| Year discovered |
Antibiotic* | Class | Comments |
| 1929 | Penicillin | ß-Lactam | Identification of activity_not isolated |
| 1932 | Sulfapyridine* | Sulfonamide | Many derivatives have been developed and remain useful drugs |
| 1939 | Polymixin | Peptide | Employed for topical application (`triple antibiotic cream') |
| 1940 | Penicillin G | ß-Lactam (penicillin) | The forerunner of a large class of antibiotics |
| 1944 | Streptomycin | Aminoglycoside(streptamine) | Important drug for TB treatment |
| 1945 | Cephalosporin C | ß-Lactam (cephalosporin) | First of its class. |
| 1947 | Chloramphenicol | Phenylpropanoid | In spite of toxicity (bone marrow suppression), widely used for typhoid, diarrheas |
| 1948 | Chlortetracycline | Tetracycline(type II polyketide) | Broad spectrum, extensively used in humans, but also for animal growth promotion |
| 1950 | Erythromycin | Macrolide(type I polyketide) | Modern derivatives (clarithromycin,azithromycin) used widely for gram-positive infections |
| 1955 | Vancomycin | Glycopeptide | Little used until the 1980s when it was introduced to treat multiply-resistant gram-positive bacterial pathogens;the `V' in VRE |
| 1955 | Amphotericin B | Polyene | First generally effective antifungal agent |
| 1955 | Virginiamycin | Streptogramins(two-component agent: macrocyclic peptolide and depsipeptide | Introduced for animal use, closely related to Synercid now used in humans |
| 1955 | Lincomycin | Lincosamide | Long-time standby for certain gram-positive infections |
| 1959 | Rifamycin | Ansamycin | Front-line drug for TB treatment |
| 1960 | Methicillin | ß-Lactam (penicillin) | The `M' in MRSA |
| 1962 | Cephalothin | ß-Lactam (cephalosporin) | |
| 1962 | Nalidixic acid* | Quinolones | The forerunner of the potent 4-fluoroquinolones (e.g. ciprofloxacin* 1983) |
| 1962 | Trimethoprim* | Substituted pyridinediamine | Often used in combination with sulfa drug. |
| 1963 | Gentamicin | Aminoglycoside(2-deoxystreptamine) | First broad-spectrum aminogycloside widely used for nosocomial infections |
| 1969 | Fosfomycin | Phosphonate | Recently introduced in North America |
| 1973 | Cefoxitin | Cephamycin | |
| 1973 | Aztreonam | Monobactam | |
| 1976 | Thienamycin | Carbapenem | All ß-lactam antibiotics, the `modern'replacements for penicillin |
| 1980 | Daptomycin | Lipopeptide | Presently in advanced trials for VRE, MRSA treatment |