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Abstract：
Haemophilus seminalis is a newly proposed species that is phylogenetically related to Haemophilus haemolyticus. The distribution of H. seminalis in the human population, its genomic diversity, and its pathogenic potential are still unclear. This study reports the finding of our comparative genomic analyses of four newly isolated Haemophilus strains (SZY H8, SZY H35, SZY H36, and SZY H68) from human sputum specimens (Guangzhou, China) along with the publicly available genomes of other phylogenetically related Haemophilus species. Based on pairwise comparisons of the 16S rRNA gene sequences, the four isolates showed <98.65% sequence identity to the type strains of all known Haemophilus species but were identified as belonging to H. seminalis, based on comparable phenotypic and genotypic features. Additionally, the four isolates showed high genome-genome relatedness indices (>95% ANI values) with 17 strains that were previously identified as either \"Haemophilus intermedius\" or hemin (X-factor)-independent H. haemolyticus and therefore required a more detailed classification study. Phylogenetically, these isolates, along with the two previously described H. seminalis isolates (a total of 23 isolates), shared a highly homologous lineage that is distinct from the clades of the main H. haemolyticus and Haemophilus influenzae strains. These isolates present an open pangenome with multiple virulence genes. Notably, all 23 isolates have a functional heme biosynthesis pathway that is similar to that of Haemophilus parainfluenzae. The phenotype of hemin (X-factor) independence and the analysis of the ispD, pepG, and moeA genes can be used to distinguish these isolates from H. haemolyticus and H. influenzae. Based on the above findings, we propose a reclassification for all \"H. intermedius\" and two H. haemolyticus isolates belonging to H. seminalis with an emended description of H. seminalis. This study provides a more accurate identification of Haemophilus isolates for use in the clinical laboratory and a better understanding of the clinical significance and genetic diversity in human environments. IMPORTANCE As a versatile opportunistic pathogen, the accurate identification of Haemophilus species is a challenge in clinical practice. In this study, we characterized the phenotypic and genotypic features of four H. seminalis strains that were isolated from human sputum specimens and propose the \"H. intermedius\" and hemin (X-factor)-independent H. haemolyticus isolates as belonging to H. seminalis. The prediction of virulence-related genes indicates that H. seminalis isolates carry several virulence genes that are likely to play an important role in its pathogenicity. In addition, we depict that the genes ispD, pepG, and moeA can be used as biomarkers for distinguishing H. seminalis from H. haemolyticus and H. influenzae. Our findings provide some insights into the identification, epidemiology, genetic diversity, pathogenic potential, and antimicrobial resistance of the newly proposed H. seminalis.
摘要：
半嗜血杆菌是一种新提出的物种，与溶血嗜血杆菌有关。半精虫在人群中的分布，它的基因组多样性，其致病潜力尚不清楚。这项研究报告了我们对人类痰标本（广州，中国）以及其他与系统发育相关的嗜血杆菌物种的公开基因组。基于16SrRNA基因序列的成对比较，这四个分离株与所有已知的嗜血杆菌物种的类型菌株的序列同一性<98.65％，但被鉴定为属于南方嗜血杆菌，基于可比较的表型和基因型特征。此外,这4个分离株与之前被鉴定为"中间嗜血杆菌"或血红素(X因子)非依赖性溶血嗜血杆菌的17个菌株显示出较高的基因组-基因组相关性指数(>95%ANI值),因此需要进行更详细的分类研究.系统发育,这些隔离物,连同先前描述的两个精原虫分离株（总共23个分离株），共享高度同源的谱系，与主要的溶血嗜血杆菌和流感嗜血杆菌菌株的进化枝不同。这些分离株呈现具有多个毒力基因的开放pangenome。值得注意的是,所有23个分离株都具有与副流感嗜血杆菌相似的功能性血红素生物合成途径。血红素（X因子）的表型独立性和ispD的分析，pepG,和moeA基因可用于区分这些分离株与溶血嗜血杆菌和流感嗜血杆菌。基于上述发现,我们建议对所有\“H.intermedius\”和两个属于精原虫的溶血嗜血杆菌分离株，并带有精原虫的修饰描述。这项研究提供了更准确的鉴定用于临床实验室的嗜血杆菌分离株，并更好地了解了人类环境中的临床意义和遗传多样性。重要性作为一种多才多艺的机会病原体，如何准确鉴定嗜血杆菌是临床实践中的一个挑战。在这项研究中,我们表征了从人痰标本中分离出的四种精原虫菌株的表型和基因型特征，并提出了“H.中间型和非血氢血红素(X因子)依赖性溶血嗜血杆菌分离株属于半嗜血杆菌。对毒力相关基因的预测表明，半倒霉分离株携带几种可能在其致病性中起重要作用的毒力基因。此外,我们描绘了基因ispD，pepG,和moeA可以用作生物标志物，用于区分嗜血杆菌和溶血嗜血杆菌和流感嗜血杆菌。我们的发现为鉴定提供了一些见解，流行病学,遗传多样性,致病潜力，和新提出的西洋草的耐药性。
