strain typing

应变分型
  • 文章类型: Observational Study
    背景:金黄色葡萄球菌是一种多宿主人畜共患病原体,可引起人类和家畜疾病。制作工匠奶酪的奶牛场对金黄色葡萄球菌的控制有着独特的关注。抗菌素抗性(AMR)金黄色葡萄球菌是公众和动物健康关注的问题。有必要研究人-动物界面AMR金黄色葡萄球菌的种群结构,并了解人畜共患传播的途径。这项横断面观察研究旨在评估从牛和人类中分离出的金黄色葡萄球菌的遗传多样性和AMR模式在生产和销售农庄奶酪的常规和有机佛蒙特州奶牛场。
    结果:注册了佛蒙特州19个奶牛场的便利样本,从四分之一牛奶(CQM)中收集了160株金黄色葡萄球菌分离株,散装罐牛奶(BTM),人手和鼻拭子。重复数据删除后,89个分离株用于分析。通过多位点序列分型确定序列类型(ST),并将其编入PubMLST数据库。鉴定了9种确定的和5种新颖的ST。对于BTM和CQM样本,在适应奶牛的CC97和CC151中鉴定出6个ST。从BTM和CQM中分离出两种人适应的ST。从人类样品中鉴定出具有八个ST的七个适应于人类的克隆复合物。从人中分离出一头适应牛的ST。使用圆盘扩散和肉汤微量稀释方法测试了分离株的抗菌敏感性。大约27%的分离株具有β-内酰胺抗性和blaZ基因阳性。与来自CQM或BTM的分离株相比,来自人拭子的金黄色葡萄球菌分离株更可能携带blaZ。从同一农场的奶牛和人类中分离出的金黄色葡萄球菌属于不同的STs。
    结论:与奶牛相比,人类更容易携带β-内酰胺抗性金黄色葡萄球菌,在有机农场中,仅从BTM中分离出适应人类的BlaZ阳性ST。此外,我们确定了宿主物种之间金黄色葡萄球菌序列类型的潜在溢出事件.有机奶牛场和传统奶牛场都存在抗青霉素的人适应金黄色葡萄球菌,这凸显了公众和动物健康交界处的“一个健康”问题,需要进一步监测。
    BACKGROUND: Staphylococcus aureus is a multi-host zoonotic pathogen causing human and livestock diseases. Dairy farms that make artisan cheese have distinctive concerns for S. aureus control. Antimicrobial-resistant (AMR) S. aureus is a public and animal health concern. There is a need to study the population structure of AMR S. aureus at the human-animal interface and understand the path of zoonotic transmission. This cross-sectional observational study aimed to assess the genetic diversity and AMR patterns of S. aureus isolated from cattle and humans on conventional and organic Vermont dairy farms that produce and sell farmstead cheese.
    RESULTS: A convenience sample of 19 dairy farms in Vermont was enrolled, and 160 S. aureus isolates were collected from cow quarter milk (CQM), bulk tank milk (BTM), human-hand and -nasal swabs. After deduplication, 89 isolates were used for the analysis. Sequence types (STs) were determined by multilocus sequence typing and cataloged to the PubMLST database. Nine defined and five novel STs were identified. For BTM and CQM samples, six STs were identified within cow-adapted CC97 and CC151. Two human-adapted STs were isolated from BTM and CQM. Seven human-adapted clonal complexes with eight STs were identified from human samples. One cow-adapted ST was isolated from a human. Antimicrobial susceptibility of the isolates was tested using disc diffusion and broth microdilution methods. Approximately 27% of the isolates were beta-lactam resistant and blaZ gene-positive. S. aureus isolates from human swabs were more likely to carry blaZ compared to isolates from CQM or BTM. S. aureus isolated from cows and humans on the same farm belonged to different STs.
    CONCLUSIONS: Humans were more likely to carry beta-lactam-resistant S. aureus compared to cows, and on organic farms only human-adapted blaZ positive STs were isolated from BTM. Moreover, we identified potential spillover events of S. aureus sequence types between host species. The presence of penicillin-resistant-human-adapted S. aureus on both organic and conventional dairy farms highlights a \"One Health\" concern at the junction of public and animal health requiring further surveillance.
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  • 文章类型: Journal Article
    Staphylococcus aureus remains a major health problem responsible for many epidemic outbreaks. Therefore, the development of efficient and rapid methods for studying molecular profiles of S. aureus strains for its further typing is in high demand. Among many techniques, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI TOF MS) represents a timely, cost-effective, and reliable strain typing approach, which is still rarely used due to insufficient knowledge about the impact of sample preparation and analysis conditions on the molecular profiles and strain classification efficiency of S. aureus. The aim of this study was to evaluate the effect of the culture conditions and matrix type on the differentiation of molecular profiles of various S. aureus strains via the MALDI TOF MS analysis and different computational methods. The analysis revealed that by changing the culture conditions, matrix type, as well as a statistical method, the differentiation of S. aureus strains can be significantly improved. Therefore, to accelerate the incorporation of the MALDI-based strain typing in routine laboratories, further studies on the standardization and searching of optimal conditions on a larger number of isolates and bacterial species are of great need.
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