2. NEWER MACROLIDES • Improved acid stability, tissue penetration. • Broader spectrum of activity.

3. ANTIMICROBIAL ACTIVITY • Most active against gram-positive cocci and bacilli. • Mycoplasma, Legionella and Chlamydia.

4. ANTIMICROBIAL ACTIVITY • Mycobacterium avium intracellulare (MAC).

5. ABSORPTION • Macrolides are incompletely but adequately absorbed from the GI tract. • Erythromycin base is inactivated by stomach acid. • Made in various acid resistant forms. • Food interferes with absorption.

6. ABSORPTION • Erythromycin estolate is absorbed best. • Usually no one preparation offers a significant therapeutic advantage. • The newer macrolides are absorbed more rapidly than erythromycin.

7. DISTRIBUTION • Well distributed except into the CNS. • In meningitis enough gets into the CNS to be therapeutically effective.

8. METABOLISM AND EXCRETION • Most of the erythromycin is metabolized. • Erythromycin is concentrated in the liver and excreted in active form in the bile.

9. THERAPEUTIC USES • A useful alternative to the penicillins. • Infections caused by pneumococci and group A streptococci with penicillin allergy. • Minor infections caused by penicillin resistant or sensitive Staph. Aureus. • Prophylaxis of rheumatic fever and subacute bacterial endocarditis.

10. MYCOPLASMA PNEUMONIA

11. MYCOPLASMA PNEUMONIA • A macrolide or tetracycline is the drug of choice for Mycoplasma infections. • Reduces the duration of fever and accelerates the clearing of the chest radiographs.

14. CONTRAINDICATIONS • Pregnancy (the estolate)-because of the possibility of hepatotoxicity. • Hepatic dysfunction.

15. DRUG-DRUG INTERACTIONS • Erythromycin (and clarithromycin) inhibit Cytochrome P-450 enzymes.

16. Demethylase Erythromycin CytP3A4 Antifungals,verapamil, diltiazem

17. DRUG-DRUG INTERACTIONS • Drugs that prolong QT interval.

18. COMPARISON OF MACROLIDES

19. KETOLIDES (Telithromycin) • Unique structure compared to macrolides, allowing it to be used in resistant respiratory infections. • Differs from erythromycin by substitution of a 3-keto group for the neutral sugar L-cladinose.

20. ANTIBACTERIAL SPECTRUM • Similar antibacterial spectrum to erythromycin but many macrolide-resistant strains are susceptible to ketolides.

21. THERAPEUTIC USES • Respiratory tract infections, including community acquired bacterial pneumonia, acute exacerbations of chronic bronchitis, sinusitis and streptococcal-pharyngitis.

22. CLINDAMYCIN • A lincosamide closely related to lincomycin.

23. ANTIBACTERIAL ACTIVITY • Similar to erythromycin. • Anaerobic bacteria, especially Bacteroides.

24. PHARMACOKINETICS • Absorbed rapidly and nearly completely following oral administration. • Widely distributed throughout the body except for the CNS.

25. Clindamycin Enterohepatic circulation

26. THERAPEUTIC USES

27. Bacteroides fragilis

29. OXAZOLIDINONES • New class of synthetic antibacterial agents. • Inhibit protein synthesis by a unique mechanism.

30. LINEZOLID (Zyvox) • The first and one of 2 oxazolidinones presently available.

31. ANTIBACTERIAL ACTIVITY • Wide spectrum of activity vs. gram positive organisms including methicillin-resistant staphylococci, penicillin resistant pneumococci and vancomycin resistant Enterococcus faecalis and E.faecium. • Several anaerobic organisms.

32. PHARMACOKINETICS • Good oral bioavailability (also given IV). • Metabolized. • No dosage adjustment necessary with impaired renal or hepatic function.

33. THERAPEUTIC USES • MRSA. • Vancomycin resistant E.faecium.

34. Vancomycin resistant enterococcal infections (VRE) • Disproportionately affects patients in the ICU, immunosuppressed hosts, particularly liver and other solid organ recipients and patients with post chemotherapy neutropenia, and patients with intravascular and bladder catheter devices.

35. VRE • Emerged during 1990’s • Enterococci already possess intrinsic and acquired resistance to most other antimicrobials (β-lactams, aminoglys, lincosamides and cotrimoxazole).

36. TREATMENT OF VRE • Approved-linezolid and quinopristin/dalfopristin • Available agents which don’t have a specific VRE approval (chloramphenicol, doxycycline, high-dose amoxicillin/sulbactam)

37. PRECAUTIONS Linezolid Tyramine MAO SSRI toxicity Serotonin Linezolid

38. STREPTOGRAMINS

39. Quinupristin/Dalfopristin (Synercid) • First streptogramin to be approved in the U.S. • Present in a ratio of 30:70.

40. ANTIBACTERIAL ACTIVITY • Bactericidal vs. susceptible strains of staphylococci and streptococci. • Bacteriostatic vs. Enterococci faecium.

41. ANTIBACTERIAL ACTIVITY • Active vs. a wide range of gram positive bacteria including staphylococci resistant to methicillin, quinolones and vancomycin; pneumococci resistant to penicillin and E.faecium strains resistant to vancomycin.

42. PHARMACOKINETICS • Administered IV (over 1 hr).

43. THERAPEUTIC USES • Vancomycin strains of E.faecium and complicated skin infections caused by Staph. • Serious infections caused by multiple drug-resistant gram-positive organisms.

44. DRUG INTERACTIONS • Inhibits cytochrome CYP3A4.

45. Review-Drugs vs. Gram+ Organisms • Penicillins (G,V and antiStaph) • 1st. Generation Cephs. • Macrolides • Vancomycin • Linezolid • Streptogramins

47. 1.5 Estolate Stearate Erythromycin Base 1.0 Serum Levels mcg/ml 0.5 0.5 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 Hours Serum Concentration After Oral Administration of Different Erythromycin Preparations

48. VANCOMYCIN • Tricyclic glycopeptide antibiotic. • Antibacterial activity-primarily active against gram positive bacteria.

49. MECHANISM OF ACTION • Bactericidal. • Inhibits cell wall synthesis (2nd stage of cell wall synthesis). • Binds with high affinity to the D-alanyl-D-alanine terminus of cell wall precursor units, at the crucial site of attachment and thereby inhibits vital peptidoglycan polymerase and transpeptidation reactions.

50. Glycopeptide Polymrer Mur NAc X Vancomycin X Glycopeptide Polymer Mur NAc X D-Alanine Transpeptidase