Villa Laura, Fernández-Colomer Belén, Fernández Javier, Adánez José, Acebes Cesar, Junco Montserrat, Vazquez Fernando
Microbiology Department, Central University Hospital of Asturias, Oviedo, Spain; Translational Microbiology and Infection Pathology Group, Health Research Institute of Asturias, Oviedo, Spain; Sexually Transmitted Infections Study Group of the Infectious Diseases and Clinical Microbiology Spanish Society (GEITS-SEIMC), Madrid, Spain.
Division of Neonatology, Department of Pediatrics, Central University Hospital of Asturias, Oviedo, Spain; Spanish National Network for Neonatal Infections Surveillance "Grupo Castrillo", Spain.
Clin Microbiol Infect. 2025 Jul 1. doi: 10.1016/j.cmi.2025.06.026.
The objective of this study was to assess the accuracy of a novel algorithm-designed in accordance with guidelines from the American College of Obstetricians and Gynecologists and the American Society for Microbiology-for detecting group B Streptococcus (GBS) colonization in pregnant women. Additionally, the study aimed to determine the potential impact of this algorithm on early-onset neonatal group B streptococcal disease (GBS-EOD) cases.
From March 2021 to March 2024, 5034 vaginal-rectal samples were collected from pregnant women at 35 weeks to 37 weeks gestation using ESwab™ medium. Samples were cultured in Todd Hewitt broth, subcultured on Granada medium, and tested with the DiaSorin Simplexa™ GBS Direct Assay (positive if Cycle threshold ≤ 35). Antimicrobial susceptibility testing was conducted on GBS isolates from penicillin-allergic women. GBS-positive women received intrapartum antibiotic prophylaxis. The study also reviewed cases of GBS-EOD during the same period.
In total, 938 (18.6%) pregnant women were colonized with GBS. Among these, 625 samples (66.6%) were culture-positive, whereas 313 (33.4%) were culture-negative, but broth-enriched nucleic acid amplification test (NAAT)-positive. No samples were broth-enriched NAAT-negative and culture-positive. The broth-enriched NAAT demonstrated a sensitivity of 100% (95% CI: 99-100%) and a specificity of 93% (95% CI: 92-94%), along with a positive predictive value of 67% (95% CI: 67-40%) and a negative predictive value of 100% (95% CI: 100-100%). There was substantial agreement between methods (Cohen's kappa = 0.76 [95% CI: 0.74-0.79]). All 45 GBS isolates from penicillin-allergic women were susceptible to penicillin, ampicillin, and vancomycin, whereas 44.4% (20/45) were resistant to erythromycin, and 40% (18/45) were resistant to clindamycin. No cases of GBS-EOD were detected among the 5563 live newborns during the study period (95% CI: 0-0.054%).
The novel algorithm was rapid, sensitive, and specific, effectively identifying candidates for intrapartum antibiotic prophylaxis, potentially reducing newborn infection and lowering GBS-EOD incidence and neonatal mortality rates. Integrating broth-enriched NAATs to verify negative culture samples could enhance detection and prevention efforts.
本研究的目的是评估一种根据美国妇产科医师学会和美国微生物学会的指南设计的新型算法检测孕妇B族链球菌（GBS）定植的准确性。此外，该研究旨在确定该算法对早发性新生儿B族链球菌病（GBS-EOD）病例的潜在影响。
从2021年3月至2024年3月，使用ESwab™培养基从妊娠35至37周的孕妇中采集5034份阴道直肠样本。样本在托德-休伊特肉汤中培养，在格拉纳达培养基上进行传代培养，并用DiaSorin Simplexa™ GBS直接检测法进行检测（循环阈值≤35为阳性）。对青霉素过敏女性的GBS分离株进行药敏试验。GBS阳性女性接受产时抗生素预防。该研究还回顾了同一时期的GBS-EOD病例。
共有938名（18.6%）孕妇感染了GBS。其中，625份样本（66.6%）培养阳性，而313份（33.4%）培养阴性，但肉汤富集核酸扩增试验（NAAT）阳性。没有样本肉汤富集NAAT阴性且培养阳性。肉汤富集NAAT的敏感性为100%（95%CI：99-100%），特异性为93%（95%CI：92-94%），阳性预测值为67%（95%CI：67-40%），阴性预测值为100%（95%CI：100-100%）。两种方法之间有高度一致性（科恩kappa系数=0.76[95%CI：0.74-0.79]）。所有45份来自青霉素过敏女性的GBS分离株对青霉素、氨苄西林和万古霉素敏感，而44.4%（20/45）对红霉素耐药，40%（18/45）对克林霉素耐药。在研究期间的5563名活产新生儿中未检测到GBS-EOD病例（95%CI：0-0.054%）。
该新型算法快速、灵敏且特异，能有效识别产时抗生素预防的候选对象，可能减少新生儿感染，降低GBS-EOD发病率和新生儿死亡率。整合肉汤富集NAAT以验证培养阴性样本可加强检测和预防工作。
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