Universal maternal screening for neonatal group B streptococcal disease

Evaluation of an in-house real-time polymerase chain reaction method to identify group B streptococcus colonization in pregnancy

AIM

The aim of this study was to evaluate the performance of in-house real-time polymerase chain reaction (qPCR) in detecting group B streptococcus (GBS) colonization compared with the standard culture method in a cohort of pregnant women.

MATERIAL AND METHODS

A total of 134 rectovaginal swabs were collected from 125 pregnant women, of whom 108 were known carriers or presented with preterm prelabor rupture of membranes. The swabs were placed in Standard Methods Broth (Todd-Hewitt broth supplemented with 6 μg/mL gentamicin and 15 μg/mL nalidixic acid) for culture identification of GBS. An in-house qPCR was also performed from the broth and after overnight incubation of the broth.

RESULTS

The detection rate of GBS in this cohort was 30.6% and 50.7% using standard culture method and qPCR, respectively. GBS-specific qPCR assay gave sensitivities of 97.6% and 100%, specificities of 73.1% and 71.0%, and negative predictive values of 98.6% and 100% from direct specimen and from broth after overnight incubation, respectively.

CONCLUSIONS

The in-house qPCR test has high sensitivity in detecting GBS colonization. The high negative predictive value helps to avoid unnecessary use of antibiotics in uncolonized women.

Maternal and neonatal risk factors for early-onset group B streptococcal disease: a case control study

Objectives

To identify the prominent maternal and neonatal risk factors associated with early-onset group B streptococcus (EOGBS) disease in neonates and to determine their importance by comparing them with a control group.

Setting

Neonatal unit at King Abdulaziz Medical City, Riyadh, Kingdom of Saudi Arabia.

Patients

Cases were infants <7 days of age with invasive group B streptococcus (GBS) disease diagnosed between January 1, 2000 and December 31, 2009. Controls were healthy infants born in the same hospital during the same period having the same birth weight and gestational age category.

Main outcome measures

Maternal risk factors for developing EOGBS disease, feto–maternal and neonatal clinical data, their morbidities, mortalities, and length of hospital stay.

Results

A total of 99 cases and 200 controls were included. The majority of cases presented in the first 72 hours of life (62/99 [63.9%]), of which 87/99 (89.7%) had at least one clinical risk factor for the development of EOGBS disease. Mothers of neonates with EOGBS disease were more likely to have GBS bacteriuria (odds ratio [OR] 10.76, 95% confidence interval [CI] 1.24–93.42), infection in the peripartum period (OR 8.92, CI 2.87–27.68), and temperature ≥38°C (OR 7.10, CI 2.50–20.17). GBS disease was associated with premature rupture of membranes and fetal tachycardia (P<0.01 for both). Neonates with EOGBS disease were more likely to have respiratory distress disease and convulsions, require tube feeding, and have longer hospital stays compared with the controls (P<0.01 for all). Stepwise multiple logistic regression has identified three risk factors that were associated with the highest tendency for the development of EOGBS disease. These were lack of antenatal attendance (OR =0.30 and CI 0.98–0.88), rupture of membranes (OR =9.62 and CI 3.1–29.4), and antibiotic use in labor (OR =0.16 and CI 0.38–0.67).

Conclusion

A number of maternal risk factors were significantly associated with EOGBS disease. Taking these factors into consideration may result in preventing the occurrence of EOGBS disease, improve maternal and neonatal medical care, decrease their hospital stay, and reduce unnecessary hospital resource utilization.

Group B streptococcus disease in neonates: To screen or not to screen?

An audit was undertaken of the prevention of early-onset Group B streptococcus (EOGBS) disease in neonates. The prevention strategy in use involved offering Intra-partum Antibiotic Prophylaxis (IAP) to mothers with identified risk factors, which include maternal fever in labour > 38 degrees C, previous baby with GBS disease, prolonged rupture of membranes > 18 h, pre-term labour, GBS urinary tract infection and known GBS carriage. The most common risk factor identified was GBS carriage (41%) which was known ante-partum but logistical problems prevented these mothers from receiving adequate prophylaxis 4 h before delivery and so were classified as at risk of GBS disease. We found an incidence of GBS in our unit of 0.55 per 1,000 births over the study period. One neonate developed EOGBS disease and the mother had no identifiable risk factor ante-partum/intra-partum. Recent recommendations from the Royal College of Obstetricians and Gynaecologists (RCOG) could reduce the number of babies having sepsis screens performed as the time interval from beginning IAP to delivery has been shortened to 2 h and routine surface cultures or blood cultures are not recommended in well newborns. The evidence is lacking at this point to recommend universal screening for GBS in all pregnant women but patients are increasingly aware of this option and may request anogenital swabs to assess GBS carriage.

An overview of the natural history of early onset group B streptococcal disease in the UK

Clinicians need information on the risk of Early Onset Group B Streptococcal disease (EOGBS) for counselling pregnant women and to decide who would benefit most from antibiotic treatment during labour. We carried out a systematic review of the research literature and conducted meta-analyses to obtain estimates for the natural history of EOGBS that are representative of the UK population. The mean rate of colonisation for the UK was 14% and we found weak evidence that the prevalence is increasing over time. Maternal GBS colonisation was more likely in women who delivered preterm compared with at term. Just over one-third of babies born to colonised mothers become colonised with GBS at birth (36%), and 3% of colonised babies develop EOGBS bacteraemia. In the UK, EOGBS constitutes one-third of all early onset bacteraemia due to pathogens, in contrast to one-half in the USA.

Population structure of group B streptococcus from a low-incidence region for invasive neonatal disease

The population structure of group B streptococcus (GBS) from a low-incidence region for invasive neonatal disease (Israel) was investigated using multilocus genotype data. The strain collection consisted of isolates from maternal carriage (n=104) and invasive neonatal disease (n=50), resolving into 46 sequence types. The most prevalent sequence types were ST-1 (17.5 %), ST-19 (10.4 %), ST-17 (9.7 %), ST-22 (8.4 %) and ST-23 (6.5 %). Serotype III was the most common, accounting for 29.2 % of the isolates. None of the serotypes was significantly associated with invasive neonatal disease. burst analysis resolved the 46 sequence types into seven lineages (clonal complexes), from which only lineage ST-17, expressing serotype III only, was significantly associated with invasive neonatal disease. Lineage ST-22 expressed mainly serotype II, and was significantly associated with carriage. The distribution of the various sequence types and lineages, and the association of lineage ST-17 with invasive disease, are consistent with the results of analyses from a global GBS isolate collection. These findings could imply that the global variation in disease incidence is independent of the circulating GBS populations, and may be more affected by other risk factors for invasive GBS disease, or by different prevention strategies.

Early-onset neonatal group B streptococcal infection in London: 1990-1999

OBJECTIVE

To identify the incidence of early-onset group B streptococcal infection and to describe the antecedent maternal risk factors, in order to provide data to inform the design of interventional strategies that could be introduced in the UK to reduce the burden of this infection.

DESIGN

A retrospective study with review of case notes of mothers and babies.

SETTING

Seven maternity units in London during 1990-1999. Population All cases of proven early-onset neonatal group B streptococcal infection.

METHODS

Identification of presence of risk factors that could be used to select women for the offer of intrapartum antibiotic prophylaxis.

MAIN OUTCOME MEASURES

Incidence and case-fatality rate of invasive early-onset group B infection.

RESULTS

One hundred and forty cases were identified among a birth cohort of 198,388 live births, an incidence of 0.71 per 1000 live births. Twenty-two babies died, a case-fatality rate of 15.6% or 1.1 per 100,000 live births. Women of black ethnic origin, and those who had had a previously affected infant, multiple pregnancy, preterm delivery, prolonged rupture of membranes or intrapartum fever all had a significantly increased risk of delivering an infected infant.

CONCLUSIONS

These data suggest that the incidence of early-onset group B streptococcal infection in these London centres is sufficiently high to warrant administration of intrapartum antibiotics to at-risk women.

[Decreasing incidence of perinatal group B streptococcal disease (Barcelona 1994-2002). Relation with hospital prevention policies]

INTRODUCTION

To analyze the incidence of perinatal sepsis due to group B streptococcus (GBS) as related to compliance with recommendations for its prevention issued by the Catalan Societies for Obstetrics, for Pediatrics, and for Infectious Diseases and Clinical Microbiology in 1997.

METHODS

The study was conducted from 1994 to 2001 in 10 Barcelona-area hospitals, where 157,848 live infants were born.

RESULTS

GBS disease was diagnosed in 129 neonates. Incidence decreased by 86.1% over the study period, from 1.92 cases per 1000 live births in 1994 to 0.26 per 1000 in 2001 (p < 0.001). Changes in the characteristics of perinatal GBS disease were observed in the 18 cases diagnosed in the last 3 years, the time when prevention policies were operative. The incidence was lower (0.28 per 1000 vs. 1.19 for the previous 5 years, p <.00006), the proportion of mothers without risk factors was greater (77.8% vs. 55.9%, p 5 0.009), and premature neonates were not affected (0% vs. 12.6%, p 5 0.003); nevertheless, mortality was similar (5.5% vs. 4.5%, p 5 0.8). Among these 18 cases of sepsis, 9 can be considered failures inherent to the prevention policy and 9 failures of compliance. Only 3 hospitals had prevention policies in 1994, whereas all 10 used intrapartum prophylaxis based on screening results in 2001.

CONCLUSIONS

A substantial decrease in the incidence of perinatal GBS disease coinciding with the application of prevention measures for this pathology has been registered in 10 participating hospitals over the 1994-2001 period.

Obstetrician preferences for prenatal strategies to reduce early-onset group B streptococcal infection in neonates: a population-based survey

OBJECTIVE

In light of a recent proposal to legislate group B streptococcal prevention strategies in New Jersey, this study examined obstetrician preferences and practices toward group B streptococcal prevention strategies in neonates.

STUDY DESIGN

This was a mail survey of American College of Obstetricians and Gynecologists Fellows in New Jersey. Physician characteristics, existing guideline preferences, and reported actual group B streptococcal prevention practices were measured.

RESULTS

Of the 695 potential respondents, 306 responses (44.7%) were received for analysis. Respondent stated preferences were for guidelines from the Centers for Disease and Prevention (74.5%), American College of Obstetricians and Gynecologists (12.7%), American Academy of Pediatrics (9.2%), and others (3.6%). The proportions of obstetricians who actually adhere to their stated preference were 57.5%, 64.1%, and 39.3% in Centers for Disease and Prevention, American College of Obstetricians and Gynecologists, and American Academy of Pediatrics group, respectively. Only 40.7% of the obstetricians cultured the anorectal/vaginal area for group B streptococcal carriers. An overwhelming 86.7% of obstetricians do not support legislation that regulates neonatal group B streptococcal preventing practices.

CONCLUSIONS

Obstetrician preferences for use of existing group B streptococcal guidelines are often not reflected by their actual stated practices. However, obstetricians do not support legislative regulation of group B streptococcal prevention practices.

Group B streptococci during pregnancy and infancy

Group B streptococcus (Streptococcus agalactiae) is still of great relevance in the perinatal period, although maternal antimicrobial prophylaxis has significantly reduced the rate of culture-confirmed invasive infection in neonates. This strategy, however, raises considerable concern because preterm delivery or late-onset sepsis cannot be prevented, and antibiotic resistance is increasing worldwide. Several advances in the development of conjugate vaccines and in research on virulence factors and pathways involved in the immune response to group B streptococcus have been accomplished, some of which might reach clinical practice in the near future.