Tetracyclines

Question 1

Doxycycline MOA

Answer 1

They work by binding to the
ribosomal 30S subunit to
inhibit protein synthesis in
bacteria, they are primarily
bacteriostatic which means
that they prevent bacteria
from multiplying but don’t
necessarily kill them.

Question 2

Doxycycline Indications

Answer 2

Pneumonia (CAP)
Cellulitis
Diabetic foot infections
Chalmydia

Question 3

Doxy spectrum of activity

Answer 3

gram positive: Staphylococcus aureus, streptococcus pneumoniae/pyrogens

gram negative: Haemophilus influenzae, Moraxella, Legionella

ATYPICAL COVERAGE

Question 4

What are atypical organisms?

Answer 4

Atypical organisms are
bacteria that do not colour
with gram staining, so are
neither gram positive or
gram negative. Atypical
organisms that can cause
Community Acquired
Pneumonia include
Mycoplasma pneumoniae,
Legionella pneumophilia,
Chlamydia pneumoniae

Question 5

Doxycycline SE

Answer 5

Hypersensitivity reactions
GI upset: nausea, vomiting, diarrhoea, abdominal pain
Photosensitivity 🌞: increased risk of sunburn – advise sunscreen & protective clothing
Headache

Question 6

Rare SE of doxy

Answer 6

Esophagitis or esophageal ulceration
↳ Take with plenty of water and remain upright for at least 30 minutes
Hepatotoxicity (rare, but more likely with high doses or in liver disease)
Tooth discolouration (in children <12 or during pregnancy – avoid use)
Benign intracranial hypertension (pseudotumor cerebri) – esp. in young women or with long-term use

Question 7

Preg and breastfeeding with doxy

Answer 7

No