Commonly Prescribed Antibiotics

Question 1

State commonly prescribed antibiotics

Answer 1

1. Penicillins
2. Tetracyclines
3. Macrolides
4. Quinolones
5. Trimethoprim and sulphonamides
6. Nitrofurans
7. Nitroimidazoles

Question 2

1. Penicillin:
   Examples?

Answer 2

Amoxicillin, flucloxacillin, phenoxymethylpenicillin, and co-amoxiclav

Question 3

1. Penicillin:
   Common Indications?

Answer 3

Community and hospital acquired pneumonia - Amoxicillin
Cellulitis - Flucloxacillin
Otitis media, sinusitis, group A streptococcal infection, rheumatic fever - Phenoxymethylpenicillin

Question 4

1. Penicillins
   Side effects?

Answer 4

GI related
Hypersensitivity - skin rashes or reaction
Anaphylactic reaction
*Co-amoxiclav one of the Cs that cause Clostridium difficile infection

Question 5

1. Penicillins:
   Key prescribing points?

Answer 5

For community acquired pneumonia - consider using CURB-65 or CRB-65 score for severity assessment (» score warrant hospital admission rather than community oral antibiotics)

Infectious mononucleosis -EBV (glandualr fever) - may present similar to tonsillitis hence get prescribed phenoxymethylpenicillin –> widespread maculopapular rash

Question 6

2. Tetracyclines:
   Examples?

Answer 6

Doxycycline, lymecycline and oxytetracycline

Question 7

2. Tetracyclines:
   Common Indications?

Answer 7

Acne vulgaris
Chlamydia
Lyme disease
Rosacea
Atypical pneumonia (mycoplasma pneumonia)

Question 8

2. Tetracyclines:
   Side effects?

Answer 8

GI disturbances
Photosensitivity
Children < 12 typically contraindicated – tooth discolouration, enamel hypoplasia, deposit in growing bones

Question 9

2. Tetracyclines:
   Key prescribing points?

Answer 9

Contraindicated in:
Pregnant women - teratogenic
Breastfeeding - secreted into breast milk
Children <12

Chlamydia - loading dose of 200mg required followed by maintenance dose 100mg

Rare but important risk - Idiopathic intracranial hypertension (IIH)
symptoms: headache, blurred vision, papilloedema
Stop Tetracyclines if IIH diagnosed

Question 10

3. Macrolides:
   Examples?

Answer 10

Azithromycin, clarithromycin, erythromycin

Question 11

3. Macrolides:
   Common indications?

Answer 11

Similar indications as penicillin antibiotics
2nd line to penicillin e.g. pen allergy
Clarithromycin - pertusis (whopping cough)
Clarithromycin - H.pylori (along with other medications)

Question 12

3. Macrolides:
   Side effects?

Answer 12

GI disturbance
QT-interval prolongation

Question 13

3. Macrolides:
   Key prescribing points?

Answer 13

They increase levels of other medication by inhibiting the enzyme required for their metabolism

Warfarin + clarithromycin/ erythromycin –> increased INR and bleeding risk

Statin –> increased risk of metabolism (statin should be stopped during treatment)

Question 14

4. Quinolones:
   Examples?

Answer 14

Ciprofloxacin and levofloxacin

Question 15

4. Quinolones:
   Common indications?

Answer 15

Ciprofloxacin (eye drops/ointments) - eye conditions such as bacterial conjunctivitis

Ciprofloxacin - pseudomonas aeruginosa in CF patients (LRTI)

UTI and GI infections

Prostatitis

Ciprofloxacin - Prophylactic treatment for patients affected with meningococcal meningitis

Question 16

4. Quinolones:
   Side effects:

Answer 16

GI disturbances

Neurological - lower seizure threshold

MSK - damage muscle tendons –> increased risk of tendon rupture

Cardiovascular - Prolong the QT interval and increased arrhythmias