Miscellaneous Antibiotics Flashcards
What is the MOA of tetracyclines?
They reversibly bind the 30S ribosome and prevent elongation of the polypeptide by blocking the addition of amino acids.
How does resistance to tetracyclines occur?
- Efflux pumps
- Enzyme inactivation
- Ribosomal protection
What are the pharmokinetics of tetracyclines?
Bacteriostatic
***Bactericidal when present at high concentrations against very susceptible organisms
What are drugs in the tetracycline class?
Tetracycline
Doxycycline
Tigecycline
What is the Gram + spectrum of action of tetracyclines?
- Staphylococcus aureus (primarilyMSSA)
- Streptococcuspneumoniae–PSSP (doxycycline – 83% susceptible)
- Bacillus spp, Listeria spp,Nocardia spp
What is the Gram - spectrum of action of tetracyclines?
- N.gonorrhea and meningitidis
- Haemophilus influenzae (90% susceptible)
- Haemophilus ducreyi(chancroid)
- Campylobacter jejuni
- Helicobacter pylori
- Vibrio cholerae, Vibrio vulnificus
- Burkholderiapseudo mallei
What are the holes in coverage of tigecycline?
Proteus
Pseudomonas
What is the spectrum of activity of tigecycline?
Has a wide spectrum of action with notable ones bing MRSA, VRE, S. maltophilia
Gram-Negative Aerobes • Acinetobacter baumannii • Aeromonas hydrophila • Citrobacter spp. • Escherichia coli • Klebsiella spp. • Serratia marcescens • Stenotrophomonas maltophilia • NOT Proteus spp or Pseudomonas aeruginosa
Gram-Positive Aerobes
• Staphylococcus aureus • MSSA, MRSA
• Enterococcus spp • VRE, VSE
Anaerobes
• Clostridium perfringens
• Bacteroides spp
What should tigecycline NOT be used for?
NOT for bacteremias or UTIs
How are the tetracyclines best absorbed?
On an empty stomach
What is the administration method of tetracycline and demeclocycline?
Oral
What is the administration method of doxycycline?
IV and oral
What is the administration method of tigecycline?
IV only
Why aren’t tetracyclines a good choice for UTIs?
They don’t concentrate well in the bladder
What is the CSF penetration of the tetracyclines?
Minimal
What is the penetration of the prostate by tetracyclines?
Good
Is dosage adjustment in renal failure necessary for tetracycline/demeclocycline?
Yes
Is dosage adjustment in renal failure necessary for tigecycline/doxycycline?
No. But adjustment for liver failure must be made for tigecycline
Are tetracyclines and tigecycline removed in hemodialysis?
No. Only minimally.
What are the main uses of the tetracyclines?
Respiratory Infection STDs RMSF Q fever Lyme Disease Polymicrobial infections (tigecycline)
What are the SE of tetracyclines?
Nausea
Vomiting
Hypersensitivity
Photosensitivity
Why should tetracyclines not be used in pregnant women?
Discoloration of permanent teeth and decreased bone growth in children
What is the mechanism of sulfonamides?
Inhibits dihydropteroate synthetase – which inhibits incorporation of p-aminobenzoic acid (PABA) into tetrahydropteroic acid