背景:木葡萄球菌是一种凝固酶阴性,在环境中发现的革兰氏阳性球菌,作为动物皮肤和粘膜表面的共生生物。尽管木耳链球菌被认为是一种非致病性细菌,几项研究已经将木耳链球菌与动物和人类的机会性感染联系起来。在巴士拉省对引起乳腺炎的病原体进行调查期间,伊拉克,我们从一头患有慢性乳腺炎的奶牛的牛奶样本中鉴定出一株耐抗生素的木耳链球菌NM36菌株。除了强大的生物膜形成,发现了多种抗生素抗性表型。为了进一步了解这些表型的遗传背景,分析了木贼NM36的全基因组。
结果:基因组由单个环状2,668,086个碱基对染色体组成,含有32.8%的GC。有2454个蛋白质编码序列,4核糖体RNA(rRNA)基因,和基因组中的50个转移RNA(tRNA)基因。此外,通过搜索具有代表性的参考基因组的序列数据来研究遗传变异。因此,进行了单核苷酸多态性分析,发现有46,610个单核苷酸多态性(SNP),523个插入,551个删除。为了克服抗生素,S.xylosusNM36已经配备了来自多个群体和家族的几种抗生素抗性基因。PathoSystems资源整合中心(PATRIC)中的基因组注释服务和使用子系统技术(RAST)注释服务器的快速注释表明,存在多个抗菌素耐药性元素,包括抗生素失活酶(BlaZ家族,FosB),抗生素抗性基因簇(TcaB,TcaB2,TcaR),参与甲氧西林抗性的蛋白质(LytH,FmtA,FemC,HmrB,HmrA),TetR家族转录调节因子,和外排泵赋予抗生素耐药性(NorA)。此外,我们对NM36菌株的生物膜和群体感应元件进行了研究和分类,发现它具有多个生物膜调节因子子集,确认其致病性。
结论:这些发现需要在处理凝固酶阴性葡萄球菌时重新评估微生物和临床干预措施,特别是在与公共卫生有关的研究中。这是第一次,根据我们的知识,木耳链球菌的整个基因组已经在伊拉克进行了测序。
BACKGROUND: Staphylococcus xylosus is a coagulase-negative, gram-positive coccus that is found in the environment and as a commensal organism on the skin and mucosal surfaces of animals. Despite the fact that S. xylosus is considered a nonpathogenic bacterium, several studies have linked S. xylosus to opportunistic infections in both animals and humans. During an investigation of mastitis-causing agents in the governorate of Basrah, Iraq, we identified an antibiotic-resistant strain of S. xylosus NM36 from a milk sample from a cow with chronic mastitis. In addition to robust biofilm formation, multiple antibiotic resistance phenotypes were found. To further understand the genetic background for these phenotypes, the full genome of S. xylosus NM36 was analyzed.
RESULTS: The genome consisted of a single circular 2,668,086 base pairs chromosome containing 32.8% G + C. There were 2454 protein-coding sequences, 4 ribosomal RNA (rRNA) genes, and 50 transfer RNA (tRNA) genes in the genome. In addition, genetic variation was studied by searching sequence data against a representative reference genome. Consequently, single-nucleotide polymorphism analysis was conducted and showed that there were 46,610 single-nucleotide polymorphisms (SNPs), 523 insertions, and 551 deletions. In order to overcome antibiotics, S. xylosus NM36 had been armed with several antibiotic resistance genes from several groups and families. The genome annotation service in PathoSystems Resource Integration Center (PATRIC) and Rapid Annotation using Subsystem Technology (RAST) annotation servers showed that there are multiple antimicrobial resistance elements, including antibiotic inactivation enzymes (BlaZ family, FosB), antibiotic resistance gene clusters (TcaB, TcaB2, TcaR), proteins involved in methicillin resistance (LytH, FmtA, FemC, HmrB, HmrA), TetR family transcriptional regulators, and efflux pumps conferring antibiotic resistance (NorA). In addition, we investigated and categorized the biofilm and quorum-sensing elements of the NM36 strain and found that it has multiple subsets of biofilm regulators, confirming its pathogenic nature.
CONCLUSIONS: These findings necessitate a reevaluation of microbial and clinical interventions when dealing with coagulase-negative staphylococci, particularly in the context of studies pertaining to public health. This is the first time, to our knowledge, that the entire genome of S. xylosus has been sequenced in Iraq.