Group B Streptococcus

Question 1

Group B Streptococci is aka?

Answer 1

Streptococcus agalactiae

Question 2

What is the epidemiology of GBS?

Answer 2

5 to 40% of women are colonized with GBS.
Early onset neonatal GBS dx <7days
Late onset neonatal dx 7-90days

Question 3

What are the risk factors for women?

Answer 3

African ethnicity
Diabetes

Question 4

What are the risk factors for early neonatal GBS?

Answer 4

Maternal GBS bacteuria
Premature rupture of membranes
Premature pregnancy <37wks
Amnionitis

Question 5

What are the risk factors for late neonatal GBS?

Answer 5

Overcrowding.
Poor hand hygiene.
Increased length of stay.

Question 6

What are the risk factors for GBS?

Answer 6

DM
Neurological impairment
Malignancy
HIV
Corticosteroids
Chronic dx
Splenectomy

Question 7

What are the virulent factors of GBS?

Answer 7

Polysaccharide capsule (high amount of sialic acid and type 3 virulent strains).

Question 8

What are the clinical features of GBS?

Answer 8

Early neonatal onset- first 6 days of life.. Mean time 12h. Pneumonia and meningitis. Transmitted by vertical transmission from uterus.

Late neonatal onset- 7 days to 3 months. Mean time 24 days. Bacteriemia. Transmitted by horizontal from nosocomial infections.

GBS infections with adults and older children include meningitis, bacteraemia, arthritis, endocarditis, post partum infection, otitis media.

Question 9

What’s the diagnosis of GBS?

Answer 9

Facultative anaerobic, catalase negative, non sporing, gram positive cocci that form chains on gram stain usually capsulated.

Culture on blood produces small circular colonies, usually surrounded by a small zone of beta haemolysis.

Identification: lancefield group B, resistant to bacitracin, do not hydrolyse aseculin, hydrolyse sodium hippurate, production of CAMP factor.

Typing - Classified as serotypes I-VIII.

Question 10

The serotyping of GBS, is done based on??

Answer 10

Basis of their capsular Polysaccharide and surface protein antigens.

Question 11

Selective media in diagnosing GBS contains?

Answer 11

Todd Hewitt broth and antimicrobials.

Question 12

What is the treatment for GBS?

Answer 12

Neonatal - IV benzyl penicillin

Adults - IV Benzyl penicillin 10-14 days, 2wks of gentamycin for endocarditis.

For penicillin allergic pts, vancomycine is used.

Question 13

Talk about the prevention of GBS?

Answer 13

Newborns with signs of sepsis should be treated with BSA.

Vaccines are under development.

Intrapatrum prophylaxis should be offered if GBS is detected during pregnancy and to women with a previous baby with neonatal GBS.

Systemic screening is not recommended in the UK.

Routine screening for antenatal carriage is controversial and varies in different countries.

Question 14

Why is systemic screening not recommended in the UK?

Answer 14

1. The impact on mortality and morbidity is not proven.
2. Many screen positive women may no longer be carriers at the point of delivery.
3. The consequences of IV antibiotics during labour are unknown.

Question 15

In test to differentiate btw GBS and GAS, GBS tests positive to??

Answer 15

Sodium hippurate and CAMP test.

Question 16

In the test to differentiate btw GBS and GAS, GAS tests positive for?

Answer 16

Bacitracin and PYR.