Isidro Joana, Menezes Juliana, Serrano Mónica, Borges Vítor, Paixão Pedro, Mimoso Margarida, Martins Filomena, Toscano Cristina, Santos Andrea, Henriques Adriano O, Oleastro Mónica
Departamento de Doenças Infecciosas, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisbon, Portugal.
Departamento de Genética Humana, Unidade de Tecnologia e Inovação, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisbon, Portugal.
Front Microbiol. 2018 Dec 6;9:2994. doi: 10.3389/fmicb.2018.02994. eCollection 2018.
infection (CDI) is prevalent in healthcare settings. The emergence of hypervirulent and antibiotic resistant strains has led to an increase in CDI incidence and frequent outbreaks. While the main virulence factors are the TcdA and TcdB toxins, antibiotic resistance is thought to play a key role in the infection by and dissemination of . A CDI outbreak involving 12 patients was detected in a tertiary care hospital, in Lisbon, which extended from January to July, with a peak in February, in 2016. The isolates, obtained from anaerobic culture of stool samples, were subjected to antimicrobial susceptibility testing with Eteststrips against 11 antibiotics, determination of toxin genes profile, PCR-ribotyping, multilocus variable-number tandem-repeat analysis (MLVA) and whole genome sequencing (WGS). Of the 12 CDI cases detected, 11 isolates from 11 patients were characterized. All isolates were / and belonged to ribotype 017, and showed high level resistance to clindamycin, erythromycin, gentamicin, imipenem, moxifloxacin, rifampicin and tetracycline. The isolates belonged to four genetically related MLVA types, with six isolates forming a clonal cluster. Three outbreak isolates, each from a different MLVA type, were selected for WGS. Bioinformatics analysis showed the presence of several antibiotic resistance determinants, including the Thr82Ile substitution in , conferring moxifloxacin resistance, the substitutions His502Asn and Arg505Lys in for rifampicin resistance, the gene, associated with tetracycline resistance, and two genes encoding putative aminoglycoside-modifying enzymes, and . Furthermore, a not previously described 61.3 kb putative mobile element was identified, presenting a mosaic structure and containing the genes , / and , associated with macrolide, lincosamide and streptogramins resistance. A substitution found in a class B penicillin-binding protein, Cys721Ser, is thought to contribute to imipenem resistance. We describe an epidemic, / , multidrug resistant clone of from ribotype 017 associated with a hospital outbreak, providing further evidence that the lack of TcdA does not impair the infectious potential of these strains. We identified several determinants of antimicrobial resistance, including new ones located in mobile elements, highlighting the importance of horizontal gene transfer in the pathogenicity and epidemiological success of .
艰难梭菌感染（CDI）在医疗机构中很普遍。高毒力和抗生素耐药菌株的出现导致CDI发病率增加和频繁暴发。虽然主要毒力因子是TcdA和TcdB毒素，但抗生素耐药性被认为在感染及传播中起关键作用。2016年，在里斯本的一家三级护理医院检测到一起涉及12名患者的CDI暴发，暴发从1月持续到7月，2月达到高峰。从粪便样本厌氧培养中获得的分离株，用Etest试纸条对11种抗生素进行药敏试验，测定毒素基因谱、PCR核糖体分型、多位点可变数目串联重复分析（MLVA）和全基因组测序（WGS）。在检测到的12例CDI病例中，对11名患者的11株分离株进行了特征分析。所有分离株均为[具体菌型]，属于核糖体分型017，对克林霉素、红霉素、庆大霉素、亚胺培南、莫西沙星、利福平和四环素表现出高水平耐药。这些分离株属于四种遗传相关的MLVA类型，其中六株形成一个克隆簇。从不同的MLVA类型中各选取一株暴发分离株进行WGS。生物信息学分析显示存在几种抗生素耐药决定因素，包括在[具体基因]中Thr82Ile替换导致对莫西沙星耐药，在[具体基因]中His502Asn和Arg505Lys替换导致对利福平耐药，与四环素耐药相关的[具体基因]，以及两个编码假定氨基糖苷修饰酶的基因[具体基因1]和[具体基因2]。此外，还鉴定出一个以前未描述的61.3 kb假定移动元件，呈现镶嵌结构，包含与大环内酯、林可酰胺和链阳菌素耐药相关的基因[具体基因3]、[具体基因4]和[具体基因5]。在B类青霉素结合蛋白中发现的Cys721Ser替换被认为有助于亚胺培南耐药。我们描述了一种来自核糖体分型017的与医院暴发相关的流行、[具体菌型]、多重耐药克隆，进一步证明缺乏TcdA并不损害这些菌株的感染潜力。我们鉴定了几种抗生素耐药决定因素，包括位于移动元件中的新因素，突出了水平基因转移在[艰难梭菌]致病性和流行病学成功中的重要性。
