Meehan M, Cafferkey M, Corcoran S, Foran A, Hapnes N, LeBlanc D, McGuinness C, Nusgen U, O'Sullivan N, Cunney R, Drew R
Epidemiology and Molecular Biology Unit, Temple Street Children's University Hospital, Temple Street, Dublin, Ireland.
Department of Clinical Microbiology, Rotunda Hospital, Dublin, Ireland.
Eur J Clin Microbiol Infect Dis. 2015 Dec;34(12):2413-20. doi: 10.1007/s10096-015-2496-5. Epub 2015 Oct 3.
Group B streptococcus (GBS) is a leading cause of invasive disease in infants. Accurate and rapid diagnosis is crucial to reduce morbidity and mortality. Real-time polymerase chain reaction (PCR) targeting the dltR gene was utilised for the direct detection of GBS DNA in blood and cerebrospinal fluid (CSF) from infants at an Irish maternity hospital. A retrospective review of laboratory and patient records during the period 2011-2013 was performed in order to evaluate PCR and culture for the diagnosis of invasive GBS disease. A total of 3570 blood and 189 CSF samples from 3510 infants had corresponding culture and PCR results. Culture and PCR exhibited concordance in 3526 GBS-negative samples and 13 (25%) GBS-positive samples (n = 53). Six (11%) and 34 (64%) GBS-positive samples were positive only in culture or PCR, respectively. Culture and PCR identified more GBS-positive infants (n = 47) than PCR (n = 43) or culture (n = 16) alone. Using culture as the reference standard, the sensitivity, specificity, and positive and negative predictive values for PCR on blood samples were 71.4%, 99.2%, 25% and 99.9%, and for CSF samples, they were 60%, 97.8%, 42.9% and 98.9%, respectively. The sensitivity and positive predictive values were improved (blood: 84.6% and 55%; CSF: 77.8% and 100%, respectively) when maternal risk factors and other laboratory test results were considered. The findings in this study recommend the use of direct GBS real-time PCR for the diagnosis of GBS infection in infants with a clinical suspicion of invasive disease and as a complement to culture, but should be interpreted in the light of other laboratory and clinical findings.
B族链球菌（GBS）是导致婴儿侵袭性疾病的主要原因。准确、快速的诊断对于降低发病率和死亡率至关重要。采用针对dltR基因的实时聚合酶链反应（PCR）直接检测爱尔兰一家妇产医院婴儿血液和脑脊液（CSF）中的GBS DNA。为评估PCR和培养法在诊断侵袭性GBS疾病中的作用，对2011 - 2013年期间的实验室和患者记录进行了回顾性分析。共有来自3510名婴儿的3570份血液样本和189份脑脊液样本有相应的培养和PCR结果。培养法和PCR在3526份GBS阴性样本以及13份（25%）GBS阳性样本（n = 53）中结果一致。分别有6份（11%）和34份（64%）GBS阳性样本仅在培养或PCR中呈阳性。培养法和PCR共同检测出的GBS阳性婴儿（n = 47）比单独使用PCR（n = 43）或培养法（n = 16）更多。以培养法作为参考标准，血液样本PCR检测的灵敏度、特异性、阳性预测值和阴性预测值分别为71.4%、99.2%、25%和99.9%，脑脊液样本的分别为60%、97.8%、42.9%和98.9%。考虑母亲的危险因素和其他实验室检测结果时，灵敏度和阳性预测值有所提高（血液样本分别为84.6%和55%；脑脊液样本分别为77.8%和100%）。本研究结果建议，对于临床怀疑有侵袭性疾病的婴儿，采用直接GBS实时PCR诊断GBS感染，并作为培养法的补充，但应结合其他实验室和临床检查结果进行解读。
