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4 - Y5 a Path lectures 2021/22 > Microbiology 9S: Neonatal and Childhood Infections > Flashcards

Microbiology 9S: Neonatal and Childhood Infections Flashcards

1
Q

Which neonatal imfections are screened for routinely during pregnancy?

A
  • Hep B
  • HIV
  • Rubella status (NOT THE INFECTION ITSELF)
  • Syphilis
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2
Q

Which neonatal infections are currently not screened for, but can be?

A
  • CMV (most common cause of congenital deafness in the UK)
  • Toxoplasmosis
  • Hep C
  • Group B Streptococcus (mother is screened only if asymptomatic bacteriuria)
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3
Q

What are some common clinical features of neonatal infection?

A
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4
Q

What is the lifecycle of toxoplasmocosis?

A
  1. Acute infection will start off in a cat
  2. It produces faeces containing oocysts
  3. Mice and birds eat the faeces
  4. Cats eat birds and mice
  • This ends up becoming a cycle
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5
Q

Is congenital toxoplasmocosis symptomsatic at birth?

A

may be asymptomatic (60%) at birth

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6
Q

What are the long term sequale of congential toxoplasmocosis?

A
  • Deafness
  • Low IQ
  • Microcephaly
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7
Q

If the baby shows symptoms of congential toxoplasmocosis at birth, what are they?

A
  • 40% of babies are symptomatic at birth (4 C’s)
    • Choroidoretinitis
    • Microc**ephaly/hydro**cephalus
    • Intracranial calcifications
    • Seizures / convulsions
    • Hepatosplenomegaly/jaundice
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8
Q

Which is the main factor affecting Congenital Rubella Syndrome’s effect on the foetus?

A

time of infeciton (during pregnancy)

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9
Q

What is the mechanism of Congenital Rubella Syndrome?

A
  • Mechanism: mitotic arrest of cells, angiopathy, growth inhibitor effect
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10
Q

What is the classic triad of features of Congenital Rubella Syndrome?

A
  • Cataracts
  • Congenital heart disease (PDA; ASD/VSD)
  • Deafness/SNHL
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11
Q

What are some other features of Congenital Rubella Syndrome?

A
  • Microphthalmia
  • Glaucoma
  • Retinopathy
  • ASD/VSD
  • Microcephaly
  • Meningoencephalopathy
  • Developmental delay
  • Growth retardation
  • Bone disease
  • Hepatosplenomegaly
  • Thrombocytopaenia
  • Rash
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12
Q

What are the features on the child of congenital Herpes Simplex Virus?

A
  • This can spread to the neonate through the genital tract –> blistering rash
  • It can cause disseminated infection with liver dysfunction and meningoencephalitis
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13
Q

When is Chlamydia trachomatis transmitted to the child?

A

during delivery

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14
Q

If the mother has Chlamydia trachomatis, is she always symptomatic?

A

no can be asymptomatic

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15
Q

What can Chlamydia trachomatis cause in the neonate?

A

neonatal conjunctivitis or pneumonia (RARE)

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16
Q

What is the Tx for Chlamydia trachomatis?

A

erthryomycin

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17
Q

Name some other congenital infections

A
  • Hep B and C
  • HIV
  • Listeria monocytogenes
  • GBS
  • Syphilis
  • Mycoplasma species
  • Parvovirus
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18
Q

When is the neonatal period?

A

first 4 weeks of life

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19
Q

How does the neontal period timings differ for a premature child?

A
  • If born premature, the neonatal period is longer and is adjusted for the expected birth date
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20
Q

Why are premature children at greater risk of infection?

A
  • Premature neonates are at INCREASED risk because:
    • Less maternal IgG
    • NICU care
    • Exposure to micro-organisms, colonisation and infection
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21
Q

What is the first, immediate step of Tx for a suspected infection in a neonate?

A

treat with ABx as soon as infection is suspected!

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22
Q

What is the timing for the term ‘early onset’ neonatal infection?

A

within 48 hours (or 3 to 5 days; definitions vary) of birth

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23
Q

Name some possible early onset neonatal infections

A
  • Group B Streptococcus
  • Escherichia coli
  • Listeria monocytogenes
  • Early-Onset Sepsis
    *
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24
Q

Name some features of Group B Streptococcus

A
  • Lancefield Group B
  • Gram +ve coccus
  • Catalase -ve
  • Beta haemolytic
  • 33% of women have GBS commensal (gut, urinary tract, etc)
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25
Q

What is the function of a catalase test?

A

The catalase test is primarily used to distinguish among Gram-positive cocci:

  • members of the genus Staphylococcus are catalase-positive
  • members of the genera Streptococcus and Enterococcus are catalase-negative.
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26
Q

What is the clinical significance of beta haemolytic bacteria?

A

can completely lyse RBCs vs non-beta haeemolytic bacteria

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27
Q

What does Group B Streptococcus infection cause in neonates?

A
  • Bacteraemia
  • Meningitis
  • Disseminated infection (i.e. joint infection)
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28
Q

What are some features of E Coli?

A
  • Gram -ve rod
  • The K1 antigen is particularly problematic
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29
Q

What does E coli cause in neonates?

A
  • Bacteraemia
  • Meningitis
  • UTI
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30
Q

What are some features of Listeria monocytogenes?

A
  • Gram +ve rod
31
Q

What does Listeria monocytogenes infection cause in the neonate?

A
  • Sepsis in both the mother and baby
32
Q

Name some neonatal risk factors for early onset sepsis

A
  • Birth asphyxia
  • Resp. distress
  • Low BP
  • Acidosis
  • Hypoglycaemia
  • Neutropenia
  • Rash
  • Hepatosplenomegaly
  • Jaundice
33
Q

Name some maternal risk factors for early onset sepsis

A
  • PROM/PPROM
  • Fever
  • Foetal distress
  • Meconium staining
  • Previous history GBS
34
Q

Name some investigations for ?early onset sepsis

A

bloods:

  • FBC
  • CRP
  • Blood culture

other:

  • Deep ear swab
  • LP
  • Surface swabs

imaging:

  • CXR (full body)
35
Q

What is the treatment for early onset neonatal sepsis?

A
  • Supportive – ventilation, circulation, nutrition
  • Antibiotics (e.g. benzylpenicillin & gentamicin  used in combination because…
    • GBS is treated by benzylpenicillin
    • E. coli is treated by gentamicin
36
Q

What is the timing for the term ‘late onset’ neonatal infection?

A
  • after 48-72 hours of birth:
37
Q

Name some possible late onset neonatal infections

A
  • Coagulase-negative Staphylococci (CoNS)
  • GBS
  • Escherichia coli
  • Listeria monocytogenes
  • Staphylococcus aureus
  • Enterococcus sp.
  • Candida species
  • Gram-negatives - Klebsiella, Enterobacter, Pseudomonas aeruginosa, Citrobacter koseri
38
Q

What are some clinical features of late onset neonatal infection?

A
  • Bradycardia
  • Apnoea
  • Poor feeding/abdominal distension
  • Irritability
  • Convulsions
  • Jaundice
  • Respiratory distress
  • Increased CRP
  • Sudden changes in WCC & platelets
  • Focal inflammation (e.g. umbilicus/drip sites)
39
Q

What are the investigations for ?late onset neonatal infection?

A

bloods:

  • FBC
  • CRP
  • Blood cultures

other:

  • Urine
  • ET (endothelin?) secretions if ventilated
  • Swabs from any infected site
40
Q

What is the Tx for late onset neonatal infection?

A
  • Treat early – low threshold for starting therapy
  • Review and stop antibiotics if cultures are negative and clinically stable
  • Antibiotics (guidelines do vary):
    • 1st line: cefotaxime + vancomycin
    • 2nd line: meropenem
    • Community-acquired: cefotaxime, amoxicillin ± gentamicin
41
Q

Is the site of infection easy to ascertain from Hx and examination?

A

may be difficult

42
Q

Name some viral infections in childhood

A

Very common

  • chickenpox,
  • HHV6,
  • EBV,
  • RSV
43
Q

What is the relationship betweeen bacterial and viral infections?

A
  • bacteria may cause secondary infection after viral illness
  • e.g. invasive Group A Streptococcus (iGAS) infection after VZV
44
Q

What are the symptoms of childhood infections?

A

Common, non-specific symptoms –> fever and abdominal pain

45
Q

What are the investigatios for ?childhood infections?

A

bloods:

  • FBC
  • CRP
  • Blood cultures

other:

  • Urine
  • Sputum, throat swabs
46
Q

Which infection is the most important cause of paediatric morbidity and mortality?

A

Meningitis

47
Q

Name the pathogens that can cause childhood meninigtis

A
  • Men B / Neisseria meningitidis
  • Streptococcus pneumoniae (Pneumococcus)
  • Haemophilus influenzae
48
Q

How is meningitis diagnosed?

A
  • Clinical features

bloods:

  • Blood cultures
  • EDTA blood for PCR
  • Clotted serum for serology

other:

  • Throat swab
  • LP if possible (may be dangerous) –> Rapid antigen test using CSF
49
Q

What are the contraindications to LP in ?(childhood) meningitis?

A
  • rasied ICP
  • bleeding disorder
  • overlying infection at LP site
  • spina bifida
50
Q

Which results can be obtained from a CSF analysis?

A
  • pressure
  • appearance
  • protein
  • glucose
  • gram stain
  • glucose - CSF:serum ratio
  • WCC
51
Q

What are the results of a CSF analysis for bacterial vs viral infections?

A

Main differences between bacterial and viral:

  • pressure: high in bacterial, normal/slightly increased in viral
  • appearance: turbid in bacterial, clear in viral
  • protein: >1 in bacterial, <1 in viral
  • glucose: low (<2.2) in bacterial, normal in viral
  • gram stain: usually +tive in bacterial, normal in viral
  • glucose - CSF:Serum ratio - see table
  • WCC: >500 bacterial, <1000 viral
  • Other: 90% polymorphonuclear neutrophils in bacterial, less likely such a large % PMN in viral
52
Q

What have vaccination programmes done for the incidence of meningitis infections?

A
  • Number of cases of meningitis from following pathogens have decreased:
    • HiB (Haemoophilius influenza type B)
    • Men C
    • pneumococcus
53
Q

Which pathogens are now the main cause of meningitis?

A

Men B / Neisseria meningitidis

54
Q

When are Men B vaccines given? What is given along with them?

A
  • Given: 2m, 4m and 12m
  • The vaccine is very immunogenic and is usually given with paracetamol because it can make the child ill
55
Q

Which pathogen is a leading cause of meningitis mortality/morbidity, especially in especially in those <2 years?

A

Streptococcus pneumoniae (Pneumococcus)

56
Q

Describe Streptococcus pneumoniae (Pneumococcus)?

A
  • Gram-positive diplococcus,
  • Alpha-haemolytic,
  • Optochin-sensitive
  • More than 90 capsular serotypes (difficult to generate a vaccine)
  • Increasing penicillin resistance
57
Q

What types of infections can Streptococcus pneumoniae (Pneumococcus) cause?

A

Meningitis, Bacteraemia, Pneumonia

58
Q

When are Streptococcus pneumoniae (Pneumococcus) vaccinations given?

A
  • Given: 12w, 12m
  • called Prevenar 13 (targets 13 serotypes)
59
Q

Describe Haemophilus influenzae:

A
  • Gram-negative rod,
  • grows glossy colonies on blood agar
  • Causes meningitis at all ages
60
Q

Describe childhood respiratory infections

A
  • 1/3 of all childhood illnesses
  • Mostly URTIs, mostly viral
  • Age is important
  • Sputum is difficult to obtain
  • Often need to give empirical antibiotics
61
Q

Name the main pathogens that cause childhood respiratory infections

A
  • Streptococcus pneumoniae
  • Mycoplasma pneumoniae
    *
62
Q

Which pathogen is the most important cause of childhood respiratory infections?

A

Streptococcus pneumoniae

63
Q

Which Abx is Streptococcus pneumoniae sensitive to?

A
  • Sensitive to amoxicillin or penicillin
64
Q

Describe the features of childhood Mycoplasma pneumoniae infection

A
  • Features:
    • Tends to affect older children (> 4 years)
    • Person-to-person droplet transmission
    • Incubation period 2-3 weeks
    • Epidemics every 3-4 years
    • Occurs in school children / young adults
    • Mainly asymptomatic
65
Q

What are the clinical features of Mycoplasma pneumoniae?

A
  • Clinical features (if not asymptomatic):
    • Fever
    • Headache
    • Myalgia
    • Pharyngitis
    • Dry cough
66
Q

What are some extrapulmonary manifestations of Mycoplasma pneumoniae?

A
  • Haemolysis
    • IgM antibodies to the I antigen on erythrocytes
    • Cold agglutinins in 60%
  • Neurological
    • Encephalitis
    • Aseptic meningitis
    • Peripheral neuropathy
    • Transverse myelitis
    • Cerebellar ataxia
  • Cardiac
  • Polyarthralgia, myalgia, arthritis
  • Otitis media
  • Bullous myringitis (vesicles on tympanic membrane – pathognomonic of mycoplasma disease)
67
Q

Which class of ABx is used to treat Mycoplasma pneumoniae?

A
  • Treated with macrolides (azithromycin)
68
Q
A
69
Q

What should you consider as differentials if a childhood respiratory tract infection fails to respond to ABx?

A
  • Whooping cough (Bordatella pertussis)
  • TB
70
Q

How are UTIs in children diagnosed?

A
  • Symptoms – If child can give a history
  • Pure growth of >105 CFU/mL
  • Pyuria – pus cells on urine microscopy
71
Q

Which main organisms are implicated in childhood UTIs?

A
  • Escherichia coli – MAIN ORGANISM
  • Other coliforms (Proteus, Klebsiella, Enterococcus sp.)
  • Coagulase-negative Staphylococcus (Staphylococcus saprophyticus)
72
Q

How are UTIs in children treated?

A
  • Early diagnosis and antibiotic treatment is important
    • Obtain sample before starting treatment
    • Renal tract imaging may be required to check for congenital anomalies
    • Antibiotic prophylaxis may be given after treatment of the infection
73
Q

What must you consider in the case of Recurrent or Persistent Infections in children?

A
  • May be a feature of immunodeficiency – either congenital (e.g. SCID) or acquired (e.g. HIV)
  • Warrants investigation by paediatric infectious diseases specialist

4 - Y5 a Path lectures 2021/22 (37 decks)

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