Infections Flashcards
Risk factors for neonatal invasive Group B streptococcus
In colonised mothers, risk factors for infection are preterm, prolonged rupture of membranes, maternal fever during labour (>38° C), maternal chorioamnionitis or previously infected infant.
Antenatal management of known GBS positive mother and their baby
- 10–30% of pregnant women have faecal or vaginal carriage of group B streptococci
- Prophylactic intrapartum antibiotics given intravenously to the mother can prevent group B streptococcus infection in the newborn baby
- In U.K. ,a risk-based approach, in which mothers with risk factors for infection are offered antibiotics
Postnatal management of known GBS positivity mothers and babies
- Causes early- and late-onset sepsis
- EARLY ONSET: 0.5–1 in 1000. Respiratory distress, pneumonia. Most have pneumonia only, but it may cause septicaemia and meningitis.
- LATE ONSET: up to 3 months of age. Mothers carry group B streptococcus are colonised on their mucous membranes or skin. Meningitis, or occasionally with focal infection (e.g. osteomyelitis or septic arthritis)
- The severity depends on the duration of the infection in utero.
- Mortality in babies with positive blood or CSF cultures is up to 10%
What is early-onset neonatal infection?
- <48h after birth
- secondary infection as foetal lungs are in direct contact with amniotic fluid
- acquired via the placenta following maternal infection (except common viral or Listeria monocytogenes)
- Presentation is with respiratory distress, apnoea
and temperature instability - Investigations: CXR, full septic screen, FBC (neutropenia), as well as
blood cultures. CRP takes 12–24 h to rise, so one normal result does not exclude infection, but two consecutive normal values are strong evidence against infection. CSF- examined and cultures. - Treatment: ABx immediately waiting for culture results. Intravenous antibiotics are given to cover group B streptococci, Listeria monocy-
togenes and other Gram-positive organisms (usually benzylpenicillin or amoxicillin), combined with cover for Gram-negative organisms (usually an aminoglycoside such as gentamicin). STOP at 48 hrs if clinical improvement, CRP and cultures -ve.
Features of neonatal sepsis
- Fever or temperature instability or hypothermia
• Poor feeding - Vomiting
- Apnoea and bradycardia
- Respiratory distress
- Abdominal distension
- Jaundice
- Neutropenia
- Hypo-/hyperglycaemia
- Shock
- Irritability
- Seizures
- Lethargy, drowsiness
- In meningitis:
- Tense or bulging fontanelle
- Head retraction (opisthotonos
What is late-onset neonatal infection?
> 48hrs after birth
Source of infection: infants environment (NICU high risk-indwelling CV catheter, invasive procedures, tracheal tubes)
Presents non-specifically
- COMMON PATHOGEN: Coagulase-negative staphylococcus (Staphylococcus epidermidis)
-OTHER PATHOGENS: Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli and Pseudomonas, Klebsiella and Serratia species)
-Treatment: flucloxacillin and gentamicin is aimed to cover most staphylococci and Gram-negative bacilli. Resistance? or the
infant’s condition does not improve, specific antibiotics (e.g. vancomycin for coagulase-negative staphylococci or enterococci) or broad-spectrum antibiotics (e.g. meropenem) may be indicated. Use of prolonged or broad-spectrum antibiotics predisposes to invasive fungal infections (e.g. Candida albicans) in premature babies. Serial measurements of an acute-phase reactant (CRP) are useful to monitor response to therapy.
Common bacterial pathogens causing disease in newborn
Group B streptococci
Listeria monocytogenes
Gram-positive organisms (Staphylococcus aureus and Enterococcus faecalis)
Gram-negative organisms (Escherichia coli and Pseudomonas, Klebsiella and Serratia species)
Coagulase-negative staphylococcus (Staphylococcus epidermidis)
Chlamydia trachomatis
Common viral pathogens causing disease in the newborn
Herpes simplex (HSV) Hepatitis B HIV CMV Rubella
Rubella features
- Infection before 8 weeks’ gestation causes deafness,
congenital heart disease and cataractsin over 80% - 13-16 week gestation: impaired hearing
- beyond 18 weeks: minimal risk
SEE PHOTO
CMV features
• 90% are normal at birth and develop normally
• 5% have clinical features at birth, such as hepatosplenomegaly and petechiae, most of whom will have neurodevelopmental disabilities such as sensorineural hearing loss, cerebral palsy, epilepsy and cognitive impairment
• 5% develop problems later in life, mainly sensorineural hearing loss.
SEE PHOTO
Toxoplasmosis features
Most infected infants are asymptomatic. About 10% have clinical manifestations, of which the most common are:
• Retinopathy, an acute fundal chorioretinitis which sometimes interferes with vision
• Cerebral calcification
• Hydrocephalus.
These infants usually have long-term neurological disabilities
SEE PHOTO
HIV management
Transmission:
- mother-to-child transmission (MTCT)
- intrauterine
- intrapartum
- breastfeeding/ postpartum - infected blood products, contaminated needles or through child sexual abuse, but this is uncommon
Diagnosis:
- <18 m: HIV DNA PCR: Two negative HIV DNA PCRs within the first 3
months of life, at least 2 weeks after completion of postnatal antiretroviral therapy, indicate the infant is not infected, although this is confirmed by the loss of transplacental maternal HIV antibodies from the infant’s circulation after 18 months of age. - > 18m: anti-bodies to the virus
Presentation:
- asymptomatic- present in adolescence
- Or AIDS within 1st year life
- Mild immunosuppression > lymphadenopathy or parotitis
- Moderate > recurrent bacterial infections, candidiasis, chronic diarrhoea and lymphocytic interstitial pneumonitis (LIP)- HIV/ EBV
- Severe AIDS > opportunistic infections, e.g. Pneumocystis jiroveci (carinii) pneumonia (PCP),severe failure to thrive, encephalopathy and malignancy (rare!)
Treatment: Antiretroviral therapy (ART) (clinical status, HIV viral load and CD4 count) except in infants who should all start ART shortly after diagnosis, because they have a higher risk of disease progression. Prophylaxis against Pneumocystis jiroveci (carinii) pneumonia (PCP), with co-trimoxazole, is prescribed for infants who are HIV-infected, and for older children with low CD4 counts.
- Immunisations (ex. BCG)
- MDT, family clinics, weight, neurodevelopment and clinical signs and
symptoms of disease. Adolescents when there may be issues relating to maintaining ART adherence and address maternal issues such as safe sex practices, fertility and pregnancy
Rick factors neonatal infection
-Prolonged ROM
-Premature ROM
-Chorioamnionitis (maternal fever during labour)
-NICU stay
-GBS risk factors (preterm, prolonged rupture of membranes, maternal
fever during labour (>38°C), maternal chorioamnionitis
or previously infected infant)
-Listeria monocytogenes (unpasteurised milk, soft cheeses, undercooked meats)
-maternal infection (STIs, GBS, viral)
Bilious vomiting- causes
Malrotation: 1–3 days of life with intestinal obstruction from Ladd bands obstructing the duodenum or volvulus (+ abdo pain and peritonitis from ischaemic bowel)
Neonatal infection in preterm
Increased risk of infection (IgG mostly transferred across the placenta in the last trimester and no IgA or IgM is transferred)
Infection in and around cervix often cause for infection shortly after birth. Several days of age and are nosocomial (indwelling
catheters or artificial ventilation).
