16. Clindamycin. Streptogramins. Oxazolidinones Flashcards
List the Streptogramins.
- Streptogramin A = Dalfopristin
- Streptogramin B = Quinupristin
What is the MOA of streptogramins?
Streptogramins bind 50s ribosomal subunit → fast bactericidal effect + long post-antibiotic effect (PAE).
What spectrum does Streptogramins cover?
Streptogramins are narrow-spectrum against Gram + (Staph incl. MRSA, VRSA; VRE; resistant pneumococci)
How are streptogramins administered and other kinetic parameters?
- Given in combo of 70% dalfopristin and 30% Quinupristin.
- Only parenteral admin via a central vein (phlebitis in peripheral veins).
- It has good IC distribution, but do not enter CNS.
- T1/2 is < 1 hour, but can admin every 8-12 hrs due to long post-abx effect (PAE).
- Elimination is 75% biliary, 25% renal (↓ dose in hepatic insufficiency).
- Interaction: inhibit CYP450 enzymes.
What are the side effects of Streptogramins?
- Phlebitis (if given in peripheral vein)
- Arthralgia and Myalgia
What are the indications of Streptogramins?
They are reserve antibiotics for severe, life threatening infections of multi-resistant Staph, Enterococcus (faecium, but NOT faecalis) + Pneumococci.
What are the side effects of Oxazolidinones?
- Thrombocytopenia: mild + reversible, after long-term use; can also cause anemia and neutropenia.
- GI effects including candidiasis
- Optic Neuropathy: ↓ acuity, scotomas and ↓ color vision; after long-term use
- Peripheral Neuropathy: “glove and stocking” pattern; also after long-term
- Reversible MAO-A inhibition: high affinity → cheese effect / serotonin syn. risk
- NO CYP inhibition!
What are the indications for Oxazolidinones therapy?
Reserve antibiotic against nosocomial pneumonia (MRSA), UTI / endocarditis (VRE) and complicated skin / soft tissue infections, as well as sepsis.
How are the kinetic parameters like for oxazolidinones?
- Good oral availability
- Wide distribution, including IC compartment, bones and CNS.
- Elimination is 50% biliary and 50% renal
What is the MOA of Oxazolidinones?
- Linezolid is the parent compound of oxazolidinone group, other compound is tedizolid.
- Oxazolidinones binds 50s ribosomal subunit to inhibit initiation complex formation.
- Unique binding site so can be effective against MLSB bacteria.
- They are bacteriostatic generally, but can be bactericidal against Staph or Strep.
- They also have a time-dependent effect.
What is the resistance mechanism againts Oxazolidinones?
Resistance is rare, but may exist via binding site alteration.
What spectrum does Oxazolidinones cover?
- They cover a narrow-spectrum for Gram + only (anaerobes or aerobes).
- Multiresistant Staph (MRSA, VRSA), and Enterococcus (VRE, both faecalis and faecium).
- Mycobacteria (is a 2nd line anti-TBC drug).
- One Gram - exception is Pasteurella multocida.
- Corynebacterium and Listeria; Pneumococci.
What is the MOA of Clindamycin?
- Clindamycin is a lincosamide → MLSB resistance-prone.
- It binds 50s subunit → blocked translocation → ↓ protein synthesis.
What are the indications for Clindamycin?
- Skin + soft tissue infections (Staph, group A Strep)
- Toxic Shock Syndrome: inhibits toxin production of Staph, Strep, and Clostridia.
- Odontogenic or Bone infections (such as osteomyelitis)
- Anaerobic infections such as aspiration pneumonia with lung abscesses (Bacteroides / Fusobacterium), penetrating wounds (C. perfringens) or abdominal infections. (General anaerobic infection rule: clindamycin better for supradiaphragmatic infections; metronidazole is better for subdiaphragmatic)
- (Community-acquired MRSA strains)
- (Topical for moderate or severe inflammatory acne)
- (With gentamicin for polymicrobial female genital tract infection / monotherapy for vaginosis via Gardnerella)
What are the side effects of Clindamycin?
- GI symptoms: Diarrhea, including C. difficile colitis.
- Neutropenia or skin rash (erythema, exanthem), more rarely.
