Bacterial, Fungal & Protozoal Infections In Childhood Flashcards
Neonatal death makes up how many % of childhood death?
40%
What is the biggest cause of neonatal death?
Preterm birth complications
What are the two biggest causes of non-neonatal childhood death (other than ‘other disorders’)?
Pneumonia
Diarrhoea
Are bacteria prokaryotes or eukaryotes?
Prokaryotes
Give two examples of eukaryotes.
Fungi
Protozoa
What is the diameter of prokaryotes in uM? What about eukaryotes?
0.2-2
10-100
What is the difference in chromosomes between pro and eukaryotes?
Pro – single, circular chromosome
Eu – multiple, linear chromosomes
What is the difference in nucleus between pro and eukaryotes?
Pro has no nucleus
Which don’t have organelles – eu or prokaryotes?
Pro
How do prokaryotes divide? How to eukaryotes divide?
Binary fission
Mitosis
Why do infections cause morbidity and mortality? (2)
Toxins
Immunopathology
What is an exotoxin?
Protein secreted by the pathogen
Give an example of a bacterial infection that causes damage via its exotoxin?
Cholera (causes diarrhoea)
What bacteria causes diphtheria?
Corynebacterium diphtheria
What are the signs/symptoms of diphtheria? (3)
Sore throat, fever, pseudo-membrane
How does diphtheria affect the heart? (2)
Myocarditis
Heart block
How does diphtheria affect the nerves? (3)
Difficulty swallowing
Paralysis
Diplopia
What exotoxin does diphtheria release? How does this work?
Diphtheria toxin (A and B subunits) – inhibits protein synthesis
What is an endotoxin? When is it released? What does it lead to?
Part of the outer membrane of Gram-negative bacteria
Released during lysis of the organism
Leads to macrophage activation
What cytokines are involved in the pathogenesis of meningococcal disease?
IL-6
TNF-alpha
What is the pathogenesis of meningococcal disease?
Activation of inflammatory cascade via LPA –> myocardial depression, endothelial dysfunction, coagulopathy –> capillary leak and shock
Why are infections different in children to adults? (6)
Immunological immaturity and lack of memory
Thinner skin
Shorter airways
Anatomy of Eustachian tube (more susceptible to otitis)
Exposure
Hygiene, nursery/daycare
What do infections often present with?
Fever
What is the definition of fever?
Temperature > 37.8
How much lower than rectal temp is taking temp via mouth?
0.5 degree lower
How much lower than rectal temp is taking temp via axilla?
1 degree lower
Give some examples of severe bacterial illnesses. (8)
Septicaemia Meningitis Pneumonia Epiglottitis Septic arthritis Osteomyelitis Tuberculosis Tetanus
Give some examples of common bacterial illnesses. (5)
Tonsillitis Otitis media Urinary tract infection Gastroenteritis Impetigo
What organisms cause septicaemia and meningitis? (3)
Streptococcus pneumoniae
Neisseria meningitidis (mostly Group B)
Haemophilus influenzae B
How do you recognise septicaemia? (5)
Tachycardia Tachypnoea Prolonged capillary refill Low BP (late sign) Rash
How is meningitis diagnosed?
LP
What are the symptoms of meningitis? (6)
High temperature Headache Vomiting Not able to tolerate bright lights Drowsy Stiff neck
What is the difference in appearance of CSF in bacterial vs viral meningitis vs TB?
Bacterial – cloudy
Viral – clear
TB - opalescent
What cells are present in bacterial vs viral meningitis vs TB?
Bacterial - neutrophils
Viral and TB – lymphocytes
How does the protein in CSF compare in bacterial vs viral meningitis vs TB?
Higher in bacterial (and much higher in TB)
How does the glucose in CSF compare in bacterial vs viral meningitis?
Bacterial – low
Viral - normal
What are the top three organisms in young infants?
Group B streptococcus
E Coli
Listeria
What antibiotic may be given in older children?
Ceftriaxone
What antibiotics may be given in young infants (<3 months)? (2)
Cefotaxime or ceftriaxone
Amoxicillin also needed for Listeria cover
What is the neonatal period?
First 28 days of life
What causes neonatal sepsis?
Maternal colonization with pathogens (colon or vaginal canal)
When does early onset sepsis occur?
48 hrs
What does late onset sepsis cause?
Meningitis
Bones and joint problems
How many % of neonatal sepsis cases’ mothers have GBS?
15-40%
Name 3 gram-positive cocci bacteria.
Staphylococcus
Streptococcus
Enterococcus
Name 4 gram-positive bacilli bacteria.
Corynebacterium
Listeria
Bacillus (cereus, anthracis)
Clostridium (tetani, botulinum, difficile)
Steptococcus pneumoniae - how many % of people have this as normal flora?
5-70% people
What predisposes to pneumococcal infection? (3)
Absent / non-functional spleen
Hypogammaglobulinaemia
HIV infection
Absent/non-functional spleen - name three possible causes. (3)
Congenital asplenia
Traumatic removal
Hyposplenism (eg sickle cell)
Splenectomy means people are more vulnerable to…? What is given daily for the rest of their lives?
Encapsulated bacteria
Pencillin
Name 3 encapsulated bacteria.
Pneumococcus
HiB
Meningococcus
Non-invasive conditions? (4)
Acute otitis media
Sinusitis
Conjunctivitis
Pneumonia
Invasive conditions? (5)
Septicaemia Meningitis Peritonitis Arthritis Osteomyelitis
Pneumococcus causes empyema. How is it managed? (2)
Chest drain +/- urokinase
Video-assisted thoracoscopic surgery
What are the two types of vaccine for pneumococcus?
Pneumococcal polysaccharide vaccine (PPV) e.g. Pneumovax (23 serotypes)
Pneumococcal conjugate vaccine (PCV) e.g.
Prevenar (13 serotypes)
When are pneumococcus vaccines given?
Given at 2, 4 and 12 months
How do conjugate vaccines work?
- B cell binds bacterial polysaccharide epitope linked to tetanus toxoid protein
- Antigen is internalised and processed
- Peptides from protein component are presented to the T cell
- Activated B cell produced antibody against polysaccharide antigen on the surface of the bacterium
What proportion of people globally are infected with mycobacterium tuberculosis?
1/3
How many people globally have mycobacterium tuberculosis DISEASE?
15 million
How is a TB cavity formed?
Childhood exposure causes primary pulmonary infection
A successful immune response leads to a well adult with immunity
Late reactivation of pulmonary disease forms a cavity
How does TB cause progressive pulmonary disease? What does this lead to?
Childhood exposure causes primary pulmonary infection
An inadequate immune response leads to progressive pulmonary disease (can be fatal)
This can spread via blood/lymph, causing miliary extrapulmonary disease (can be fatal)
What bacteria causes tetanus? What type of bacteria is this?
Clostridium tetani
Gram positive bacillus
Where are Clostridium tetani spores found?
Soil
What does the tetanus toxin (exotoxin) interact with?
NMJ
How does tetanus present in infants? (5)
Weakness Lethargy Poor suck Spasms Fits
How many fungi species have been named? How many cause disease?
> 100,000
<500
What are the two types of fungi?
Yeasts
Moulds
Give an example of a yeast.
Candida
Give an example of a mould.
Aspergillus
Which is more common - superficial or invasive mycoses? In whom does invasive mycoses occur?
Superficial
Invasive mycoses occur in immunocompromised hosts
Give two examples of superficial mycoses? How are they treated?
Candidiasis (nappy rash)
Tinea corporis (ringworm)
Topical antifungal e.g. Nystatin
Give two examples of invasive mycoses.
Candidaemia
Pulmonary aspergillosis
Who and what can candidaemia affect? How is it treated?
Preterm babies
Kidneys and brain
Long course of IV antifungal
Who does pulmonary aspergillosis affect?
Child with chronic granulomatous disease (affects neutrophil function)
What is neutropenia? What are the causes?
Low neutrophil count
Congenital e.g. Kostmann disease
Aquired e.g. chemotherapy
How does chronic granulomatous disease cause impaired function of neutrophils?
Causes impaired oxidative burst
What is another cause of impaired function of neutrophils?
Leukocyte adhesion defect (cannot migrate to sites of infection)
What are the congenital causes of T cell defects? (2)
Severe combined immunodeficiency (SCID)
Wiskott-Aldrich syndrome
What is an acquired cause of T cell defects?
HIV
What are the three main classifications of protozoa?
Sporozoa
Amoebae
Flagellates
SPOROZOA - give three examples.
Plasmodium species (malaria) Toxoplasma gondii (toxoplasmosis) Cryptosporidium (diarrhoea)
AMOEBAE - give an example.
Entamoeba histolytica (amoebic dysentery)
FLAGELLATES - give three examples.
Giardia (diarrhoea, malabsorption)
Trypanasoma (sleeping sickness, Chagas)
Leishmania (leishmaniasis)
What are the four main species that cause malaria?
P. falciparum – most severe, cerebral malaria
P. vivax
P. ovale
P. malariae
Which species causes cerebral malaria?
P. falciparum
What are the non-specific symptoms of malaria? (4)
Fever, lethargy, vomiting, diarrhoea
What does severe malaria cause? (4)
Anaemia
Respiratory distress
Cerebral malaria (coma, seizures)
Hypoglycaemia
How many children die each year of malaria?
1 million
What new treatments are there for malaria?
What is the benefit of these?
Artemisinin derivatives
Combination treatment (eg Coartem: artemether-lumefantrine)
More rapid reduction in parasitaemia
What causes congenital toxoplasmosis?
What are the oocysts excreted by?
Where does it multiple?
Toxoplasma gondii
Cats
Macrophages
