1. PENICILLINS
   1. PENICILLIN G
      1. Only naturally occurring penicillin ( all others are semi synthetic penicillins)
      2. MoA
         1. Bacteria develop resistance by producing -lactamases, which destroy the B-lactam ring, e.g. S. aureus, E. coli, gonococci, H. influenzae, etc
         2. (ii) due to altered PBPs, which have less affinity for B-lactams, e.g. S. pneumoniae
         3. (iii) due to decreased ability of the drug to penetrate to its site of action.
      3. INDICATIONS
         1. used in Vincent’s angina, necrotizing gingivitis, periodontal infections,
         2. Pneumococcal infections:
         3. Streptococcal infections: Penicillin G is useful for the treatment of streptococcal pharyngitis, otitis
         4. rheumatic fever.
         5. Meningococcal meningitis
         6. Gonococcal infections:
         7. Syphillis
         8. Diptheria
         9. clostridial infections
      4. Adverse effects
         1. relatively safe. They may cause hypersensitivity reactions, such as skin rashes, urticaria,
         2. fever, dermatitis, bronchospasm, angioedema, joint pain, serum sickness or anaphylactic reaction.
         3. anaphylactic shock:severe hypotension, bronchospasm and laryngeal oedema
         4. Jarisch–Herxheimer reaction:
            1. It is an acute exacerbation of signs and symptoms of syphilis during penicillin therapy due to release of endotoxins from the dead organisms.
      5. LIMITATIONS
         1. Not effective orally
         2. Short duration of action
         3. Narrow spectrum of activity
         4. Development of penicillinase ( B lactamase) or altered penicillin binding proteins have made gram positive bacteria resistant to penicillin G
         5. Causes hypersensitivity reactions
   2. ANTI Pseudomonal PENICILLINS
      1. CLASSIFICATION
         1. carbenicillin, carbenicillin indanyl, ticarcillin, mezlocillin and piperacillin.
      2. INDICATIONS
         1. Serious infections—bacteremias, pneumonias, UTIs, burns, etc. by P. aeruginosa and Proteus are more effectively treated with piperacillin.
         2. Carbenicillin indanyl is used orally for the treatment of UTI caused by P. aeruginosa and Proteus spp.
         3. Ticarcillin with b-lactamase inhibitor is used along with an aminoglycoside for the treatment of mixed nosocomial infection
      3. Adverse effects
         1. Congestive cardiac failure may be precipitated due to sodium
         2. content of carbenicillin sodium. It can also interfere with platelet function and cause bleeding.
   3. Aminopenicillin
      1. To overcome most of the above drawbacks, semisynthetic penicillins have been developed
      2. INDICATIONS
         1. dentistry: Amoxicillin is used alone or with metronidazole in acute necrotizing ulcerative gingivitis, dentoalveolar abscess, osteomyelitis of mandible, etc.
         2. the treatment of Ludwig’s angina in immunocompetent individuals.
         3. 2. Upper respiratory infections
            1. pharyngitis, sinusitis, otitis media, bronchitis, etc. caused by S. pyogenes, S. pneumoniae and H.
         4. 3. Subacute bacterial endocarditis: Aminopenicillins in combination with gentamicin have been used
         5. 4. Urinary tract infections:
         6. 5. Meningitis: A combination of ampicillin, vancomycin and third-generation cephalosporins is used
         7. 6. Bacillary dysentery:
   4. NEWER PENICILLINS
      1. Acid resistant penicillins
      2. Benzathine penicillin
      3. Extended spectrum penicillins
      4. Penicillinase resistant penicillin
      5. Anti pseudomonal penicillin
   5. Organisms resistant to methicillin ( MRSA) are resistant to all other beta lactam drugs. These resistant organisms are treated by vancomycin or teicoplanin.
2. B-Lactamase Inhibitors
   1. CLASSIFICATION
      1. clavulanic acid, sulbactam and tazobactam
   2. INDICATIONS
      1. CLAVULANIC ACID
         1. Skin, soft tissue, otitis media, respiratory and urinary tract infections
         2. caused by B-lactamase-producing strains of S. aureus, E. coli, H. influenzae and gonococci
      2. SULBACTAM
         1. Intra-abdominal and pelvic infections (mixed aerobic and anaero-bic infections) due to -lactamase-producing strains of S. aureus,
         2. gram negative aerobes and anaerobes
      3. TAZOBACTAM
         1. Severe infections caused byB-lactamase-producing strains of gram-negative bacilli
3. MONOBACTAMS
   1. acts by inhibiting the bacterial cell wall synthesis. It is effective only against gram-negative bacteria,
   2. It is resistant to most b-lactamases. It is administered only parenterally .
   3. The main advantage with aztreonam is lack of cross-reactivity with other b-lactam antibiotics
   4. It is useful for the treatment of hospital-acquired–gram-negative infections
4. CARBApenemes
   1. CLASSIFICATION
      1. Meropenem
         1. Injected intravenously.
         2. Not destroyed by dehydropeptidase – does not require cilastatin coadministration
         3. Seizures less likely
         4. Also effective against imipenem resistant P. aeruginosa.
      2. Imipenem
         1. example of a carbapenem, is a semisynthetic -lactam antibiotic.
      3. Faropenem
         1. Orally effective.
         2. Used for respiratory and genitourinary infections.
5. CEPHALOSPORINS
   1. CLASSIFICATION
      1. First Generation
         1. Cephalexin (O)
         2. Cefadroxil (O)
         3. Cephalothin (i.m.)
         4. Cephradine (O, i.m.,
         5. Cefazolin (i.m., i.v.)
      2. Second Generation
         1. Cefaclor (O)
         2. Cefuroxime axetil (O)
         3. Cefuroxime (i.m.,
         4. Cefoxitin (i.m., i.v.)
         5. Cefotetan (i.m.)
         6. Cefprozil (O)
      3. Third Generation
         1. cefixime (O)
         2. Cefpodoxime proxetil
         3. Ceftriaxone (i.m., i.v.)
         4. Cefotaxime (i.m., i.v.)
         5. Ceftizoxime (i.m., i.v.)
         6. Ceftibuten (O)
         7. Cefdinir (O)
         8. Ceftazidime (i.m., i.v.)
         9. Cefoperazone (i.m., i.v.)
      4. Fourth Generation
         1. Cefpirome
         2. Cefepime
   2. INDICATIONS
   3. ADVERSE EFFECTS
      1. Hypersensitivity: The most common adverse effects are allergic reactions. They are skin rashes, urticaria and rarely anaphylaxis.
      2. Cross-reactivity to penicillin is seen in few patients.
      3. 2. Gastrointestinal disturbances—mainly diarrhoea, vomiting and anorexia can also occur.
      4. 3. Pain at the site of i.m. injection mainly with cephalothin. Intravenous cephalosporins can cause thrombophlebitis
      5. 4. Nephrotoxicity may occur. Co-administration of cephalothin and gentamicin increases the nephrotoxicity
      6. 5. Intolerance to alcohol (a disulfi ram-like reaction) has been reported with cefotetan and cefoperazone.
      7. 6. Severe bleeding can occur either due to hypoprothrombinaemia (which responds to vitamin K therapy) or thrombocytopaenia and/or platelet dysfunction.