同时携带 blaCTX-M、blaTEM、blaSHV、blaampC 和插入序列 IS26 和 orf513 的柠檬酸杆菌属：一个最近引起人们关注的抗生素耐药性的进化现象。
Citrobacter spp. simultaneously harboring blaCTX-M, blaTEM, blaSHV, blaampC, and insertion sequences IS26 and orf513: an evolutionary phenomenon of recent concern for antibiotic resistance.
机构信息
Section of Antimicrobial Agents and Drug Resistance Research and Microbial Biotechnology, Department of Medical Microbiology, Jawaharlal Nehru Medical College and Hospital, Aligarh Muslim University, Aligarh-202002, Uttar Pradesh, India.
出版信息
J Clin Microbiol. 2010 May;48(5):1833-8. doi: 10.1128/JCM.01467-09. Epub 2010 Mar 10.
A collection of 40 confirmed isolates of Citrobacter spp., obtained from the culture of 5,732 clinical samples during 2006 to 2008, was studied for the presence of blaCTX-M, blaTEM, blaSHV, and blaampC by monoplex and multiplex PCRs. These isolates were also looked at for the presence of insertion elements IS26 and orf513, which play an important role in the resistance gene pool. blaCTX-M, blaTEM, blaSHV, and blaampC were noticed in 67.5%, 40%, 25%, and 40% of isolates, respectively. Sequencing for the specific CTX-M type revealed the presence of CTX-M-15-type extended-spectrum beta-lactamases (ESBL). sul1-type integrons were detected in 32.5% (13/40) of isolates, and a single plasmid of ca. approximately 22 kb was also noticed in all the isolates harboring bla genes. A total of 48.2% (13/27) of isolates harboring blaCTX-M alleles were found to carry IS26 elements and 53.4% (7/13) of isolates harboring the sul1-type integrons were found to carry orf513. Alarmingly, a few isolates simultaneously carried IS26 and orf513, reflecting the occurrence of complex evolution. All the Citrobacter isolates were noticed to produce an amplicon of 400 bp in an IS26 PCR, similar to that of the predominant UK CTX-M-15-producing Escherichia coli clone (clone A) and suggesting a probable genetic relatedness between the two, which could not be proved with British and Indian E. coli isolates in our earlier studies. Here, a first report is being presented describing the occurrence of blaCTX-M-15 in Indian Citrobacter spp. This is also the first report describing the simultaneous occurrence of blaTEM, blaSHV, and blaampC along with blaCTX-M in class 1 integrons. The recent findings indicate that the genetic environment of blaCTX-M-15 has changed through the insertion of IS26 and orf513, although the consequences of these events remain uncertain. It perhaps also suggests a "turnover" of these mobile elements in the population over time.
从 2006 年至 2008 年采集的 5732 份临床样本的培养物中收集了 40 株确认的柠檬酸杆菌属分离株，通过单重和多重 PCR 研究了 blaCTX-M、blaTEM、blaSHV 和 blaampC 的存在情况。还观察了这些分离株中插入元件 IS26 和 orf513 的存在情况，它们在耐药基因库中起着重要作用。分别在 67.5%、40%、25%和 40%的分离株中发现了 blaCTX-M、blaTEM、blaSHV 和 blaampC。针对特定 CTX-M 型的测序显示存在 CTX-M-15 型扩展谱β-内酰胺酶（ESBL）。在 32.5%（13/40）的分离株中检测到 sul1 型整合子，并且在所有携带 bla 基因的分离株中还注意到约 22kb 的单个质粒。携带 blaCTX-M 等位基因的 48.2%（13/27）的分离株被发现携带 IS26 元件，携带 sul1 型整合子的 53.4%（7/13）的分离株被发现携带 orf513。令人震惊的是，少数分离株同时携带 IS26 和 orf513，反映出复杂的进化发生。所有柠檬酸杆菌分离株在 IS26 PCR 中均产生 400bp 的扩增子，与英国主要的 CTX-M-15 产生大肠杆菌克隆（克隆 A）相似，这表明两者之间可能存在遗传相关性，但在我们之前的研究中，与英国和印度的大肠杆菌分离株无法证明这一点。在这里，首次报道了在印度柠檬酸杆菌属中发现 blaCTX-M-15。这也是首次报道同时在类 1 整合子中发现 blaTEM、blaSHV 和 blaampC 以及 blaCTX-M。最近的发现表明，blaCTX-M-15 的遗传环境已通过插入 IS26 和 orf513 发生改变，尽管这些事件的后果尚不确定。这或许也表明这些移动元件在人群中的“更替”。
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