Antimicrobial Chemotherapy

Question 1

What are the indications for using antimicrobials?

Answer 1

Therapy: empiric or directed (based in microbiology results)

Prophylaxis: Primary (e.g. antimalarial, preop, post exposure) or secondary (prevent second episode e.g. pneumocystitis in a HIV patient)

Question 2

How do we best select the right antimicrobial for treatment?

Answer 2

Work out the causative organism by culture and sensitivity; but also use clinical experience to develop a likely idea.

Question 3

What bacteria commonly cause soft tissue infection?

Answer 3

Strep pyogenes
Staph aureus
Strep group C or G
E. coli
Pseudomonas aeruginosa
Clostridium species

Question 4

What bacteria commonly cause pneumonia?

Answer 4

Strep pneumonia
Haemophilus influenzae
Staph aureus
Klebsiella pneumonia
Moraxella catarrhalis
Mycoplasma pneumonia
Legionella pneumonia
Chlamydia pneumonia

Question 5

When might we use combination antimicrobial therapy?

Answer 5

TB/HIV
Severe sepsis
Mixed organisms

Question 6

What kind of factors need to be considered when choosing IV vs Oral antibiotic therapy?

Answer 6

Really give oral wherever possible. Consider the bioavailability of it and make sure they aren’t vomiting and don’t have malabsorption.

Use IV in more severe infections but watch out for cannula issues like thrombosis and infection

Question 7

What are the potential side effects of antimicrobials?

Answer 7

Allergy (immediate or delayed hypersensitivity)
GI - nausea, vomiting, diarrhoea, c. diff
Candida - thrush in broad spectrum
Liver - especially tetracyclines and B drugs
Kidney - gentamicin and vancomycin
Neurological - ototoxic, optic neuropathy (ethambutol), convulsions, encephalopathy, peripheral neuropathy (isoniazid)
Haematological - marrow toxic, anaemia