preventing early-onset group b streptococcal infection in newborn babies
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Preventing early-onset group B Streptococcal infection in newborn babies. Group B Streptococcus. Streptococcus agalactiae Gram positive coccus Normal body commensal of intestines and vagina First recognised as a major perinatal pathogen in the 1970s - PowerPoint PPT PresentationTRANSCRIPT
September 2007 Charity No. 1112065 Company Reg No 5587535 1
Preventing early-onset group B Streptococcal infection
in newborn babies
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Group B Streptococcus
Streptococcus agalactiae Gram positive coccus Normal body commensal of intestines and vagina First recognised as a major perinatal pathogen in the 1970s Commonest cause of bacterial infection in newborn babies
Underlying rate estimated as one per 1,000 newborn babies in the UK– UK research suggests the true incidence may be as high as 3.5 per 1000 (Luck et al, 2003)
Mortality rate approximately 10% 30% of survivors of GBS meningitis will have neurological sequelae
Early and late onset presentations Up to 90% GBS infection apparent within 48 hours of birth Remains uniformly sensitive to penicillin (some tolerance to
clindamycin)
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Reported cases of GBS infection in England &
Wales 1990-95
0
50
100
150
200
250
300
350
400
1990 1991 1992 1993 1994 1995
Year
Cases p
er
Year
Infants
6 - 11 months
3 - 5 months
1 - 2 months
1 - 3 weeks
<1 week
Source: CDSC
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GBS – Colonisation
Normal flora in intestinal tract and vagina Carriage is asymptomatic Up to 30% adults carry GBS in intestines Up to 25% of women carry GBS in the vagina Occasionally in the throat (around 5%)
Colonisation can be intermittent 90% of adults do not have protective antibodies to
GBS GBS can traverse macroscopically intact amniotic
membranes GBS grows well in amniotic fluid GBS survives well on skin of newborn infant
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Screening Antenatally for GBS carriage
Between 35 and 37 weeks GBS carriage can be intermittent so best to swab close to delivery.
– Research shows reliable tests done within 5 weeks of delivery are highly predictive of carriage at delivery (Yancey et al 1996)
Must take vaginal and rectal swabs Low vaginal plus anorectal swabs are much more effective than HVS
Must use selective method with enrichment medium Recognised as optimal for detecting GBS carriage by the Royal College of
Obstetricians and The Health Protection Agency (BSOP 58)
Available privately (contact GBSS for availability) and from a handful of NHS hospitals
STANDARD CULTURE METHOD TOO INSENSITIVE FOR SCREENING Standard culture method (direct plating) instead of using enriched culture
medium reduces detection by 50%
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Options to reduce GBS infection in newborn
babies Waiting & treating babies after delivery
Too late for some & won’t prevent most GBS infection
Difficult to justify
Intrapartum antimicrobial prophylaxis (IAP) Only method of prevention available at present Largest study performed in Chicago
– Boyer et al. N Eng J Med 1986;314:1665 Penicillin G recommended
– Clindamycin recommended for penicillin-allergic women
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Options for selecting which women receive IAP
1. IAP to all women who have one or more risk factors (including incidental finding of GBS carriage/UTI)
2. IAP to all women identified as GBS carriers through screening (using enriched culture media) at 35-37 weeks
3. IAP only to women where a rapid test is positive
4. IAP to all women identified as GBS carriers through screening (using enriched culture media) who also have one or more risk factors
5. IAP to all women found to carry GBS through screening AND ALSO to women with one or more risk factors
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Option 1: Risk Factor ApproachIAP to all women with one or more risk factors
IAP to all women with one or more of the following recognised risk factors: pregnant woman has had a baby who developed a GBS infection pregnant woman has GBS bacteria in her urine during the current
pregnancy (which should be treated at the time of diagnosis) pregnant woman has been found to carry GBS during the current
pregnancy pregnant woman has a raised temperature (≥37.8°C) during labour labour or membrane rupture is preterm (<37 completed weeks of
pregnancy) prolonged rupture of membranes (≥18 hours before delivery)
Advantages/disadvantages Cheap (no bacteriological screening costs involved)
Relatively large amounts of antibiotics prescribed (about 30% of all women)
A significant number of cases will still occur (estimated 40%+)
Not tested in a trial
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Option 2: Screening ApproachIAP to all women identified as GBS carriers
IAP to all women identified as GBS carriers through screening (using enriched broth media) at 35+ weeks’ gestation
Advantages/disadvantages Selective enriched culture media is not routinely or widely available in
the NHS when testing for GBS carriage, though recognised as optimal by RCOG & HPA
Relatively large amounts of antibiotics prescribed Not tested in a trial Most potential cases would be covered, but not all
A few women will be –ve when tested but +ve at delivery – Yancey research found 4% of women with negative results would become positive
and 13% of women with positive results would become negative Some carriers will miss or refuse screening Some carriers will deliver before test conducted/test results
available
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Option 3: Intrapartum Screening ApproachScreen all women for GBS at onset of labour
IAP only to women where a rapid test for GBS taken at the onset of labour is positive
Advantages/disadvantages Less antibiotic use, targetting only women carrying GBS at delivery
Relatively expensive
Will miss a significant number of cases EXISTING RELIABLE TESTS ARE NOT FAST ENOUGH (taking 48 hours or
more for the results to be available)– Most women would deliver before the results are available
EXISTING FAST TESTS ARE NOT RELIABLE ENOUGH– Too many women would be incorrectly told they don’t carry GBS
Not tested in a trial
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Option 4: Combined Approach 1IAP to all GBS carriers with a risk factor
IAP to all women identified as GBS carriers through screening (using enriched culture media) who also have one or more of the following risk factors:
– Preterm labour or membrane rupture (<37 completed weeks of pregnancy)– Prolonged rupture of membranes (≥18 hours before delivery)– Maternal pyrexia (≥ 37.8oC)– Previous baby with GBS infection
Advantages/disadvantages Expensive
Well researched
Smaller proportion of women receiving IAP
Mass screening using enriched culture method culture is more expensive
Many cases will still occur (estimated 40%+)
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Option 5: Combined Approach 2IAP to GBS carriers & to women with 1+ risk
factors
IAP to all women found to carry GBS through sensitive screening in the current pregnancy AND to women with one or more risk factor, regardless of screening test result
– Preterm labour or membrane rupture (<37 completed weeks of pregnancy)– Prolonged rupture of membranes (≥18 hours before delivery)– Maternal pyrexia (≥ 37.8oC)– Previous GBS baby
More expensive
Relatively large amounts of antibiotics prescribed (around 30% of pregnant women)
More potential cases of GBS infection covered than restricting IAP to women with risk factors or carriage alone – estimated 80-90% prevention
Not tested in a trial
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UK Guidelines for Prevention: 1 - HPA
HPA GBS Working Group
In 1998, the then Public Health Laboratory Service (PHLS) (subsequently incorporated into the Health Protection Agency (HPA)) established a multi-disciplinary GBS Working Group, whose remit was to produce evidence-based national guidelines for the control and prevention of invasive neonatal GBS disease
In June 2001, they issued their interim “good practice’ recommendations, advocating a risk based approach
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UK Guidelines for Prevention: 2 – NICE
Antenatal CareNICE’S Antenatal Care Guidelines CG6, Oct 03 Don’t recommend screening as “evidence of its clinical effectiveness and
cost effectiveness remains uncertain.” Yet all the evidence shows screening and offering IV antibiotics in labour to
higher-risk women is clinically effective. – Where such programmes have been introduced, there have been dramatic reductions in incidence, including
the US, Australia, New Zealand, Belgium, France, Spain & Italy.
The cost effectiveness issue is less clear – a cost/benefit analysis of sponsored by the HTA, published September 2007 shows current practice is not cost
effective – testing low-risk women and offering IAP to high risk women was shown to be most cost effective while limiting antibiotic use (Colbourne paper)
“pregnant women should be offered evidence based information and support to enable them to make informed decisions regarding their care … addressing women’s choices should be recognised as being integral to the decision making process.” Yet information on GBS is not widely nor routinely available. And reliable tests
are only available privately.
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UK Guidelines for Prevention: 3 - RCOG
Royal College of Obstetricians & Gynaecologists Green Top Guideline No 36 "Prevention of early onset neonatal Group B streptococcal disease" 2003 (due for review November 2006)
Risk factor approach Gives estimates of relative risk for morbidity or mortality for recognised risk factors
Calculations significantly underestimate true incidence of GBS infection in the UK and so underestimate the relative risks while overestimating the numbers needed to treat for benefit Authors of the source of incidence figures (Heath et all, 2004) estimates an under-reporting of 21-42% Incidence figures take no account of probable cases of GBS infection (Luck et al 2002)
Will prevent most lethal cases of EOGBS infection when fully implemented (RCOG audit dated Jan 2007 shows few hospitals fully comply)
Until sensitive screening is routinely available for all pregnant women, GBSS endorses these guidelines This is a key starting position to preventing early onset GBS infection, but even more cases could be
prevented through offering sensitive screening to pregnant women
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GBSS Recommendation: 1
Sensitive tests for GBS carriage using rectal & vaginal swabs taken should be freely available to all women at 35-37 weeks of pregnancy
IAP should be offered to all women identified as GBS carriers in the current
pregnancy, all women who have previously had a GBS baby, and all women who deliver < 37 completed weeks of
pregnancy where a sensitive test result for GBS carriage is either positive or unavailable
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GBSS Recommendation: 2
Until sensitive tests for GBS carriage is freely and routinely available to all women at 35-37 weeks of pregnancy:
Pregnant women should be informed about GBS Pregnant women should be informed that a sensitive test for
GBS is available privately, and given information on how to obtain it
IAP should be offered to All women who have previously had a GBS baby All women found during the current pregnancy to have GBS in the urine (which
should be treated at the time of diagnosis) All women identified as carriers (using any screening method) during the current
pregnancy All women not screened using sensitive tests who have one or more of the
following risk factors– Prolonged rupture of membranes (≥18 hours before delivery)– Preterm labour or membrane rupture (<37 completed weeks of pregnancy)– Maternal pyrexia (≥ 37.8oC)
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Intrapartum Antimicrobial Prophylaxis
Penicillin G
3 g (or 5 mU) IV initially and then 1.5 g (or 2.5 mU) at 4-hourly intervals until delivery.
Clindamycin
For women who are allergic to penicillin, 900 mg IV every 8 hours until delivery.
Intravenous antibiotics should be given for at least 4 hours before delivery, where possible lesser times are better than nothing and 2+ hours should give
considerable reassurance.
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Option 6: IAP Chart
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Paediatric prevention strategy for babies born at
higher risk
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Babies Colonised with GBS
Culture results are ‘history’ Swabs from baby Vaginal swab at time of delivery
Antibiotic treatment for a healthy colonised baby is not indicated
Can send baby home
‘Educate’ parents what symptoms to watch for what to do if they develop
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Transmission of GBS to baby
0.6%Ear ly-o nset G B S in fectio n
(septicaem ia, pneum o n ia and /o r m en ingit is)
99.4%A sym pto m atic
50%B aby co lo n ised w ith G B S
50%N ew bo r n baby no t co lo n ised
M o ther co lo n ised w ith G B S at deliver y(up to 30% o f w o m en)
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Types of GBS infection (1)
Early-onset GBS infection (EOGBS) Apparent within first 6 days of life, and usually within 12-24
hours of delivery
Usually septicaemia with pneumonia
Typical symptoms– Grunting– Poor feeding– Lethargy– Low blood pressure– Irritability– Low blood sugar– Abnormally high or low temperature– Abnormally high or low heart rates – Abnormally high or low breathing rates
Even with the best medical care, 10% of babies with EOGBS die
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Types of GBS infection (2)
Late-onset GBS infection (LOGBS) Develops 6 days-3 months
Usually meningitis with septicaemia
Typical symptoms of late-onset GBS infection– Fever– Poor feeding and/or vomiting– Impaired consciousness– Plus any symptoms of meningitis
Even with the best medical care– 10% of babies sick with LOGBS die – up to 50% of survivors of GBS meningitis suffer long term
handicaps
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Baby successfully treated for GBS infection
GBS infections have a relatively high incidence of recurrence (1-3%)
Consider low dose oral penicillin daily for 3 months
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The Future: Vaccination
Best approach for preventing both EOGBS and LOGBS infection, plus maternal GBS infection
Target would be pregnant women or women before they become pregnant
Vaccine needs to be multivalent
Medical research is urgently needed into developing a viable vaccine for group B Strep infection
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Key References
Centers for Disease Control & Prevention. Prevention of Perinatal Group B Streptococcal Disease: Revised Guidelines from CDC. MMWR Reports & Recommendations Vol. 51(No. RR 11) 16 August 2002.
Heath PT, Balfour G, Weisner AM, Efstratiou A, Lamagni TL, Tighe H, O'Connell LAF, Cafferkey M, Verlander NQ, Nicoll A & McCartney AC on behalf of the PHLS GBS Working Group. Group B streptococcal disease in UK and Irish Infants <90 days of age. Lancet 2004 Jan 24, Vol 363(9405):292.
Luck S, Torny M, d'Agapeyeff K, Pitt A, Heath P, Breathnach A & Bedford Russell A. Estimated early-onset group B streptococcal neonatal disease. Lancet, 2003 Jun 07; 361(9373): 1953-1954
PHLS Communicable Disease Surveillance Unit. Incidence of group B streptococcal disease in infants aged less than 90 days. CDR weekly Vol. 12(No 16):3. 18 April 2002.
Colbourn TE, Asseburg C, Bojke L, Philips Z, Welton NJ, Claxton K, Ades AE, and Gilbert RE. Preventive strategies for group B streptococcal and other bacterial infections in early infancy: cost effectiveness and value of information analyses. BMJ 2007 335: 655
Royal College of Obstetricians & Gynaecologists Clinical Green Top Guideline. Prevention of Early Onset Neonatal Group B Streptococcal Disease (36) – Nov 2003
Law MR, Palomaki G, Alfirevic Z, Gilbert G, Heath P, McCartney C, Reid T, Schrag S on behalf of the Medical Screening Society Working Group on GBS disease. The prevention of neonatal group B streptococcal disease. J Med Screen 2005;12:60-68.
Yancey MK, Schuchat A, Brown LK, Ventura VL, Markenson GR. The accuracy of late antenatal screening cultures in predicting genital GBS colonization at delivery. Obstet Gynecol Nov 1996; 88(5):811-5.
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Group B Strep Support
Registered charity set up in 1996
Aims: To inform health professionals and individuals how
most EOGBS infection can be prevented; and
To offer information and support to families affected by GBS;
To generate continued support for research into preventing GBS infections.
Funded by donations
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GBSS Materials Available
LEAFLETS GBS & pregnancy (introduction for
pregnant women)
Congratulations on the safe arrival of your baby (introduction for parents of a health baby)
Understanding your baby’s GBS infection (introduction for parents of a GBS baby)
For women who carry GBS (detailed leaflet for women who know they carry GBS)
If your baby was infected by GBS (detailed leaflet for parents of babies affected by GBS)
GBS: The Facts (detailed leaflet, including medical reference list)
POSTERS Pregnant? (for pregnant women)
Labour & Delivery Prevention Guidelines
Understanding your baby’s GBS infection – for SCBUs
Saving Babies’ Lives – A2
STICKERS GBS Alert - 35 per page for pregnant
women’s notes
I am GBS Aware - 35 per page for pregnant women’s notes
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GBSS Medical Advisory Panel
Professor Philip Steer, BSc, MD, FRCOG (Chair) Professor of Obstetrics, Academic Department of
Obstetrics and Gynaecology, Imperial College Faculty of Medicine, Chelsea and Westminster Hospital
Dr Alison Bedford-Russell MRCP Consultant Neonatologist, Birmingham Heartlands
Hospital
Dr A Christine McCartney OBE FRCPath Director, Regional Microbiology Network, Health
Protection Agency Central Office