50S Inhibitors Flashcards
What are the 3 clinically relevant Lincosamides?
- Lincomycin
- Clindamycin
- Pirlimycin
What is the MOA of Lincosamides?
Bind to the 50S subunit of the ribosome and prevent exiting of the growing peptide chain.
Is the MOA of Lincosamides reversible or non-reversible? Bacteriostatic or bactericidal?
Reversible –> Bacteriostatic
What is the spectrum of the Lincosamides?
- Gram (+) aerobes: Staph & Strep
- Gram (+) anaerobes
- Gram (-) aerobes: Campylobacter & Brachyspira
- Gram (-) anaerobes: Bacteroides & Fusobacterium
- Eukaryotes: Toxoplasma (Clindamycin)
Which is better with anaerobes, Clindamycin or Lincomycin?
Clindamycin
Which is better with Staphylococcus, Clindamycin or Lincomycin?
Clindamycin
What is Pirlimycin used against?
Bovine mastitis
How is Pirlimycin administered?
Intramammary
When is Pirlimycin NOT to be used vs. mastitis?
NOT to be used vs. gram (-) bacilli
How do bacteria mount resistance to Lincosamides?
Via methylation of the ribosome, so the ribosome cannot produce proteins.
The methylation process through which Lincosamides mount resistance to bacteria confers resistance to what 3 drug classes?
- Phenicols
- Macrolides
- Streptogramins
Clindamycin causes ____ ____ due to inhibition of good intestinal microbes.
Pseudomembranous colitis
Which drug can be given in conjunction with Clindamycin to prevent pseudomembranous colitis?
Metronidazole
What is virginiamycin a mixture of?
- Virginamycin M (Group A)
2. Virginamycin S (Group B)
What is synercid a mixture of?
- Dalfopristin (Group A)
2. Quinupristin (Group B)
What is the MOA for the Streptogramins?
50S inhibitors
Are Streptogramins bacteriostatic or bactericidal?
Bactericidal (2 drugs combined)
Group B Streptogramins share cross-resistance with which 2 antimicrobial classes?
- Macrolides
2. Lincosamides
Do Group A Streptogramins share cross-resistance with Group B?
No
Are Streptogramins water or fat soluble?
Water soluble
Are Streptogramins orally bioavailable?
No - poor oral bioavailability
How do Streptogramins have to be administered?
Injected
What is the spectrum of the Streptogramins?
Gram (+) aerobes and anaerobes
What are the 2 clinically relevant phenols?
- Chloramphenicol
2. Florfenicol
What is the MOA of the phenols?
50S inhibitors
What is the spectrum of the Phenols (chloramphenicol and florfenicl)?
Very broad, including Rickettsia
Which 2 organisms are the Phenols resistant to?
- Nocardia
2. Mycoplasma
How do bacteria mount resistance to the Phenols?
The bacteria modify the drug via acetylation
Which of the following has 2 targets for resistance: Chloramphenicol or Florfenicol?
Chloramphenicol
Which of the following only has 1 target for resistance: Chloramphenicol or Florfenicol?
Florfenicol
Resistance to which is less likely, Chloramphenicol or Florfenicol?
Florfenicol
Which drug is the “broadest”, Chloramphenicol or Florfenicol?
Florfenicol
Why are the Phenols good against meningitis?
60% of the plasma concentration reaches the CSF
Which is more likely to cause aplastic anemia in a human, Chloramphenicol or Florfenicol?
Chloramphenicol
How do the Phenols cause aplastic anemia?
Inhibit mitochondrial protein synthesis in erythropoeitic cells
What is Florfenicol used against in the cow?
Bovine respiratory disease
What is Florfenicol + NSAID?
Flunixin
What is the MOA of the pleuromutilins?
50S inhibitors
What are the 2 clinically relevant Pleuromutilins?
- Tiamutilin
2. Valnemulin
What is the spectrum of the Pleuromutilins?
Gram (+)
What is the MOA of the oxazolidinones?
50S inhibitors
What is the spectrum of the Oxazolidinones?
Gram (+) aerobes and anaerobes
What is 1 clinically relevant oxazolidinone?
Linezolid
