CELL WALL SYNTHESIS INHIBITORS

1. CELL WALL SYNTHESIS INHIBITORS

2. CELL WALL SYN. INHIBITORS • BETA LACTAM ANTI BIOTICS • PENCILLINS • CEPHALOSPORINS • CARBAPENEMS • MONOBACTAMS

4. Beta- Lactam Antibiotics

5. Beta- Lactam Antibiotics Strep throat IM, syphilis Skin infections fm staph/strep Bacterial URI SE: Hypersensitivity is primary problem. Pruritic rash. Anaphylaxis also occurs.

6. Penicillins • Bactericidal • Peptidoglycan cell wall organisms • Not effective against Mycobacterium, Protozoa , Fungi & viruses.

7. Interfere with last step of bacterial synthesis—trans peptidation • Results in exposure of less stable membrane. • Cell lysis occurs through osmotic pressure or activation of autolysins • Thus they are bactericidal.

8. Penicillin binding proteins • Penicillins inactivate many proteins on the bacterial cell membrane. These pbps are bacterial enzymes involved in the synthesis of the cell wall • Inhibition of trans peptidase • Production of autolysins

9. Antistaphylococcal penicillins • All are stable to penicillinase • Cloxacillin • Dicloxacillin • Methicillin • Nafcillin • Oxacillin

10. Antipseudomonal penicillins • Particularly active against P. aeruginosa • Azlocillin • Carbenicillin • Mezlocillin • Piperacillin • Ticarcillin

11. Clinical use of penicillin G. • Pneumococcal pneumonia • Syphilis single treatment with penicillin is curative. No resistance has been reported • gonorrhea

12. ROUTES : • PENCILLIN V , AMOXICILLIN + CLAVULANIC ACID ORAL • DEPOT : PROCAINE PENCILLIN G, BENZATHINE PENCILLIN G • DO NOT CROSS BBB UNLESS INFLAMED • EXCRETION : TUBULAR SECRETION

13. SE • HYPERSENSITIVITY—the metabolite penicilloic acid serves as a hapten to cause immune reaction. • Maculopapular rash—ampicillin • Angioedema • anaphylaxis

14. DIARRHEA– disruption of the normal balance of intestinal micro organisms. Pseudo membranous colitis may also occur. • NEPHRITIS ( Mostly Methicillin) • NEUROTOXICITY– care in epileptics • CATION TOXICITY • Platelet dysfunction ( Carbenicillin & Ticarcillin

15. Resistance • Beta lactamase enzyme hydrolyzes the cyclic bond of the beta lactam ring—results in loss of bactericidal activity. • Decreased penetration of the antibiotic through the outer cell membrane prevents the drug from reaching the target pbp.

16. Beta- Lactam Antibiotics Commonly used, some resistance, lower cost Also commonly used, less resistance, higher cost $ $ $ $ Expensive $ $ $ $ Resistant/ Severe Infections SE: all have some degree of cross reactivity w/pen allergic pt. 5-15%

17. 1st Generation • Cefazolin • Cephalexin • Cefadroxil • Cephradine • Broad spectrum, mostly oral, commonly used, some resistance, lower cost, • Active against - Proteus, E. coli, K. pneumonia (PEcK)

18. 2nd Generation • Cefamandole • Cefoxitin • Cefaclor • Cefotetan • Cefuroxime • Less resistance, higher cost, oral/IM/IV. • H. influenza, Enterobacter, Neisseria + 1st (HEN PEcK)

19. 3rd Generation • Cefoperazone • Ceftriaxone • Cefixime • Cefotaxime • Ceftazidime • Expensive, for resistant/severe infections, Septic shock, MENINGITIS.

20. 4th Generation • Cefepime • Newer agent • Very broad spectrum activity

21. Common usage • Cephalexin - Pharyngitis • Cefazolin - Bone penetration • Cefoxitin – Anaerobes ( Bacteroides fragilis) abdominal sepsis and PID • Ceftazidime – most active against P. aeruginosa • Ceftriaxone – good bone penetration, Neisseria

22. DISTRIBUTION • BBB: ONLY 3rd GENERATION • MENINGITIS : CEFTRIAXONE, CEFOTAXIME • EXCRETION : RENAL SECRETION (Ceftriaxone, Cefoperazone excreted mostly through bile)

23. Cephalosporins are mostly not effective against • MRSA, • Listeria monocytogenes • Clostridium difficile • Enterococci. • Newer agent classified as 4th generation (Cefepime) has shown some effectiveness

24. SE • HYPERSENSITIVITY • CEFOPERAZONE, CEFAMANDOLE – CI IN ALCOHOL • BLEEDING

25. Beta- Lactam Antibiotics Nephrotoxic Nephrotoxic & Ototoxic

26. CARBAPENEMS Eg; Imipenem/Cilastatin Cilastatin is not a antibiotic , it’s a peptidase inhibitor that protects imipenem from degradation. Broad spectrum, Mostly IV route and excreted by glomerular filtration. SE: Diarrhea, seizures if increased plasma levels.

27. Carbapenems • Empiric therapy – active against G positive and negative • Eosinophilia , neutropenia

28. MONOBACTAMS • Eg; Aztreonam Only in this class. Narrow spectrum – enterobacteria. IV & IM routes , excreted through urine. Relatively non toxic, but can cause skin rash, phlebitis.

29. Vancomycin • Inhibits synthesis of bacterial cell wall phospholipids and Peptidoglycan • Reserved for serious infections with gram +ve • Used mainly for Methicillin resistant Staphylococcus aureus (MRSA) and Methicillin resistant Staphylococcus epidermidis (MRSE) • And also for antibiotic associated Colitis due to Clostridium difficile or Staphylococci

30. Slow IV route preferred, • Excretion – glomerular filtration • SE: fever, chills , phlebitis at the site of the injection • Shock reported with fast rapid administration along with Flushing due to histamine release. ( RED MAN SYNDROME)

31. BETA LACTAMASE INHIBITORS • CLAVULANIC ACID • SULBACTAM • TAZOBACTAM • NO ANTI BACTERIAL ACTIVITY