Tetracyclines

Question 1

What is the MOA for tetracyclines?

Answer 1

• Bind the 30s subunit to block t-RNA from binding to the A site
• Prevents elongation of the peptide

Question 2

Are tetracyclines bacteriostatic or bacteriocidal?

Answer 2

Static

Once the drug is gone, synthesis resumes

Question 3

Name the tetracyclines

Answer 3

Oxytetracycline
Tetracycline
Methacycline
Doxycycline
Minocycline
Demeclocycline

Question 4

Which tetracycline is used for streptomyces rimosus?

Answer 4

Oxytetracycline

Question 5

Which tetracycline is used for strepromyces aureofaciens?

Answer 5

Demeclocycline

Question 6

Which tetracycline is semisynthetic?

Answer 6

MInocycline

Question 7

What type of bacteria are tetracyclines useful against?

Answer 7

Gram +
Gram -
Anaerobes
Aerobes

Question 8

What diseases are tetracyclines useful against?

Answer 8

Rickettsia
Chlamydia
Lyme's disease
Legionella
Spirochetes
Mycoplasma
Anthras (prevention)
Community acquired pneumonia

Question 9

How are tetracyclines administered?

Answer 9

Oral and parenteral

Question 10

How do tetracyclines enter the cell?

Answer 10

Enter bacteria by diffusion AND active transport

Question 11

True or False: Tetracyclines enter the CNS

Answer 11

True

Question 12

True or False: Tetracyclines cross the placenta

Answer 12

True

Question 13

True or False: Tetracyclines can be found in breast milk

Answer 13

True

Question 14

Absorption of tetracyclines are impaired by…

Answer 14

Milk and antacids

They chelate divalent cations

Question 15

How are tetracyclines excreted?

Answer 15

Glomerular filtration
Some biliary excretion

Doxycycline is mainly excreted in the FECES; some urine

Question 16

What results from tetracycline toxicity

Answer 16

GI disturbances (nausea, vomiting, epigastric burning)
Photosensitivity
Super-infections (C diff, candida thrush, pseudomonas, proteus)
Stains bone and teeth
Renal and hepatic toxicity
Vestibular disturbances
Hypersensitivity reactions

Question 17

Which tetracycline causes vestribular disturbances?

Answer 17

Minocycline

Question 18

True or False: Tetracyclines are safe in pregnancy

Answer 18

False

Can cross placenta and pregnant women are at risk for renal and hepatic toxicity

Question 19

What causes resistance with tetracyclines?

Answer 19

Plasmid mediated addition of efflux transporters

Ribosomal produced “protection protein” displaces tetracyclines

Increased enzymatic inactivation

Question 20

True or false: There is cross-resistance among the different tetracyclines

Answer 20

Depends on the mechanism of resistance!

Question 21

What is Tigecycline?

Answer 21

It’s a glycyclcycline related to minocycline

Also considered a 2nd generation tetracycline

Question 22

When do we use Tigecycline?

Answer 22

When there is an infection that has developed resistance to tetracyclines

Question 23

How is Tigecycline administered?

Answer 23

IV infusions

Question 24

How is tigecycline excreted?

Answer 24

Excreted in bile and urine unchanged

Question 25

What infections are tigecycline used for?

Answer 25

Complicated skin/skin structure/intra-abdominal iknfections

Effective in other tetracycline resistant organisms