C.16. Clindamycin. Streptogramins. Oxazolidinones. Flashcards
what class of Ab does Clindamycin belong to?
Lincosamides
*lincomycin
what is the mechanism of action of Clindamycin?
similar to macrolides
binds to the 50s subunit, blocks protein synthesis
bacteriostatic effect
what is the spectrum and clincal use of Clindamycin?
narrow (9):
- gram + cocci
- staph and strep. skin and soft tissue infection
- community-acquired MRSA
- Osteomyelitis (by staph)
- endocarditis prophylaxis
- pneumonitis jirovecii, toxoplasmosis
- polymicrobial infections of the GI and female genital tract (with Aminoglycosides)
- B. fragilis infection (lung abscess) -anaerobe infections
- acne (topical)
what is the metabolism of Clindamycin?
hepatic
excreted in the bile and urine both intact and metabolized
absorption of Clindamycin
80-90% , good
↑ concentration on abscess and bones
what is the mechanisms of resistance of Clindamycin?
- methylation of ribosomal binding site
- enzymatic inactivation
- poor penetration via the outer membrane of gram - bacteria (intrinsic resistant)
side effects of Clindamycin
GI symptoms skin rash Neutropenia Hepatotoxicity C. difficile superinfection (pseudomembranous colitis)
mechanism of action of streptogramin (Quinuproistin, Dalfopristin)
binds to the 50s ribosomal subunit, blocking the exit channel on the ribosome, through which nascent polypeptides are extruded
Bactericidal effect
what is the ratio of the combination of Quinupristin and Dalfoprisitn?
30:70
Quinupristin: Dalfopristin
what is the clinical use of Quinupristin with Dalfopristin?
effective against MRSA, PRSP, VRSA, and resistant strains of E. faecium
*considered as ‘reserve antibiotics’ for complicated resistant infections
what is the clinical use of Quinupristin with Dalfopristin?
effective against MRSA, PRSP, VRSA, and resistant strains of E. faecium
*considered as ‘reserve antibiotics’ for complicated resistant infections
how are streptogramins given?
IV
dynamic properties of streptogramins
inhibition of CYP450 enzymes
↑ level of Benzo, warfarin
mechanism of resistance to streptogramins
efflux pump
*E. faecalis is resistant
side effects of streptogramins
arthralgia-myalgia syndrome
GI problems
↑ bilirubin
allergy
mechanism of action of Oxazolidinon (Linezolid)
binds to the 50s ribosomal subunit. inhibits the formation of initiation complex in bacterial translation system
Bacteriostatic effect
Clinical use of Linezolid
effective against multidrug-resistant gram + cocci
MRSA, PRSP, VRE
how is Linezolid given?
oral or Parenteral
important properties of Linezolid
Inhibitor of MAO-A and MAO-B –> possible risk of cheese reaction!
T1/2 4-6 hours
hepatic metabolism
mechanism of resistance of Linezolid
altered affinity to the binding site
*resistant strains are rare
side effects of Linezolid
myelosuppression: thrombocytopenia, Neutropenia (weekly blood control is needed)
optic neuropathy
Serotonin Syndrome (in combination with SSRI’S)
how can clindamycin be given?
oral, parenteral, and topical (acne)
