lung infection and immunity Flashcards
acute vs chronic lung infection: recall the differences in pathogenesis between acute and chronic lung infections e.g. pneumococcal pneumonia vs bronchiectasis
bacterial source of acute lung infection pneumoccocal pneumonia
Streptococcus pneumoniae
pathogens associated with community acquired pneumonia (CAP)
presentation of acute pneuomonia result of cooperative bacteria and viruses
are causes of hospital-acqiured pneumonia same as communtiy acquired pneumonia
no
typical community acquired pneumonia pathogens
S. pneumoniae, H. influenzae, M. catarrhalis
atypical community acquired pneumonia pathogens
M. pneumoniae, C. pneumoniae, L. pneumophilia
risk factors for pneumonia
age, smoking, excess alcohol, contact with < 15 years, poverty, overcrowding, some medications, medical history (e.g. COPD, asthma, heart, liver, diabetes), animal contact, geographical variations
diagnosing pneumonia
acute lower respiratory tract symptoms (coughing, green (neutrophil)/rusty (dead cell) sputum, dyspnoea as alveoli fill with pus), new focal chest signs, >1 systemic feature (fever, shivers, aches, high temperature), no other explanation for illness, CRB65 (confusion, respiratory rate, blood pressure, age) severity score, stabbing chest pain due to peripheral inflammation, X-ray with dense debris seen in lungs (fibrin, bacteria)
supportive therapy for pneumonia
antibiotics, oxygen (hypoxia), fluids (dehydration), analgesia (pain), nebulised saline
pneumonia antibiotic therapy examples
amoxicillin, clarithromycin, benzylpenicillin IV
features and outcome of acute antibiotic therapy for pneumonia
rapid time of antibiotic administration to reduce septic shock; 1 week treatment leaving airways unscarred and some effort made to clear infections
effect of viral infection on lung
mediator release, cellular inflamation, local immune memory; damage to epithelium - loss of cilia, bacterial growth, poor antigen barrier, loss of chemoreceptors
common cold agents
many viruses (influenza, respiratory syncytial etc.), atypical bacteria
features of severe viral disease
RNA sequence, viral load, DNA, environment - mediators, cell stress, epithelial damage, viral spread
causes of severe flu
highly pathogenic strains (zoonotic), absence of prior immunity, predisposing illness/conditions
feature of influenza infection and effect on vaccines
no re-infection by same strain; imperfect vaccines
respiratory syncytial virus (RSV) features
unstable; recurrent re-infection (filamentous) with similar strains; no vaccine
what does RSV cause in neonates
bronchiolitis
is RSV likely to be present upon hospital admission
no
viral load: influenza vs RSV
influenza - rapid viral load; RSV - delayed viral load
why is lung susceptible to infection
not sterile - contains many organisms causing pneumonia
define bronchiectasis as an example of a chronic lung infection
chronic condition where airways become abnormally widened, secondary to chronic inflammation, leading to build-up of excess mucus (more vulnerable to infection)
pathogenesis of bronchiectasis
inflammation permanently destroying tissue and muscles surrounding bronchi, causing them to widen, become scarred, inflamed and filled with excess mucus; this triggering persistent coughing, SOB, chronic fatigue, and make the lungs more vulnerable to infection as they harbour bacteria
causes of bronchiectasis
severe pneumonia, whooping cough, TB, measles, immunodeficiency, connective tissue diseases (e.g. rheumatoid arthritis), CF, cilia abnormalities
treatment of bronchiecstasis
physiotherapy to empty phlegm, antibiotics to clear infection
acute inflammation: neutrophils and anti-protease balance
neutrophils secrete proteases to destroy microbes during inflammation and infection, and normally this is balanced by anti-proteases in the airways
chronic inflammation: neutrophils and anti-protease imbalance
number of neutrophils is so large that the anti-proteases are overwhelmed leading to increased free proteases causing damage to the airway epithelia (which in turn makes it easier to be infected, creating a vicious cycle)
