Atypical pneumonia Flashcards
For which of the aetiological agents in this lecture is serology testing not useful as a means of diagnosing clinical infection? & is difficult to culture
Pneumocystis jivrovecii
describe the lifecycle of Chlamydophila sp? (5 steps)
- Inhalation of Elementary body (EB): spore-like structure containing DNA
- enter host cell & EB differentaite into intracell. reticulte-body stage (RB)
- Multiplication of RB by binary fusion
- RB differentiate back to EB
- Lysis of host cell
How does atypical pneumonia differ from classical bacterial pneumonia?
Atypical | Classical
Less common | common org
Slow onset | Rapid onset of symptoms
Dry cough | productive w/ sputum
Mild breathing problems | SOB
Mild Chest pain | Chest pain
List 5 viral causes of atypical pneumonia?
RSV
Influenza A and B
Parainfluenza virus T3
SARS
CMV
Why is it important to determine the aetiology of atypical pneumonia?
Identifying the specific causative agent allows us to know
- the pathogenisis of the org
- Clinical outcomes
- appropriate Treatment
a) Which three organisms in this lecture can be described as obligate intracellular bacteria?
b) pathogenesis
Chlamydophila psittaci
Chlamydophila pneumoniae
Coxiella burnettii
b) prevents action of host Aby and complement, elementary body/spore-like body
Which of these organisms can be cultured on agar and what type of agar is used?
- Chlamydophila psittaci and C. pneumoniae: Tiss. culture
- Coxiella burnettii: Embryonated chicken eggs & tiss. culture w/ human lung fibroblast or heart tissue
Pneumocystis jirovecii
a) Natural reservoir
b) How do humans acquire pathogen
c) pathogenic features
a) environment? (used to be a disease in rodents)
b) inhalation?
c) Attach to T1 pneumocytes & replicate extracell. (in alveolar lining fluid) => foamy exudate -> hypoxemia
Mononuclear inflammatory resp
Mycoplasma pneumoniae
a) Natural reservoir
b) How do humans acquire pathogen
c) pathogenic features
a) Plants, animals, water supply
b) Inhalation of respiratory aerosols/droplets human to human
c) Attach to mucosal surfaces & remain localised
Legionella pneumophilia
a) Natural reservoir
b) How do humans acquire pathogen
c) pathogenic features
a) Soil & water even chlorinated
b) inhale aerosols/vapour (from water supply)
c) Produce endotoxin & cytotoxin; pili adherance, Replicate in macrophage & lyse
Coxiella burnetti
a) Natural reservoir
b) How do humans acquire pathogen
c) pathogenic features
a) animal: cattle, sheep, goats
b) inhalation of aerosols (dust/fluid) or ingest unpasteurised milk
c) resistant endospore-like body
list 3 pathogens that cause community-acquired Acute pneumonia
- S. pneumoniae
- H. influenzae
- M. catarrhalis
list 3 pathogens that cause hospital-acquired Acute pneumonia
- Enterobacteriacea (K.pneumoniae)
- pseudomonas sp
- S. aureus
Lab dx of Chlamydophila (psittaci, pneumoniae)
- Gram: resemble GNB but no peptidoglycan
- Culture: monoclonal Aby in tiss. culture
- Serology: ELISA; immunofluorescence
- PCR
- Heat labile: put in viral transport media
Lab dx of Coxiella burnetti
- Gram: (not stain) GNCB
- Culture: emryonated eggs, tiss. culture w/ monoclonal Aby
- Serology: indirect immunofluorescence for Aby lvls
- PCR
