Immunopathogenesis Flashcards
immunopathogenesis
pathologies caused by immune reactions, following an infection, rather than the pathogen itself
viral bronchiolitis: definition and aetiological agents
inflammation of the bronchioles following viral infection
respiratory syncytial virus (RSV), rhinovirus, influenza virus, human metapneumovirus
Risk factors for severe immunopathological disease in infants
prematurity (more than 4 wks early), chronic lung disease or congenital heart disease, low birth weight, other kids at home, bad living conditions, attending nursery etc
RSV induced diseases - descending infection
rhinitis otitis media tracheobronchitis bronchiolitis pneumonia asthma
• RSV bronchiolitis and pneumonia - pathology and clinical signs
o Pathology – necrosis and sloughing of small airway epithelium, oedema, increased mucous secretion, interstitial infiltration, alveolar filling
Clinical – hyperinflation, atelectasis (collapsed lung), wheezing
pathogenesis of RSV
virus replication causes immune response in lungs.
cyto/chemokine release, neutrophil infiltration, lymphocytes and eosinophils
perivascular and peribronchiolar cuffing occur, trapping air in lower lungs
= lung hyperinflation
removal of RSV doesn’t stop the pathway.
systemic inflammatory response syndrome (SIRS)
Temperature >38ºC or <36ºC
Heart rate >90bpm
Resp rate >20 breaths/min or PaCO2 of <32 mmHg
WBCc >12,000 cells/mm3, <4000 cells/mm3, or >10% immature forms
Sepsis
presence of SIRS associated with a confirmed infectious process
severe sepsis
sepsis with either hypotension or systemic manifestations of hypoperfusion (lactic acidosis, oliguria, altered mental status)
septic shock
sepsis with hypotension despite adequate fluid resuscitation, associated with hypoperfusion abnormalities
bacterial causes of septicaemia in previously healthy adult - Skin
staphylococcus aureus and other gram positive cocci
bacterial causes of septicaemia in previously healthy adult - urinary tract
escherichia coli and other aerobic gram negative rods
bacterial causes of septicaemia in previously healthy adult - respiratory tract
streptococcus pneumoniae
bacterial causes of septicaemia in previously healthy adult - bladder or bowel
enterococcus faecialis, e. coli and other gram negative rods, bacteroides fragilis
bacterial causes of septicaemia in previously healthy adult - pelvic organs
nesseria gonorrhoeae, anaerobes
bacterial causes of septicaemia in hospitalised patients - urinary catheter
E. coli Klebsiella spp. Proteus spp. Serratia spp. Pseudomonas spp.
bacterial causes of septicaemia in hospitalised patients - Intravenous catheter
Staphylococcus aureus Staph. epidermidis Klebsiella spp. Pseudonomas spp. Candida albicans
bacterial causes of septicaemia in hospitalised patients - peritoneal catheter
staph epidermidis
bacterial causes of septicaemia in hospitalised patients - wound/deep infection
staph. aureus, e. coli, sometimes anaerobes
bacterial causes of septicaemia in hospitalised patients - burns
gram positive cocci, pseudonomonas spp. candida albicans
sepsis - pathophysiology
ACTIVATION of host defence mechanisms by endotoxins (gram -ve, lead to cytokine release) and exotoxins (gram +ve)
INFLAMMATION - neutrophils, monocytes are activated, –> vasodilation, diffuse endothelial permeability, activation of coagulation pathways
SEPSIS - fever, vascular collapse/shock. cna lead to septic shock
consequenses of septic shock caused by the coagulation pathway
capillary microthrombi
end organ ischaemia
consequenses of septic shock caused by the dysfunction of capillary endothelium
vasodilation
capillary leakage
global tissue hypoxia
organ dysfunction and failure
