Overview of Antimicrobials Dr W.D. Colby Microbiology & Immunology
Classes of Antimicrobials ß-lactams Aminoglycosides Extended macrolide family Glycopeptides Quinolones Tetracyclines Miscellaneous
ß-lactams Inhibit cell wall synthesis by blocking peptidoglycan cross linking enzymes (PBPs) Penicillins Cephalosporins Cephamycins Carbapenems (thienamycins) Monobactams
Penicillins Natural Aminopenicillins Penicillinase-resistant semisynthetic penicillins Antipseudomonal penicillins
Cephalosporins 1st generation 2nd generation 3rd generation 4th generation
Carbapenems Very broad spectrum ß-lactamase resistant Imipenem/cilastatin Meropenem
The Extended Macrolide Family Bind to 50 S ribosomal subunit and inhibit protein synthesis Macrolides Azalides (azithromycin) Ketolides (telithromycin) Oxazolidinones (linezolid) Quinupristin/dalfopristin Clindamycin
Tetracyclines Bind to 30 S ribosomal subunit and inhibit protein synthesis Tetracycline Doxycycline Minocycline
Aminoglycosides Drugs of fear: ototoxic, vestibulotoxic, nephrotoxic Bind to 30 S ribosomal unit Gentamicin Tobramycin Amikacin
Glycopeptides Inhibit synthesis of cell wall phospholipids and peptidoglycan polymerization Effective against Gram positives Vancomycin Teichoplanin
Quinolones Bind to DNA gyrase and topoisomerase II 1st generation 2nd generation 3rd generation 4th generation
Evolution of Quinolones Increasing activity vs Gram +ve, atypicals and anaerobes Moxifloxacin is a new generation quinolone. Early quinolones had excellent gram-ve coverage, but little gram+ve, atypical or anaerobic coverage. As the quinolones evolved, the gram+ve coverage, atypical and anaerobic coverage increased, while maintaining gram-ve coverage. Unfortunately the newer generation quinolones are less active against Pseudomonas spp as Cipro. Moxifloxacin has comparable gram-ve coverage to Cipro and Levo, with superior Gram+ve coverage. Moxifloxacin also has activity against all of the common atypical respiratory pathogens.
Miscellaneous Co-trimoxazole Metronidazole Fusidic acid