直接乳胶凝集试验、富集后乳胶凝集试验和培养法在孕晚期B族链球菌筛查中的诊断性能：一项比较研究
Diagnostic performance of direct latex agglutination, post-enrichment latex agglutination and culture methods in screening of group B streptococci in late pregnancy: a comparative study.
作者信息
El Shahaway Alia A, El Maghraby Hanaa M, Mohammed Heba A, Abd Elhady Rasha R, Abdelrhman Amr Ahmed
机构信息
Department of Medical Microbiology and Immunology, Faculty of Medicine, Zagazig University, Zagazig, Egypt.
Department of Obstetrics and Gynecology, Faculty of Medicine, Zagazig University, Zagazig, Egypt.
出版信息
Infect Drug Resist. 2019 Aug 22;12:2583-2588. doi: 10.2147/IDR.S203543. eCollection 2019.
BACKGROUND
Group B streptococcus (GBS) is one of the main causes of neonatal sepsis.
PURPOSE
Evaluation of the diagnostic performance of direct latex agglutination test (DLA), post-enrichment latex agglutination (LA) test, and direct culture on chromogenic media in rapid identification of GBS carrier in pregnant women in comparison with the conventional post-enrichment CDC-recommended culture method and further to estimate GBS carriage prevalence and its antimicrobial susceptibility.
METHODS
Two hundred pregnant women at gestational age (35-37 weeks) were enrolled. Three low vaginal swabs were obtained from each participant. One swab was directly inoculated into Strep B Select (SBS) agar. The second swab was inoculated in enrichment Lim broth for immunological antigen detection by post-enrichment latex agglutination (5 h and 24 h) and subculture for bacteriological detection. The third swab was used for immunological detection of GBS antigen by direct latex agglutination. The isolated GBS was subjected to antimicrobial susceptibility testing.
RESULTS
Among 200 pregnant women, 47 (23.5%) were GBS carriers. Considering post-enrichment subculture on SBS medium as a gold standard, the sensitivities for post-enrichment 5 h and 24 h LA were 66% and 95.7%, respectively. However, direct cultivation of the vaginal swabs on SBS medium and DLA recorded 83% and 4.3%, respectively, for sensitivity. All GBS isolates (100%) were sensitive to penicillin G, ampicillin, ceftriaxone, and vancomycin. In contrast, 21.3% and 12.8% of isolated GBS were resistant to erythromycin and clindamycin, respectively.
CONCLUSION
Group B streptococcal antigen detection by latex agglutination after 5 h enrichment is a reliable, easy, and relatively rapid method for screening of GBS carriage in pregnant woman not in labor. Latex agglutination after 18-24 h enrichment can be used alternative to standard subculture method for screening GBS carriage.
背景
B族链球菌（GBS）是新生儿败血症的主要病因之一。
目的
与传统的富集后美国疾病控制与预防中心（CDC）推荐的培养方法相比，评估直接乳胶凝集试验（DLA）、富集后乳胶凝集（LA）试验以及在显色培养基上直接培养用于快速鉴定孕妇GBS携带者的诊断性能，并进一步估计GBS携带率及其抗菌药物敏感性。
方法
招募200名孕龄为（35 - 37周）的孕妇。从每位参与者处获取三根低位阴道拭子。一根拭子直接接种到B族链球菌选择（SBS）琼脂中。第二根拭子接种到富集的淋球菌肉汤中，用于通过富集后乳胶凝集试验（5小时和24小时）进行免疫抗原检测以及用于细菌学检测的传代培养。第三根拭子用于通过直接乳胶凝集试验进行GBS抗原的免疫检测。对分离出的GBS进行抗菌药物敏感性测试。
结果
在200名孕妇中，47名（23.5%）为GBS携带者。以在SBS培养基上进行富集后传代培养作为金标准，富集后5小时和24小时LA试验的敏感性分别为66%和95.7%。然而，阴道拭子在SBS培养基上直接培养和DLA试验的敏感性分别为83%和4.3%。所有GBS分离株（100%）对青霉素G、氨苄西林、头孢曲松和万古霉素敏感。相比之下，分离出的GBS分别有21.3%和12.8%对红霉素和克林霉素耐药。
结论
富集5小时后通过乳胶凝集试验检测B族链球菌抗原是一种可靠、简便且相对快速的方法，用于筛查未临产孕妇的GBS携带情况。富集18 - 24小时后的乳胶凝集试验可替代标准传代培养方法用于筛查GBS携带情况。
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