Infectious Diseases for Finals

Question 1

What is a Ghon focus?

Answer 1

Formed in primary pulmonary TB, where there is an area of infection in the lung which is infiltrated by macrophages which ingest the bacillus causing a granulomatous lesion.

Question 2

What is a Ghon complex?

Answer 2

Ghon focus plus affected hilar lymph nodes

Question 3

What test might be done to investigate latent TB in patients who are unsuitable for the Mantoux test?

Answer 3

Interferon gamma (also done to confirm diagnosis after positive Mantoux test)

Question 4

Which patients might give rise to a false negative Mantoux test in the investigation of TB?

Answer 4

HIV
Miliary TB
Age less than 6 months
Lymphoma
Sarcoidosis

Question 5

What is the treatment for active TB?

Answer 5

Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
All 4 for 2 months, then rifampicin and isoniazid continued for 4 further months

Question 6

True / False: TB is a notifiable disease

Answer 6

True

Question 7

What might be seen on chest x-ray in a patient with pulmonary TB?

Answer 7

Cavitating lung lesion - likely upper zone
Fibrosis, calcification, consolidation
Hilar enlargement

Question 8

How is the diagnosis of pulmonary TB made?

Answer 8

Suspicious chest x-ray findings

Sputum culture: 3x samples sent for microscopy and culture for acid fast bacilli

Question 9

How long are patients with TB meningitis treated for?

Answer 9

12 months

Steroids also added to regime

Question 10

List some side effects of rifampicin

Answer 10

Turns secretions orange
Flu-like symptoms
Liver enzyme inducer
Transaminitis
Thrombocytopenia

Question 11

What drug should be given alongside isoniazid? Why?

Answer 11

Piridoxine - Reduced peripheral neuropathy associated with isoniazid

Question 12

Give some side effects of isoniazid

Answer 12

Liver enzyme inhibitor
Peripheral neuropathy
Hepatitis
Agranulocytosis

Question 13

Give some side effects of pyrazinamide

Answer 13

Arthralgia, myalgia
Gout
Hepatitis

Question 14

Give some side effects of ethambutol

Answer 14

Reduced colour vision and visual acuity

Question 15

What is the most common causative organism in native valve infective endocarditis?

Answer 15

Staphylococcus aureus

Question 16

What is the likely causative organism in new prosthetic valve infective endocarditis?

Answer 16

Coagulase negative staphylococcus e.g. Staph epidermidis

Question 17

List some signs of immune complex formation seen in infective endocarditis

Answer 17

Splinter haemorrhages
Osler nodes
Janeway lesions
Roth spots (on retina)

Question 18

How is the diagnosis of infective endocarditis made?

Answer 18

Use Duke’s Criteria: Diagnose if 2 major, 1 major and 3 minor, or all 5 minor criteria met……
MAJOR criteria:
- Positive blood culture on 2 separate samples, or persistently positive cultures more than 12 hr apart
- ECHO shows endocardium involvement or new heart murmur
MINOR criteria:
- IVDU or predisposing heart condition
- Fever above 38 degrees
- Vascular or immunological signs
- Positive blood culture which doesn’t meet major criteria
- Positive ECHO findings which don’t meet major criteria

Question 19

What is the treatment for native valve endocarditis?

Answer 19

Amoxicillin and gentamicin IV for 2/52, then amoxicillin PO alone for 4/52

If viridans group strep confirmed on cultures: BenPen and gentamicin IV for 2/52, then amoxicillin PO alone for 4/52

Question 20

What is the treatment for infective endocarditis in a known IVDU? Why?

Answer 20

Flucloxicillin as Staph aureus is most likely cause

Question 21

What is the treatment for infective endocarditis in a new prosthetic valve?

Answer 21

Teicoplanin + Gentamicin + Rifampicin

Question 22

What is the treatment for infective endocarditis in a prosthetic valve older than 6 weeks?

Answer 22

Treat the same as for native valve endocarditis

Question 23

What is the treatment for infective endocarditis in a patient who is penicillin allergic?

Answer 23

Teicoplanin and gentamicin