2020臺灣產食動物中所分離帶有超廣譜乙內醯胺酶大腸桿菌之盛行率及特性分析

The Prevalence and the Characteristics of the Extended-Spectrum β-Lactamases-Producing Escherichia coli from Food Animals in Taiwan in 2020

李得亨(Te-Heng 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(2021年)

https://doi.org/10.6342/NTU202101218

摘要

超廣譜乙內醯胺酶 (extend-spectrum β-lactamase, ESBL) 為一種能夠破壞乙內醯胺類抗生素的酵素，包含第三代頭孢菌素，從而使細菌產生抗藥性。大腸桿菌為常見的共生菌，廣泛存在於動物腸道中，並能透過污染食物鏈的方式影響人體健康。因此，帶有ESBL的大腸桿菌 (ESBL-producing E. coli) 為公共健康的隱患之一。本研究旨在調查2020年間ESBL-producing E. coli在台灣健康產食動物中的盛行率與特性分析。總計共分析490株大腸桿菌，其ESBL-producing E. coli的盛行率在雞、豬及牛分別為10.9% (17/156)、4.27% (7/164) 及8.82% (15/170)。總體盛行率為7.96% (39/490)。ESBL基因型檢測結果顯示，在雞隻檢體中，檢測到CTX-M-1group與TEM group。而豬隻檢體則有CTX-M-1group、CTX-M-2 group、CTX-M-9 group與TEM group。牛隻除了沒有檢測到CTX-M-2 group 以外，其餘的基因型與豬隻檢體相同。綜合三個物種來說，檢出率最高的基因型為CTX-M-1 group (32/46, 69.6%)，而CTX-M-8、CTX-M-25與SHV基因型則均未檢出。針對常見的13種抗生素進行藥物敏感性試驗，包括amoxicillin/clavulanic acid、ampicillin、cephalothin、ceftiofur、nalidixic acid、ciprofloxacin、enrofloxacin、tetracycline、doxycycline、amikacin、streptomycin、gentamicin、sulfamethoxazole/trimethoprim。結果顯示所有的ESBL-producing E. coli都具有多重抗藥性，除了對乙內醯胺類抗生素具有高比例的抗藥性外，對四環黴素、磺胺劑與鏈黴素也同樣具有高比例的抗藥性。這些細菌對於amoxicillin/clavulanic acid、氨基配糖體類 (鏈黴素除外) 與奎諾酮類抗生素，則呈現較高的感受性。另外，接合試驗結果顯示，多數菌株具有水平轉移ESBL基因的能力。在牛隻檢體中100% 均可轉移，而在雞隻與豬隻檢體中，則分別為94.1% 與54.1%。多重序列分型法結果顯示ESBL-producing E. coli的分型具有高度多樣性，共分離出28種不同的序列分型。最常見的為ST162與ST1249，分別各有4株。依照物種進行菌株的親緣樹分析，發現物種內的菌株間無緊密的親緣關係，因此沒有特定的演化趨勢可循。本研究提供了健康產食動物中ESBL-producing E. coli的盛行率與特性分析，可做為流行病學研究或抗藥性監測的初步參考。ESBL-producing microorganism的檢測應持續進行，以便擬定合適的抗生素使用策略並期許能減緩抗藥性細菌的浮現。

關鍵字

超廣譜乙內醯胺酶 ； 大腸桿菌 ； 多重抗藥性 ； 產食動物 ； 接合試驗 ； 多重序列分型法

並列摘要

Extend-spectrum β-lactamases (ESBLs) can hydrolyze β-lactam antibiotics, including the third-generation cephalosporins, and confer bacteria to resist antibiotic treatment. E. coli, as a commensal flora, is widely distributed in animal intestines and could pose a threat to human health through contaminating the food chain. Hence, the ESBL-producing E. coli is a potential hazard against public health. This study aimed to investigate the prevalence and the characteristics of the ESBL-producing E. coli from food animals in Taiwan in 2020. Totally, 490 bacterial isolates were analyzed in the present study. The result revealed that the prevalence in chicken, pigs, and cattle was 10.9% (17/156), 4.27% (7/164), and 8.82 (15/170), respectively. The total prevalence among the three species was 7.96% (39/490). The CTX-M-1 group and the TEM group were the ESBL genes detected in chicken isolates. Pig isolates carried CTX-M-1group, CTX-M-2 group, CTX-M-9 group, and TEM group, whereas cattle isolates possessed the same ESBL genes as the pig isolates except CTX-M-2 group. The most frequently detected ESBL gene was CTX-M-1 group (32/46, 69.6%) in all isolates, while CTX-M-8 group, CTX-M-25 group, and SHV group were not found. All the 39 ESBL-producing E. coli exhibited multidrug-resistance properties. Besides to β-lactam antibiotics, these isolates were also highly resistant to tetracycline, sulfonamides, and streptomycin. However, they were relatively susceptible to amoxicillin/clavulanic acid, aminoglycosides (except streptomycin), and quinolones. The conjugation test demonstrated that all the cattle isolates could transfer ESBL genes horizontally, while chicken and pig isolates showed 94.1% and 54.1% of the transfer rate, respectively. In total, there were 28 sequence types (STs) identified from the 39 ESBL-producing E. coli, indicating the high diversity in sequence types of these isolates. The most frequently found clones were ST162 (n=4) and ST1249 (n=4). Through phylogenetic analysis, no close related clones among the ESBL-producing E. coli were observed, which may suggest that there was no specific evolution pattern of these ESBL-producing E. coli. This study provides a comprehensive analysis of the prevalence and the characteristics of the ESBL-producing E. coli from the healthy food animals, which can serve as a preliminary reference for epidemiology research and antibiotic surveillance programs. In order to manage proper antibiotic tactics and decrease the emergence of antimicrobial resistance, continuous surveillance of the ESBLs-producing microorganisms from food animals is essential.

並列關鍵字

extend-spectrum β-lactamases ； Escherichia. coli ； multidrug resistance ； food animals ； conjugation ； multilocus sequence typing

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