Tetracyclines Flashcards
What is the MOA for tetracyclines?
- Bind the 30s subunit to block t-RNA from binding to the A site
- Prevents elongation of the peptide
Are tetracyclines bacteriostatic or bacteriocidal?
Static
Once the drug is gone, synthesis resumes
Name the tetracyclines
Oxytetracycline Tetracycline Methacycline Doxycycline Minocycline Demeclocycline
Which tetracycline is used for streptomyces rimosus?
Oxytetracycline
Which tetracycline is used for strepromyces aureofaciens?
Demeclocycline
Which tetracycline is semisynthetic?
MInocycline
What type of bacteria are tetracyclines useful against?
Gram +
Gram -
Anaerobes
Aerobes
What diseases are tetracyclines useful against?
Rickettsia Chlamydia Lyme's disease Legionella Spirochetes Mycoplasma Anthras (prevention) Community acquired pneumonia
How are tetracyclines administered?
Oral and parenteral
How do tetracyclines enter the cell?
Enter bacteria by diffusion AND active transport
True or False: Tetracyclines enter the CNS
True
True or False: Tetracyclines cross the placenta
True
True or False: Tetracyclines can be found in breast milk
True
Absorption of tetracyclines are impaired by…
Milk and antacids
They chelate divalent cations
How are tetracyclines excreted?
Glomerular filtration
Some biliary excretion
Doxycycline is mainly excreted in the FECES; some urine
What results from tetracycline toxicity
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
Which tetracycline causes vestribular disturbances?
Minocycline
True or False: Tetracyclines are safe in pregnancy
False
Can cross placenta and pregnant women are at risk for renal and hepatic toxicity
What causes resistance with tetracyclines?
Plasmid mediated addition of efflux transporters
Ribosomal produced “protection protein” displaces tetracyclines
Increased enzymatic inactivation
True or false: There is cross-resistance among the different tetracyclines
Depends on the mechanism of resistance!
What is Tigecycline?
It’s a glycyclcycline related to minocycline
Also considered a 2nd generation tetracycline
When do we use Tigecycline?
When there is an infection that has developed resistance to tetracyclines
How is Tigecycline administered?
IV infusions
How is tigecycline excreted?
Excreted in bile and urine unchanged
What infections are tigecycline used for?
Complicated skin/skin structure/intra-abdominal iknfections
Effective in other tetracycline resistant organisms
