Johannessen Helene, Anthonisen Inger Lill, Zecic Nermin, Hegstad Kristin, Ranheim Trond Egil, Skaare Dagfinn
Department of Microbiology, Vestfold Hospital Trust, Tønsberg, Norway.
Norwegian National Advisory Unit on Detection of Antimicrobial Resistance, Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway.
Front Microbiol. 2022 Jul 22;13:945411. doi: 10.3389/fmicb.2022.945411. eCollection 2022.
A multidrug-resistant (MDR) strain of , Hi-228, with phenotypic resistance toward ampicillin, cefotaxime, chloramphenicol, gentamicin, and azithromycin, was isolated in Oslo, Norway. The strain was part of a clonal outbreak (2016-2017) comprising five ST143 strains with identical resistotypes. Hi-228 carries a novel integrative and conjugative element (ICE), Tn, contributing to this remarkable and previously unreported MDR profile. Tn contains the following resistance genes: , '-Im, ″-Ib, (E), and . The latter four are previously unreported or rarely reported in . In this study, we investigated the genetic environment, mechanisms of transfer, impact on phenotypic susceptibility, and fitness cost of this ICE. We found that Tn has an overall structure similar to the previously described ICE Tn, with and carried by Tn and Tn, respectively. The major difference between Tn and Tn is that Tn lacks (B) but carries the resistance gene pairs '-Im and ″-Ib and (E) and . The gene pairs are located on the novel transposable elements Tn and Tn, which have high sequence identities to a plasmid in and an ICE in streptococcal species, respectively. Tn does circularize and is transferable, however, at a low frequency. Head-to-head competition experiments showed that uptake of Tn reduces bacterial fitness. Our study shows that MDR strains are capable of clonal spread and that the supragenome comprises an increasingly wide range of transferable resistance genes, with evidence of transfer from unrelated genera. The findings offer a glimpse into the genome dynamics of , highlighting the importance of rational antibiotic usage to contain antimicrobial resistance and the emergence of MDR strains in this important pathogen.
在挪威奥斯陆分离出一株对氨苄西林、头孢噻肟、氯霉素、庆大霉素和阿奇霉素具有表型抗性的多重耐药（MDR）菌株Hi-228。该菌株是一个克隆性暴发（2016 - 2017年）的一部分，该暴发包含五个具有相同耐药型的ST143菌株。Hi-228携带一种新型整合和接合元件（ICE）Tn，导致了这种显著且此前未报道的MDR谱型。Tn包含以下耐药基因：、'-Im、″-Ib、（E）和。后四个基因在中此前未报道或很少报道。在本研究中，我们调查了该ICE的遗传环境、转移机制、对表型敏感性的影响以及适应性代价。我们发现Tn的整体结构与先前描述的ICE Tn相似，其中和分别由Tn和Tn携带。Tn和Tn之间的主要差异在于Tn缺乏（B），但携带耐药基因对'-Im和″-Ib以及（E）和。这些基因对位于新型转座元件Tn和Tn上，它们分别与中的一个质粒和链球菌属中的一个ICE具有高度序列同一性。然而，Tn确实会环化并且可转移，但频率较低。头对头竞争实验表明，摄取Tn会降低细菌适应性。我们的研究表明，MDR菌株能够进行克隆传播，并且的超基因组包含越来越广泛的可转移耐药基因，有证据表明这些基因可从无关属转移而来。这些发现让我们得以一窥的基因组动态，凸显了合理使用抗生素以控制抗菌药物耐药性以及这种重要病原体中MDR菌株出现的重要性。
