Impact of a risk-based prevention policy on neonatal group B streptococcal disease

Group B streptococcal immunisation of pregnant women for the prevention of early and late onset Group B streptococcal infection of the neonate as well as adult disease

INTRODUCTION

Early onset neonatal Group B streptococcal disease is preventable. Intrapartum antibiotic prophylaxis has resulted in a significant reduction in neonatal mortality and morbidity. National guidelines for the selection of women eligible for intrapartum antibiotic prophylaxis, whether screening-based or risk-based, differ according to the local burden of disease. Despite the introduction of intrapartum antibiotic prophylaxis, there remains a significant burden of disease, which can be resolved by better adherence to guidelines, rapid identification of maternal colonization or in the future, vaccination. Areas covered: The introduction of a vaccine to women in the third trimester is likely to further reduce the burden of disease and provide benefits beyond the prevention of early neonatal disease, including meningitis and disability following late onset disease. Development of specific polyvalent vaccines continues, but testing has challenges and may require surrogate markers or molecular-based techniques to manipulate antigenicity and immunogenicity. Expert commentary: Group B streptococcal vaccination using conjugated polyvalent vaccines against the major disease causing serotypes of Group B streptococcus, either alone, or in combination with a policy of intrapartum antibiotic prophylaxis, may decrease the burden of Group B streptococcus beyond that achieved by current use of intrapartum antibiotic prophylaxis alone.

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).

Application d’un protocole de prévention de l’infection materno-fœtale à streptocoque β hémolytique au sein du réseau périnatal Aurore

OBJECTIVE

Our purpose was to measure the compliance with the network hospitals protocol for preventing neonatal group B streptococcal sepsis.

MATERIALS AND METHOD

All vaginal deliveries during a one-week period in 37 maternities of the perinatal network were reviewed retrospectively.

RESULTS

A total of 752 records were reviewed. Compliance with the protocol regarding the time of culture was 91.1%. Overall, prevalence of group B streptococcal carriage was 14.2%. Among patients eligible for intrapartum antibiotics, 46.4% received adequate prophylaxis. Considering the length of labor, one out of two patients could have received intrapartum adequate antibiotics. Regarding newborns, 86.1% received adequate medical surveillance. There was no confirmed case of group B streptococcal sepsis during the week of study.

CONCLUSION

All the maternities of network Aurore accepted and adopted evaluation principle. Some elements of protocol could be better applied, in particular delivering adequate intrapartum antibiotic prophylaxis.

Antibiotic Prophylaxis and Non–Group B Streptococcal Neonatal Sepsis

OBJECTIVE

To assess the effect of increased use of intravenous penicillin for group B streptococcus (Streptococcus agalactiae, GBS) antibiotic prophylaxis on non-GBS neonatal sepsis and antibiotic resistance.

METHODS

We undertook a nonconcurrent cohort study. Microbiology cultures originating from infants with early-onset neonatal sepsis in our neonatal intensive care unit (NICU) from 1992 to 1999 were reviewed. Prevalence of non-GBS neonatal sepsis in the control period (January 1, 1992, through June 30, 1995) was compared with that in the study period (October 1, 1995, through August 31, 1999), when the protocol changed. Chi-squared or Fisher exact tests were used to determine statistical significance. Resistance patterns were compared in similar fashion.

RESULTS

The prevalence of non-GBS neonatal sepsis was 1.2 per 1,000 (36 of 31,133) live births before and 1.1 per 1,000 (32 of 28,733) live births after institution of the Centers for Disease Control and Prevention culture-based protocol (P = .97). Our power analysis assumed a doubling in the rate of non-GBS sepsis and required 21,220 live births per arm. Gram-negative and gram-positive sepsis prevalences were not significantly different. Escherichia coli and GBS resistance patterns did not change.

CONCLUSION

Institution of a protocol for GBS antibiotic prophylaxis significantly decreased the rate of GBS neonatal sepsis but did not increase the rate of non-GBS neonatal sepsis. Antibiotic resistance patterns of these organisms were not affected.

Maternal colonisation with group B streptococcus and effectiveness of a culture-based protocol to prevent early-onset neonatal sepsis

This study was conducted to find out the group B streptococcus colonisation of pregnant women in Kocaeli, Turkey. A culture plus individualised high-risk-based antibiotic prophylaxis was compared with high-risk-based approach alone. The screening of women was performed via vaginal and anal cultures for group B streptococcus (GBS). The maternal GBS colonisation rate was found to be 6.5%. All colonised women or preterm labours with unavailable culture results until delivery received prophylactic antibiotics. Neonatal colonisation rate and early-onset neonatal sepsis due to GBS was 1/200. The unscreened 900 women received prophylactic antibiotics due to a risk factor-based approach. The neonatal colonisation rate was 17/900 (p = 0.1), and the rate of early-onset neonatal sepsis was 3/900 (p = 0.6). A culture plus individualised high-risk-based antibiotic prophylaxis provided an insignificant change in neonatal colonisation and early-onset neonatal sepsis with GBS when compared with high-risk-based approach alone.

"Real World" compliance with strategies to prevent early-onset group B streptococcal disease

OBJECTIVE

To assess the "real-world" compliance with risk- and culture-based strategies to prevent early-onset group B streptococcal disease.

STUDY DESIGN

We retrospectively reviewed the medical records of consecutive term pregnancies delivered at three institutions (a subset of practices at an academic hospital using the culture-based strategy, an academic hospital using the risk-based strategy, and a community hospital using both) between January and March 1998. We abstracted demographic data and risk factors for group B streptococcus, group B streptococcal culture information, documentation of intrapartum antibiotic prophylaxis, and adverse drug reactions. We compared intrapartum compliance with the intended strategy.

RESULTS

There were a total of 505 women managed with the risk-based strategy. Of those, 79 had a risk factor for group B streptococcal disease and 72/79 (91.1%) received intrapartum antibiotic prophylaxis. There were a total of 428 women managed with the culture-based strategy. Of those, 70 had positive cultures and 67 (95.7%) received intrapartum antibiotic prophylaxis. An additional 39 women in the culture-based group had no documentation that cultures had been done. Of those, eight (20.5%) had risk factors and all eight received intrapartum antibiotic prophylaxis. Compliance with the risk-based strategy was 91.1 versus 96.2% with the culture-based strategy (p=0.3). Among women managed using the risk-based strategy, 5/426 (1.2%) received intrapartum antibiotic prophylaxis without an identifiable risk factor. Among women in the culture-based strategy, 5/359 (1.4%) received intrapartum antibiotic prophylaxis with documented negative group B streptococcal cultures (p=0.5). When examined by site, compliance with the intended strategy was 91.2% at the academic hospital using the risk-based strategy, 100% at the academic hospital using the culture-based strategy, 90.9% at the community practices using the risk-based strategy, and 82.4% at the community practices using the culture-based strategy.

CONCLUSION

Overall, intrapartum compliance with the risk-based approach was similar to the culture-based approach. However, there were more cultures not done and cultures done at inappropriate gestations at the community hospital practice.

Effects of intrapartum antimicrobial prophylaxis for prevention of group-B-streptococcal disease on the incidence and ecology of early-onset neonatal sepsis

Sepsis occurring in the first week of life can be a devastating neonatal problem. Group B streptococci (GBS) and enterobacteriaceae are the main causes of early-onset sepsis in more developed countries. Intrapartum antimicrobial prophylaxis (IAP) has lowered the incidence of early-onset GBS sepsis by 50-80%. However, there are concerns that the use of IAP may select for infections caused by enterobacteriaceae, including some strains resistant to antimicrobials. We explored potential associations between IAP use and changes in the causes of early-onset sepsis. We concluded that there have been substantial declines in the incidence of early-onset infections due to GBS and, in some settings, other bacteria. Increases in the frequencies of non-GBS or antimicrobial-resistant early-onset sepsis have been limited to preterm, low-birthweight, or very-low-birthweight neonates. We propose systematic monitoring of early-onset sepsis, coupled with targeted research, to inform periodic reassessment of prevention strategies.

High burden of invasive Streptococcus agalactiae disease in South African infants

The epidemiology of invasive Streptococcus agalactiae (GBS) disease was evaluated in South African children. Records of 208/220 children in whom GBS was isolated between January 1997 and December 1999 were reviewed. These included 63%, 31.7% and 5.3% children with early- (EOD, <7 days of age), late- (LOD, age 7-90 days) and childhood-onset disease (COD, age >90 days), respectively. The overall burden of EOD and LOD were 2.06 and 1/1000 live births, respectively. The overall mortality was 19.8% and 13.6% for infants with EOD and LOD, respectively. Risk factors for mortality in infants with EOD and LOD included septic shock (82.1% vs 1.9%), prematurity (35.2% vs 9.6%), low birthweight (29.2% vs 11.0%) and a leucocyte count <5000/mm(3) (43.5% vs 18.6%). Eight (72.7%) of 11 children with COD had an immunosuppressive, predisposing cause for invasive bacterial disease. In infants with EOD and LOD, serotype III isolates caused 49.2% and 75.7% of disease, respectively, and, together with serotype Ia isolates, caused 78.9% and 100% of invasive disease, respectively. Invasive GBS disease is common in South African infants and current strategies aimed at reducing the burden of the disease should be reconsidered.

Early-onset group B streptococcal infection after a combined maternal and neonatal group B streptococcal chemoprophylaxis strategy

OBJECTIVE

In January 1995, a combined maternal and neonatal protocol for prevention of early-onset group B streptococcal (GBS) infection was implemented that consisted of a risk factor-based approach for maternal intrapartum chemoprophylaxis using ampicillin combined with a single intramuscular dose of penicillin given to all newborns within 1 hour of delivery. The objective of this study was to review the cases of early-onset GBS infections that occurred from 1995 to 1999 to identify factors associated with their continued occurrence despite implementation of a GBS chemoprophylaxis protocol.

METHODS

Infants <or=72 hours of age with early-onset GBS infection born at Parkland Memorial Hospital in Dallas from January 1995 to December 1999 were identified through a prospective laboratory-based surveillance system. Maternal and infant medical records were reviewed for clinical and demographic data.

RESULTS

There were 32 cases (0.47/1000 live births) of early-onset GBS infection for the 5-year period. This represented a 76% reduction compared with the rate from 1986 to 1994 (1.95/1000), when there was no protocol for GBS chemoprophylaxis. Thirteen cases (41%) did not have any identifiable maternal risk factor. Of the 19 cases (59%) with risk factors, maternal intrapartum fever was the most frequent (15 [79%]), followed by prematurity (6 [32%]) and prolonged rupture of membranes (6 [32%]). Among the 19 mothers with risk factors, 15 (79%) mothers received intrapartum chemoprophylaxis, and 12 (80%) of the 15 mothers had intrapartum fever. Only 33% of mothers with risk factors received >or=2 doses of intrapartum chemoprophylaxis, and among those with intrapartum fever, 25% received >or=2 doses. None of the 32 infants with early-onset GBS infection received the combination of intrapartum ampicillin and postnatal penicillin.

CONCLUSIONS

A combined obstetric and neonatal chemoprophylaxis protocol significantly reduced early-onset GBS infection. Maternal intrapartum fever was the most frequent risk factor associated with failure of chemoprophylaxis.

Screening strategies for group B streptococcus in the third trimester of pregnancy

PURPOSE

To identify the best screening protocol to prevent neonatal group B streptococcal (GBS) sepsis through literature review.

DATA SOURCES

Selected research articles, texts, and Internet sources.

CONCLUSIONS

Centers for Disease Control and Prevention (CDC), American Academy of Pediatrics (AAP), American College of Obstetricians and Gynecologists (ACOG), and American College of Nurse Midwives (ACNM) have issued guidelines describing methods to identify pregnant women at risk of intrapartum transmission of GBS to their babies. Studies have been conducted to discover the superiority of one prevention method over the other but no consensus has been reached.

IMPLICATIONS FOR PRACTICE

Before widely used prevention methods, approximately 8,000 babies each year became infected with GBS; of those, 400 died and many survivors suffered life-long sequelae. Adoption of an appropriate protocol can prevent transmission of GBS from a colonized mother to her infant. Clinicians should implement either universal culture-based or risk factor-based screening guidelines for prenatal diagnosis and intrapartum prophylaxis of GBS disease.

A population-based comparison of strategies to prevent early-onset group B streptococcal disease in neonates

BACKGROUND

Guidelines issued in 1996 in the United States recommend either screening of pregnant women for group B streptococcal colonization by means of cultures (screening approach) or assessing clinical risk factors (risk-based approach) to identify candidates for intrapartum antibiotic prophylaxis.

METHODS

In a multistate retrospective cohort study, we compared the effectiveness of the screening and risk-based approaches in preventing early-onset group B streptococcal disease (in infants less than seven days old). We studied a stratified random sample of the 629,912 live births in 1998 and 1999 in eight geographical areas where there was active surveillance for group B streptococcal infection, including all births in which the neonate had early-onset disease. Women with no documented culture for group B streptococcus were considered to have been cared for according to the risk-based approach.

RESULTS

We studied 5144 births, including 312 in which the newborn had early-onset group B streptococcal disease. Antenatal screening was documented for 52 percent of the mothers. The risk of early-onset disease was significantly lower among the infants of screened women than among those in the risk-based group (adjusted relative risk, 0.46; 95 percent confidence interval, 0.36 to 0.60). Because women whose providers had no strategy for prophylaxis may have been misclassified in the risk-based group, we excluded all women with risk factors and adequate time for prophylaxis who did not receive antibiotics. The adjusted relative risk of early-onset disease associated with the screening approach in this secondary analysis was similar--0.48 (95 percent confidence interval, 0.37 to 0.63).

CONCLUSIONS

Routine screening for group B streptococcus during pregnancy prevents more cases of early-onset disease than the risk-based approach. Recommendations that endorse both strategies as equivalent warrant reconsideration.

Chlorhexidine vaginal flushings versus systemic ampicillin in the prevention of vertical transmission of neonatal group B streptococcus, at term

OBJECTIVE

To investigate the efficacy of intrapartum vaginal flushings with chlorhexidine compared with ampicillin in preventing group B streptococcus transmission to neonates.

METHODS

This was a randomized controlled study, including singleton pregnancies delivering vaginally. Rupture of membranes, when present, must not have occurred more than 6 h previously. Women with any gestational complication, with a newborn previously affected by group B streptococcus sepsis or whose cervical dilatation was greater than 5 cm were excluded. A total of 244 group B streptococcus-colonized mothers at term (screened at 36-38 weeks) were randomized to receive either 140 ml chlorhexidine 0.2% by vaginal flushings every 6 h or ampicillin 2 g intravenously every 6 h until delivery. Neonatal swabs were taken at birth, at three different sites (nose, ear and gastric juice).

RESULTS

A total of 108 women were treated with ampicillin and 109 with chlorhexidine. Their ages and gestational weeks at delivery were similar in the two groups. Nulliparous women were equally distributed between the two groups (ampicillin, 87%; chlorhexidine, 89%). Clinical data such as birth weight (ampicillin, 3,365 +/- 390 g; chlorhexidine, 3,440 +/- 452 g), Apgar scores at 1 min (ampicillin, 8.4 +/- 0.9; chlorhexidine, 8.2 +/- 1.4) and at 5 min (ampicillin, 9.7 +/- 0.6; chlorhexidine, 9.6 +/- 1.1) were similar for the two groups, as was the rate of neonatal group B streptococcus colonization (chlorhexidine, 15.6%; ampicillin, 12%). Escherichia coli, on the other hand, was significantly more prevalent in the ampicillin (7.4%) than in the chlorhexidine group (1.8%, p < 0.05). Six neonates were transferred to the neonatal intensive care unit, including two cases of early-onset sepsis (one in each group).

CONCLUSIONS

In this carefully screened target population, intrapartum vaginal flushings with chlorhexidine in colonized mothers display the same efficacy as ampicillin in preventing vertical transmission of group B streptococcus. Moreover, the rate of neonatal E. coli colonization was reduced by chlorhexidine.

Capsulate bacteria and the lung

Capsulate bacteria cause the majority of community-acquired pneumonia presenting to hospital world-wide, at all ages. They are united by the virulence factor of their differing capsular polysaccharides, enabling them to evade phagocytosis. All cause invasive disease beyond the respiratory tract, including septicaemia and central nervous system infection. Recent advances in vaccine development have made the capsular polysaccharide an achievable target for vaccine strategies across all ages, with impacts already seen upon Streptococcus pneumoniae and Haemophilus influenzae type b pneumonia in countries able to afford these new vaccines.

Choosing a strategy to prevent neonatal early-onset group B streptococcal sepsis: economic evaluation

OBJECTIVE

To determine the most appropriate strategy to prevent neonatal streptococcal sepsis in a setting with a low incidence of the disease.

DESIGN

Decision analysis and economic evaluation.

SETTING

Geneva University Hospitals, Switzerland.

POPULATION

Pregnant women at 35-37 weeks of gestation and in labour.

METHODS

Local data and data from the literature were used in a decision analysis to compare the current policy of antibiotic administration at Geneva University Hospitals with the recommended preventive strategies.

MAIN OUTCOME MEASURES

Number of episodes of sepsis averted; cost and number needed to treat to prevent one episode of sepsis; and proportion of women receiving antibiotics during labour.

RESULTS

Compared with the current policy, the risk factors strategy would prevent 69 streptococcal sepsis per million deliveries and the screening strategy would prevent 102 cases of sepsis per million deliveries. Cost per averted sepsis case would be 60 pounds, 700 and 473 pounds, 600, respectively. The number needed to treat to prevent one sepsis would be 1,087 with a risk factors strategy and 1,029 with a screening strategy. Preventive strategies would increase the proportion of women receiving antibiotics during labour from 6% with the current policy, to 13.5% and 16.5% respectively.

CONCLUSIONS

Preventive strategies are more effective than the current policy, but imply increased hospital costs and a notable increase in the proportion of women receiving antibiotics during labour, which may be unjustified in a low incidence setting.

The effectiveness of risk-based intrapartum chemoprophylaxis for the prevention of early-onset neonatal group B streptococcal disease

OBJECTIVE

Our purpose was to evaluate the effectiveness of a risk-based intrapartum antibiotic prophylaxis strategy for the prevention of early-onset neonatal group B streptococcal disease.

STUDY DESIGN

Cases and controls were selected from infants born to women with one or more risk factors: preterm labor or rupture of membranes, prolonged rupture of membranes (>18 hours), fever during labor, or previous child with group B streptococcal disease. Cases were matched with controls by birth hospital and gestational age. Data abstracted from medical records were analyzed to estimate the effectiveness of intrapartum antibiotic prophylaxis.

RESULTS

We analyzed data from 109 cases and 207 controls. Nineteen (17%) case versus 69 (33%) control mothers received an acceptable regimen of intrapartum antibiotic prophylaxis. In adjusted analyses, the effectiveness of intrapartum antibiotic prophylaxis was 86% (95% confidence interval, 66%-94%). When the first dose of antibiotics was given > or =2 hours before delivery, the effectiveness increased to 89% (95% confidence interval, 70%-96%); when it was given within 2 hours of delivery, the effectiveness was 71% (95% confidence interval, -8%-92%). Effectiveness was lowest in mothers with intrapartum fever (72%, 95% confidence interval, -9%-93%). On the basis of a 70% prevalence of maternal risk factors expected among cases in the absence of intrapartum antibiotic prophylaxis, we estimate that the risk-based strategy could reduce early-onset group B streptococcal disease by 60%.

CONCLUSIONS

The risk-based approach to intrapartum antibiotic prophylaxis is effective in preventing early-onset group B streptococcal disease. To achieve the maximum preventive effect, the first dose of antibiotics should be administered at least 2 hours before delivery.

Prevention of early-onset invasive neonatal group B streptococcal disease in a private hospital setting: the superiority of culture-based protocols

OBJECTIVE

In a large private tertiary care hospital we compared the two different approaches to group B streptococcal screening and intrapartum chemoprophylaxis suggested by The American College of Obstetricians and Gynecologists, the American Academy of Pediatrics, and the Centers for Disease Control and Prevention: risk factor-based protocol and culture-based protocol.

STUDY DESIGN

A 2-year baseline period was followed by sequential prospective observational studies of the impacts of two different group B streptococcal management protocols, 3 years with the risk-based approach and 2 years with the culture-based approach of universal screening at 35 to 37 weeks' gestation.

RESULTS

During the baseline period the rate of early-onset group B streptococcal infection was 1. 1 cases per 1000 births (n = 8 cases per 6829 births). With the risk-based strategy the rate was also 1.1 cases per 1000 births (15 cases/13,270 births). After we switched to the culture-based protocol for 2 years, there were no cases of early-onset group B streptococcal infections among 9304 births (P =.001; chi(2) = 10.9). There were no increases in other early-onset infections or in antibiotic resistance.

CONCLUSIONS

In our setting, which included good prenatal care and good communication between laboratories and the hospital, the approach based on maternal culture at 35 to 37 weeks' gestation and treatment during labor of all patients with positive results significantly reduced early-onset group B streptococcal infections without increasing infections from resistant organisms.

Performance of a group B streptococcal prophylaxis protocol combining high-risk treatment and low-risk screening

OBJECTIVE

This study was undertaken to evaluate a group B streptococcal protocol in a large community hospital that combined treatment of high-risk patients with rapid screening of low-risk patients.

STUDY DESIGN

In a prospective cohort study from 1994 through 1996 laboring patients in a level III community hospital were considered to be at high risk for neonatal group B streptococcal transmission if they were at <37 weeks' gestation, if they had rupture of membranes >12 hours, if they were known carriers of group B streptococci, if they had a temperature > or =100 degrees F, if the gestation was complicated by fetal growth restriction or was a multiple gestation, or if they had a previous neonate infected with group B streptococci. High-risk patients were treated intravenously with antibiotics during labor. Low-risk patients were screened for group B streptococcal antigen by means of a rapid optical immunoassay. Patients with positive screening results were treated. Neonatal morbidity and mortality were evaluated.

RESULTS

Two of 9932 infants delivered had group B streptococcal sepsis diagnosed. In the 2 previous years without a protocol 9 cases of neonatal group B streptococcal sepsis had been diagnosed in 8188 deliveries (P =.0287 by Fisher exact test). The 2 cases of group B streptococcal sepsis during the protocol were as follows: 1 infant born to a high-risk mother with delay in treatment and 1 infant born to a low-risk mother with negative results of both culture and rapid screen during labor. During the previous period 7 infected infants had been born to high-risk mothers and 2 had been born to low-risk mothers. The maternal group B streptococcal carriage rate during the study was 18%. Group B streptococcal rapid optical immunoassay sensitivity was 81%. Elapsed time from screening to treatment was < or =2(1/2) hours for 93% of patients. No maternal anaphylaxis, no increase in bacterial neonatal sepsis caused by organisms other than group B streptococci, and no protocol-related group B streptococcal antibiotic resistance were noted.

CONCLUSION

Successful implementation and maintenance of a protocol combining treatment of high-risk patients with rapid screening of low-risk patients during labor reduced neonatal group B streptococcal sepsis.

Chemoprophylaxis of early-onset group B streptococcal disease in 1999

The evolution of the guidelines for selective intrapartum chemoprophylaxis (SIC) of group B streptococcal early-onset disease is reviewed here. To assess the benefits of the risk-based and culture-based strategies for prevention, observational studies since 1996 are summarized. The effect of chorioamnionitis on group B streptococcal early-onset disease, despite SIC, is emphasized. Optimal management remains controversial, and alternative strategies for the selection of women for chemoprophylaxis and for the management of infants are discussed.

Group B streptococcus

During the 1990s the focus of group B streptococcus (GBS) disease research has shifted to prevention. Increased use of intrapartum antimicrobial prophylaxis in North America and Australia has led to substantial declines in perinatal disease. Vaccine development (initiated two decades earlier) has yielded results--for example, polysaccharide-protein conjugate vaccines given to women of reproductive age proved to be highly immunogenic and well tolerated. Also economic evaluations have assessed the cost-effectiveness of prevention strategies in different populations. Although GBS has traditionally been considered a perinatal pathogen, the burden of invasive GBS disease among nonpregnant adults has been measured. Adverse outcomes of pregnancy attributable to GBS were addressed through a multicentre study which confirmed the important role of heavy colonisation with GBS in preterm low-birthweight deliveries. Finally, the pathogen itself has continued to evolve: new capsular serotypes described in the past decade are now causing an important proportion of clinical infections.

Epidemiology of group B streptococcal disease in the United States: shifting paradigms

Since its emergence 25 years ago, group B streptococcus has become recognized as a cause of serious illness in newborns, pregnant women, and adults with chronic medical conditions. Heavy colonization of the genital tract with group B streptococcus also increases the risk that a woman will deliver a preterm low-birthweight infant. Early-onset infections (occurring at < 7 days of age) are associated with much lower fatality than when they were first described, and their incidence is finally decreasing as the use of preventive antibiotics during childbirth increases among women at risk. New serotypes of group B streptococcus have emerged as important pathogens in adults and newborns. Clinical and laboratory practices--in obstetrics, pediatrics, and clinical microbiology--have an impact on disease and/or its prevention, and protocols established at the institutional level appear to be critical tools for the reduction of perinatal disease due to group B streptococcus. Since intrapartum antibiotics will prevent at best only a portion of the full burden of group B streptococcal disease, critical developments in vaccine evaluation, including study of polysaccharide-protein conjugate vaccines, offer the potential for enhanced prevention in the relatively near future.