發(fā)布者：抗性基因網(wǎng) 時(shí)間：2023-06-14 瀏覽量：1660
摘要
? ? ? 雖然對(duì)抗生素耐藥性質(zhì)粒的最詳細(xì)分析集中在臨床分離株中發(fā)現(xiàn)的那些，但對(duì)流動(dòng)遺傳元件的巨大環(huán)境庫(kù)及其編碼的耐藥性和毒力因子知之甚少。我們從受廢水影響的沿海濕地中選擇性分離出三株耐頭孢噻肟大腸桿菌。頭孢噻肟耐藥表型在一小時(shí)后可傳播給實(shí)驗(yàn)室大腸桿菌菌株，每個(gè)受體的頻率高達(dá)10?3個(gè)轉(zhuǎn)偶聯(lián)物。其中兩個(gè)質(zhì)粒也將頭孢噻肟耐藥性轉(zhuǎn)移到了惡臭假單胞菌，但這些質(zhì)粒無(wú)法將這種耐藥性從惡臭假單胞桿菌反向轉(zhuǎn)移到大腸桿菌。除了頭孢菌素外，大腸桿菌跨偶聯(lián)物還遺傳了對(duì)至少七類不同抗生素的耐藥性。完整的核苷酸序列顯示具有全球分布的復(fù)制子序列類型F31:A4:B1和F18:B1:C4的大型IncF型質(zhì)粒攜帶不同的抗生素耐藥性和毒力基因。質(zhì)粒編碼超廣譜β-內(nèi)酰胺酶blaCTX-M-15或blaCTX-M-55，每個(gè)都與插入序列ISEc9相關(guān)，盡管在不同的局部排列中。盡管抗性譜相似，但質(zhì)粒只有一個(gè)共同的抗性基因，氨基糖苷乙酰轉(zhuǎn)移酶aac（3）-IIe。質(zhì)粒附屬貨物還包括參與鐵獲取和防御宿主免疫的毒力因子。盡管它們的序列相似，但還是檢測(cè)到了一些大規(guī)模重組事件，包括重排和反轉(zhuǎn)?？傊?，用單一抗生素頭孢噻肟進(jìn)行篩選，產(chǎn)生了具有多重耐藥性和毒力因子的偶聯(lián)質(zhì)粒。顯然，限制抗生素耐藥性和毒力在細(xì)菌中傳播的努力必須包括更好地了解自然和人類影響環(huán)境中的流動(dòng)元素。
Abstract
While most detailed analyses of antibiotic resistance plasmids focus on those found in clinical isolates, less is known about the vast environmental reservoir of mobile genetic elements and the resistance and virulence factors they encode. We selectively isolated three strains of cefotaxime-resistant Escherichia coli from a wastewater-impacted coastal wetland. The cefotaxime-resistant phenotype was transmissible to a lab strain of E. coli after one hour, with frequencies as high as 10?3 transconjugants per recipient. Two of the plasmids also transferred cefotaxime resistance to Pseudomonas putida, but these were unable to back-transfer this resistance from P. putida to E. coli. In addition to the cephalosporins, E. coli transconjugants inherited resistance to at least seven distinct classes of antibiotics. Complete nucleotide sequences revealed large IncF-type plasmids with globally distributed replicon sequence types F31:A4:B1 and F18:B1:C4 carrying diverse antibiotic resistance and virulence genes. The plasmids encoded extended-spectrum β-lactamases blaCTX-M-15 or blaCTX-M-55, each associated with the insertion sequence ISEc9, although in different local arrangements. Despite similar resistance profiles, the plasmids shared only one resistance gene in common, the aminoglycoside acetyltransferase aac(3)-IIe. Plasmid accessory cargo also included virulence factors involved in iron acquisition and defense against host immunity. Despite their sequence similarities, several large-scale recombination events were detected, including rearrangements and inversions. In conclusion, selection with a single antibiotic, cefotaxime, yielded conjugative plasmids conferring multiple resistance and virulence factors. Clearly, efforts to limit the spread of antibiotic resistance and virulence among bacteria must include a greater understanding of mobile elements in the natural and human-impacted environments.
https://www.sciencedirect.com/science/article/abs/pii/S0147619X23000136