Infectious Diseases for Finals Flashcards
What is a Ghon focus?
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.
What is a Ghon complex?
Ghon focus plus affected hilar lymph nodes
What test might be done to investigate latent TB in patients who are unsuitable for the Mantoux test?
Interferon gamma (also done to confirm diagnosis after positive Mantoux test)
Which patients might give rise to a false negative Mantoux test in the investigation of TB?
HIV Miliary TB Age less than 6 months Lymphoma Sarcoidosis
What is the treatment for active TB?
Rifampicin Isoniazid Pyrazinamide Ethambutol All 4 for 2 months, then rifampicin and isoniazid continued for 4 further months
True / False: TB is a notifiable disease
True
What might be seen on chest x-ray in a patient with pulmonary TB?
Cavitating lung lesion - likely upper zone
Fibrosis, calcification, consolidation
Hilar enlargement
How is the diagnosis of pulmonary TB made?
Suspicious chest x-ray findings
Sputum culture: 3x samples sent for microscopy and culture for acid fast bacilli
How long are patients with TB meningitis treated for?
12 months
Steroids also added to regime
List some side effects of rifampicin
Turns secretions orange Flu-like symptoms Liver enzyme inducer Transaminitis Thrombocytopenia
What drug should be given alongside isoniazid? Why?
Piridoxine - Reduced peripheral neuropathy associated with isoniazid
Give some side effects of isoniazid
Liver enzyme inhibitor
Peripheral neuropathy
Hepatitis
Agranulocytosis
Give some side effects of pyrazinamide
Arthralgia, myalgia
Gout
Hepatitis
Give some side effects of ethambutol
Reduced colour vision and visual acuity
What is the most common causative organism in native valve infective endocarditis?
Staphylococcus aureus
What is the likely causative organism in new prosthetic valve infective endocarditis?
Coagulase negative staphylococcus e.g. Staph epidermidis
List some signs of immune complex formation seen in infective endocarditis
Splinter haemorrhages
Osler nodes
Janeway lesions
Roth spots (on retina)
How is the diagnosis of infective endocarditis made?
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
What is the treatment for native valve endocarditis?
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
What is the treatment for infective endocarditis in a known IVDU? Why?
Flucloxicillin as Staph aureus is most likely cause
What is the treatment for infective endocarditis in a new prosthetic valve?
Teicoplanin + Gentamicin + Rifampicin
What is the treatment for infective endocarditis in a prosthetic valve older than 6 weeks?
Treat the same as for native valve endocarditis
What is the treatment for infective endocarditis in a patient who is penicillin allergic?
Teicoplanin and gentamicin
