Group B Strep

Question 1

What is name of organism in Group B strep

try and spell out

Answer 1

Streptococcus agalactiae

Question 2

Where is Streptococcus agalactiae (GBS) usually found in body?

Answer 2

It is a commensal organism in the vagina or rectum (in ~25% preganant women)

Question 3

How does GBS cause illness?

Answer 3

Transmission during delivery

Question 4

What are risk factors for GBS infection?

Answer 4

• GBS infection in a previous baby
• Prematurity < 37 weeks
• Rupture of membranes > 24 hours before delivery
• Pyrexia during labour (over 38)
• Positive test for GBS in the mother
• Mother diagnosed with a UTI found to be GBS during pregnancy

from TMPaeds

Question 5

What is gram stain of GBS?

Answer 5

gram positive cocci
typically grow in chains

Question 6

What conditions can Streptococcus agalactiae cause?

Answer 6

GBS disease of the newborn
Chorioamniotis
Endometritis

Question 7

How does GBS present?
1. in mother
2. in baby

Answer 7

1. colonisation of vagina is asymptomatic. An infection by GBS may present as UTI (frequency, urgency, dysuria), chorioamnioitis (fever, lower abdo/uterine tenderness, foul discharge, maternal or fetal tachycardia (intrapartum), endometritis (fever, lower abdo pain, intermenstrual bleed, foul discharge - post partum)
2. neonatal infection = pyrexia, cyanosis, difficulty breathing, poor feeding, floppiness. May also present with symptoms of sepsis, pneumonia and /or meningitis

Question 8

What investigations would you do to check for GBS?

Answer 8

• high vaginal swab
• rectal swab
  these are cultured on enriched culture medium, or PCR is used
• if woman is symptomatic of UTI - GBS may be detected on urine cultures

Question 9

What is the rationale to not screen pregnant women routinely for GBS?

Answer 9

• Most GBS infections occur in the preterm population – and these would be missed by screening as they would likely have already delivered by the screening date.
• Not all women who screen positive at screening are GBS positive at delivery – and these women would receive inappropriate treatment.

i.e. colonisation status will change throughout pregnancy

Question 10

In labour, give all women IV antibiotics if:…
what?

Answer 10

1. if they have a GBS +ve HVS at any time in this pregnancy or previous pregnancy
2. had a baby previously infected with GBS
3. have documented GBS bacteruria in this pregnancy
4. gestation < 37weeks
5. have intrapartum fever
6. if GBS +ve and have prelabour rupture of membranes at term - give abx and induce labour
7. if membranes are ruptured for over 18hrs and don’t know culture results from HVS

Can remember as 7 Ps?
1. Positive GBS
2. Previous GBS
3. Pee - GBS bacteruria
4. Preterm < 37 weeks
5. Pyrexia
6. Prelabour rupture
7. Prolonged rupture

Question 11

What abx are given to woman needing them to treat GBS?

Answer 11

Benzypenicillin 3g IV as a loading dose
Followed by 1.5g 4 hourly throughout labour

If allergic to penicillin = give clindamycin 900mg IV 8 hourly

Question 12

What is main neonatal risk of GBS ?

Answer 12

Severe, early onset infection - cause 20% mortality

Question 13

How do you treat neonate faling ill? You suspect they have meningitis from GBS

Answer 13

Benzylpenicillin 25-50mg/kg over an 8-12hr slow IV.

Question 14

When is GBS abx not indicated for a preganant woman?

Answer 14

Planned C section
Why? it is the rupture of membranes that exposes the baby to GBS.