Microbiological Diagnosis of Chest Infection

Question 1

Diagnostic techniques for patients who you think have a respiratory tract infection

Answer 1

MC+S and blood
Antigen detection mechanisms
Nucleic acid amplification (PCR)
Serology (antibody measurement)

Question 2

What does MC+S stand for?

Answer 2

Microscopy and culture of sputum and blood

Question 3

Example of a normal upper respiratory flora

Answer 3

Strep viridans

Question 4

Example of the major respiratory pathogens

Answer 4

Strep pneumoniae
Haemophilus influenza
Moraxella catarrhalis

Question 5

Examples of non respiratory pathogens

Answer 5

E coli

Staph aureus

Question 6

Tests for TB

Answer 6

ZN or auramine phenol stain
Acid and alcohol fast bacilli (AAFB)
Extended culture for weeks for mycobacteria

Question 7

What is bronchio-alveolar lavage (BAL)?

Answer 7

Lower airway sample collected at bronchoscopy

Question 8

Many patients with pneumonia have what?

Answer 8

Bacteraemia

Question 9

What is bacteraemia?

Answer 9

Viable bacteria in the blood

Question 10

Atypical causes of resp infection

Answer 10

Legionella pneumophila
Mycoplasma pneumoniae
Chlamydia psittaci (birds)
Coxiella burnetti (Q fever)

Question 11

What organisms can be detected by their antigens?

Answer 11

Legionella and pneumococcal antigen - detected in urine

Viruses in nasopharyngeal secretions

Question 12

How can antigens be detected?

Answer 12

Aggulation
EIA
Immunofluorescence

Question 13

What is latex agglutination?

Answer 13

Latex particles coated with monoclonal antibodies - specific for the antibodies in question

Question 14

What does ELI stand for?

Answer 14

Enzyme immuno-assay

Question 15

What does ELISA stand for/

Answer 15

Enzyme linked immunosorbent assay

Question 16

What does PCR stand for and what does it detect?

Answer 16

Polymerase chain reaction

Detects DNA

Question 17

How can PCR aid respiratory diagnosis?

Answer 17

Throat swabs
Other resp samples
Flocked swabs

Question 18

What swabs are used for bacterial culture?

Answer 18

Charcoal swabs

Question 19

Examples of respiratory viruses

Answer 19

Inflenzae A or B
Adenoviruses
RSV
Parainfluenzae viruses
Metpneumonvirus
Coronavirus 
Rhinovirus

Question 20

What is IgM a marker of?

Answer 20

Current infection

Question 21

What is IgG a marker of?

Answer 21

Previous infection