Infection risk

Published on 03/06/2015 by admin

Filed under Neonatal - Perinatal Medicine

Last modified 22/04/2025

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CHAPTER 17 Infection risk

David Cartwright, Mark Davies, Garry Inglis

Infection risk and signs

All babies born after labour or ruptured membranes, either vaginally or by caesarean section, should be regarded as potentially infected — regardless of your supposed knowledge of maternal colonisation status.

Risks of infection increase with:

• prolonged rupture of membranes, especially ≥18 hours
• multiple vaginal examinations
• known colonisation with pathogenic organisms, e.g. group B Streptococcus (GBS)
• a previously affected infant with early-onset septicaemia.

Signs of infection before delivery may include:

• maternal fever ≥38°C
• maternal tachycardia
• fetal tachycardia
• premature rupture of membranes
• preterm labour.

Signs of infection after birth may include:

• unexpected need for resuscitation
• early onset of apnoea
• fever
• poor peripheral perfusion
• respiratory distress.

Haematological evidence of infection includes:

• neutropaenia
• a left shift — immature : total (IT) neutrophil ratio ≥0.2
• toxic changes seen in neutrophils (toxic granulations, vacuolation, Dohle bodies, intracellular bacteria).

Antibiotic use

There is no magic formula that tells us which babies must be treated with antibiotics.

• If a baby is infected, early treatment is essential. This means treating all babies with reasonable risks, as above, with antibiotics for 36–48 hours until the blood culture is negative (with no haematological evidence of infection) and the baby is known to be well.
• Treat all babies with respiratory distress with antibiotics — the only possible exception is those babies born by ‘cold’ elective Caesarean section or a Caesarean section for pre-eclampsia or intrauterine growth restriction.
• Treat all babies whose mother has had fever ≥38°C with antibiotics.
• Treat all babies born after preterm labour with antibiotics, unless they are completely well and there are no other risk factors.

Antibiotics should be given within half an hour of a decision to start them.

Always take a blood culture before commencing antibiotics.

Arrange a full blood count (FBC) and film examination for the next convenient blood collection time.

For early septicaemia

The most common organisms to cover are group B β-haemolytic Streptococcus (GBS), Escherichia coli and other coliforms.

Antibiotics of first choice are:

• a penicillin — e.g. IV penicillin; and
• an aminoglycoside or a 3rd-generation cephalosporin — e.g. IV gentamicin.

For suspected late-onset or nosocomial infection (appearing >48 hours after nursery admission)

Late-onset infection can present in many ways (including signs common in babies without infection), therefore any concerns about an infant should prompt the question: Could this be due to infection? Always err on the side of taking cultures and starting antibiotics.

Common signs include:

• lethargy
• increasing frequency and severity of apnoea and/or desaturation episodes
• change in respiratory status
• gut stasis
• temperature instability
• hypo- or hyperglycaemia
• ‘not herself’, etc.

The basic principle is to cover:

• possible infecting organisms (including known colonising organisms) — e.g. babies with in situ devices, such as central venous lines, will be more prone to infection with coagulase negative staphylococci (e.g. Staphylococcus epidermidis); babies with gut problems will be more prone to infection with gut organisms such as enterococcus and coliforms; and/or
• known organisms that cause late infection in your nursery.

This cover will usually include cover for Gram-positive (with e.g. ampicillin, flucloxacillin or a 1st-generation cephalosporin) and Gram-negative (with e.g. gentamicin or a 3rd-generation cephalosporin) organisms. The antibiotics often have a synergistic effect with each other.

• We usually use ampicillin 50 mg/kg every 12 hours and either cefotaxime 50 mg/kg every 12 hours or gentamicin 2.5 mg/kg daily or every 36 hours (see page 80).

Under some circumstances broader coverage is justified. This may include cover for anaerobes or fungi. Some justify the empirical use of vancomycin on the grounds that most of their infecting organisms are coagulase-negative staphylococci. However, using too much vancomycin will one day lead to the emergence of vancomycin-resistant organisms.

Prevention of neonatal early-onset GBS disease (EOGBSD)

The prevention of early-onset GBS disease requires strategies for both the mother and the baby.

There are two obstetric approaches:

• swab all pregnant women late in the 3rd trimester for GBS, and if positive treat mother with intrapartum antibiotic prophylaxis; or
• use intrapartum antibiotic prophylaxis for mothers who have risk factors.

The neonatal approach is outlined below.

Queensland approach

Following consideration of all available information and in the light of the current low rate (0.39/1000 births) of EOGBSD in Queensland in 2002, the Perinatal Clinical Practice Guidelines Working Party on Early Onset Group B Streptococcal Disease and Prelabour Rupture of the Membranes at Term (coordinated by the Centre for Clinical Studies, Mater Hospital, South Brisbane and the Southern Zone Maternal Neonatal and Gynaecology Network, Southern Zone Management Unit) reached a consensus to continue to recommend the modified risk factor approach.

They have produced the Clinical Practice Guidelines for the prevention of neonatal early-onset group B streptococcal disease (EOGBSD) for Queensland hospitals.

Our suggested approach in light of these guidelines is:

1. Routine antenatal screening for GBS is not recommended.
2. Intrapartum antibiotic prophylaxis for EOGBSD during the first stage of labour (delivery anticipated within 6 hours) should be offered to:

— women who have had a previous infant with EOGBSD
— women who are known to have had a positive GBS culture during this pregnancy from the urinary, genital or lower intestinal tract
— women who might have >18 hours of ruptured membranes before delivery
— women in preterm labour at a gestational age of 34 weeks or less (i.e. <35 weeks).

3. Women with an intrapartum fever of ≥38°C or with other indications of chorioamnionitis require broad-spectrum antibiotic treatment (not prophylaxis) and treatment needs to be continued following delivery. The paediatric staff must be notified immediately if a mother shows signs of sepsis within 24 hours of delivery.
4. The antibiotic regimen recommended for intrapartum GBS prophylaxis is:

— penicillin 1.2 g IV load, then 0.6 g IV every 4–6 hours during the course of labour

or

— for those women with a history of penicillin allergy, clindamycin 900 mg IV every 8 hours, or erythromycin 500 mg IV every 6 hours until delivery.

5. Units should be familiar with their anaphylaxis protocol.
6. For all newborns, follow the Neonatal Sepsis Protocol (Fig 17.1 on page 112; modified from the above guidelines).
image

Figure 17.1 Neonatal sepsis protocol

EOGBSD = early-onset GBS disease; FBC = full blood count;

GA = gestational age (weeks); GBS = group B Streptococcus;

ROM = rupture of membranes

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