Early-Onset Infection ✅ Flashcards
What can infection in the newborn be divided on the basis on?
Time during pregnancy/postnatal when the infection is acquired or presents
What are the categories of neonatal infection?
- Congenital
- Early onset
- Late onset
What is considered to be early onset infection in neonates?
<72 hours after birth
Why are newborn infants particularly vulnerable to bacterial infection?
Because of their immature immune system
How does the immune system of a neonate compare to older infants?
They are more dependant on non-specific innate immune system than older infants, because adaptive immune system is both immunologically naive and relatively slow to function, with overall reduced T-cell, B-cell, and neutrophil function
What kind of pathogens are neonates particularly susceptible to?
Pathogens with polysaccharide capsules
Give 2 examples of pathogens with polysaccharide capsules?
- Group B strep
- E. Coli
Why are neonates particularly susceptible to pathogens with polysaccharide capsules?
Because they have relatively low complement and impaired opsonisation
How does the complement pathway of a neonate compare to older children?
Overall activity of the alternative complement pathway is diminished, and the classical complement pathway activation cannot take place due to lack of specific antibodies
Where do the pathogens come from in early-onset infection?
The infant is exposed to bacterial organisms from maternal ascending infection or during passage through the birth canal
What is the most common organism causing early onset infection?
GBS
What other organisms might cause early onset infection?
- Gram -ve organisms
- Listeria monocytogenes
- Staphylococcus
What are the maternal risk factors for early-onset infection?
- GBS colonisation or bacteriuria during pregnancy
- Prolonged rupture of membranes
- Preterm prolonged rupture of membranes
- Prolonged labour
- Maternal sepsis or chorioamnionitis
- Frequent pelvic examinations
- History of early onset GBS sepsis in a previous infant
What is considered to be prolonged rupture of membranes?
> 18-24 hours
What is considered to be preterm prolonged rupture of membranes?
<37 weeks of gestation
What is considered to be prolonged labour?
> 12 hours
What are the clinical features of chorioamnionitis?
- Temperature >38
- Leucocytosis
- Tender uterus
- Purulent liquor
What is the fatality rate of GBS sepsis in term infants?
6%
What is the fatality rate of GBS sepsis in preterm infants?
Up to 20%
What is the rate of GBS colonisation in pregnant women in the UK?
21%
In what % of women with GBS colonisation does early-onset infection occur?
Less than 1%
What is the overall incidence of early onset GBS infection?
0.5/1000 live births
Where is universal screening of pregnant women for GBS performed?
USA, Canada, and Australia
What is done with women who test positive for GBS in pregnancy in countries that universally screen?
Intrapartum antibiotic prophylaxis is given to colonised mothers between 35 and 37 weeks gestation, or before this if in labour
What effect has universal screening for GBS had on the US?
It has lead to a significant reduction in culture positive early-onset disease and sepsis related mortality in the first week. Late onset disease has been unaffected.
What % of UK maternal units practice universal GBS screening?
Less than 1%
What approach to GBS in pregnancy has been adopted in the UK?
A risk factor based approach
What is the risk factor based approach to GBS in pregnancy in the UK?
Intrapartum antibiotic prophylaxis if certain criteria are met
When will intrapartum antibiotic prophylaxis against GBS be given?
- History of invasive GBS infection in previous baby
- GBS bacteriuria or positive vaginal swab in current pregnancy
- Pyrexia (<38) in labour, or chorioamnionitis
When is intrapartum antibiotic prophylaxis not required for GBS, even when the criteria are met?
If delivery by pre-labour lower segment C-section with intact membranes
What are the risk factors for early-onset GBS sepsis?
- Intrapartum fever over 38
- Prolonged rupture of membranes (>18 hours) at term
- Prematurity
- Positive GBS swab in previous or current pregnancy
Is the presence of a single risk factor an indicator for starting antibiotics/doing a septic screen in GBS?
No
By how much does the presence of 1 risk factor increase the risk of GBS sepsis?
1%
By how much does the presence of 2 risk factors increase the risk of GBS sepsis?
5%
By how much does having 3 risk factors increase the risk of GBS sepsis?
25x the baseline
What is considered a major risk factor for early-onset GBS sepsis?
- Matnal sepsis
- Chorioamnionitis
- GBS bacteruria
- Invasive GBS infection in previous infant
What % of infants with early onset GBS sepsis present on day 1?
94%
What proportion of infants presenting with GBS sepsis have one or more risk factor before or during labour?
2/3
What warning signs are found in a significant proportion of neonates presenting with early-onset sepsi?
- Signs of fetal distress
- Emergency delivery
- Low Apgar scores
What % of infants with early-onset GBS infection present with sepsis?
79%
What % of infants with early-onset GBS infection present with meningitis?
12%
What % of infants with early onset GBS infection present with pneumonia?
8%
What % of infants with early onset GBS infection present with focal infection?
1%
How is a diagnosis of GBS sepsis confirmed?
Blood culture
How much blood is required for blood culture?
At least 1ml
Why is it recommended that at least 1ml is taken for blood culture?
Smaller blood volumes reduces test sensitivity
Why should an LP be considered in early-onset GBS infection?
Up to 23% of neonates with bacteraemia have meningitis, and a negative blood culture does not rule out meningitis
When should an LP be done in early-onset GBS infection?
- Clinical deterioration on antibiotic treatment
- Positive blood culture
Why is it important to make a diagnosis of meningitis in early-onset GBS infection?
A prolonged course of antibiotics is indicated
Why is CRP not that helpful in early-onset GBS sepsis/
A raised CRP depends on an inflammatory response with the release of IL-6, so is rarely helpful in initial evaluation of possible infection
What is the importance of a raised CRP in early-onset sepsis?
In early-onset sepsis, a single raised CRP 24 hours into illness has a 93% sensitivity for ‘probably sepsis\
When can CRP be particularly helpful as a negative test?
After 18-24 hours - 99% predictive of non-infected infant
What are the NICE guidelines for stopping antibiotics in early onset GBS infection?
Consider stopping at 36 hours if;
- CRP concentration and trend is reassuring
- Blood culture negative
- Risk factors for infection were not strong
- Baby has no clinical indicators for infection
Should routine superficial swabs or gastric aspirated be taken in early onset GBS sepsis?
No - no added value
What does the management of early onset GBS sepsis rely on?
Early recognition from high levels of clinical suspicion, and prompt initiation of antibiotics and supportive treatment
Is the use of intravenous immunoglobulin as an adjunctive therapy helpful in early-onset GBS infection?
No
