Haemophilus influenzae colonizes the respiratory tract in humans and causes both invasive and noninvasive infections. Resistance to extended-spectrum cephalosporins in H. influenzae is rare in Europe. In this study, we defined acquired resistance gene loci and ftsI mutations in multidrug-resistant (MDR) and/or PBP3-mediated beta-lactam-resistant (rPBP3) H. influenzae strains, intending to understand the mode of spread of antibiotic resistance determinants in this species. Horizontal transfer of mobile genetic elements and transformation with resistance-conferring ftsI alleles were contributory. We found one small plasmid and three novel integrative conjugative elements (ICEs) which carry different combinations of resistance genes. Demonstration of transfer and/or ICE circular forms showed that the ICEs are functional. Two extensively MDR genetically unrelated H. influenzae strains (F and G) from the same geographical region shared an identical novel MDR ICE (Tn6686) harboring bla TEM-1, catA2-like, and tet(B). The first Nordic case of MDR H. influenzae septicemia, strain 0, originating from the same geographical area as these strains, had a similar resistance pattern but contained another ICE [Tn6687 with bla TEM-1, catP and tet(B)] with an overall structure quite similar to that of Tn6686. Comparison of the complete ftsI genes among rPBP3 strains revealed that the entire gene or certain regions of it are identical in genetically unrelated strains, indicating horizontal gene transfer. Our findings illustrate that H. influenzae is capable of acquiring resistance against a wide range of commonly used antibiotics through horizontal gene transfer, in terms of conjugative transfer of ICEs and transformation of chromosomal genes.IMPORTANCE Haemophilus influenzae colonizes the respiratory tract in humans and causes both invasive and noninvasive infections. As a threat to treatment, resistance against critically important antibiotics is on the rise in H. influenzae Identifying mechanisms for horizontal acquisition of resistance genes is important to understand how multidrug resistance develops. The present study explores the antimicrobial resistance genes and their context in beta-lactam-resistant H. influenzae with coresistance to up to four non-beta-lactam groups. The results reveal that this organism is capable of acquiring resistance to a wide range of commonly used antibiotics through conjugative transfer of mobile genetic elements and transformation of chromosomal genes, resulting in mosaic genes with a broader resistance spectrum. Strains with chromosomally mediated resistance to extended-spectrum cephalosporins, co-trimoxazole, and quinolones combined with mobile genetic elements carrying genes mediating resistance to ampicillin, tetracyclines, and chloramphenicol have been reported, and further dissemination of such strains represents a particular concern.

中文翻译：

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水平基因转移在流感嗜血杆菌多药耐药性发展中的作用。

流感嗜血杆菌定居于人类呼吸道，并引起侵入性和非侵入性感染。在欧洲，对流感嗜血杆菌对广谱头孢菌素的耐药性罕见。在这项研究中，我们定义了耐多药（MDR）和/或PBP3介导的β-内酰胺耐药（rPBP3）流感嗜血杆菌菌株中的获得性耐药基因位点和ftsI突变，旨在了解抗生素耐药性决定簇的传播方式在这个物种中。可移动遗传元件的水平转移和具有抗性的ftsI等位基因的转化是重要的。我们发现了一个小的质粒和三个新颖的整合共轭元件（ICEs），它们携带了不同的抗性基因组合。转移和/或ICE循环形式的演示表明ICE具有功能。来自同一地理区域的两个广泛的MDR遗传无关的流感嗜血杆菌菌株（F和G）共享相同的新型MDR ICE（Tn6686），其中带有bla TEM-1，catA2类和tet（B）。北欧首例MDR流感败血病，菌株0，与这些菌株在相同的地理区域，具有相似的抗药性模式，但包含另一个ICE [Tn6687，bla TEM-1，catP和tet（B）]，带有总体结构与Tn6686非常相似。rPBP3菌株之间完整的ftsI基因的比较表明，在遗传无关的菌株中，整个基因或其某些区域是相同的，表明水平基因转移。我们的发现表明，流感嗜血杆菌能够通过水平基因转移获得对多种常用抗生素的抗药性，ICE的共轭转移和染色体基因的转化。重要信息流感嗜血杆菌定居于人类呼吸道，并引起侵入性和非侵入性感染。作为对治疗的威胁，流感嗜血杆菌对至关重要的抗生素的耐药性正在上升。水平获取耐药基因的识别机制对于理解多药耐药性的发展很重要。本研究探索了对多达四个非β-内酰胺基团具有耐药性的抗β-内酰胺类流感嗜血杆菌的抗菌素耐药基因及其背景。结果表明，这种生物能够通过移动遗传元件的结合转移和染色体基因的转化来获得对多种常用抗生素的抗性，从而产生具有更广泛抗性谱的镶嵌基因。已经报道了具有染色体介导的对广谱头孢菌素，复方新诺明和喹诺酮类耐药的菌株，结合携带携带介导氨苄青霉素，四环素和氯霉素抗性的基因的活动遗传元件，这种菌株的进一步传播引起了特别关注。