Prevention of perinatal group B streptococcal disease: screening
practice in public hospitals in Victoria
Mary Connellan and Euan M Wallace
MJA 2000; 172: 317-320
For editorial comment, see Oats
More articles on Infectious diseases and parasitology
Objectives: To survey clinical protocols for
prevention of early-onset group B streptococcal disease (EOGBSD) of
the newborn in public maternity hospitals.|
Design: Postal questionnaire with telephone follow-up
Setting: All hospitals that undertook deliveries in
public patients in the State of Victoria, November 1997 to January
Results: The survey was sent to 84 hospitals: 71 responded
and 64 met the criteria and provided usable data (76% response rate).
These 64 represented 42 784 births (68% of births in Victoria in 1996).
Most hospitals (62; 97%) undertook actions that would identify and
treat pregnant women at risk of EOGBSD. 48 (75%) performed
bacteriological screening for maternal GBS carriage, but only 20 of
these had a unified protocol. Screening was mostly by low vaginal swab
(15 hospitals) and before 30 weeks' gestation (12 hospitals). Low
vaginal swab plus anal swab was used in only one hospital.
Bacteriological screening was significantly more common in
metropolitan hospitals than in rural hospitals (100% versus 67%;
P = 0.007, Fisher's exact test). Targeting of prophylaxis by
recognised risk factors was reported by 59 (92%) hospitals, 45 of
which also undertook screening. There was considerable variation in
the specific risk factors used.
Conclusions: While there was clearly widespread
awareness of EOGBSD in Victorian public hospitals, prevention
programs varied considerably. The development of consensus
practice guidelines might improve EOGBSD prevention, reducing
morbidity, mortality and costs.
Since the 1970s, group B streptococci (GBS) have been recognised as a
major cause of neonatal systemic infection in the first week of life --
so called early-onset group B streptococcal disease (EOGBSD).
The reported incidence of this condition varies between 1 and 4
per 1000 livebirths.1 Infants acquire the
infection by vertical transmission from an asymptomatic mother
during delivery.2 Clinical disease manifests
at birth or within 24-48 hours as pneumonia, septicaemia or, less
In Australia, the prevalence of GBS vaginal carriage has been
estimated at 12%-15%,3-5 and about 1%-2% of infants
born to women carrying GBS develop EOGBSD, with about 6% of cases being
fatal.2,5-7The risks of
EOGBSD and death are particularly high in preterm
infants.2 However, antibiotic
prophylaxis given to "at risk" women during labour has been shown to
significantly reduce the incidence of EOGBSD, and is an important and
worthwhile public health measure.2,7-9
While the value of prophylactic antibiotic intervention in at-risk
women is now widely agreed, the best means of targeting these women is
perhaps less clear. Comprehensive reviews of the available evidence
have been published both in Australia1,5,10 and
overseas.2,11-13 There are two broad
approaches to targeting prophylaxis -- identification of GBS
carriers by bacteriological screening or treating by clinical risk
No trials have compared the efficacy of the two approaches. It is
therefore perhaps not surprising that, anecdotally, GBS
intervention practices differ greatly between public hospitals
across the State of Victoria. However, no objective data are
available to assess the extent of these differences and the
appropriateness of current practice.
We surveyed all public maternity hospitals in Victoria to explore
what GBS intervention programs were in place and, in particular, to
assess whether practice was in line with currently available
The Victorian Perinatal Data Collection Unit, Melbourne, provided
contact details of all maternity hospitals in Victoria and
identified those that undertook deliveries in public patients.
Between November 1997 and January 1998, a six-page survey form
containing 18 questions was sent to the Delivery Suite Nursing Unit
Manager, or equivalent, in each of these hospitals. The survey was
multiple-choice format with some free-text fields.
Non-respondents were sent a second copy of the survey form two months
later and were telephoned if necessary.
Data on deliveries in 1996 were supplied by the Victorian Perinatal
Data Collection Unit. Statistical analyses were performed using
Statview 4.1.14 Significance was
taken as P < 0.05.
Of the 84 hospitals surveyed, 71 responded and 64 met the criteria and
provided usable data, giving a final response rate of 76% (three
respondents delivered only private patients, one cared for
postnatal women only, and three did not provide GBS screening
information). The 64 hospitals that provided usable data accounted
for 42 784 births in 1996 (68% of all births and 93% of all births to
public patients in Victoria) and comprised 16 hospitals in
metropolitan Melbourne and 48 rural hospitals.
Of the 64 hospitals, 62 (97%) reported undertaking procedures that
would identify and treat at least some women with a baby at risk of
EOGBSD; 48 hospitals (75%) undertook routine antenatal screening
for maternal GBS carriage, including 45 which also offered
antibiotic prophylaxis on the basis of risk factors. Another 14
hospitals (22%) used the latter approach alone.
Screening for GBS|
The hospitals which undertook routine antenatal bacteriological
screening accounted for 97% of all deliveries in the 64 responding
hospitals. They comprised all 16 metropolitan hospitals and 32 of the
48 rural hospitals, a significant difference in proportions between
metropolitan and rural hospitals (P = 0.007, Fisher's exact
Of the 48 hospitals that undertook screening, 20 had a unified
hospital screening protocol, with the remainder using
individual-doctor protocols. The 20 with a unified protocol
comprised nine of the 16 metropolitan hospitals and 11 of the 32 rural
hospitals (P = 0.22, Fisher's exact test).
Characteristics of the screening protocols among these 20
hospitals are shown in Box 1. Most protocols (65%) were less than five
years old, and 40% were less than two years old. The most common
approach to bacteriological screening was to perform a low vaginal
swab only (15 of 20 hospitals), or, less commonly, a high vaginal swab
only (four hospitals). Only one hospital performed a low vaginal swab
combined with an anal swab. All but one hospital screened only once in
the pregnancy, either before 30 weeks' gestation (12 hospitals) or
between 30 and 34 weeks' gestation (seven). The hospital that
screened more than once did not specify gestations. All hospitals
that performed bacteriological screening administered
intrapartum antibiotics to all women who were GBS-positive.
Screening of private patients|
Bacteriological screening was offered to private patients by some or
all obstetricians at 37 of the 64 hospitals. This was a smaller
proportion of hospitals than offered screening to public patients,
although the difference did not reach significance (P = 0.06,
Fisher's exact test). In only 18 of these 37 hospitals did all
obstetricians offer screening to their private patients. In 13
hospitals, none offered screening to private patients, and in 14 the
respondent did not know if it was offered.
Targeting of prophylaxis by recognised clinical risk factors was
reported by 59 of the 64 hospitals (92%). Criteria used are shown in Box
2. Antibiotics were reported to be given most commonly for clinical
signs of intrapartum infection (51 hospitals) and pre-labour
rupture of the membranes (43 hospitals), although the time from
membrane rupture to starting antibiotic administration varied
considerably. Only 10 hospitals administered antibiotics to women
admitted in preterm labour below a specified gestation. All were
metropolitan hospitals that also performed routine
bacteriological screening. Only four hospitals (6%) administered
antibiotics on the basis of all five recognised criteria. Two of these
also undertook screening.
With regard to the antibiotic used as chemoprophylaxis, 14 of the 20
hospitals with a unified protocol used penicillin, four amoxycillin
and two ampicillin. The 14 hospitals using penicillin all had
different treatment regimens. Of the hospitals that lacked a unified
protocol, only four reported the antibiotic regimen used --
penicillin in three and amoxycillin in one.
To our knowledge, this is the first survey of GBS screening practices
in pregnancy to be reported in Australia. It reveals that prenatal
screening and prophylaxis for GBS infection were widely practised in
public hospitals in Victoria. However, the specific strategies
varied considerably, and, while this variation is understandable
(given the lack of robust comparative data for the various possible
approaches2,10,12,15), it translated
into a less than ideal approach in many centres.
Current evidence suggests that the optimum approach to reduce EOGBSD
is to offer intrapartum chemoprophylaxis, using penicillin (or
erythromycin in women allergic to penicillin) to at-risk
mother-infant pairs. These at-risk pairs are identified by
bacteriological screening, involving a low vaginal and anal swab
performed at 36-38 weeks' gestation and/or by clinical risk factors
In our survey, most hospitals reported targeting prophylaxis
through bacteriological screening. However, the varied approaches
to this screening revealed that current practice may not be as
effective as possible. In addition, while most hospitals undertook
screening, only 20 had a unified protocol, while the remaining 28
reported that protocols differed between doctors. This, together
with the variable practice for private patients, suggests that it may
be useful to develop more uniform Australian guidelines. Indeed,
that only two hospitals (3% of respondents) reported a current
protocol that would be expected to maximally prevent EOGBSD
(targeting prophylaxis by bacteriological screening and by all risk
factors shown in Box 3) suggests that the introduction of uniform
practice guidelines would be worthwhile.
The most common differences between the reported screening
protocols and an approach expected to minimise EOGBSD were the
maternal sites sampled and the timing of screening. GBS carriage
within individuals is not constant. Consequently, bacteriological
swabs taken at 28 weeks' gestation have only a 50%-70% positive
predictive value for carriage at delivery, while about 5%-10% of
women who are GBS-positive at delivery are negative at 28
weeks.3,13,16 Therefore, the
closer to delivery that bacteriological screening is undertaken,
the greater its utility, both as sensitivity and specificity are
increased,2,10,16 and as the costs of
screening are saved for the 5% of pregnant women who deliver preterm
(and should receive prophylaxis irrespective of the screening
bacteriological screening is probably best undertaken at 36-38
weeks' rather than at less than 30 weeks' gestation,
the most popular time in our survey.
Nevertheless, despite these theoretical considerations, a
significant reduction in the incidence of EOGBSD was recently
reported by King George V Hospital, Sydney, where screening is
performed at 28 weeks' gestation.17 This result emphasises
that bacteriological screening at 28 weeks' gestation is preferable
to no screening at all.
Detection of GBS is increased by 5%-25% if an anal swab is collected in
addition to a vaginal swab.16,18,19 Only one hospital
in our survey reported collecting both swabs; most took only a low
vaginal swab. It has been suggested that Australian women would find
collection of anal swabs unacceptable,20 but no objective evidence
has been presented for this. Furthermore, most United States centres
surveyed by the Centers for Disease Control took anal
swabs,21 suggesting that the
practice may be more acceptable than is assumed. It would certainly be
worthwhile asking Australian women, and reappraising the method of
screening most appropriate for our population. Collection of high
vaginal swabs, reported by four hospitals in our survey, is
inappropriate for GBS screening.
The most cost-effective approach to preventing EOGBSD is to offer
antibiotic prophylaxis to women with identified risk factors,
without bacteriological screening.15 This approach has been
recommended by some Australian groups (Professor James King, Mater
Perinatal Epidemiology Unit, Mater Misericordiae Mothers'
Hospital, Brisbane, Qld, personal communication). Most hospitals
surveyed (92%) offered prophylaxis on the basis of risk factors, but
only four (6%) used all recognised risk factors appropriately (Box
3). As the relative risk of EOGBSD is significantly greater in preterm
neonates than in babies born at term,7 any EOGBSD prevention
program should ideally include intrapartum prophylaxis for any
woman labouring before 37 weeks' gestation, irrespective of whether
she was screened earlier in pregnancy or of the result of that
screening.2,11 It was disappointing
that only a minority of the hospitals surveyed had such a policy,
particularly as infection per se is a major recognised cause
of preterm labour. That no rural hospital had such a policy may reflect
that these hospitals transfer such women for level 3 neonatal care,
and that preparation for transfer focuses more on tocolytic
therapy and corticosteroid prophylaxis. If so, then an educational
campaign to encourage early antibiotic treatment instituted at the
referring hospital might be worthwhile.
We were also surprised that only a few hospitals offered antibiotic
prophylaxis to women who had had a previous baby with EOGBSD. Neonatal
EOGBSD is a devastating infection, and, in our experience, parents
who have had an infected child usually seek interventions to prevent
infection in a future delivery. That most clinicians and hospitals do
not routinely offer prophylaxis in this situation suggests a lack of
awareness that this history is an important risk factor. Similarly,
the variable responses to the other accepted risk factors suggest
that a significant proportion of health providers are either unaware
of the epidemiology of EOGBSD or do not perceive EOGBSD as an important
Our survey of Victorian public hospitals showed that, while most are
clearly aware of EOGBSD, only a minority currently have a strategy
that maximises prevention of EOGBSD and represents most
cost-effective practice. However, very minor changes in practice
would be expected to improve EOGBSD prevention and significantly
reduce costs,15 for both screening and
treatment. Accordingly, our data support the case for a
comprehensive, statewide, or possibly national, education
program, and for the development and introduction of uniform
consensus practice guidelines.
The authors would like to thank the participating hospitals as well as
Dr Jane Halliday and Ms Sofia Mercer, from the Victorian Perinatal
Data Collection Unit. EMW was partly funded by a Charles and Sylvia
Viertel Clinical Investigator Fellowship.
Disclosure: We are not aware of any conflict of interest
arising from performing or reporting this work.
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(Received 10 Nov 1999, accepted 14 Feb 2000)
Monash Medical Centre, Melbourne, VIC.
Mary Connellan, RM, MPH, Midwife, Women's Health Program,
Southern Healthcare Network;
Euan M Wallace, MD, FRACOG,
Senior Lecturer, Department of Obstetrics and Gynaecology, Monash
Reprints: Dr E M Wallace, Department of Obstetrics and
Gynaecology, Monash University, Monash Medical Centre, 246 Clayton
Road, Clayton, VIC 3168.
1: Characteristics of screening for group B streptococcus in 20 hospitals with a unified screening protocol
|Number of hospitals|
|Years since screening protocol introduced|
| < 2||8 (40%)|
| 2-5||5 (25%)|
| > 5-9||1 (5%)|
| > 9||2 (10%)|
| Not known||4 (20%)|
|Form of screening|
| Low vaginal swab only||15 (75%)|
| High vaginal swab only||4 (20%)|
| Low vaginal swab and anal swab||1 (5%)|
|Frequency per pregnancy|
| Once only||19 (95%)|
| More than once||1 (5%)|
| < 30 weeks' gestation||12 (60%)|
| 30-34 weeks' gestation||7 (35%)|
| Unknown||1 (5%)*|
|*The hospital that screened more than once did not specify gestations.
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2: Criteria for intrapartum administration of antibiotics in 64 hospitals in Victoria|
|Criteria||Number of hospitals using|
|Clinical signs of intrapartum infection||51 (80%)|
|Pre-labour rupture of membranes||43 (67%)|
| < 6h||4 (6%)|
| > 12-18h||10 (16%)|
| > 18-24h||4 (6%)|
| > 24h||21 (33%)|
| Doctor-dependent||4 (6%)|
|Previous GBS-affected baby||30 (47%)|
|GBS-positive vaginal swab in previous pregnancy||22 (34%)|
|Preterm labour||10 (16%)|
| Gestation < 37 weeks||7 (11%)|
| Gestation < 34 weeks||2 (3%)|
| Gestation < 32 weeks||1 (2%)|
|GBS=Group B streptococcus.
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