An outbreak of group B streptococcus infection in a neonatal nursery and subsequent trial for prophylaxis of nosocomial transmission

An outbreak of sepsis and meningitis caused by group B streptococcus occurred in three very low birthweight infants. To prevent further nosocomial transmission, immune globulin and ampicillin sodium were administered intravenously to other very low birthweight infants. After this prophylaxis, no other infants were involved in this outbreak. Immuno- and chemoprophylaxis may be considered as procedures to prevent nosocomial infection for very low birthweight infants.     

产时抗菌药物预防治疗B族链球菌感染对早发型新生儿败血症发生率及病原菌分布的影响

目的 了解产时抗菌药物预防（intrapartum antibiotic prophylaxis,IAP）治疗B族链球菌（Group B streptococcus,GBS）感染对早发型新生儿败血症（early-onset neonatal sepsis,EONS）发生率及病原菌分布的影响。 方法 回顾性分析GBS筛查阳性的494例孕产妇及其所分娩的526例新生儿的临床资料。根据孕产妇是否接受IAP治疗将新生儿分为IAP组（304例）和对照组（222例）,比较两组间的各项临床指标、EONS发生率、血培养病原菌分布情况。 结果 IAP组出现异常临床表现的患儿比例显著低于对照组（P<0.001）。IAP组EONS发生率显著低于对照组（P=0.022）。IAP组和对照组EONS患儿血培养检测病原菌种类最多分别为大肠埃希菌（2.3%）和GBS（3.2%）。IAP组氨苄青霉素耐药性大肠埃希菌的检出率显著高于对照组（P=0.029）。 结论 IAP治疗虽可降低GBS阳性孕产妇所娩新生儿的EONS发生率,但IAP治疗后氨苄青霉素耐药性大肠埃希菌感染率升高,提示应强化对EONS患儿血培养结果的监测,根据药敏试验结果及时调整诊疗计划。     

新生儿B族链球菌感染预防策略的研究进展

B 族链球菌可引起新生儿早发型和晚发型疾病,主要危险因素是母亲胃肠道和生殖道的定植。目前对存在危险因素的妊娠妇女有两种筛选方案：高危因素评估方案和普遍筛查方案;美国等国家采取产时抗生素预防性治疗措施,使早发型B 族链球菌疾病的发病率大幅度降低,但对晚发型疾病的发病率影响不大。抗生素预防性治疗首选青霉素,对青霉素过敏者需依据菌株药敏结果选择药物。抗生素预防性治疗措施存在一定的弊端,需积极研发其他的预防措施来预防B 族链球菌感染。     

新生儿肺炎死亡病例中B族链球菌的检测

目的对北京儿童医院新生儿肺炎死亡病例进行B族链球菌（GBS）回顾性检测,旨在初步揭示GBS感染在新生儿重症肺炎中的地位。方法收集200例1953年到2004年间新生儿肺炎死亡病例（研究组）和34例非感染性疾病新生儿死亡病例（对照组）的尸检病理标本,提取石蜡组织DNA,通过PCR和Southem blot技术检测GBS特异性基因片断咖基因。同时对所选病例的临床资料进行复习。结果（1）研究组200例中,PCR对GBS检出率为26％,Southern blot检出率为65％,检出率均明显高于对照组（PCR3％,x^2=8．82,P〈0．01;Southern blot,18％,x^2=26．77,P〈0．01）。（2）研究组中,年龄小于7d的病例（早发型）103例,年龄大于7d的病例（晚发型）97例,小于7d的患儿GBS检出率明显高于大于7d的患儿,其中PCR检出率在前者为37％,后者为13％（x^2=15．537,P〈0．01）,Southern blot检出率在前者为72％,后者为52％（x^2=4．37,P〈0．05）。早发型阳性病例中,39％为早产儿（29／74）。（3）研究组中,75例有完整临床资料,其中35例可查到一项或多项与GBS感染有关的危险因素,如早产,低体重,胎膜早破,羊水异常等,GBS检测结果均为阳性。阳性病例中,早发型最常见的表现有青紫、窒息,呼吸困难,晚发型最常见的表现有咳喘,呼吸困难。对照组中,1例PCR检测阳性者患恶性畸胎瘤,其他5例仅Southern blot检测阳性者分别为核黄疸、肝癌、先天性无肛合并膀胱尿道瘘、新生儿自然出血、先天性低位无肛合并直肠会阴瘘患者。结论GBS是新生儿肺炎死亡病例中的重要病原,尤其在早发型肺炎病例中GBS感染占很大比重。Southern blot是在石蜡标本中检测GBS的较为敏感方法。     

Prevention of neonatal group B streptococcus disease in the 21st century

There have been significant reductions in early-onset neonatal group B streptococcus (GBS) disease following implementation of maternal intrapartum antibiotic prophylaxis (IAP) policies. Nevertheless, GBS remains a leading cause of neonatal sepsis in Australia and New Zealand resulting in considerable morbidity and mortality, particularly among preterm infants. In the United States, the universal screening-based approach for identifying women for IAP results in apparently lower rates of early-onset neonatal GBS infection than risk-based assessment. In addition, IAP has altered the profile of newborn infants who develop early-onset disease. Many affected infants lack the typical intrapartum risk factors for GBS infection, are born to mothers with a negative GBS screen or represent missed opportunities for prevention. Clinicians should remain alert for signs of sepsis in any newborn infant. We provide an update of GBS preventative management strategies in the perinatal period taking into account recent United States, Australian and New Zealand guidelines.     

Horizontal transmission of group B streptococcus in a neonatal intensive care unit

The incidence of early-onset group B streptococcal (GBS) sepsis in the neonatal population has decreased substantially since the introduction of maternal intrapartum antibiotic prophylaxis and routine prenatal screening. However, these strategies have not reduced the incidence of late-onset GBS infections. Additional research pertaining to the transmission of late-onset GBS infections is required to develop effective preventive methods. The present report describes probable horizontal transmission of late-onset GBS infection among three infants in a neonatal intensive care unit. GBS strain confirmation was based on the microbiological picture, antibiogram and pulsed-field gel electrophoresis. These cases highlight the morbidity associated with late-onset GBS disease and the importance of considering horizontal transmission as an etiological factor in GBS infection in the newborn period. Further studies assessing horizontal transmission in late-onset GBS disease may improve prevention and early intervention.     

早发型新生儿B族链球菌败血症的围生期临床特征

目的 探讨早发型新生儿B族链球菌(GBS)败血症的围生期临床特征,提高对本病的认识和治疗水平.方法 收集2005-2009年我院分娩的新生儿资料,回顾性分析GBS败血症患儿的围生期因素、发病时间、临床表现、实验室检查、治疗和预后.结果 GBS败血症7例,均为早发型感染,检出率为0.113‰.早产儿1例,生后即反应低下、呻吟、呼吸困难;实验室检查:WBC2.6×109/L,N 0.76,CRP 55 mg/L,需呼吸机治疗.足月儿6例,于生后48 h内发病,临床表现有呼吸困难、精神反应差、青紫、发热、肌张力异常等,其中1例合并化脓性脑膜炎者出现惊厥;实验室检查:WBC 1.9～24.9×109/L,N 0.38～0.88,CRP 17～＞160 mg/L,1例需经鼻持续气道正压通气辅助呼吸.7例均合并肺炎,青霉素联合头孢吡肟或美罗培南治疗有效.结论 我国存在新生儿GBS败血症散发病例,病情严重.应重视围生期高危因素和早期临床表现.尽早行病原学检测,选择敏感抗生素治疗可有效降低病死率.     

Issues of antimicrobial resistance in group B streptococcus in the era of intrapartum antibiotic prophylaxis

The implementation of a culture screening-based approach to intrapartum antibiotic prophylaxis has been associated with substantial reduction in the incidence of early-onset group B streptococcal disease. Antibiotic prophylaxis is recognized as an interim strategy awaiting the licensure of a safe and effective conjugate vaccine for prevention of group B streptococcal infections in all susceptible populations. This article addresses concerns relating to antimicrobial resistance among group B streptococci that have arisen from use of intrapartum antibiotic prophylaxis and from increases in resistance in other gram-positive bacteria related genetically to group B streptococci.     

B组链球菌的分子生物学诊断和基因分型研究进展

B组链球菌（Group B Streptococci,GBS）是一种革兰阳性链球菌,以其细胞壁多糖类C物质属于Lancefield抗原结构分类中的B群而得名。根据其荚膜多糖抗原性的不同,又分为9种血清型（Ⅰa、Ⅰb、Ⅱ～Ⅷ型）。GBS感染是各国孕产妇和新生儿面临的严重问题。它可以引起新生儿早发和晚发型感染。早发型感染（生后7d以内）主要引起肺炎和败血症,是新生儿死亡的主要原因之一。而晚发型GBS感染（7d～3个月）主要引起脑膜炎,可导致严重的神经系统后遗症及听力丧失等不可逆损害。     

新生儿B族链球菌感染分子机制研究进展

B族链球菌(group B streptococcus,GBS)是新生儿侵袭性感染的主要致病菌,可引起新生儿肺炎、败血症和脑膜炎等.出生时吸入GBS污染的羊水和阴道内液体是新生儿感染的最主要途径.新生儿GBS感染分子机制研究有助于进一步阐明人类早期有效的先天免疫形成和发育,为GBS感染化学治疗和免疫预防提供新的思路.     

B族链球菌的红霉素耐药基因研究

目的 比较不同地区B族链球菌（GBS）对红霉素耐药性的差异及耐药基因谱特点。方法 用琼脂稀释法，测定红霉素、克林霉素对不同地区（北京，广州，俄罗斯圣彼得堡）的113株GBS的最低抑菌浓度（MIC），同时用PCR和核酸杂交的方法，检测红霉素耐药基因mreA、mefA、ermA、ermB、ermC在该批菌株中的出现规律及其与红霉素耐药性的关系。结果 （1）北京、广州两地GBS菌株总耐药率为46％，与克林霉素耐药性的一致率为93．8％；所有ermA基因均来自北京菌株，而广州菌株不含该基因。（2）含ermA和（或）ermB基因的GBS占所有菌株的30．09％，其耐药率高达97．06％，在已检测的GBS菌株中未发现ermC基因。（3）分别有53株和18株含mreA和mefA的GBS以及1株含ermA的菌株仍对红霉素敏感。2株GBS不含上述任何一种基因，但仍对红霉素耐药。结论 （1）北京、广州两地GBS对红霉素普遍具有较高的耐药率，且与大环内酯－林可霉素－链阳性霉素B类抗生素之间存在较严重的交叉耐药，临床使用抗生素时应尽量避免重复选择此类抗生素；（2）ermA和ermB是决定我国北京、广州GBS对红霉素耐药的重要基因；（3）GBS的耐药性还有其他分子生物学机制参与。