Neonatal early-onset group B streptococcal disease in the era of intrapartum chemoprophylaxis: residual problems

Intrapartum beta-lactam antibiotics for preventing group B streptococcal early-onset disease: can we abandon the concept of 'inadequate' intrapartum antibiotic prophylaxis?

Introduction: Neonatal sepsis remains a serious and potentially fatal illness. Intrapartum antibiotic prophylaxis (IAP) prevents group B streptococcal (GBS) early-onset sepsis. The optimal duration of IAP (adequate IAP) to reduce vertical transmission of GBS has been debated. Understanding the mechanism of action of IAP may help in minimizing neonatal evaluation and unnecessary antibiotic use.Areas covered: In recent years, several studies on pharmacokinetics and clinical use of IAP have been published. Although penicillin and ampicillin are the most preferred antibiotics, the clinical efficacy of non-beta-lactam antibiotics, including clindamycin and vancomycin, used in cases of penicillin anaphylaxis-associated allergy, remains debatable. This is a narrative review of the literature regarding the impact of 'inadequate' IAP on the clinical management of women and newborns.Expert opinion: Recent evidence suggests that 'inadequate' IAP with beta-lactams is more effective in preventing vertical transmission of GBS than previously thought. Newborns exposed to intrapartum beta-lactams and who are asymptomatic at birth are likely uninfected, irrespective of IAP duration before delivery. Hence, we may abandon the concept of 'inadequate' IAP with beta-lactams in early-onset GBS sepsis, relying primarily on clinical signs observed at birth for managing IAP-exposed neonates.

The Accuracy of Group Beta Streptococcus Rectovaginal Cultures at 35 to 37 Weeks of Gestation in Predicting Colonization Intrapartum

Objective  This study aims to investigate accuracy of group beta Streptococcus (GBS) rectovaginal cultures at 35 to 37 weeks in predicting intrapartum colonization. Study Design  Institutional review board (IRB) approved prospective cohort study of 302 women from October 2015 to May 2017. Patients had the following tests for GBS: first trimester urine culture, rectovaginal culture at 35 to 37 weeks, and intrapartum rectovaginal culture. Outcomes included accuracy of 35- to 37-week GBS rectovaginal culture in detecting results intrapartum, and accuracy of first trimester urine culture in comparison to intrapartum rectovaginal cultures. Results  There was sufficient evidence of agreement between results at 35 to 37 weeks with intrapartum cultures ( p  = 0.001). However, agreement was weak, 11 patients (3.7%) were GBS positive intrapartum but negative at 35 to 37 weeks; and 33 patients (11%) were initially GBS positive but were negative intrapartum. Sensitivity and specificity of the 35- to 37-week culture was 69% (95% confidence interval [CI]:54-84%) and 87% (95% CI: 83-91%), respectively. There was also weak agreement between first trimester urine culture and intrapartum rectovaginal culture. Specificity for this assessment was 98% (95% CI: 97-100%) and was significantly different compared with antepartum GBS culture ( p  < 0.001). Accuracy between antepartum GBS rectovaginal culture and urine culture was similar (85 vs. 87%, p  = 0.47). Conclusion  The 35- to 37-week GBS rectovaginal culture might be a poor predictor for intrapartum colonization.

Outcome of a screening program for the prevention of neonatal early-onset group B Streptococcus infection: a population-based cohort study in Inner Mongolia, China

PURPOSE

Invasive early-onset group B Streptococcus infection (EOGBS) is an important cause of severe neonatal complications but study on comprehensive GBS screening is lacking in China. This study aims to investigate the outcome of a regional anterpartum screening program for EOGBS prevention and to estimate the pros and cons of a new GBS screening strategy employed.

METHODS

We performed an optimized hospital strategy for GBS screening, which targeted expectant mothers (including those with preterm births) from January 2016 to December 2016 in a population-based cohort. Three common screening strategies were simulated to estimate the availability of the hospital strategy used in this study.

RESULTS

Altogether, 9770 eligible women were tested and the rate of GBS carriage was 2.7  % (266/9770). In total, 198 of the 266 maternal GBS carriers accepted intrapartum antibiotic prophylaxis (IAP) treatment. Among the 9860 neonates of 9770 mothers, four cases of EOGBS infection were identified and one case was missed (EOGBS incidence with screening and IAP: 0.5/1000). Risk factors for maternal GBS colonization included preterm birth (between 35 and 37 weeks) [odds ratio (OR)=1.7 (95  % confidence interval: 1.22-2.33)], region of origin, resident areas, maternal age (older than 34 years) [OR=1.5 (1.06-2.09)], prelabour rupture of membranes [OR=1.8 (1.34-2.35)], gestational diabetes mellitus [OR=1.6 (1.14-2.28)] and maternal mild anemia (Hb: 90-110 g dl^-1) [OR=1.5 (1.16-2.06)]. This new screening strategy resulted in less antibiotic exposure and least number of cases missed.

CONCLUSIONS

Our findings illustrate that this perinatal screening (including preterm births) for prevention of EOGBS infection can be implemented in the Inner Mongolian area.

Effectiveness of intrapartum antibiotic prophylaxis for early-onset group B Streptococcal infection: An integrative review

BACKGROUND

In some countries, up to 30% of women are exposed to intrapartum antibiotic prophylaxis for prevention of early-onset group B Streptococcal infection. Intrapartum antibiotic prophylaxis aims to reduce the risk of neonatal morbidity and mortality from this infection. The intervention may adversely affect non-pathogenic bacteria which are passed to the newborn during birth and are considered important in optimising health. Since many women are offered intrapartum antibiotic prophylaxis, effectiveness and implications of this intervention need to be established. This review considers clinical trials and observational studies analysing the effectiveness of intrapartum antibiotic prophylaxis.

METHODS

An integrative literature review was conducted. One systematic review, three clinical trials and five observational studies were identified for appraisal.

FINDINGS

Randomised controlled trials found intrapartum antibiotic prophylaxis effective but all retrieved randomised clinical trials had significant methodological flaws. High quality observational studies reported high rates of effectiveness but revealed less than optimal adherence to screening and administration of the prophylaxis. Scant consideration was given to short term risks, and long-term consequences were not addressed.

DISCUSSION

Studies found intrapartum antibiotic prophylaxis to be effective. However, evidence was not robust and screening and prophylaxis have limitations. Emerging evidence links intrapartum antibiotic prophylaxis to adverse short and longer-term neonatal outcomes.

CONCLUSION

Our review found high quality evidence of the effectiveness of intrapartum antibiotic prophylaxis was limited. Lack of consideration of potential risks of the intervention was evident. Women should be enabled to make informed decisions about GBS management. More research needs to be done in this area.

Risk factors for group B streptococcal disease in neonates of mothers with negative antenatal testing

OBJECTIVE

The aim of this study was to identify risk factors for early-onset group B Streptococcus (EOGBS) disease in neonates of mothers with negative antenatal screening.

STUDY DESIGN

We performed a retrospective cohort study of neonates born to mothers with negative antenatal GBS screening between 2002 and 2012. Our primary outcome was EOGBS infection. We used multivariable logistic regression to assess factors associated with EOGBS.

RESULTS

EOGBS was confirmed in 492 of the 179 818 neonates that met the study inclusion criteria. Risk factors for EOGBS included black race (reference: white, odds ratio (OR) =1.81 (95% confidence interval: 1.43, 2.31)), maternal age <18 years (reference: >35 years, OR=2.63 (1.54, 4.51)) and maternal age 18 to 35 years (reference: >35 years, OR=1.94 (1.30, 2.88)).

CONCLUSION

Maternal age <18 years and black race were the strongest predictors of EOGBS. Further research investigating contributors to the discordance between screening results and neonatal outcomes in these populations is needed.

Routine culture-based screening versus risk-based management for the prevention of early-onset group B streptococcus disease in the neonate: a systematic review

BACKGROUND

Early-onset group B streptococcus disease, recognized as the most common cause of early onset neonatal sepsis in developed countries, is transmitted vertically from the group B streptococcus carrier mother to the neonate in the peripartum. Accordingly, early-onset group B streptococcus disease is prevented by halting the transmission of the microorganism from the mother to the infant. Two main methods, routine culture-based screening and risk-based management, may be used in the identification of mothers requiring intrapartum antibiotic prophylaxis in labor. While there are advantages and disadvantages to each, there is limited high level evidence available as to which method is superior.

OBJECTIVES

To identify the effectiveness of risk-based management versus routine culture-based screening in the prevention of early-onset group B streptococcus disease in the neonate.

INCLUSION CRITERIA

TYPES OF PARTICIPANTS

This review considered studies which treated pregnant women with intrapartum antibiotic prophylaxis following risk- and culture-based protocols for the prevention of early-onset group B streptococcus disease in the neonate. Types of intervention: This review considered studies that evaluated risk-based management against routine culture-based screening for the prevention of early-onset group B streptococcus disease in the neonate. Types of studies: This review looked for highest evidence available which in this case consisted of one quasi experimental study and eight comparative cohort studies with historical or concurrent control groups. Types of outcomes: Incidence of early-onset group B streptococcus disease in neonates as measured by positive group B streptococcus culture from an otherwise sterile site. Secondary outcomes include neonatal death due to group B streptococcus sepsis and percentage of women who received intrapartum antibiotic prophylaxis.

SEARCH STRATEGY

A multi-step search strategy was used to find studies which were limited to the English language and published between January 2000 and June 2013.

METHODOLOGICAL QUALITY

The quality of the eligible studies was assessed independently by two reviewers using the Joanna Briggs Institute quality assessment tool for observational studies.

DATA COLLECTION

Data was extracted using a standardized extraction tool from the Joanna Briggs Institute.

DATA SYNTHESIS

Quantitative papers were, where possible, pooled for meta-analysis using Joanna Briggs Institute Meta Analysis of Statistics Assessment and Review Instrument effect sizes expressed as odds ratio and their 95% confidence intervals were calculated. Heterogeneity was assessed statistically using the standard Chi-square.

RESULTS

The results of this review come from nine studies published in peer reviewed journals. The treatment group consists of those screened as per the culture-based protocol, the control group the risk-based protocol. For combined term and preterm infants the odds of early-onset group B streptococcus disease for the treatment vs control groups is 0.45 (95% CI 0.37 to 0.53). The odds ratio in term infants is 0.45 (95% CI 0.36 to 0.57). Preterm infants are four times (OR 4.20 [95% CI 3.36 to 5.24]) more likely to develop early-onset group B streptococcus disease than term infants regardless of prevention technique. One study provides information on neonatal mortality in which there is one neonatal death in the risk-based cohort and none in the culture-based. The TRUNCATED AT 500 WORDS.

[Prevention of Neonatal Group B Sreptococcal Infection. Spanish Recommendations. Update 2012. SEIMC/SEGO/SEN/SEQ/SEMFYC Consensus Document]

Group B streptococci (GBS) remain the most common cause of early onset neonatal sepsis. In 2003 the Spanish Societies of Obstetrics and Gynaecology, Neonatology, Infectious Diseases and Clinical Microbiology, Chemotherapy, and Family and Community Medicine published updated recommendations for the prevention of early onset neonatal GBS infection. It was recommended to study all pregnant women at 35-37 weeks gestation to determine whether they were colonised by GBS, and to administer intrapartum antibiotic prophylaxis (IAP) to all colonised women. There has been a significant reduction in neonatal GBS infection in Spain following the widespread application of IAP. Today most cases of early onset GBS neonatal infection are due to false negative results in detecting GBS, to the lack of communication between laboratories and obstetric units, and to failures in implementing the prevention protocol. In 2010, new recommendations were published by the CDC, and this fact, together with the new knowledge and experience available, has led to the publishing of these new recommendations. The main changes in these revised recommendations include: microbiological methods to identify pregnant GBS carriers and for testing GBS antibiotic sensitivity, and the antibiotics used for IAP are updated; The significance of the presence of GBS in urine, including criteria for the diagnosis of UTI and asymptomatic bacteriuria in pregnancy are clarified; IAP in preterm labour and premature rupture of membranes, and the management of the newborn in relation to GBS carrier status of the mother are also revised. These recommendations are only addressed to the prevention of GBS early neonatal infection, are not effective against late neonatal infection.

Universal screening vs. risk-based strategy for prevention of early-onset neonatal Group-B streptococcal disease

OBJECTIVE

To evaluate the difference between universal screening and risk-based strategies in the prevention of early-onset Group-B streptococcal (EOGBS) disease.

SUBJECTS

Cases of EOGBS disease from 2003 to 2009 were identified by a search of the microbiology laboratory's computerized database.

INTERVENTIONS

Maternal screening for Group-B Streptococci was done for all pregnant women by taking rectovaginal swabs and urine culture at 35-37 weeks of gestation and for all high-risk cases at the time of presentation.

RESULTS

From 2003 to 2009, a total of 87,260 live births were recorded, 1948 neonates were very low-birth weight. We reviewed labor and delivery records for 1268 live births randomly sampled from total live births. Forty-five cases of EOGBS disease were identified during the period of study (overall incidence of 0.51 cases per 1000 live births).

Policy statement—Recommendations for the prevention of perinatal group B streptococcal (GBS) disease

The Centers for Disease Control and Prevention (CDC) guidelines for the prevention of perinatal group B streptococcal (GBS) disease were initially published in 1996. The American Academy of Pediatrics (AAP) also published a policy statement on this topic in 1997. In 2002, the CDC published revised guidelines that recommended universal antenatal GBS screening; the AAP endorsed these guidelines and published recommendations based on them in the 2003 Red Book. Since then, the incidence of early-onset GBS disease in neonates has decreased by an estimated 80%. However, in 2010, GBS disease remained the leading cause of early-onset neonatal sepsis. The CDC issued revised guidelines in 2010 based on evaluation of data generated after 2002. These revised and comprehensive guidelines, which have been endorsed by the AAP, reaffirm the major prevention strategy--universal antenatal GBS screening and intrapartum antibiotic prophylaxis for culture-positive and high-risk women--and include new recommendations for laboratory methods for identification of GBS colonization during pregnancy, algorithms for screening and intrapartum prophylaxis for women with preterm labor and premature rupture of membranes, updated prophylaxis recommendations for women with a penicillin allergy, and a revised algorithm for the care of newborn infants. The purpose of this policy statement is to review and discuss the differences between the 2002 and 2010 CDC guidelines that are most relevant for the practice of pediatrics.

Group B streptococcal disease in infants: progress in prevention and continued challenges

The burden of early-onset disease caused by group B Streptococcus (GBS) has decreased dramatically in the United States over the past 20 years. Universal culture-based screening at 35 to 37 weeks gestational age and use of intrapartum antibiotic prophylaxis are the cornerstones of prevention measures that have led to this decline. GBS, however, remains the leading cause of early-onset neonatal sepsis in the United States. Revised guidelines for prevention of perinatal GBS are planned for issuance in 2010. This article discusses implementation challenges for clinicians caring for pregnant women and newborns and presents an updated algorithm for neonatal management.

Group B Streptococcus early-onset disease in Emilia-romagna: review after introduction of a screening-based approach

BACKGROUND

Group B Streptococcus (GBS) is a leading cause of neonatal bacterial infections. Early-onset infections have decreased in recent years but, despite considerable efforts poured into prevention, cases continue to occur.

OBJECTIVES

To analyze trends and identify determining factors for the persistence of the GBS infections. To evaluate the impact of antenatal screening and intrapartum chemoprophylaxis on the clinical presentation of the infection.

METHODS

A prospective cohort, population-based study has been ongoing in Emilia-Romagna (Italy) since 2003. Invasive GBS infections, observed between 2003 and 2008 in infants aged < 7 days were analyzed.

RESULTS

Among 214,120 live births, 61 early-infections were observed. Fourteen infants (23.0%) were born preterm. Among 47 infants who were delivered at term, 28 were born to mothers who had no risk factors and 7 were born to mothers who had none other than GBS colonization. Forty-one women at term had been screened prenatally; among them, only 10 were documented as GBS culture-positive.Disease severity was highest in infants at lower gestational ages, but most meningitis cases were observed in term infants born to mothers who were GBS culture-negative at screening.Nine newborns had culture-proven infection despite having received intrapartum antibiotics. They were born to mothers with > or =1 obstetrical risk factors and 5 mothers had been treated during labor with macrolides.

CONCLUSION

Most infections presented in infants whose mothers had been screened as GBS culture-negative. Missed opportunities for prevention contributed more than prophylaxis failures to the early-onset disease burden.

[Late onset group B Streptococcus infection: 7 year experience in a tertiary hospital (2000-2006)]

INTRODUCTION

Group B Streptococcus (GBS) is a major cause of neonatal infection. Two forms of the disease have been described according to the age of presentation: early, beginning in the first 6 days of life, and late, occurring from day 7 up to 3 months of age.

OBJECTIVES

To analyze the epidemiology of the late onset form of GBS disease in a tertiary hospital after implementing preventive strategies aimed to reduce the rate of vertical transmission.

METHODS

We retrospectively reviewed the medical records of children diagnosed with late GBS infection between January 2000 and December 2006. Diagnostic criteria included a positive blood culture and/or a positive cerebrospinal fluid (CSF) culture for GBS in any patient aged between 7 and 89 days.

RESULTS

24 patients were identified, most of them presenting after January 2005. Median age was 36.2 days (range 9 to 81). GBS isolates in blood were found in 20 patients, 1 in CSF and 3 in both. Most frequently children presented with fever (70.8 %) and irritability (54.1 %). Five patients (20.8 %) had a cellulitis-adenitis syndrome. Cefotaxime and ampicillin were the most often used antibiotic combination. No ampicillin resistances were found.

CONCLUSIONS

The number of children with late GBS disease has increased in our center. Accordingly, the recent recommendations for the prevention of perinatal GBS vertical transmission were not effective for reducing late GBS infection. This may be due to horizontal infections from maternal sources, community or cross infections. It is important to maintain clinical suspicion of late GBS infection and start early antibiotic treatment.

Evaluation of the Universal Screening Strategy in Qatar for the Management of Pregnant Women Carrying Group B Streptococci

Group B Streptococcus infection (GBS) has emerged as a serious disease, infecting 18,000 people in the United States annually including life-threatening illness in about 8,000 newly-born infants. To evaluate the efficiency of the current universal screening strategy for the management of GBS carriers a retrospective analysis was made of the records of 1,620 pregnant women in Qatar, 550 of whom were found to be carriers. These latter were then used as a group to be compared with 450 uninfected pregnant women in terms of nationality, parity, age, treatment, and outcome. Young and nullipara pregnant women had a high incidence of GBS but there was no significant effect on birth mortality and morbidity regardless of whether or not they received treatment with antibiotics. It is suggested that the cost of screening for GBS at the 35 th week of gestation cannot be justified.

Group B streptococcal infections in a northern region of Italy

BACKGROUND

Group B streptococcus is a leading cause of neonatal bacterial infections. Despite adoption of preventive strategies, cases of infection continue to occur and there is concern that widespread antimicrobial prophylaxis might delay rather than prevent disease onset, increasing the rates of late-onset diseases.

OBJECTIVES

The purpose of this study was to determine the incidence and clinical features of early- and late-onset group B streptococcus disease in a northern region of Italy where a screening-based approach had been proposed.

METHODS

A population-based study was prospectively conducted in Emilia-Romagna, Italy. Infections that occurred during 2003-2005 in infants aged <3 months were analyzed.

RESULTS

Among 112,933 live births, 56 cases of invasive disease (30 early- and 26 late-onset disease) were observed, giving an annual group B streptococcus disease incidence of 0.50 per 1000 live births. Eleven infants with early-onset disease showed no signs of illness or were mildly ill, whereas 19 had moderate-to-severe symptoms, and culture-proven meningitis was found in 2. Risk factors were detected in 12 women. Twenty-two mothers had antenatal screening; 5 were group B streptococcus colonized, but 17 were culture-negative. Prophylaxis was administered in 3 women. Three infants with late-onset diseases were mildly ill, whereas 23 had moderate-to-severe symptoms. Risk factors were found in 7 mothers. Late-onset diseases were clinically more severe than early-onset diseases; meningitis was diagnosed in 12 infants, and 4 of 26 died.

CONCLUSIONS

The incidence of early-onset disease was low. Some early infections were still observed because of negative screening results or missed opportunity for prevention. Late-onset diseases accounted for most meningitis cases and deaths. Strict adherence to protocols and adoption of optimal culture methods would further improve prevention of early-onset disease, but the aim of future strategies should be the prevention of all invasive diseases.

A trial of preventing early- and late-onset Group B streptococcal sepsis with combined intrapartum chemoprophylaxis and universal neonatal screening

BACKGROUND

Prevention of early-onset Group B Streptococcal (GBS) infection has been attempted by employing universal maternal screening for GBS, intrapartum chemoprophylaxis, and a single dose of penicillin given to neonates in the first hour of life. This strategy, however, does not seem to prevent the occurrence of late-onset neonatal group B streptococcal disease.

STUDY DESIGN

We assessed early and late-onset GBS disease with the use of a before-after study designed to evaluate the implementation of intrapartum antimicrobial prophylaxis. Moreover, universal neonatal screening for colonization of GBS was carried out with swabs of the external ear canal. Newborns with GBS colonization received a preventive treatment with oral amoxicillin for 10 days.

RESULTS

Early-onset GBS infection decreased from 0.5 per thousand at baseline period to 0.19 per thousand at the study period. The incidence of late-onset GBS disease decreased from 1:1348 (0.74 per thousand) to 1:20,710 (0.048 per thousand). The overall cost for universal neonatal screening paid for by the Italian Health System in the study period was 31,065 US dollars with an antibiotic prophylaxis cost of 2,399 US dollars.

CONCLUSIONS

A combined strategy based on GBS culture screening and assessment of risk factors for perinatal GBS disease can significantly reduce the rate of both early and late-onset GBS infections.

Duration of Intrapartum Prophylaxis for Neonatal Group B Streptococcal Disease

OBJECTIVE

To examine published evidence regarding duration of intrapartum antibiotic prophylaxis administered to pregnant women colonized with group B Streptococcus (GBS) to reduce infant colonization with GBS and to prevent early-onset GBS sepsis.

DATA SOURCES

A search was conducted in The Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2006), MEDLINE (1966 to January 2006), EMBASE (1980 to January 2006), CINAHL (1982 to January 2006), and in protocols and guidelines of the Centers for Disease Control and Prevention, American Academy of Pediatrics, and American College of Obstetrics and Gynecology.

METHODS OF STUDY SELECTION

All randomized controlled trials and observational studies in which duration of intrapartum antibiotic prophylaxis is reported relative to subsequent neonatal GBS colonization or sepsis were considered. Case series and study designs using historical cohorts or controls for comparison were excluded.

TABULATION, INTEGRATION, AND RESULTS

Three prospective cohort studies and one case-control study met inclusion criteria. Heterogeneity of study design and assembly of cohorts precluded meta-analysis. A systematic review of the individual studies was performed. All studies were rated as fair or poor validity with regard to their ability to evaluate duration of intrapartum prophylaxis and transmission of GBS to the newborn. All 4 studies were largely composed of women with existing risk factors for GBS disease of the newborn. One study supported more than 1 hour of prophylaxis, two studies supported more than 2 hours of prophylaxis, and one was inconclusive.

CONCLUSION

Despite unequivocal clinical guidelines recommending at least 4 hours of intrapartum antibiotic prophylaxis, there are no well-designed studies examining duration of intrapartum antibiotic prophylaxis for prevention of early-onset GBS disease of the newborn. We recommend continuing to initiate intrapartum prophylaxis according to the American College of Obstetricians and Gynecologists guidelines; however, the transmission of GBS to neonates exposed to less than 4 hours of intrapartum prophylaxis and their subsequent management require further study.

Real-time polymerase chain reaction for the rapid detection of group B streptococcal colonization in neonates

BACKGROUND

Group B streptococcal (GBS) infection remains a leading cause of neonatal sepsis. Currently, the management guidelines of neonates born to women with unknown GBS status at delivery are unclear. In this cohort, who undergo at least a 48-hour observation, a rapid method of detection of GBS colonization would allow targeted evaluation and treatment, as well as prevent delayed discharge.

OBJECTIVE

The goal of this research was to evaluate the validity of rapid fluorescent real-time polymerase chain reaction in comparison with standard culture to detect GBS colonization in infants born to women whose GBS status is unknown at delivery.

DESIGN/METHODS

Neonates at >32 weeks' gestation born to women whose GBS status was unknown at delivery were included. Samples were obtained from the ear, nose, rectum, and gastric aspirate for immediate culture and real-time polymerase chain reaction after DNA extraction using the LightCycler. Melting point curves were generated, and confirmatory agar gel electrophoresis was performed.

RESULTS

The study population (n = 94) had a mean +/- SD gestational age of 38 +/- 2 weeks and birth weight of 3002 +/- 548 g. The rates of GBS colonization by culture were 17% and 51% by real-time polymerase chain reaction. The 4 surface sites had comparable rates of GBS. The overall sensitivities, specificities, and positive and negative predictive values of real-time polymerase chain reaction were: 90%, 80.3%, 28%, and 98.9%.

CONCLUSIONS

Real-time polymerase chain reaction resulted in a threefold higher rate of detection of GBS colonization and had an excellent negative predictive value in a cohort of neonates with unknown maternal GBS status at delivery. Thus, real-time polymerase chain reaction would be a useful clinical tool in the management of those infants potentially at risk for invasive GBS infection and would allow earlier discharge for those found to be not at risk.

Sensitivities of antigen detection and PCR assays greatly increased compared to that of the standard culture method for screening for group B streptococcus carriage in pregnant women

Group B streptococcus (GBS) is a major cause of serious infections in neonates. The 2002 revised guidelines of the Centers for Disease Control and Prevention (CDC) for the prevention of perinatal GBS disease recommend that all pregnant women be screened for GBS carriage at between 35 and 37 weeks of gestation and that intrapartum antibiotic prophylaxis be given to carriers. We studied the performances of four different GBS detection assays in the context of antenatal screening. Between May and August 2004, the 605 vaginorectal swab specimens received at our bacteriology laboratory for GBS antenatal detection were tested by the four assays. The standard culture method was done according to the CDC recommendations. The three experimental assays performed with the growth from the selective enrichment (LIM) broth (Todd-Hewitt broth with 15 mug/ml nalidixic acid and 10 mug/ml colistin) after overnight incubation were a GBS antigen detection assay (PathoDx) and two PCR assays (for cfb and scpB). The most accurate assay was the scpB PCR (sensitivity, 99.6%; specificity, 100%), followed by the cfb PCR (sensitivity, 75.3%; specificity, 100%), GBS antigen detection (sensitivity, 57.3%; specificity, 99.5%), and standard culture (sensitivity, 42.3%; specificity, 100%). The GBS antigen detection assay was found to be more sensitive than the standard culture method, and moreover, the assay has a low cost and is easy to perform in all obstetrical centers which have access to the most basic of diagnostic microbiology services. We believe that antigen detection on incubated LIM broth should replace the standard culture method for screening for GBS carriage at 35 to 37 weeks of gestation. The impact of the greater sensitivities of PCR assays on the diminution of neonatal GBS infections remains to be demonstrated.

Early-onset group B streptococcal disease in the era of maternal screening

BACKGROUND

With the widespread implementation of intrapartum antibiotic prophylaxis (IAP), the rate of early-onset neonatal sepsis and meningitis caused by Streptococcus agalactiae (group B streptococcus [GBS]) has decreased dramatically, especially in term infants. However, cases of GBS disease continue to occur despite IAP and incur significant morbidity and mortality. Inaccurate screening results, improper implementation of IAP, or antibiotic failure all may contribute to persistent disease.

OBJECTIVE

To determine if clinical, procedural, or microbiologic factors influenced persistent early-onset GBS disease (EOGBS) cases in a single large maternity service after the institution of a screening-based protocol for IAP.

METHODS

Retrospective review of all cases of culture-proven EOGBS at the Brigham and Women's Hospital (Boston, MA) from 1997 to 2003. Serotyping and surface protein analyses were performed on available disease isolates.

RESULTS

A total of 67260 infants were live-born during this period. Twenty-five cases of EOGBS (0.37 of 1000 live births) were identified. The overall incidence of EOGBS progressively decreased with different approaches to IAP. Of the 25 cases identified after institution of a screening-based protocol, 17 (68%) occurred in term infants (1 death), and 8 (32%) occurred in preterm infants (3 deaths). Among the mothers of term infants, 14 of 17 (82%) had been screened GBS negative; 1 was GBS unknown. More than half of the mothers of term infants who had screened GBS negative (8 of 14) had intrapartum risk factors for neonatal infection but did not receive antibiotics before delivery. Ten of the 17 term infants were evaluated for infection because of clinical signs of illness, and the remainder were evaluated because of intrapartum sepsis risk factors. Of the mothers of preterm infants, by the time of delivery 3 of 8 had been documented as GBS positive, 2 of 8 had been documented GBS negative, and 3 of 8 remained unknown. Only 1 of 25 women received adequate IAP, but the isolate was resistant to the administered antibiotic (clindamycin). Antibiotic resistance was not a factor in any other case, and no dominant serovariant was identified among tested isolates. Procedural errors (lack of recognition of documented GBS colonization or failure to evaluate infants at risk for sepsis) were identified in 4 cases.

CONCLUSIONS

The majority of the remaining cases of EOGBS occurred in infants whose mothers screened negative for GBS colonization. Even in the setting of a maternal GBS-screening program, efforts to evaluate and treat infants with intrapartum clinical risk factors for early-onset sepsis remain important. Until effective vaccines against GBS are available for clinical use, development and implementation of rapid and sensitive techniques for screening for GBS status and antibiotic susceptibility at presentation may help prevent additional cases of invasive GBS disease.