MICRO: Neonatal and childhood infections Flashcards
What congenital infections are screened for during pregnancy in the UK and other countries?
UK:
- HepB
- HIV
- Syphilis
Other countries also check for:
- Toxoplasmosis
- Rubella
- CMV
- GBS
- HepC
What are the TORCH infections?
Congenital infection screen, they can present with variable signs:
- Toxoplasmosis
- Other – syphilis; HIV; hepatitis B/C
- Rubella
- Cytomegalovirus (CMV)
- Herpes simplex virus (HSV)
What are 3 common clinical features of congenital infections?
- Low platelets, rash
- Cerebral abnormalities
- Hepatosplenomegaly/hepatitis/jaundice
What is the main host of toxoplasmosis? Once infected where does toxoplasmosis localise?
Cats - although other hosts exist
Neural and muscle tissue
What are the symptoms of congenital toxoplasmosis? What are the long term complications?
Symptoms at birth (in 40%):
- Seizures
- Intracranial calcifications
- Choroidoretinitis
- Hydrocephalus
- Hepatosplenomegaly/jaundice
Long term sequelae (in 60%):
- Deafness,
- Low IQ
- Microcephaly
What is the mechanism of congenital rubella syndrome?
Rubell causes mitotic arrest of cells; angiopathy; growth inhibitor effect
What are the features of congenital rubella syndrome?
Eyes: cataracts; microphthalmia; glaucoma; retinopathy
Cardiovascular: PDA; ASD/VSD
Ears: deafness
Brain: microcephaly; meningoencephalitis; developmental delay
Other: growth retardation; bone disease; hepatosplenomegaly; thrombocytopenia; rash
What are these features of?
Congenital rubella syndrome - cataracts and rash
What could be the cause of this rash?
Herpes simpex virus (HSV) - worst when primary infection is acquired by the mother in the third trimester
What are two features of congenital chalmydia infection in a neonate? What antibiotic is used?
Infection transmitted during delivery
Causes neonatal conjunctivitis, or rarely pneumonia
Tx: macrolide e.g. erythromycin
Define the neonatal period.
First 4-6 weeks of life (if born prematurely then this is longer and adjusted for expected birth date)
What are the reasons for increased incidence and severity of infections in neonates?
Immature host defences
Risk increases with increased prematurity because there is less maternal IgG, and more exposure to microorganissm for colonisation and infection duirng this period.
What is meant by ‘early onset’ neonatal infection ?
Within 48 hours of birth
What are the microbiological features of GBS?
- Gram positive coccus
- Catalase negative
- Beta-haemolytic
- Lancefield Group B
What 3 types of infections does GBS commonly cause in the neonate?
- Bacteraemia
- Meningitis
- Disseminated infection e.g. joint
What 3 infections does E coli commonly cause in the neonate?
- Bacteraemia
- Meningitis
- UTI
What microorganism is shown?
Listeria monocytogenes - rare but more commonly seen in the immunocompromised. Gram +ve rod, shows some haemolysis on blood agar.
What are 4 maternal risk factors for early-onset sepsis in a neonate?
- PROM/prem. Labour
- Fever
- Foetal distress
- Meconium staining
- Previous history
What are 4 fetal/neonatal risk factors for early onset sepsis?
- Birth asphyxia
- Resp. distress
- Low BP
- Acidosis
- Hypoglycaemia
- Neutropenia
- Rash
- Hepatosplenomegaly
- Jaundice
Give 3 causes of early onset neonatal infections.
- GBS (most common)
- E coli
- Listeria
List the investigations which should be done in early onset sepsis.
- FBC
- CRP
- Blood culture
- Deep ear swab
- Surface swabs
- LP
- CXR
List the investigations that should be done in late-onset sepsis.
- FBC
- CRP
- Blood culture(s)
- Urine
- ET secretions if ventilated
- Swabs from any infected sites
List the investigations that should be done for infections during childhood.
- FBC
- CRP
- Blood cultures
- Urine
- +/- Sputum; throat swabs etc
LP less done in childhood
What antibiotics should be used for early-onset neonatal sepsis?
Benzylpenicillin (for GBS) and gentamicin (for E coli) +/- amoxicilllin (for Listeria)
Define late-onset sepsis.
After 48-72 hours
List 3 most common causes of late-onset neonatal sepsis.
- Coagulase negative Staphylococci (CoNS) e.g. Staphylococcus epidermidis (most common)
- Group B streptococci
- E. coli
- Listeria monocytogenes
Other:
- S. aureus
- Enterococcus sp.
- Gram -ve – Klebsiella spp. /Enterobacter spp. Pseudomonas aeruginosa/Citrobacter koseri
- Candida
What are the clincial features of sepsis in a neonate?
- Bradycardia
- Apnoea
- Poor feeding/bilious aspirates/ abdominal distension
- Irritability
- Convulsions
- Jaundice
- Respiratory distress
Other:
- Increased CRP; sudden changes in WCC/platelets
- Focal inflammation – e.g. Umbilicus; drip sites etc.
What antibiotics are used for late onset sepsis?
1st line: cefotaxime & vancomycin
2nd line: meropenem
Community acquired: cefotaxime, amoxicillin +/-gentamicin
What condition is the most common bacterial cause of paediatric morbidity and mortality?
Meningitis
What investigations should be done for meningitis?
- Blood cultures
- Throat swab
- LP
- Rapid antigen screen
- EDTA blood for PCR
- Clotted serum for serology
Describe the CSF characteristics of bacteria, viral and fungal meningitis.
Rapid antigen tests can be useful; if no growth then try PCR.
Which microorganisms are shown?
Neisseria meningitidis
Gram -ve
What is the biggest cause of meningitis in children in the UK?
Meningitis B
What microorganism is shown?
Streptococcus pneumoniae - gram +ve cocci arranged in pairs, alpha haemolytic
What types of infections are caused by streptococcus pneumoniae?
- Meningitis
- Bacteraemia
- Pneumonia
Especially in children <2yo
What is shown?
Streptococcus pneumoniae - alpha haemolysis (green around the colonies). Autolysis in the centre (doughnut shaped)
What type of vaccine is the pneumococcal vaccine?
Conjugated vaccine (immunogenic in children from 2 months, serotypes conjugated to a carrier ) - 13 different serotypes
NB: this used to be a polysaccharide vaccine but children <2yo had a poor response.
What microorganism is shown?
Haemophilus influenzae
What causes meningitis at different ages in children?
What is the biggest cause of deaths in children under 5 years? (WHO 2016)
- Prematurity (16%)
- Pneumonia (13%)
WHO 2022 - “Globally, infectious diseases, including pneumonia, diarrhoea and malaria, along with pre-term birth complications, birth asphyxia and trauma and congenital anomalies remain the leading causes of death for children under 5 years.”
What is the most common cause of respiratory infections in children?
S. pneumoniae (pneumococcus)- –most UK strains remain sensitive to penicillin or amoxicillin
What is a common cause of respiratory infections in older children (>4yrs)? What antibiotic is used?
Mycoplasma pneumoniae - macrolides are the treatment of choice e.g. azithromycin
How common do outbreaks of Mycoplasma pneumonia occur? What is the incubation period?
Epidemics occur every 3-4 years - in school aged children and young adults. Incubates for 2-3 weeks
What are the classical symptoms of mycoplasma pneumoniae?
Many asymptomatic
Classically presents:
- Fever
- Headache
- Myalgia
- Pharyngitis
- Dry cough
What are the extrapulmonary symptoms of mycoplasma pneumoniae?
Haemolysis - IgM antibodies to the I antigen on erythrocyte; cold agglutinins.
Neurological (1% cases) - encephalitis most common; aseptic meningitis, peripheral neuropathy, transverse myelitis, cerebellar ataxia; aetiology unknown.
Cardiac
Polyarthralgia, myalgia, arthritis
Otitis media and bullous myringitis
How much growth to diagnose UTI?
Pure growth >105cfu/ml
If leukocyte negative and nitrite negative then UTI unlikely.
How common are UTIs in children?
3% of girls
1% of boys
What are the most common bacterial causes of UTI in children?
E coli (most common)
Other coliforms:
- Proteus species
- Klebsiella enterococcus
- Coagulase negative staphylococcus e.g. Staph saprophyticus
GBS
MenB
Pneumonia (13%) but also prematurity (16%)
