3. Bacterial Infections in Childhood Flashcards
What is this condition?
Widespread purpuric rash - meningococcal septicaemia
What are exotoxins?
Give some examples.
What are endotoxins?
Meningococcal disease causes activation of inflammatory cascade via lipopolysaccharides. What 3 things can this lead to?
Proteins secreted by pathogen.
Cholera toxin, diptheria (Corynebacterium diptheriae) affects the heart (myocarditis) or nerves (paralysis, diplopia)
Part of outer membrane of gram -ve bacteria (lipopolysaccharide) released during lysis of the organism. Leads to macrophage activation.
Myocardial depression, endothelial dysfunction leading to capillary leak and shock, coagulopathy
What differences are there in children vs adults when it comes to contracting bacterial infections?
Infections often present with fever. What is the definition of fever?
What are some common childhood bacterial illnesses?
What are some severe childhood bacterial illnesses?
Immunological (immaturity, lack of memory), Anatomical (thinner skin, shorter airways, anatomy of Eustachian tube -> otitis), Exposure (hygiene, nursery/day care)
Temperature >37.8oC (mouth is O.5oC lower than rectal temp, armpit is 1oc lower than rectal temp; rectal temp = gold standard)
Tonsilitis, otitis media, UTI, gastroenteritis, impetigo
Septicaemia, meningitis, pneumonia, epiglottitis, septic arthritis, osteomyelitis, tuberculosis, tetanus
List some organisms that cause septicaemia and meningitis.
How would you recognise septicaemia?
What is meningitis?
Describe a typical clinical presentation of childhood meningitis.
Streptococcus pneumoniae, Neisseria meningitidis (mostly group B), Haemophilus influenza B (HiB)
Tachycardia, tachypnoea, prolonged capillary refill, low BP (late sign), rash (tumbler/glass test!)
Swelling and inflammation of meninges.
High temperature, headache, vomiting, unable to tolerate bright light, drowsy, stiff neck
How is meningitis diagnosed?
How might this be used to distinguish between bacterial, viral and TB meningitis?
Lumbar puncture
LP fluid analysis:
Bacterial: cloudy fluid, lots of polymorphs, high protein and low glucose.
Viral: clear fluid, lots of lymphocytes
TB: opalescent fluid, lots of lymphocytes, high protein and low glucose
Briefly describe the routine immunisation schedule for babies.
What are the top 3 organisms in young infants?
What is the antibiotic of choice for:
a) children >3m?
b) children <3m?
8 weeks: 5 in one (diptheria, tetanus, pertussis, polio and HiB), PCV, rotavirus, men B
12 weeks: 5 in one, rotavirus. 16 weeks: 5 in one, rotavirus, pneumococcal. 1 year: MMR, PCV, men B, HiB and men C
Group B streptoccus (carried by lots of pregnant women in birth canal), E coli, Listeria (so don’t eat soft cheese etc.)
a) Ceftriaxone (covers G +ve and -ve, good CSF penetration, 1/day)
b) Cefotaxime or ceftriaxone, and amoxicillin needed for Listeria cover (it’s resistant to cephalosporins)
What are the 2 different types of neonatal sepsis?
List some important gram positive cocci and bacilli.
Early onset (within 48hrs) and late onset (organisms more likely to have settled in organs, bones and joints. Meningitis.)
Cocci: staphylococcus, streptococcus, enterococcus
Bacilli: corynebacterium (causes diptheria), listeria, bacillus (cereus, anthracis), clostridium (tetani, botulinum, difficile)
Describe Streptococcus pneumoniae.
What immune defects predispose to pneumococcal infection?
How would an inividual undergoing a splenectomy be managed?
What invasive and non-invasive infections can pneumococcus cause?
Normal flora in 5-70% people. Diplococci. [Pic]
Absent/non functional spleen (congenital asplenia, traumatic removal, hyposplenism e.g. sickle cell b/c causes anaemia), Hypogammaglobulinaemia, HIV (B cells don’t produce Abs)
Vaccination (against pneumoccus, HiB and meningococcus b/c vulnerable to encapsulated bacteria), lifelong penicillin daily
Non-invasive: acute otitis media, sinusitis, conjunctivitis, pneumonia. Invasive: septicaemia, meningitis, peritonitis, arthiritis, osteomyelitis.
Describe otitis media in children.
Describe the 2 types of pneumococcal pneumonia.
Pneumococcus lives in nose, travels to ear through Eustachian tube (much straighter in children so connection to middle ear easier), infection behind ear drum (otitis media), pus builds up and ear drum bursts, pus leaves ear. NB: if mucosa inflamed, bacteria can enter blood from nose -> meningitis, sepsis, osteomyelitis etc.
Lobar pneumonia [L] or empyema [R] (pleural infusion infected - pus in pleural space, managed by chest drain +/- urokinase, or video assisted thoracoscopic surgery (VATS))
What is this condition? (Can be caused by pneumococcus)
Osteomyelitis. Only seen on X ray about 10d after so need MRI instead.
How would septic arthritis be confirmed and treated?
What are the 2 types of vaccine for pneumoccus?
Ultrasound scan to confirm effusion in knee joint. Needs washout in theatre and antibiotics for a few weeks. Can be caused by pneumococcus.
Pneumococcal polysaccharide vaccine (PPV)(Pneumovax, 23 serotypes). Pneumococcal conjugate vaccine (PCV)(Prevenar, 13 serotypes, given at 2, 4 and 12m)
Describe some different outcomes of Mycobacterium tuberculosis.
Childhood exposure (longterm) -> primary pulmonary infection -> sucessful immune response -> well adult -> immunity (live MTb)
OR
Immunity (live MTb) -> late reactivation of pulmonary disease -> forms cavity in lungs
OR
Primary pulmonary infection -> inadequate immune response -> progressive pulmonary disease -> death OR lympho/haematogenous spread -> miliary extra-pulmonary disease -> death
What causes tetanus? (Bacteria and human practice)
What are the signs/symptoms of tetanus in a baby?
Infectious diseases are a result of interaction between what 2 things?
Clostridium tetani, G +ve, spores in soil, tetnaus toxin (endotoxin) interacts with NMJ. Caused by lack of maternal vaccination in pregnancy, unclean blade to cut cord, application of mud/dung to cord.
Weak, lethargic, poor suck, spasms, fits, acrched back and stiff arms
Pathogenic virulence and host susceptibility
What 2 main groups are fungi classified into?
Differentiate between 2 types of fungal disease in children: superficial and invasive mycoses.
Give examples of:
a) superficial mycoses
b) invasive mycoses
Yeasts e.g candida, unicellular/oval/round, asexual budding. Moulds e.g. aspergillus, filamentous fungi, branching filaments (hyphae).
Superficial: common, normal hosts, treat and get better. Invasive: rare, oppertunistic infections in immunocompromised hosts
a) Candidiasis (nappy rash, treat with topical antifungal), Tinea corporis (ringworm, treat with topical/oral antifungal)
b) Candidaemia in v. preterm infant, can affect kidneys and brain, treat with long course of IV antifungal. Pulmonary aspergillosis: child with chronic granulomatous disease (affects neutrophil function)
Give examples of neutropenia and impaired function in children with neurophil defects.
Give examples of congenital and acquired T-cell defects in children.
Low neutrophil count, congenital (e.g. Kostmann disease) or acquired (e.g. chemo). Leukocyte adhesion defect (can’t migrate to sites of infection), chronic granulomatous disease (impaired oxidative burst so no free radicals produced etc.)
Congenital: severe combined immunodeficiency (SCID), Wiskott-Aldrich syndrome. Acquired: HIV infection
What 3 categories are protozoa classified into?
What 4 main Plasmodium spp transmit malaria?
Breifly describe the malaria life cycle.
Sporozoa: (Plasmodium spp (malaria), Toxoplasma gondii (toxoplasmosis), Cryptosporidium (diarrhoea). Amoebae: Entamoeba histolytica (amoebic dysentry). Flagellates: Giardia (diarrhoea, malabsorption), Trypanasoma (sleeping sickness, Chagas), Leishmania (leishmaniasis).
P. falciparum (most severe), P. vivax, P. ovale, P. malariae
3 main stages: bitten by female mosquito -> sporozoites (from saliva). 1st cycle in liver hepatocytes -> schizont. Ruptures and affects RBC -> symptoms.
