南和屏東共 16 個豬場的下痢仔豬，其中 54 株大腸桿菌分離株 (19.64%) 經表現型確認試驗確定為 ESBL producer。具 ESBL 的大腸桿菌在不同地區的檢出率如下：嘉義 27.71% (23/83)、台南 20.00% (6/30) 和屏東 21.01% (25/119)，台中、南投、彰化和雲林的豬場沒有從棉棒中分離到任何具 ESBL 的大腸桿菌。抗微生物藥物敏感性方面，所有的 54 株 ESBL 分離株對於 ampicillin、amoxicillin、penicillin-G、cephalexin、cephalothin、ceftiofur、chlortetracycline、oxytetracycline 和 tetracycline 都顯示抗藥性，只有amikacin (20.37%)、amoxicillin-clavulanic acid (42.59%)、gentamicin (62.96%)、doxycycline (48.15%) 和 colistin (0.00%) 部分呈現非抗藥性。ESBL 基因型的結果中，TEM 和 CTX-M group 是兩個主要的 ESBL 基因型，blaSHV 則沒有發現於這 54 株 ESBL 陽性大腸桿菌分離株中。27 株分離株帶有 blaTEM-116、blaCTX-M-55 和 blaCTX-M-15 分別有 34 株 (34/54, 62.96%) 和 16 株 (16/54, 29.63%) 分離株，其中，有 23 株 ESBL 陽性大腸桿菌分離株同時帶有 blaTEM-116 和 blaCTX-M-55 (18/23, 33.33%)/blaCTX-M-15 (5/23, 9.26%)，另外還有唯一一株具有 blaTEM-116、blaCTX-M-55 和 blaCTX-M-65。多重基因座序列分型法 (Multilocus sequence typing, MLST) 分析顯示 ST10 clonal complexes 是最主要的族群，包括 ST10、ST167、ST44 和 ST617。ST4981 和 ST167 是在所有 ESBL 分離株中最常見的序列型。ST4981 和 ST10 分別在嘉義和屏東地區為主要流行序列型，台南地區則沒有特別流行的 ST 序列。
此研究為首次於台灣豬源大腸桿菌中檢測出 TEM-116、CTX-M-15 和 CTX-M-55乙內醯胺酶序列，抗藥性程度的增加也可能顯示著治療上的困難。從公共衛生的觀點看，下痢仔豬有可能是傳遞 ESBL 的重要保菌宿主之一，這類相關的議題值得更深入的調查研究。

關鍵字

廣效性乙內醯胺酶 ； 大腸桿菌 ； 多重基因座序列分析 ； 下痢仔豬

並列摘要

Extended spectrum β-lactamases (ESBLs) are enzymes capable of hydrolyzing beta-lactam antimicrobials, including the third-generation cephalosporins. Although the global emergence and spread of ESBLs is a serious antimicrobial resistance problem, there are limited surveillance studies regarding the ESBL of livestock in Taiwan. The objective of the present study was to analyze the fecal carriage of ESBL-producing Escherichia coli isolates from the piglets with diarrhea in the Central and Southern Taiwan during 2015. Two hundred and seventy-five fecal swabs were obtained from the piglets with diarrhea in 16 pig farms located in Taichung, Nantou, Chunghua, Yunlin, Chiayi, Tainan and Pingtung. Fifty-four E.coli isolates (19.64%) were confirmed as ESBL producers by the phenotypic confirmatory tests. The ESBL-producing E. coli detection rates in different regions were as follows: Chiayi 27.71% (23/83), Tainan 20.00% (6/30) and Pingtung 21.01% (25/119). No ESBL-producers were detected from the pig farms located in Taichung, Nantou, Chunghua and Yunlin. In respect of the antibiotic susceptibility, all 54 ESBL isolates showed resistance to ampicillin, amoxicillin, penicillin-G, cephalexin, cephalothin, ceftiofur, chlortetracycline, oxytetracycline and tetracycline, while parts of those isolates exhibited non-resistance to amikacin (20.37%), amoxicillin-clavulanic acid (42.59%), gentamicin (62.96%), doxycycline (48.15%) and colistin (0.00%). As for the results of ESBL genotype, TEM and CTX-M groups were the two major ESBL genes and no blaSHV was detected in 54 ESBL-positive E.coli isolates. Twenty-seven isolates harbored the blaTEM-116 gene. The blaCTX-M-55 and blaCTX-M-15 were identified in 34 (34/54, 62.96%) and 16 (16/54, 29.63%) isolates respectively. Among them, 23 ESBL-positive E.coli isolates carried both the blaTEM-116 and blaCTX-M-55 (18/23, 33.33%) /blaCTX-M-15 (5/23, 9.26%), while only one isolate possessed blaTEM-116, blaCTX-M-55 and blaCTX-M-65. Multilocus sequence typing (MLST) revealed that ST10 clonal complexes were the predominant group, including ST10, ST167, ST44 and ST617. ST4981 and ST167 were the most common sequence types in all ESBL isolates. ST4981 and ST10 were the dominant type in Chiayi and Pingtung, respectively, whereas no particular ST type was dominant in Tainan.
This study reported for the first time that TEM-116, CTX-M-15 and CTX-M-55 β-lactamases sequences were present in the E. coli strains isolated from swine in Taiwan. Increased level of antibiotic resistance may also indicate the difficulty in clinical treatment. From the point of view of public health, the piglets with diarrhea may be one of the reservoirs in transmission ESBLs, and such issue warrants further investigation.

並列關鍵字

ESBL ； TEM-116 ； CTX-M-55 ； E. coli ； MLST ； piglets with diarrhea

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