Group B Streptococcus

Principle studies reviewed;

Early-onset neonatal group B streptococcal infections in New Zealand 1998-1999;

Grimwood, K., Darlow, B.A., Gosling, R., Lennon, D.R., Martin, D.R., Stone, P.R., (2002)

Journal of Paediatric and Child Health ( 38), 272-277.

Risk factors for early onset neonatal group B streptococcal sepsis: case-control study

Oddie, S., Embleton, N.D., British Medical Journal http://bmj/cgi/reprint/325/7359/308.pdf

Cochrane Reviews

Intrapartum antibiotics for group B streptococcal colonisation. (Smaill, F., 1999)

Antibiotic regimens for management of intra-amniotic infection. (Hopkins, l., Smaill, F., 2002)

Antibiotics for prelabour rupture of membranes at or near term. (Flenady, V., King, J., 2002)

Antibiotics for preterm labour with intact membranes. (King, J., Flenady, V., 1999)

Other main texts used;

Epidemiology of group B streptococcal disease in the United States: shifting paradigms. Schuchat, A., (1998) Clinical Microbiology Reviews. 11, (3) 497-513

Group B streptococcal infections in newborns. Mullaney, D.M., (2001) JOGNN, 30, 649-658

Maternal screening and treatment for group B streptococcus. Dotti, C.James, (2001) JOGNN 30. 659-666

Broad-spectrum antibiotics for spontaneous preterm labour. The Oracle II randomised trial. Kenyon, D.J., Taylor, D.J., Tarnow-Mordi, W., (2001) The Lancet. (357) 989-994.

What is Group B Strep; Gram + Bacteria, found initially in bowel, spread is forwards

to vagina and lastly urinary. This is why urinary culture of GBS is thought to be more significant in pregnancy and indication of possible heavy growth.

GBS colonisation is transient, it comes and goes without intervention.

Newborn infection can be early onset, within 7 days or late 7 days to 3months of age.

GBS colonises 10-30% of women.

It is identified by different serotypes 1a, 1b, 11, 111, and V. (111 is most virulent and most common cause of meningitis in newborns)

History of GBS Identified as major cause of neonatal infection

and morbidity in late 1960s and early 1970s

Antibiotic prophylaxis has been introduced steadily since the 1980s. In the US the rate of GBS in newborns has fallen from 1.7:1000 to 0.6:1000.

Steady decline in early onset GBS infection in babies, no difference in late onset rate.

Grimwood et al NZ study 112,402 total births in NZ in 1998 &

1999 All level 11 and level 111 neonatal

units participated. 56 babies had early onset GBS

disease = 0.5:1000 live births 7 babies had meningitis. 1 baby died.

Grimwood et al NZ study continued; 5 of the mothers of GBS babies

received intrapartum antibiotics.

32 had risk factors present but did not receive antibiotics

19 had no identifiable risk factors.

Grimwood maternal risk factors associated with GBS infection; Young maternal age <21 = 13/56 =23%

Primiparas = 35/56 = 63%

Gestation < 37 weeks = 21/56 = 38%

Membranes ruptured >12hrs=21/56=38%

Maternal fever>38°C =12/56= 21%

Forceps or LUSCS =32/56= 57%

Oddie et al Northern England UK study; Compared babies who developed early

onset GBS disease with controls who did not = 37 babies

4 controls for each GBS baby were chosen from the same delivery suite as the GBS baby = 147 controls

All neonates born in Northern region between 1/4/98-31/3/00.

Oddie et al Northern England UK study 36 Babies developed GBS in first week of

life

62,786 babies live births were registered

= incidence rate of 0.57:1,000 live births

3 stillborn found to have GBS 1 of whom died in labour.

Oddie et al Northern England UK study 6 babies died

5 were premature <36 weeks gestation

1 full term admitted to NICU on day 3 with convulsions.

Both Oddie et al and Grimwood et al agree that given incidence of less than 1.4:1000 live births antibiotic prophylaxis based on risk factors during labour is the best course of action

The Oracle II randomised trial.

Looked at antibiotic prophylaxis for spontaneous preterm labour < 37/40.

Intact membranes.

Assigned to one of 4 groups 1611 assigned erythromycin 1550 assigned co-amoxiclav 1565 assigned erythromycin+co-amoxiclav 1569 assigned placebo.

The Oracle II randomised trial. There were no significant differences in any of the

outcomes between the different antibiotic groups or the placebo group.

There were a significantly higher number of babies with necrotising enterocolitis in the group receiving co-amoxiclav.

Conclude “Our trial indicates that antibiotics should not be routinely prescribed to women in spontaneous preterm labour without clinical evidence of infection or preterm/ prelabour rupture of the membranes”

Cochrane reviews;

All agreed that there needs to be more than one risk factor present to warrant routine antibiotic prophylaxis in labour.

Study on antibiotics for colonisation appeared to reduce neonatal infection; studies were poorly constructed. Strategies to determine colonisation and

maternal risk factors are needed.

Antibiotics: Ampicillin was initially preferred but concern has

arisen regarding resistance developing in other organisms eg E Coli which can also cause neonatal infection. (Schuchat). Ampicillin has a broad spectrum and is quick acting.

Penicillin G now preferred, narrower spectrum, however is not as quick acting.

Dose of 1.2 gm stat and 0.6 gm 4 hourly until birth.

Aim for at least two doses before baby is born. No antibiotic 100% effective, 10% will be

ineffective (Grimwood et al)

Antibiotic reactions; 1:10 women having IV antibiotics will

experience a mild reaction to penicillin

1:50,000 to 100,000 women having IV antibiotics will experience a potentially fatal anaphylactic reaction.

Salkind, A.R., Cuddy, P.G., Foxworth, J.W., 2001 JAMA 285. 2498-2505.

Ewan (1998 BMJ 316. 1442-1445 ) states that 3 times this many may experience severe respiratory symptoms.

Other considerations; GBS has become a problem during a

period of increasing medicalisation. Have the procedures and manipulations

that have been introduced since the 1950s played a part in the increasing virulence of this naturally occurring organism?

How much has awareness and changes in practice in recent years contributed to decline in GBS rates.

Some other considerations;

Treating women based on risk factors will result in treating 16% of pregnant women with IV antibiotics to prevent 90% of cases of GBS disease in newborn occurring at a rate of 0.5:1000.

The Cochrane studies did not prove any benefit in treating most of the common risk factors unless there is more than one factor.

Schuchat states that risks associated with previous GBS baby are anecdotal and unproven.

Signs of GBS disease in the newborn:

Signs of Group B streptococcal disease in the newborn:

Early signs;

Nasal flaringChest indrawingGrunting with respirationsSleepy babyPoor feederCannot hold body temperature

Late signs, rapid onset or severe disease;

Early signs and or,Floppy babyPale babyAsphyxiaSeizuresRapidly worsening respiratory distress.

The New Zealand College of Midwives consensus statement NZCOM supports a risk-based approach as

an effective strategy for preventing GBS transmission to babies. A risk based approach means assessing the woman for the presence of GBS risk factors when she is in labour. The risk factors that have been demonstrated as being of importance are any of the following: o previous GBS-affected infant o GBS bacteruria this pregnancy o preterm (< 37 weeks) labour and imminent birth o intrapartum fever > 380C o membrane rupture > 18 hrs.

The New Zealand College of Midwives NZCOM does not support the screening of all women

during pregnancy for GBS. The risk-based screening approach requires fewer women and babies to be exposed to antibiotics.

Rationale: • GBS remains an important and preventable public health

problem in New Zealand. • Early-onset neonatal Group B Streptococcus (GBS) infection

is the leading cause of infectious disease in the newborn. • There is sufficient evidence about the significance of these

risk factors in relation to the increased risk of transmission of GBS.

• Antibiotics during labour have been demonstrated to interrupt the transmission of GBS from the birth canal to the baby around the time of birth.

When any of the GBS risk factors have been identified, the rationale for the management of them needs to be discussed with the woman. The recommendations are:

• Information about GBS is given to the woman in order that she understands both the potential implications for her baby as a result of presenting with these risk factors and the available treatment options. • Antibiotics for GBS are only offered to women in labour who present with the risk factors. • A history of penicillin allergy should be sought from all women. • All newborn babies showing signs of sepsis should undergo immediate referral and assessment from a paediatrician. This will include a full blood count and blood cultures. While waiting for culture results antibiotic therapy is recommended for at least 48-hours.

NZCOM consensus continued All babies born to women with suspected chorioamnionitis,

irrespective of their gestation, condition at birth or exposure to intrapartum antibiotics, require immediate assessment and referral to a paediatrician. Antibiotic therapy is recommended for babies showing signs of sepsis.

• Healthy-appearing babies born at > 35-weeks gestation to women with GBS risk factors and who have received appropriate antibiotics > 4-hours before birth require no investigations or treatment, but should be observed closely for at least 24 hours post-partum. This includes close observation at home

Well-appearing babies born at > 35-weeks gestation to women with GBS risks factors who have received either no or inadequate (< 4-hours) antibiotics during labour should be observed closely for at least 24-hours. It is recommended that this be in hospital and that referral may be considered.

• Well-appearing babies born at < 35-week gestation to women without chorioamnionitis, who have not received antibiotics > 4 hours before birth need close observation for at least 48-hours. It is recommended that this be in hospital and that referral may be considered.

Recommendations for practice; Women need to be informed of the risks

and benefits of treatment.

Women need to be made aware of GBS and what to look for in their infant.

This subject needs to be broached in a way that does not further reduce women’s confidence in their own bodies.

Recommendations for practice;

Midwives need to consider GBS when deciding if vaginal examinations are necessary, however necessary vaginal examinations should not be withheld.

Midwives should consider the risks and benefits when considering rupturing membranes.

Consideration of factors such as maternal age and parity may also play a part when women present in labour with risk factors for GBS.

Women should be informed about what to look for in a newborn re GBS and seek help quickly.

Conclusion:Although it is obvious that some babies benefit from

intrapartum antibiotic prophylaxis this is not without risk to the mother.

Consideration also needs to be given to the growing problem of antibiotic resistance.

There have not been any proven clinical benefits from treating women who have only one risk factor in labour.

Regardless of what we do some babies will always develop GBS disease either early or late onset it is therefore important women and midwives are alert to the signs of GBS.