16. Clindamycin. Streptogramins. Oxazolidinones

Question 1

Clindamycin

Answer 1

Lincosamide
Protein synthesis inhibitor S50 subunit (works like macrolide)
Bacteriostatic/cidal concentration dependant

Spectrum: G+ive (including streptococcus, MRSA and anaerobic bacteria)
Clinical use: 1st line for osteomyelitis

Administration: IV, IM or Oral
Distribution: good distribution including bone and abscess but not to CNS
Metabolism: Oxidative metabolism
Elimination: Bille

Adverse effect: colitis, pseudomembranous colitis (C.difficile)

Question 2

Streptogramins

Answer 2

Streptogramins A = Dalfopristin

Streptogramins B = Quinupristin

Question 3

Oxazolidinones

Answer 3

Linezolid

Question 4

Lincosamide

Answer 4

Clindamycin

Question 5

Streptogramins A

Answer 5

Dalfopristin

bacteriostatic
disrupts elongation

Resistance: can change form bactericidal to static by enzyme modification
!!!Acetyltransferase inactivates A

Question 6

Streptogramins B

Answer 6

Quinupristin

bacteriostatic
Releases incomplete peptide chains

Resistance: can change form bactericidal to static by enzyme modification
!!!Methylase interferase with B

Question 7

Streptogramins A + B together

Answer 7

bactericidal.
Given in mixture of 70:30 (A:B)
Protein synthesis inhibitor - bind to different sites on the S50 ribosome

Long PAE
Spectrum: G+ive cocci (also MDR strains) - intracellular bacteria, E.faecium and VRE

Administration: IV (central venous cannula)
Distribution: good distribution, penetrates macrophages, low penetration to CNS
Metabolism: Hepatic metabolism | Inhibits CYP3A4
Elimination: Bille

Adverse effect: Infusion related phlebitis, hyperbilirubinemia, Arthralgia-myalgia

Question 8

Linezolid

Answer 8

Oxazolidinones

Protein synthesis inhibitor S50 subunit - inhibiting the formation of the 70S complex
Weak MAO inhibitor
Bacteriostatic but bactericidal against streptococci.

Developed to combat resistant G+ive organisms (MRSA, VRE and penicillin resistant streptococci)
Spectrum: G+ive cocci and rods

Administration: IV and Oral
Distribution: wide distribution, courses BBB (treat meningitis)
Metabolism: Oxidation

Adverse effect: GI Disturbances | thrombocytopenia (mainly if taken for more than 10 days)
!!! serotonin syndrome
optic and peripheral neuropathy