Let's talk about Tetracyclines and how awesome they are! 🧵

#IDXPosts #IDTwitter #IDX #podcast #ID #infection #infectiousdisease #antibiotics First discovered in 1951, They're typically divided into 3 generations:

1st Gen:
Tetracycline, Oxytetracycline

2nd Gen:
Demeclocycline, Doxycycline, Minocycline

3rd Gen:
- Glycylcyclines (Tigecycline)
- Aminomethylcycline (Eravacycline, Omadacycline, Sarecycline)

A Precis on PBPs. 🧵

Penicillin Binding Proteins are the transpeptidase enzymes that cross-link bacterial cell wall peptidoglycan; but how do they work and what do you need to know as an infectionologist?

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Link to episode:
podcasts.apple.com/gb/podcast/id-…
Let's start with Peptidoglycan; these make up 90% of the G+ / 10% of the G- cell wall; they're made of alternating monomers of NAG (N-acetylglucosamine) & NAM (N-acetylmuramic acid). The NAM monomer has a side-chain, and this is what is X-linked to strengthen the cell wall!
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Lets talk about Antibiotic PK. This week's 🧵: Elimination!

How does an antibiotic leave the body? We discuss this in detail in this week's episode, available here:


There are 2 components: Metabolism and Excretion
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Metabolism: This is optional if your drug is polar already; otherwise, the body changes the drug to make it more polarised so it can be excreted (normally in urine). 2 ways to do this:
- Phase I: CYP450 isoenzyme oxidation
- Phase II: Conjugation with polar groups
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Lets talk about Antibiotic PK. This week's 🧵: Distribution!

This is where the drug goes after it's absorbed/injected. Where it goes = what target sites it can be used at.

Main drug factors: Hydrophilic vs Lipophilic, plasma protein binding, and peripheral tissue binding

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Let's talk about Bioavailability. 🧵

As a general rule,
-Highly bioavailable: >70%
-Medium 50 - 70%
-Low <50%

1/x Highly bioavailable ABx:
-BL: Amox, Cefalexin, Pivmecillinam
-Quinolones
-Trimethoprim/Sulfamethoxazole
-Protein synthesis inhibitors: Tetracyclines, Linezolid, Clindamycin, Chloramphenicol
-Other: MNZ, Nitrofurantoin.

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