对从巴格达临床标本中分离出的三种革兰氏阴性菌中对替加环素不敏感菌株的替加环素耐药性进行测序分析。
Sequencing analysis of tigecycline resistance among tigecycline non-susceptible in three species of G-ve bacteria isolated from clinical specimens in Baghdad.
作者信息
Khlaif Mariam Mahdi, Hussein Nadheema Hammood
机构信息
Branch of Microbiology, Department of Biology, College of Science, Mustansiriyah University, POX 10244, Baghdad, Iraq.
出版信息
Mol Biol Rep. 2022 Dec;49(12):11811-11820. doi: 10.1007/s11033-022-07997-8. Epub 2022 Oct 7.
BACKGROUND
Recent emergence of high-level tigecycline resistance is mediated by tet(X) genes in Gram-negative bacteria, which undoubtedly constitutes a serious threat for public health worldwide. This study aims to identify tigecycline non-susceptible isolates and detect the presence of genes that are responsible for tigecycline resistance among local isolates in Iraq for the first time.
METHODS
Thirteen clinical isolates of Klebsiella pneumonia, Acinetobacter baumannii and Pseudomonas aeruginosa tigecycline non-susceptible were investigated from blood, sputum and burns specimens. The susceptibility of different antibiotics was tested by the VITEK-2 system. To detect tigecycline resistance genes, PCR was employed.
RESULTS
Strains studied in this work were extremely drug-resistant and they were resistant to most antibiotic classes that were studied. The plasmid-encoded tet(X), tet(X1), tet(X2), tet(X3), tet(X4), tet(X5), tet(M) and tet(O) genes were not detected in the 13 isolates. The results showed that there is a clear presence of tet(A) and tet(B) genes in tigecycline non-susceptible isolates. All 13 (100%) tigecycline non-susceptible K. pneumoniae, A. baumannii and P. aeruginosa isolates harbored the tet(B) gene. In contrast, 4 (30.77%) tigecycline non-susceptible P. aeruginosa isolates harbored the tet(A) gene and there was no tigecycline non-susceptible A. baumannii isolate harboring the tet(A) gene (0%), but one (7.69%) tigecycline non-susceptible K. pneumoniae isolate harbored the tet(A) gene. A phylogenetic tree, which is based on the nucleotide sequences of the tet(A) gene, showed that the sequence of the local isolate was 87% similar to the nucleotide sequences for all the isolates used for comparison from GenBank and the local isolate displayed genetic diversity.
CONCLUSIONS
According to this study, tet(B) and tet(A) play an important role in the appearance of tigecycline non-susceptible Gram-negative isolates.
背景
近期革兰氏阴性菌中高水平替加环素耐药性的出现是由tet(X)基因介导的，这无疑对全球公共卫生构成严重威胁。本研究旨在首次鉴定伊拉克当地分离株中对替加环素不敏感的菌株，并检测导致替加环素耐药的基因的存在情况。
方法
从血液、痰液和烧伤标本中调查了13株对替加环素不敏感的肺炎克雷伯菌、鲍曼不动杆菌和铜绿假单胞菌临床分离株。通过VITEK-2系统检测不同抗生素的敏感性。采用聚合酶链反应（PCR）检测替加环素耐药基因。
结果
本研究中的菌株具有极强的耐药性，对所研究的大多数抗生素类别均耐药。在这13株分离株中未检测到质粒编码的tet(X)、tet(X1)、tet(X2)、tet(X3)、tet(X4)、tet(X5)、tet(M)和tet(O)基因。结果表明，对替加环素不敏感的分离株中明显存在tet(A)和tet(B)基因。所有13株（100%）对替加环素不敏感的肺炎克雷伯菌、鲍曼不动杆菌和铜绿假单胞菌分离株均携带tet(B)基因。相比之下，4株（30.77%）对替加环素不敏感的铜绿假单胞菌分离株携带tet(A)基因，没有对替加环素不敏感的鲍曼不动杆菌分离株携带tet(A)基因（0%），但有1株（7.69%）对替加环素不敏感的肺炎克雷伯菌分离株携带tet(A)基因。基于tet(A)基因核苷酸序列构建的系统发育树显示，本地分离株的序列与来自GenBank用于比较的所有分离株的核苷酸序列相似度为87%，且本地分离株表现出遗传多样性。
结论
根据本研究，tet(B)和tet(A)在对替加环素不敏感的革兰氏阴性分离株的出现中起重要作用。
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