[26] Group B Streptococcal Infection In Pregnancy Flashcards
What is group B streptococcus?
A commensal bacterium found in the vagina or rectum
In what % of pregnant women is group B streptococcus found?
25%
What is true in most cases of group B streptococcus?
Colonisation has no symptoms or consequence
What can sometimes happen with group B streptococcus infection in pregnancy?
It can cause infection in the neonate, called GBS disease of the newborn
What is the incidence rate of early onset GBS?
0.05%
What is the mortality rate in babies that develop GBS?
5%
What kind of bacteria are streptococci?
Gram positive cocci
How do streptococci typically grow?
In chains
What can streptococci be classified into?
Alpha, beta, and gamma haemolytic groups
What can beta haemolytic streptococci be further divided into?
A-H (but not including E)
What is the pathogen in group B streptococcus?
Streptococcus agalactiae
Other than GBS disease of the newborn, what can streptococcus agalactiae cause?
Chorioamnioitis or endometritis in the mother
What are the risk factors for colonisation with group B strep?
Poorly understood
What are the risk factors for GBS infection in the newborn?
- GBS infection in previous baby
- Prematurity <37 weeks
- Rupture of membranes >24 hours before delivery
- Pyrexia during labour
- Positive test for GBS in mother
- Mother diagnosed with UTI found to be GBS in pregnancy
Does maternal vaginal or rectal colonisation with GBS cause symptoms?
No
How can GBS infection in the mother manifest?
- UTI
- Chorioamnioitis
- Endometritis
How does a UTI caused by GBS present?
- Frequency
- Urgency
- Dysuria
When does chorioamnioitis caused by GBS occur?
Intrapartum
How does chorioamnioitis caused by GBS present?
- Fever
- Lower abdominal/uterine tenderness
- Foul discharge
- Maternal and/or fetal tachycardia
When does endometritis caused by GBS occur?
Postpartum
How does endometritis caused by GBS present?
- Fever
- Lower abdominal pain
- Intermenstural bleeding
- Foul discharge
How is the presence of group B streptococcus detected?
Swabs
How are the swabs for group B streptococcus taken?
A single swab is used for the vagina, and then the rectum
What are the ways of detecting GBS on swabs?
- Culturing on ‘enriched culture medium’
- PCR
When might GBS be detected on urine cultures?
If the woman is symptomatic for a UTI
When does screening for GBS occur, if performed?
Between 35-37 weeks
How does screening for GBS differ across the country?
In the UK, different hospital trusts have different policies for testing for GBS in pregnancy
What does RCOG recommend regarding GBS screening?
Women are not screened routinely, but only women identified as being high risk for GBS are tested
What is classified as high risk for GBS?
- Symptoms of UTI or chorioamnioitis during pregnancy
- STI symptoms pre-pregnancy
- Previous GBS infected baby
Why is screening not recommended to be performed routinely?
- Most GBS infections occur in the pre-term population, and they would be missed by screening as they would likely have delivered before the screening date
- Not all women who screen positive for GBS are positive at delivery, and these women would receive inappropriate treatment
What treatment is used for GBS?
High dose IV penicillin, usually benzylpenicillin, throughout labour
What antibiotic is used for treatment throughout labour of GBS in penicillin allergic patients?
Cefurozime or clindamycin
When is antibiotic treatment during labour for GBS indicated?
- GBS positive swabs
- UTI caused by GBS during this pregnancy
- Previous baby with GBS infection
- Pyrexia during labour
- Labour onset <37 weeks
- Rupture of membranes >18 hours
What will be done if there is rupture of membranes in woman >37 weeks gestation who is known to be GBS positive?
She will be induced immediately
Why would a GBS positive woman >37 weeks gestation with rupture of membranes be induced immediately?
To reduce the amount of time the fetus is exposed
Which women can choose whether or not to have antibiotics for GBS in labour?
Women who have been GBS positive in previous pregnancy, but baby was unaffected
What typically happens with women who have been GBS positive in previous pregnancy, but the baby was not affected?
They are tested during weeks 35-37 to see if they are carrying GBS in the current pregnancy
What is the purpose of testing women who have been GBS positive in a previous pregnancy but the baby was not affected at 35-37 weeks?
To help stratify the risk to the neonate
Are antibiotics indicated in planned C-sections for GBS positive women?
No
Why are antibiotics not indicated for GBS positive women when they are having planned C-sections?
As it is the rupture of membranes that exposes the baby to GBS
