Bacterial, fungal + protozoal infection in childhood Flashcards
What are the most common infection-related deaths in childhood?
Pneumonia
Diarrhoea
What are exotoxins? Give 2 common examples.
Bacterial toxins secreted by the pathogen
Examples: cholera toxin A and diphtheria toxin A
What effects does diphtheria toxin A have on the body?
It inhibits protein synthesis
Acts on:
1. heart - can cause myocarditis + heart block
2. nerves - cause difficulty swallowing, paralysis + diplopia
What are endotoxins?
forms part of the outer membrane of gram negative bacteria
they are released during lysis of organisms
leads to macrophage activation
What is the endotoxin in meningococcal disease (Neisseria meningitidis)? How is it related to septic shock?
Endotoxin = Lipopolysaccharide (LPS)
The body will have an inflammatory reaction to LPS which will cause most of the symptoms of septic shock
What are the results of the activation of the inflammatory cascade via LPS?
Cause:
myocardial depression
endothelial dysfunction = capillary leak + shock
coagulopathy
What temperature is considered to be a fever? How does this vary depending on method of measurement?
> 37.8 degrees celsius = fever
- 0.5 degrees lower in mouth vs rectum
- 1 degree lower in arm vs rectum
Which bacterial infections are common and which are severe?
Severe:
- septicaemia
- meningitis
- pneumonia
- epiglottitis
- septic arthritis
- osteomyelitis
- tuberculosis
- tetanus
Common:
- tonsilitis
- otitis media
- UTI
- gastroenteritis
- Impetigo
Which encapsulated organisms cause septicaemia + meningitis?
Streptococcus pneumoniae
Neisseria meningitidis (Group B, C, W)
Haemophilus influenza B (HiB)
What are the clinical symptoms of septicaemia?
tachycardia tachypnoea prolonged capillary refill low BP = late sign rash
What are the clinical symptoms of meningitis in a child?
high temperature headaches vomiting photophobia drowsiness stiff neck
At what age would a lumbar puncture be performed on a child?
> 3 months
What type of bacteria is tetanus? Which organism is it caused by?
Gram positive bacillus
Clostridium tetani
How would you treat young infants and older children infected by Strep B, E. Coli or Listeria?
Infants: combination fo cefotaxime/ceftriaxone and amoxicillin
Older children: Ceftriaxone
When does neonatal sepsis occur? When is early onset and late onset?
First 28 days of life
Early onset = within 48 hours
Late onset = within 3 days (settles in meninges + brain)
Name common gram positive organisms (cocci + bacilli).
Cocci:
- Staphylococcus
- Streptococcus
- Enterococcus
Bacilli:
- Corynebacterium
- Listeria
- Bacillus - cereus, anthracis
- Clostridium - tetani, botulinium, difficile
What immune defects will predispose someone to pneumococcal infection?
- Absent/non functional spleen
- vulnerable to encapsulated bacteria
- congenital asplenia
- traumatic removal
- hyposplenism - Hypogammaglobulinaemia
- HIV infection
What are the non-invasive and invasive clinical features of pneumococcus?
Non-invasive:
- acute otitis media
- sinusitis
- conjunctivitis
- pneumonia
Invasive: (enters blood)
- septicaemia
- meningitis
- peritonitis
- arthritis
- osteomyelitis
What two vaccines are there for pneumococcal infections?
Pneumococcal polysaccharide vaccine (PPV)
Pneumococcal conjugate vaccine (PCV)
- protein allows the engagement of helper t cells
- protein is internalised + present as a little fragment for recognition
What are common examples of superficial mycosis (fungal infection)?
Candidiasis (nappy rash) and tinea corporis (ring worm)
- occurs in normal hosts
What are common examples of invasive mycosis (fungal infection)?
Rare: candidaemia (affects kidney + brain) and pulmonary aspergillosis (in children with chronic granulomatous disease)
- is an opportunistic infection - common in immunocompromised hosts
How are protozoa classified?
- Sporozoa
- plasmodium species (malaria)
- toxoplasma gondii (toxoplasmosis)
- cryptosporidium (diarrhoea) - Amoebae
- entamoeba histolytica - Flagellates
- giardia (diarrhoea, malabsorption)
- trypansoma (sleeping sickness, Chagas)
- Leishmania
What are the four main species of malaria?
P:
- falciparum
- vivax
- ovale
- malariae
What signs/symptoms indicate meningitis in an infant?
Tense/bulging soft spot fever very sleepy tachypnea/dyspnea extreme shivering pin prick rash/marks sometimes diarrhoea cold hands + feet stiff body blotchy skin irritable vomiting/refusing to feed
