Neonatal and Childhood Infections Flashcards
Define congenital infections.
Babies are born with congenital infections i.e. transmitted vertically from mother to baby.
Infection can occur at any time during pregnancy, between first trimester and birth.
What is included in current maternal screening?
Hep B
HIV
Syphilis
What is not currently screened but is possible?
CMV
Toxoplasmosis
Hep C
Group B Streptococcus
Rubella
What is the presentation of congenital infections?
Varied presentations and non-specific signs.
Need to be considered in any sick neonate.
What is TORCH?
- Toxoplasmosis
- Other – syphilis; HIV; hepatitis B/C
- Rubella
- Cytomegalovirus (CMV)
- Herpes simplex virus (HSV)
What are common signs of congenital infections?
Common clinical features:
- Mild/no apparent maternal infection
- Wide range of severity in the baby
- Similar clinical presentation
- Serological diagnosis
- Long term sequelae if untreated
Examples:
- Low platelets, rash
- Cerebral abnormalities
- Hepatosplenomegaly/hepatitis/jaundice
What is toxoplasmosis?
The only known definitive hosts for Toxoplasma gondii are members of family Felidae (domestic cats and their relatives).
Unsporulated oocysts are shed in the cat’s feces. Although oocysts are usually only shed for 1-2 weeks, large numbers may be shed. Oocysts take 1-5 days to sporulate in the environment and become infective. Intermediate hosts in nature (including birds and rodents) become infected after ingesting soil, water or plant material contaminated with oocysts.
Oocysts transform into tachyzoites shortly after ingestion. These tachyzoites localize in neural and muscle tissue and develop into tissue cyst bradyzoites. Cats become infected after consuming intermediate hosts harboring tissue cysts. Cats may also become infected directly by ingestion of sporulated oocysts. Animals bred for human consumption and wild game may also become infected with tissue cysts after ingestion of sporulated oocysts in the environment.
How can humans contract toxoplasmosis?
Humans can become infected by any of several routes:
- Eating undercooked meat of animals harboring tissue cysts.
- Consuming food or water contaminated with cat feces or by contaminated environmental samples (such as fecal-contaminated soil or changing the litter box of a pet cat).
- Blood transfusion or organ transplantation.
- Transplacentally from mother to fetus.
In the human host, the parasites form tissue cysts, most commonly in skeletal muscle, myocardium, brain, and eyes; these cysts may remain throughout the life of the host.
How is toxoplasmosis diagnosed?
Diagnosis is usually achieved by serology, although tissue cysts may be observed in stained biopsy specimens. Diagnosis of congenital infections can be achieved by detecting T. gondii DNA in amniotic fluid using molecular methods such as PCR.
How does congenital toxoplasmosis present?
May be asymptomatic at birth – 60% but may still go on to suffer long term sequelae:
- Deafness, low IQ, microcephaly
40% symptomatic at birth:
- Choroidoretinitis
- Microcephaly/hydrocephalus
- Intracranial calcifications
- Seizures
- Hepatosplenomegaly/jaundice
How does congenital rubella syndrome affect children?
Effect on foetus – dependent on time of infection.
Mechanism: Mitotic arrest of cells; angiopathy; growth inhibitor effect.
- Eyes: Cataracts; microphthalmia; glaucoma; retinopathy
- Cardiovascular syndrome: PDA; ASD/VSD
- Ears: Deafness
- Brain: Microcephaly; meningoencephalitis; developmental delay
- Other: Growth retardation; bone disease; hepatosplenomegaly; thrombocytopenia; rash
What are other congenital infections to be aware of?
- Hepatitis B and C
- HIV
- Syphilis
- Listeria monocytogenes
- Group B Streptococcus
- Parvovirus
-
Chlamydia trachomatis
- Infection transmitted during delivery
- Mother may be asymptomatic
- Causes neonatal conjunctivitis, or rarely pneumonia
- Treated with erythromycin
Define neonatal infections.
Definition varies: First 4-6 weeks of life.
If born early (premature), neonatal period longer and is adjusted for expected birth date.
Higher incidence of infections. Can become ill rapidly and seriously. Unlike adults or older children – need to treat with antibiotics when first suspicion of infection.
What is the aetiology/risk factors of neonatal infections?
Immature host defences.
Increased risk with increased prematurity:
- Less maternal IgG
- NICU care
- Exposure to microorganisms; colonisation and infection
What are features of neonatal infections? What are some causative organisms of neonatal infections?
Early and late onset infection.
Early onset – usually within 48 hours of birth: Some definitions 3-5 days.
Organisms:
- Group B streptococci
- E. coli
- Listeria monocytogenes
What is Group B Strep.?
Gram positive coccus, catalase negative.
Beta-haemolytic.
Lancefield Group B.
In neonates:
- Bacteraemia
- Meningitis
- Disseminated infection e.g. joint infections
What is E. Coli?
Gram negative rod
In neonates:
- Bacteraemia
- Meningitis
- UTI
What are maternal risk factors for early onset sepsis?
- PROM/prem. Labour
- Fever
- Foetal distress
- Meconium staining
- Previous history
What are neonatal risk factors for early onset sepsis?
- Birth asphyxia
- Resp. distress
- Low BP
- Acidosis
- Hypoglycaemia
- Neutropenia
- Rash
- Hepatosplenomegaly
- Jaundice
What are appropriate investigations for early onset sepsis?
Full blood count
C-reactive protein (CRP)
Blood culture
Deep ear swab
Lumbar puncture (CSF)
Surface swabs
Chest X-ray (full body)
What is the management for early onset sepsis?
Supportive management:
- Ventilation
- Circulation
- Nutrition
- Antibiotics: e.g. benzylpenicillin & gentamicin
What are causative organisms of late onset sepsis (48-72 hours)?
- Coagulase negative Staphylococci (CoNS)
- Group B streptococci
- E. coli
- Listeria monocytogenes
- S. aureus
- Enterococcus sp.
- Gram negatives – Klebsiella spp. /Enterobacter spp. /Pseudomonas aeruginosa/Citrobacter koseri.
- Candida species
What are the clinical features of late onset sepsis?
- Bradycardia
- Apnoea
- Poor feeding/bilious aspirates/ abdominal distension
- Irritability
- Convulsions
- Jaundice
- Respiratory distress
- Increased CRP; sudden changes in WCC/platelets
- Focal inflammation – e.g. Umbilicus; drip sites etc.
What are appropriate investigations for late onset sepsis?
- FBC
- CRP
- Blood culture(s)
- Urine
- ET secretions if ventilated
- Swabs from any infected sites
What is the treatment for late onset sepsis?
Treat early – Lower threshold for starting therapy.
Review and stop antibiotics if cultures negative and clinically stable.
What is an example of an antibiotic regimen for late onset sepsis?
1st line: Cefotaxime & vancomycin
2nd line: Meropenem
Community acquired late onset neonatal infections: cefotaxime, amoxicillin +/-gentamicin
What are common causative organisms of childhood infections?
Child’s age is important in considering likely pathogens:
Viral infections are very common e.g. Chickenpox (VZV); Herpes simplex – cold sores/stomatitis; HHV6; HHV8; EBV; CMV; RSV; enteroviruses etc.
Bacterial infections are important and may cause secondary infection after viral illness e.g. iGAS disease post VZV infection.
What are common presenting symptoms of childhood infections?
May be difficult to ascertain site of infection from history/examination depending on age of child. Common non-specific symptoms:
- Fever
- Abdominal pain
What are appropriate investigations of childhood infections?
- FBC
- CRP
- Blood cultures
- Urine
- +/- Sputum; throat swabs etc
What is the most important bacterial cause of paediatric morbidity and mortality?
Meningitis
How is meningitis diagnosed?
- Clinical features
- Lab tests:
- Blood cultures
- Throat swab
- LP for CSF if possible
- Rapid antigen screen
- EDTA blood for PCR
- Clotted serum for serology if needed later
What is the leading cause of morbidity and mortality especially in children < 2y.o?
Streptococcus pneumoniae
What is Streptococcus pneumoniae?
Gram positive diplococcus – alpha haemolytic streptococcus
Meningitis, bacteraemia, pneumonia
>90 capsular serotypes
Increasing penicillin resistance
What are pneumococcal conjugate vaccines?
Due to large health burden and emergence of antibiotic resistance - vaccination programme introduced in the USA in 2000.
Previously available pneumococcal polysaccharide vaccine were 23 capsular types of pneumococcus.
Children< 2years had poor response, but antibody response improved by conjugating the polysaccharide to proteins such as CRM. This conjugated vaccine is immunogenic in children from 2 months.
What are the most common causes of meningitis in a child <3 months?
N. meningitidis
S. pneumoniae
H. influenzae (Hib) if unvaccinated
GBS
E. coli
Listeria sp.
What are the most common causes of meningitis in a child aged 3mo-5y?
N. meningitidis
S. pneumoniae
Hib if unvaccinated
What are the most common causes of meningitis in a child aged >6 years?
N. meningitidis
S. pneumoniae
What are respiratory tract infections?
Account for 1/3 of all childhood illnesses
Mostly upper respiratory tract infections
Mostly viral
Age is important
Sputum is often difficult to obtain
Often need to give empiric treatment
What are the most common causative organisms of respiratory tract infections?
S. pneumoniae (pneumococcus) is the most important bacterial cause.
Most UK strains remain sensitive to penicillin or amoxicillin.
Mycoplasma pneumoniae tends to affect older children (>4 years) – Macrolides are treatment of choice e.g. Azithromycin.
How is Mycoplasma pneumoniae transmitted?
Acquired by droplet transmission person to person.
Epidemics occur every 3-4 years. Occurs in school age children and young adults.
Incubation period 2-3 weeks.
How does infection with Mycoplasma pneumoniae present?
Many asymptomatic.
Classically presents:
- Fever
- Headache
- Myalgia
- Pharyngitis
- Dry cough
What are extrapulmonary manifestations of Mycoplasma pneumoniae?
Haemolysis:
- IgM antibodies to the I antigen on erythrocyte
- Cold agglutinins in 60% patients
Neurological (1% cases):
- Encephalitis most common.
- Aseptic meningitis, peripheral neuropathy, transverse myelitis, cerebellar ataxia.
- Aetiology unknown ?antibodies cross react with galactocerebroside.
Cardiac
Polyarthralgia, myalgia, arthritis
Otitis media and bullous myringitis
If a respiratory tract infection fails to recover, what should you consider?
- Whooping cough – Bordetella pertussis especially if unvaccinated
- TB including MDRTB and XDRTB
What are urinary tract infections?
Common. Up to 3% girls and 1% boys by age 11.
Diagnosis:
- Symptoms: If child old enough to give clear history
- Pure growth >105cfu/ml
- Pyuria: Pus cells on urine microscopy
N.B. Get sample before starting treatment
What are common causative organisms of urinary tract infections?
E. coli
Other coliforms e.g. Proteus species, Klebsiella Enterococcus sp.
Coagulase negative Staphylococcus e.g. Staph saprophyticus
What is the management for urinary tract infections?
Early diagnosis and antibiotic treatment important (Nitrofurantoin 7d)
Renal tract imaging
Antibiotic prophylaxis after treatment of the infection (NICE guidance)
What may recurrent or persistent infections be indicative of?
May be a sign of immunodeficiency – either congenital or acquired – e.g. HIV, SCID.
Warrants investigation by Paediatric Infectious Diseases doctors.
