Microbiological Diagnosis of Chest Infection Flashcards
Diagnostic techniques for patients who you think have a respiratory tract infection
MC+S and blood
Antigen detection mechanisms
Nucleic acid amplification (PCR)
Serology (antibody measurement)
What does MC+S stand for?
Microscopy and culture of sputum and blood
Example of a normal upper respiratory flora
Strep viridans
Example of the major respiratory pathogens
Strep pneumoniae
Haemophilus influenza
Moraxella catarrhalis
Examples of non respiratory pathogens
E coli
Staph aureus
Tests for TB
ZN or auramine phenol stain
Acid and alcohol fast bacilli (AAFB)
Extended culture for weeks for mycobacteria
What is bronchio-alveolar lavage (BAL)?
Lower airway sample collected at bronchoscopy
Many patients with pneumonia have what?
Bacteraemia
What is bacteraemia?
Viable bacteria in the blood
Atypical causes of resp infection
Legionella pneumophila
Mycoplasma pneumoniae
Chlamydia psittaci (birds)
Coxiella burnetti (Q fever)
What organisms can be detected by their antigens?
Legionella and pneumococcal antigen - detected in urine
Viruses in nasopharyngeal secretions
How can antigens be detected?
Aggulation
EIA
Immunofluorescence
What is latex agglutination?
Latex particles coated with monoclonal antibodies - specific for the antibodies in question
What does ELI stand for?
Enzyme immuno-assay
What does ELISA stand for/
Enzyme linked immunosorbent assay
What does PCR stand for and what does it detect?
Polymerase chain reaction
Detects DNA
How can PCR aid respiratory diagnosis?
Throat swabs
Other resp samples
Flocked swabs
What swabs are used for bacterial culture?
Charcoal swabs
Examples of respiratory viruses
Inflenzae A or B Adenoviruses RSV Parainfluenzae viruses Metpneumonvirus Coronavirus Rhinovirus
What is IgM a marker of?
Current infection
What is IgG a marker of?
Previous infection
