T9: Infections in the newborn baby

Question 1

Define the following terms:
Neonate
Bacterial sepsis in a neonate
Perinatal and congenital infection
perinatal infection
Postnatal infection

Answer 1

• Baby younger than or 28 days old
• Clinical syndrome of systemic signs of infection and bacteremia
• Before delivery/ during pregnancy
• During pregnancy or delivery
• Acquired after birth

Question 2

For infections in the neonate, there are some maternal (5) and neonatal risk factors (6) . List these

Answer 2

Maternal factors: chorioamnionitis, delivery < 37 weeks, prolonged ROM, intrapartum maternal temperature, and maternal GBS colonization
Neonatal factors: premature, LBW, asphyxia, male, congenital abnormality

Question 3

Neonates are predisposed to infection, owing to their cellular immunity. Explain

How do neonates acquire the following:

• IgM
• IgG
• IgA

Neonates have an impaired complement system. What are the consequences of this?

Answer 3

CELLULAR IMMUNITY- Neutrophils are NB PMN cells in killing bacteria but in neonates: deficient chemostasis and therefore decreased killing ability. Impaired macrophage chemostasis and decreased cytokine production
IgG= preformed immunoglobulins acquired via the placenta
IgM= there are few IgM in the neonate
IgA= acquired via breast milk

As a result of an immature complement cascade, there is the impaired killing of Gram negatives.

Question 4

Differentiate between early-onset and late-onset sepsis (time)

Early-onset sepsis is usually due to maternal factors. List 2 of these.

List 5 organisms involved in early-onset sepsis in the neonate

Answer 4

• Early-onset is within the first 72 hours or 1 week of life whilst late-onset is after 7 days
• Transplacental (hematogenous) and via ascending infection from the cervix
• E.coli, listeria monocytogenes, GBS, H. influenza, and coagulase-negative staphylococcus

Question 5

Account for late-onset sepsis

List causes of late-onset sepsis

Answer 5

Late-onset sepsis is due to environmental factors: e.g. caregivers with bacterial colonization, indwelling catheters, indwelling lines

Causes of early-onset sepsis (except for H influenza) plus anaerobes, Serratia, S. aureus, acinetobacter. pseudomonas, klebsiella, candida

Question 6

EARLY-ONSET SEPSIS
- Name the group B streptococcus responsible for early neonatal sepsis and its serotypes
GBS colonizes the maternal GIT and the birth canal. As a result, we should have an approach to it. How do you approach GBS in:
- Pregnancy
- A neonate with GBS (early disease vs late disease)

Answer 6

• Streptococcus agalactia neonatal serotypes 1,2,3
• In pregnancy, give intrapartum prophylaxis: ampicillin/ penicillin in mothers with GBS and screen mothers at 37 weeks of pregnancy.
• Give penicillin in neonates with GBS. Early disease happens in <24 hours» rapid multisystem illness, respiratory distress. Late-onset sepsis happens > 7 days later presenting with meningitis (insidious onset multisystem)

Question 7

LISTERIA MONOCYTOGENES

• How is it mostly acquired?
• Who is more at risk for this? What are the consequences and what should you advise?

NEONATAL LISTERIOSIS

• Neonatal listeriosis can happen early or late: state when do these happen and what are their implications
• How do you treat neonatal listeriosis

Answer 7

• Mostly food-borne
• Pregnant women are at 20x at risk and they are at risk of premature labor or stillbirths. Advise against eating raw meat, wash vegetables and avoid unpasteurized dairy.
• Early disease: early-onset sepsis in utero» premature birth, septicemia, and resp distress
  Late disease: via vaginal transmission» meningitis (+/- rash)
  Treat with Ampicillin + gentamicin

Question 8

ESCHERICHIA COLI

• What is the most common presentation
• List 4 other presentations
• How do you treat E.coli in neonates?

Answer 8

• Meningitis in 34%

- Bacteraemia, omphalitis, UTI, NEC

Question 9

LATE ONSET SEPSIS

• Differentiate between Gram + and - in terms of onset and treatment
• What are the causative organisms

Answer 9

• Gram positives> insidious onset whilst Gram - is rapid onset. Rx of Gram + vancomycin (Linezolid) and Gram - is cephalosporins or cabapenem
• Gram + is S. aureus, central lines are the culprits. causing thrombophlebitis, abscess, omphalitis, osteomyelitis, septic arthritis
• Gram negative is enterobacter (E.coli, Klebsiela, Proteus) and non-fermenters (pseudomonas, acinetobacter)