infectiuo Flashcards
effect of virus on the lung
cellular inflammation
local immune memory
loss of chemoreceptors
poor barrier to hygiene
promote bacterial growth as immune system fights virus cant fight bacteria
loss of cilia - less able to clear bacteria
mediator release
microbiomes
in lung and pharynx as dense as on skin
these bacteria cause pneumonia
common cold agents
rhinovirus coronaviruses influenza viruses parainfluenza viruses resp syncytial virus adenovirus enteroviruses mycoplasma chlamydia exchange between hosts through air virus previously been GI - evolved because of ease of transmission
community acquired pneumonia
eading infectious cause of hospitalisation and deaths in US adults
exceeds $1obillion annually
cooperation between bacteria and virus in the disease - influenza A and B, and resp syncytial virus present
what causes hospital acquired pneumonia
staphylococcus aureus 28% pseudomonas aeruginosa 21.8% klebsiella species 9.8% E coli 6.9% Acinetobacter 6.8% Enterobacter 6.3%
what causes CAP
strep pneumonia - classic presentation: cough, rusty sputum, cold sore
myxoplasma pneumonia - incidious atypical disease
staph aureus - people who are sick in other ways/immuneparetic
chlamidophilia pneumoniae - rare
haemophilus influenza - people with asthma, colo9nised with pneumonia after a viral infection
typical V atypical pathogens in CAP
typical - streptococcus pneumoniae, haemophilus influenzae, Moraxella catarrhalis
atypical pathogens - mycoplasma pneumoniae, chlamysia pneumonae, legionella pneuomophilia
atypical not covered by penicillins - need additional agents eg macrolides
pneumonia and age
after 70 the presenting rate of pneumonia increases
but younger eg 60, there is a higher fatality rate in the people who get the condition
age risk factor because of susceptibility to the virus
risk factor for pneumonia
age <2, >65 smoking alcohol contact with children <15 poverty and overcrowding - confound with passive smoking inhaled corticosteroids immunosuppressants - steroids proton pump inhibitors COPD asthma heart disease liver disease DM HIV malignancy hyposplenism complement or Ig deficiencies risk factors for aspiration previous pneumonia geo variations animal healthcare contacts
symptoms of pneumonia
hypoxic febrile - temp 38degrees crepitations - crackle in lungs new respiratory symptoms orb signs pleuritic chest pain confused new X ray changes
what is pneumonia a disease of
interstitium
affect GE
investigations for CAP
chest xray - could be pneumponia even if normal
blood test - full count - see if responding should be neutrophils and WBC, check urea electrolytes liver func and C reactive protein - check for risk of combined disease part of the septic syndrome
arterial blood gases - how sevele lung desaturation is and look for lactic acidosis
microbiological investigations - sputum culture, blood culture, urine antigen tests for legionella pneumophilia and streptococcus pneumonia
guidelines for diagnosing pneumonia
acute lower resp tract syndrome
new focal chest sign and signs on X ray
>1 systemic feature eg fever, shiver ache, pain, temp> 38degrees
no other explanation
CRB 65 severity score
1 point for every feature confusion resp rate >=30/min SBP <90 or DBP <=60mmHg >=65years 0 = low severity - home and AB 12 - moderate, consider hospital 3-4 high severity - urgent hospital, empirical AB if life threatening, may need ventilation consider social setting and home support
supportive therapy for pneumonia
oxygen - for hypoxia fluids for dehydration analgia for pain nebulised saline - may help expectoration chest physiotherapy
AB therapy that is given for pneumonia
low severity - amoxicillin with doxycycline - effective and low side effect profile - especially with haemophilus
severe - benzylpenicillin IV or telcoplanin and clathiro PO
for 5-7 days
7-14 days for atypicals
time frame of delivery of AB for pneumonia
crucial
in severe AB delivered as soon as possible
for every hour dekay in septic shock - chance of survival reduced by 7.9%
duration 1wk
Influenza pandemic
helitrope hue
could detect bacteria - haemophilus influenza
show association with bacterial colonisation and pneumonia
treatment for flu
Tamiflu and IV clarithromycin early
otherwise need prol0ngued ventilation
signs of flu
fever cough aches breathless at rest nausea increased SOB at rest
what causes severe disease
RNA sequence
viral load
DNA
environment
cause epithelial damage and storm of mediators
secondary bacteria infection
from host and virus - host genetics - variation in IFITN3
what causes sever flu
highly pathogenic strains - zoonotic ijnnate immune deficiency - IFITN3 local absence of B cells absence of T cells frail elderly COPD asthma DM obesity pregnancy V young
global changes in RSV and flu prevalence per month
swing between N and S hemispheres
RSV slightly predates flu
influenza
no reinfection by the same strain imperfect vaccines homotypic immunity vaccine induced immunity fades annual vaccine required perfect virus - runs away from immune system by evolving
RSV
infectious form is filamentus recurrent reinfection with similar strains controls the immune system no vaccine poor immunogenity vaccine enhanced disease researched field relatively stable but does evolve - now have niche strains
