Inhibitors of bacterial protein synthesis 2

Question 1

Nitrobenzene antibiotic

Answer 1

Chloramphenicol

Question 2

Chloramphenicol - MoA

Answer 2

It binds reversibly to the 50S subunit of the bacterial ribosome and inhibits peptide bond formation

Question 3

Chloramphenicol - Clinical use

Answer 3

Broad-spectrum antibiotic that is active against pathogens causing meningitis, including pneumococci, meningococci, and H. influenzae Salmonella Bacteroides Brain abcess Rickettsiae (typhus, rocky mountain spotted fever) Neiserria meningitidis

Question 4

Chloramphenicol - Special considerations

Answer 4

High concentrations in CNS Lipophilic, well absorbed from gut Partly metabolized by glucoronate conjugation (neonates obs)

Question 5

Chloramphenicol - Adverse effects

Answer 5

Gray baby syndrome characterized by cyanosis, weakness, respiratory depression, and shock Reversible, dose-dependent anemia caused by blockade of iron incorporation into heme Aplastic anemia (rare) Nausea, vomiting, diarrhea, Oral/vaginal candidiasis

Question 6

Chloramphenicol and Clindamycin: Administration Elimination

Answer 6

Clindamycin: Oral, IV or Topical Hepatic metabolism; renal excretion Chloramphenicol: IV Hepatic metabolism; renal, biliary and fecal excretion

Question 7

Streptogramin antibiotic

Answer 7

Quinupristin-Dalfopristin

Question 8

Quinupristin-Dalfopristin - MoA

Answer 8

Binds to 50S ribosomal subunit. Inhibits tRNA synthesis + inhibits peptidyl transferase Inhibits protein synthesis when administered in 30:70.

Question 9

Quinupristin-Dalfopristin - Clinical use

Answer 9

Bactericidal against susceptible strains of staphylococci and streptococci but bacteriostatic against Enterococcus faecium Active against many gram-postitive bacteria, including multidrug-resistant straphylococci, penicillin-resistant pneumococci, and vancomycin-resistant E. faecium, but not E. fecalis Bacteremia Pneumonia Skin and soft tissue infections Peritonitis Endocarditis Aortic graft infections

Question 10

Quinupristin-Dalfopristin - Adverse effects

Answer 10

Infusion site reactions Arthralgia Myalgia Diarrhea Nausea

Question 11

Linezolid - MoA

Answer 11

Binds to 23S ribosomal RNA of the 50S subunit, preventing formation of 70S initiation complex

Question 12

Linezolid - Clinical use

Answer 12

Active against aerobic gram-positive bacteria Bactericidal against most strains of streptococci Bacteriostatic against enterococci and staphylococci Vancomycin-resistant E. faecium; pneumonia caused by methicillin-sensitive S. aureus and MRSA; and skin and soft tissue infections caused by methicillin-sensitive or methicillin-resistant staphylococci and Streptococcus pyogenes, or Steptococcus agalactiae Given IV for serious infections such as necrotizing fasciits and pneumonia Orally for mild to moderate skin and soft tissue infections

Question 13

Linezolid - Adverse effects

Answer 13

serotonin toxicity with fluoxetine Thrombocytopenia Anemia Neutropenia in patients with renal insufficiency or during prolonged therapy

Question 14

Mupirocin - MoA

Answer 14

Competetive inhibition of isoleucine, preventing addition of isoleucine to protein

Question 15

Mupirocin - Clinical use

Answer 15

Active against gram-positive cocci, including most strains of methicillin-resistant staphylococci Impetigo by streptococci and staphylococci Nasal colonization of methicillin-resistant staphylococci