Early-onset and late-onset neonatal group B streptococcal disease--United States, 1996-2004

In 2002, CDC, the American College of Obstetricians and Gynecologists (ACOG), and the American Academy of Pediatrics (AAP) issued revised guidelines for prevention of perinatal invasive group B streptococcal (GBS) disease. These guidelines recommend universal screening of pregnant women for rectovaginal GBS colonization at 35-37 weeks' gestation and administering intrapartum antimicrobial prophylaxis to carriers. To assess the impact of the guidelines on multistate trends in neonatal GBS disease incidence, CDC analyzed data from the Active Bacterial Core surveillance (ABCs) system from 1996-2004. This report summarizes the results of that analysis, which determined that incidence of GBS disease in infants aged 0-6 days (i.e., early-onset disease) in 2004 had decreased by 31% from 2000-2001, the period immediately before universal screening was implemented. Incidence of GBS disease in infants aged 7-89 days (i.e., late-onset disease) remained unchanged during the 9-year period reviewed. Continued monitoring is needed to assess the impact of the 2002 guidelines on early-onset disease and the long-term effect of widespread intrapartum use of antimicrobial agents on neonatal GBS disease.     

Diminishing racial disparities in early-onset neonatal group B streptococcal disease--United States, 2000-2003

Increased use of intrapartum antibiotics to prevent perinatal group B streptococcal (GBS) disease during the 1990s led to substantial declines in the incidence of GBS disease in newborns. Despite this success, at the end of the 1990s, early-onset GBS disease (in infants aged <7 days) continued to be a leading infectious cause of neonatal mortality in the United States, and black infants remained at higher risk than white infants. In 2002, CDC and the American College of Obstetricians and Gynecologists (ACOG) revised guidelines for prevention of early-onset GBS disease to recommend late prenatal screening of all pregnant women and intrapartum antibiotic prophylaxis (IAP) for GBS carriers. These guidelines were expected to result in further declines in early-onset disease. This report updates early-onset incidence trends since 1999 analyzed by using population-based, multistate data from the Active Bacterial Core surveillance (ABCs)/Emerging Infections Program Network. The results of the analysis indicated that 1) after a plateau in early-onset disease incidence during 1999-2002, rates declined 34% in 2003 and 2) although racial disparities in incidence persist, rates for blacks now approach the 2010 national health objective of 0.5 cases per 1,000 live births. Continued implementation of screening and prophylaxis guidelines by clinicians and public health practitioners should lead to further declines in racial disparities.     

Neonatal group B streptococcal disease: how infection control teams can contribute to prevention efforts.

Group B streptococcal (GBS) disease is a leading cause of morbidity and mortality among newborns. Many cases of newborn GBS disease can be prevented by the administration of intrapartum antibiotic prophylaxis. Current consensus guidelines for prevention of perinatal GBS disease have led to substantial declines in the incidence of GBS disease occurring in newborns <7 days of age (early-onset disease). Despite declines in the incidence of early-onset disease, approximately 20% of pregnant women are colonized with GBS at the time of labor and thus have the risk of transmitting the bacteria to their newborns. Consequently, continued and improved implementation of prevention efforts is essential. Infection control teams can contribute uniquely to prevention of perinatal GBS disease by serving as hospital champions of GBS disease prevention. In particular, teams can coordinate with administration and staff to encourage establishment and effective implementation of GBS prevention policies; facilitate improved laboratory processing of prenatal GBS screening specimens; monitor any adverse consequences of increased use of intrapartum antibiotics within the hospital; and investigate GBS cases that occur to determine whether they could have been prevented. By spearheading efforts to improve implementation of perinatal GBS disease prevention at the hospital level, hospital epidemiologists and infection control practitioners can play an important role in reducing the burden of early-onset GBS disease.     

Epidemiology of neonatal group B streptococcal disease in The Netherlands 1997-98

Group B streptococcal (GBS) infection is still an important cause of morbidity and mortality in newborn infants. In The Netherlands, there are no published data on the incidence of neonatal GBS infection. We collected data of all infants with GBS disease during the first 3 months of life, as reported to the Dutch Paediatric Surveillance Unit (DPSU) during a period of 2 years (1997-98). Neonates with early-onset GBS disease (both sepsis and probable sepsis) were included for further analysis. The level of completeness of the DPSU data was determined by capture-recapture techniques. The incidence of early-onset GBS disease in The Netherlands in 1997-98, as calculated from the DPSU data, was 0.9 per 1000 live births. After correction for under-reporting, the incidence was estimated to be 1.9 per 1000 live births. The case fatality rate of early-onset GBS disease was only 5%. Despite the decrease in the mortality rate during the last decades, it remains a serious condition with potential irreversible brain damage. Therefore, formal guidelines for the prevention of neonatal early-onset GBS disease in The Netherlands were introduced in 1999. The data collected in this study may serve as baseline data for evaluation of the effect of these guidelines.     

Perinatal group B streptococcal disease after universal screening recommendations--United States, 2003-2005

Group B streptococcus (GBS) is a leading cause of neonatal morbidity and mortality in the United States. In 2002, CDC, the American College of Obstetricians and Gynecologists (ACOG), and the American Academy of Pediatrics (AAP) issued revised guidelines for the prevention of perinatal GBS disease. These guidelines recommend universal screening of pregnant women by culture for rectovaginal GBS colonization at 35-37 weeks' gestation and the use of intrapartum antibiotic prophylaxis for GBS carriers. To examine rates of neonatal and pregnancy-associated GBS disease after the revised guidelines were issued, CDC analyzed surveillance data from the Active Bacterial Core surveillance (ABCs) system from the period 2003-2005 and compared them with data from 2000-2001, the period immediately preceding the universal screening recommendations. This report describes the results of that analysis, which indicated that annual incidence of early onset GBS disease (i.e., in infants aged 0-6 days) was 33% lower during 2003-2005 than during 2000-2001. However, although incidence among white infants decreased steadily during 2003-2005, incidence increased 70% among black infants. Incidence of GBS disease among infants aged 7-89 days (i.e., late-onset disease) and pregnant women remained stable after revised universal screening guidelines were issued. Continued surveillance is needed to monitor the impact of the guidelines on perinatal GBS disease and trends in racial disparities and to guide interventions to reduce disparities.     

Invasive Early-Onset Neonatal Group B Streptococcal Cases – Alaska, 2000–2004

Objective: We conducted a review of invasive early-onset neonatal group B Streptococcus (GBS) infections that occurred during 2000–2004 in Alaska to determine the proportion of cases that might have been prevented by complete implementation of the 2002 Centers for Disease Control and Prevention (CDC) guidelines. Methods: Cases were identified from statewide laboratory-based surveillance conducted by the CDC Arctic Investigations Program, and from the Alaska Medicaid database using International Classification of Diseases 9 codes 038.0, 041.02, 320.2, and 482.3. Neonates were considered to have early-onset disease if clinical illness within 6 days after birth was accompanied by GBS isolation from a normally sterile site. Maternal and neonatal medical records were reviewed. Potentially preventable cases were those for whom the 2002 CDC GBS maternal screening and intrapartum antimicrobial prophylaxis (IAP) guidelines were not completely implemented. Preventability of events not related to clinician implementation of the guidelines were not considered. Results: Twenty-one neonates with invasive early-onset GBS disease were identified (0.42/1,000 live births). Three of the eight mothers for whom IAP was indicated, did not receive adequate IAP. Nine of the 13 mothers for whom there was no indication for IAP, had not been screened appropriately. Therefore, a total of 12 neonates were determined to have had potentially preventable GBS disease. Conclusions: Over 50% of the invasive early-onset neonatal GBS cases in Alaska were potentially preventable. The majority of these cases may have been prevented by closer adherence to either specific IAP administration guidelines or to maternal screening guidelines. Financial support or conflicts of interest: Dr. Gessner has received funding support from sanofi-pasteur, a vaccine manufacturer, and research support from TAP Pharmaceuticals. None of the other authors have financial support to declare. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.     

孕晚期 B族链球菌带菌者母儿结局及高危因素分析

目的：了解孕晚期孕妇B族链球菌（ GBS）的带菌情况及应用抗生素预防性治疗后的母儿结局,并分析GBS带菌的高危因素。方法回顾性收集2014年1月至2014年12月在北京妇产医院分娩体验门诊就诊的孕妇4959例,于孕35～37周采集阴道下1／3及肛门括约肌上2～3cm处直肠标本（共1份）,采用PCR法进行GBS检测,其中278例检测出B族链球菌阳性者为研究组,随机抽取同期产检332例检测GBS阴性者为对照组。 GBS阳性者临产后或胎膜早破时给予抗生素预防感染,分析其妊娠结局及GBS带菌的高危因素。结果 GBS阳性者278例,带菌率为5．61％。 GBS阳性组年龄显著高于GBS阴性组（ t＝2．941,P＜0．05）,两组文化程度有显著性差异（χ2＝8．108,P＜0．05）,而两组经产妇所占比例无显著性差异（χ2＝2．593,P＞0．05）。新生儿中无GBS感染导致肺炎、败血症、脑膜炎等发生,1例可疑GBS感染,1例新生儿脓疱疹。 GBS阳性组新生儿窒息发生率显著高于GBS阴性组（χ2＝4．809,P＜0．05）,两组胎膜早破、胎儿窘迫、产时发热比较均无显著性差异（χ2值分别为1．180、0．009、2．187,均P＞0．05）,两组新生儿体重、产后出血比较均无显著性差异（t值分别为0．497、0．529,均P＞0．05）。年龄、阴道炎是GBS定植的危险因素（OR值分别为1．071、2．955,均P＜0．05）,而糖尿病不是GBS定植的高危因素（OR＝1．108,P＞0．05）。结论 GBS阳性孕妇临产后使用抗生素规范治疗可改善母儿结局,建议对GBS高危人群进行筛查。     

Status of vaccine research and development of vaccines for GBS

Streptococcus agalactiae (group B streptococcus (GBS)) is the leading cause of neonatal sepsis and meningitis in many countries. Intrapartum antibiotic strategies have reduced the incidence of early-onset neonatal GBS in a number of countries but have had no impact on late onset GBS infection (LOD). In low/middle income settings, the disease burden remains uncertain although in several countries of Southern Africa appears comparable to or higher than that of high-income countries. As disease may be rapidly fulminating cases can be missed before appropriate samples are obtained and this may lead to underestimation of the true burden. Given the rapid onset and progression within hours of birth as well as the deficiencies in IAP strategies and absence of a solution for preventing LOD, it is clear that administration of a suitable vaccine in pregnancy could provide a better solution in all settings; it should also be cost effective. The current leading vaccine candidates are CPS-protein conjugate vaccines but protein-based vaccines are also in development and one has recently commenced clinical trials.     

Prevention of perinatal group B streptococcal disease. Revised guidelines from CDC.

Group B streptococcus (GBS) remains a leading cause of serious neonatal infection despite great progress in perinatal GBS disease prevention in the 1990s. In 1996, CDC, in collaboration with other agencies, published guidelines for the prevention of perinatal group B streptococcal disease (CDC. Prevention of perinatal group B streptococcal disease: a public health perspective. MMWR 1996;45[RR-7]:1-24). Data collected after the issuance of the 1996 guidelines prompted reevaluation of prevention strategies at a meeting of clinical and public health representatives in November 2001. This report replaces CDC's 1996 guidelines. The recommendations are based on available evidence and expert opinion where sufficient evidence was lacking. Although many of the recommendations in the 2002 guidelines are the same as those in 1996, they include some key changes: * Recommendation of universal prenatal screening for vaginal and rectal GBS colonization of all pregnant women at 35-37 weeks' gestation, based on recent documentation in a large retrospective cohort study of a strong protective effect of this culture-based screening strategy relative to the risk-based strategy * Updated prophylaxis regimens for women with penicillin allergy * Detailed instruction on prenatal specimen collection and expanded methods of GBS culture processing, including instructions on antimicrobial susceptibility testing * Recommendation against routine intrapartum antibiotic prophylaxis for GBS-colonized women undergoing planned cesarean deliveries who have not begun labor or had rupture of membranes * A suggested algorithm for management of patients with threatened preterm delivery * An updated algorithm for management of newborns exposed to intrapartum antibiotic prophylaxis Although universal screening for GBS colonization is anticipated to result in further reductions in the burden of GBS disease, the need to monitor for potential adverse consequences of intrapartum antibiotic use, such as emergence of bacterial antimicrobial resistance or increased incidence or severity of non-GBS neonatal pathogens, continues, and intrapartum antibiotics are still viewed as an interim strategy until GBS vaccines achieve licensure.     

新生儿无乳链球菌败血症8例临床分析并文献复习

目的：探讨新生儿无乳链球菌（GBS）败血症的临床特点并进行相关文献复习。方法：回顾性分析2012-2014年青岛市妇女儿童医院新生儿重症监护室住院的8例GBS败血症患儿的一般资料、临床特征、影像学检查结果、治疗及转归。结果：8例GBS败血症患儿4例为早发型,4例为晚发型;1例早产儿,7例足月顺产儿;7例发热伴不同程度的神经系统异常症状,1例无异常症状及体征,血培养均提示为青霉素及万古霉素敏感;5例合并化脓性脑膜炎,1例头颅MRI出现脑软化灶,2例蛛网膜下腔出血;影像学检查：2例MRI异常,4例正常,2例未做。随访至今,2例死亡,1例运动发育落后,5例生长发育正常。结论：新生儿GBS败血症死亡率、致残率高。强有力、足量、足疗程抗感染外,产前产时GBS筛查和预防性应用抗生素应积极尽早开展,以减少后遗症发生。     

Hospital-based policies for prevention perinatal Group B streptococcal disease--United States, 1999

Group B streptococcus (GBS) is the leading cause of sepsis, meningitis, and pneumonia in newborns in the United States (1). Because intrapartum prophylactic antibiotics reduce mother-to-child GBS transmission (2), in 1996, CDC, the American College of Obstetricians and Gynecologists, and the American Academy of Pediatrics recommended that hospitals adopt formal GBS prevention policies (2-4). From 1994 to 1997, the proportion of hospitals with formal intrapartum GBS prevention policies increased from 39% to 59% (5,6); hospitals that implemented policies reported less GBS disease among neonates (7). In 1999, CDC's Active Bacterial Core Surveillance (ABCs) system surveyed hospitals in eight states about their GBS prevention policies. This report summarizes the results of that analysis and indicates that in 1999, the proportion of hospitals with formal policies had not changed since 1997; however, a higher proportion of hospitals have implemented measures to improve policy compliance.     

Cost-effectiveness of a potential group B streptococcal vaccine program for pregnant women in South Africa

Background

In low- and middle-income countries neonatal infections are important causes of infant mortality. Group B streptococcus (GBS) is a major pathogen. A GBS polysaccharide–protein conjugate vaccine, the only option that has the potential to prevent both early- and late-onset GBS disease, has completed Phase II trials. Screening-based intrapartum antibiotic prophylaxis (IAP) for pregnant women, an effective strategy in high-income countries, is often not practical in these settings. Risk factor-based IAP (RFB-IAP) for women with risk factors at delivery has had limited success in preventing neonatal infection. We evaluated the cost and health impacts of maternal GBS vaccination in South Africa.

Methods and findings

We developed a decision-analytic model for an annual cohort of pregnant women that simulates the natural history of GBS disease in their infants. We compared four strategies: doing nothing, maternal GBS vaccination, RFB-IAP, and vaccination plus RFB-IAP. Assuming vaccine efficacy varies from 50% to 90% against covered serotypes and 75% of pregnant women are vaccinated, GBS vaccination alone prevents 30–54% of infant GBS cases compared to doing nothing. For vaccine prices between $10 and $30, and mid-range efficacy, its cost ranges from $676 to $2390 per disability-adjusted life-year (DALY) averted ($US 2010), compared to doing nothing. RFB-IAP alone, compared to doing nothing, prevents 10% of infant GBS cases at a cost of $240/DALY. Vaccine plus RFB-IAP prevents 48% of cases at a cost of $664–2128/DALY.

Conclusions

Vaccination would substantially reduce the burden of infant GBS disease in South Africa and would be very cost-effective by WHO guidelines. RFB-IAP is also very cost-effective, but prevents only 10% of cases. Vaccination plus RFB-IAP is more effective and more costly than vaccination alone, and consistently very cost-effective.     

孕妇孕晚期 GBS定植及新生儿早发型 GBS感染趋势

目的：观察孕晚期B族链球菌（ GBS）的定植情况以及母婴垂直传播率,评估新生儿早发型GBS疾病（ EOD）的发病趋势。方法选择2014年1月至2015年3月在南京医学院附属苏州母子医疗保健中心住院分娩的3487例孕妇进行阴道GBS筛查,根据美国疾病控制中心（ CDC）推荐的培养筛查策略评估孕妇孕晚期GBS的定植率;对1018对孕妇－新生儿配对病例进行垂直传播筛查,追踪新生儿结局,统计母婴垂直传播率及新生儿EOD的发病率。结果在培养筛查组,3487例孕妇标本中有142例GBS培养阳性,孕妇阴道GBS定植率为4．07％;在母婴垂直传播筛查组,1018对配对标本中,有52例孕妇GBS培养阳性,其分娩新生儿有4例阳性,垂直传播率为7．69％。在1062例纳入研究的新生儿中有1例发生EOD,其发病率为0．94‰（1／1062）。结论虽然孕妇孕晚期GBS定植率低,但其垂直传播率及新生儿EOD发病率均较高。有必要于有条件的地区进一步推行GBS产前筛查和相关治疗。     

Invasive group B streptococcal disease in infants: a 19-year nationwide study. Serotype distribution, incidence and recurrent infection

During the period 1984-2002, 472 cases of invasive group B streptococcal (GBS) disease in infants aged 0-90 days in Denmark were registered. The overall incidence was 0.4/1000 live births. Most infants (73%) had early-onset GBS infection with 53% registered within the first day. Serotype III predominated (59%) with other serotypes as follows: Ia (16%), Ib (8%), NT (7%), II (6%), other serotypes (5%). Recurrence of GBS infection was registered in six infants, and the interval with no antibiotic therapy varied from 2 to 39 days. The serotypes of the isolates obtained from first and second episodes were identical (serotype III in five, and serotype Ia in one infant). Paired isolates were indistinguishable by PFGE and antibiotic susceptibility testing. Invasive GBS infections in infants are still a problem in Denmark, and recurrent infections are registered in 1% of these infants.     

Increased Risk for Group B Streptococcus Sepsis in Young Infants Exposed to HIV,Soweto, South Africa, 2004–2008

Although group B Streptococcus (GBS) is a leading cause of severe invasive disease in young infants worldwide, epidemiologic data and knowledge about risk factors for the disease are lacking from low- to middle-income countries. To determine the epidemiology of invasive GBS disease among young infants in a setting with high maternal HIV infection, we conducted hospital-based surveillance during 2004–2008 in Soweto, South Africa. Overall GBS incidence was 2.72 cases/1,000 live births (1.50 and 1.22, respectively, among infants with early-onset disease [EOD] and late-onset [LOD] disease). Risk for EOD and LOD was higher for HIV-exposed than HIV-unexposed infants. GBS serotypes Ia and III accounted for 84.0% of cases, and 16.9% of infected infants died. We estimate that use of trivalent GBS vaccine (serotypes Ia, Ib, and III) could prevent 2,105 invasive GBS cases and 278 deaths annually among infants in South Africa; therefore, vaccination of all pregnant women in this country should be explored.     

Group B streptococcal disease in the United States, 1990: report from a multistate active surveillance system.

Group B streptococcal (GBS) disease is the most common cause of neonatal sepsis and meningitis in the United States. It is also an important cause of morbidity among pregnant women and adults with underlying medical conditions. Because most states have not designated GBS disease as a reportable condition, previous estimates of the incidence of GBS disease were based on studies from single hospitals or small geographic areas. This report summarizes the results of population-based active surveillance for invasive GBS disease in counties within four states that had an aggregate population of 10.1 million persons in 1990. A case of GBS disease was defined as isolation of group B streptococcus from a normally sterile anatomic site in a resident of one of the surveillance areas. Age- and race-adjusted projections to the U.S. population suggest that > 15,000 cases and > 1,300 deaths due to GBS disease occur each year. The projected age- and race-adjusted national incidence is 1.8/1,000 live births for neonatal GBS disease and 4.0/100,000 population per year for adult GBS disease. Intrapartum chemoprophylaxis for pregnant women at risk for delivering infants with GBS disease is the most effective strategy available for prevention of neonatal disease. Development of effective GBS vaccines may prevent GBS disease in both infants and adults. Ongoing surveillance for GBS disease is important for targeting preventive measures and determining their effectiveness.     

Cost-effectiveness of a potential group B streptococcal vaccine for pregnant women in the United States

BackgroundIn the U.S., intrapartum antibiotic prophylaxis (IAP) for pregnant women colonized with group B streptococcus (GBS) has reduced GBS disease in the first week of life (early-onset/EOGBS). Nonetheless, GBS remains a leading cause of neonatal sepsis, including 1000 late-onset (LOGBS) cases annually. A maternal vaccine under development could prevent EOGBS and LOGBS.MethodsUsing a decision-analytic model, we compared the public health impact, costs, and cost-effectiveness of five strategies to prevent GBS disease in infants: (1) no prevention; (2) currently recommended screening/IAP; (3) maternal GBS immunization; (4) maternal immunization with IAP when indicated for unimmunized women; (5) maternal immunization plus screening/IAP for all women. We modeled a pentavalent vaccine covering serotypes 1a, 1b, II, III, and V, which cause almost all GBS disease.ResultsIn the base case, screening/IAP alone prevents 46% of EOGBS compared to no prevention, at a cost of $70,275 per quality-adjusted life-year (QALY) from a healthcare and $51,249/QALY from a societal perspective (2013 US$). At coverage rates typical of maternal vaccines in the U.S., a pentavalent vaccine alone would not prevent as much disease as screening/IAP until its efficacy approached 90%, but would cost less per QALY. At vaccine efficacy of ≥70%, maternal immunization together with IAP for unimmunized women would prevent more disease than screening/IAP, at a similar cost/QALY.ConclusionsGBS maternal immunization, with IAP as indicated for unvaccinated women, could be an attractive alternative to screening/IAP if a pentavalent vaccine is sufficiently effective. Coverage, typically low for maternal vaccines, is key to the vaccine’s public health impact.     

围生期B族链球菌感染的诊治及其疫苗研究

B族链球菌(GBS)是导致多种不良妊娠结局的病原菌,也是引起新生儿败血症、脑膜炎等并发症及导致围生儿死亡的重要原因。导致GBS感染的血清型共计分为10种。围生期孕妇GBS筛查,可为临床对孕妇及时采取产时抗菌药物预防(IAP)措施,预防围生儿GBS感染提供参考依据,并有效降低围生儿GBS感染率。GBS疫苗作为预防GBS感染的一种简便、安全策略,日益受到重视。接种GBS疫苗是目前最有可能通过母体免疫预防新生儿GBS感染的措施,但是对新生儿晚发型GBS感染无预防作用。笔者拟就围生期GBS感染导致的不良妊娠结局,GBS感染的危险因素、地域差异及其诊断、治疗与GBS疫苗最新研究进展进行综述。     

The projected health benefits of maternal group B streptococcal vaccination in the era of chemoprophylaxis

While maternal antibiotic prophylaxis has greatly reduced early-onset group B streptococcal (GBS) disease in the United States, a GBS vaccine currently under development could potentially prevent additional GBS cases and preterm births. A decision analytic model was created to compare preventive strategies using adolescent, maternal (prenatal), or postpartum vaccination with selective chemoprophylactic strategies. The current practice of culture-based chemoprophylaxis was predicted to prevent 55% of early plus late-onset GBS infections. Maternal vaccination strategies were superior to current practice, preventing 68-69% of all GBS infections and 4% of very preterm births (<32 weeks gestation). The most effective adolescent vaccination strategy combined vaccination with culture-based chemoprophylaxis for all women and prevented 66% of all GBS infections. All other strategies were similar in efficacy to current practice or inferior. Maternal GBS vaccination is predicted to prevent more cases of neonatal GBS disease than current practice and would prevent approximately one in 25 very preterm births.     

Control of neonatal group B streptococcal infection.

Group B beta-haemolytic streptococcus (GBS) is the leading cause of life-threatening perinatal infection in developed countries. As immunization of women is not yet available, selective intrapartum chemoprophylaxis appears to be the best current strategy for preventing disease. All pregnant women should be screened for GBS at 26 to 28 weeks gestation. During labour, all colonized women with risk factors for invasive GBS neonatal infection should be treated with intravenous penicillin or ampicillin. Risk factors include preterm labour, premature rupture of membranes, intrapartum fever, multiple births, prolonged rupture of membranes, maternal diabetes, previous sibling with invasive GBS disease, and maternal GBS bacteriuria. The latter two categories warrant chemoprophylaxis regardless of maternal colonization status.