Streptococcus agalactiae (S. agalactiae) is an important pathogen that can lead to neonatus and mother infection. The current existing techniques for the identification of S. agalactiae are limited by accuracy, speed and high-cost. Therefore, a new multiple cross displacement amplification (MCDA) assay was developed for test of the target pathogen immediately from vaginal and rectal swabs. MCDA primers screening were conducted targeting S. agalactiae pcsB gene, and one set of MCDA primers with better rapidity and efficiency was selected for establishing the S. agalactiae-MCDA assay. As a result, the MCDA method could be completed at a constant temperature of 61 °C, without the requirement of special equipment. The detection limit is 250 fg (31.5 copies) per reaction, all S. agalactiae strains displayed positive results, but not for non-S. agalactiae strains. The visual MCDA assay detected 16 positive samples from 200 clinical specimen, which were also detected positive by enrichment/qPCR. While the CHROMagar culture detected 6 positive samples. Thus, the MCDA assay is prefer to enrichment/qPCR and culture for detecting S. agalactiae from clinical specimen. Particularly, the whole test of MCDA takes about 63.1 min, including sample collection (3 min), DNA preparation (15 min), MCDA reaction (45 min) and result reporting (6 s). In addition, the cost was very economic, with only US$ 4.9. These results indicated that our S. agalaciae-MCDA assay is a rapid, sensitive and cost-efficient technique for target pathogen detection, and is more suitable than conventional assays for an urgent detection, especially for 'on-site' laboratories and resource-constrained settings.

无乳链球菌（S. agalactiae）是一种重要的病原体，可导致新生儿和母亲感染。目前用于鉴定无乳链球菌的现有技术受到准确性，速度和高成本的限制。因此，开发了一种新的多重交叉置换扩增（MCDA）测定法，用于立即从阴道和直肠拭子中检测目标病原体。针对无乳链球菌pcsB基因进行了MCDA引物筛选，并选择了一组速度和效率更高的MCDA引物来建立无乳链球菌。MCDA分析。结果，无需专用设备即可在61°C的恒定温度下完成MCDA方法。每个反应的检出限为250 fg（31.5拷贝），所有无乳链球菌菌株均显示阳性结果，而非非无乳链球菌菌株均未显示阳性结果。视觉MCDA分析从200个临床样本中检测出16个阳性样本，这些样本也通过富集/ qPCR检测为阳性。而CHROMagar培养物检测到6个阳性样品。因此，MCDA分析更适合于通过扩增/ qPCR和培养来检测无乳链球菌。从临床标本。特别是，MCDA的整个测试大约需要63.1分钟，包括样品收集（3分钟），DNA制备（15分钟），MCDA反应（45分钟）和结果报告（6 s）。此外，成本非常经济，仅为4.9美元。这些结果表明，我们的银藻链球菌-MCDA检测是一种快速，灵敏且经济高效的技术，可用于靶标病原体检测，比常规检测更适合紧急检测，尤其是对于“现场”实验室和资源紧张的环境设置。