Antibacterial drug Penicillin

Antibiotics, e.g. Benzylpenicillin Gentamicin Nystatin Penicillin notatum, P. chrysogenum Micromonospora purpurea Streptomyces noursei Antibacterial drug Antibacterial drug Antifungal drug... 

Before the 1930s bacterial diseases were a major cause of death. Pneumonia and tuberculosis were major killers. Since the advent of the sulfa drugs and penicillins many bacterial diseases have been controlled. The antibacterial drugs will be discussed by type. We will see that some of these are antibiotics, an antibacterial substance produced by a living organism such as a bacterium or fungus, rather than synthesized in the laboratory. 

Figure 9.3 Targets for antibacterial drugs. The various classes of antibacterial drugs exert their effects at one of the four fundamental structural components of bacteria. Each of these components is vulnerable to drug attack. Penicillin, for example, attacks at the level of the cell wall chloramphenicol, however, works at the level of bacterial protein synthesis.

Bacterial resistance can occur because of several mechanisms.28,76 Certain bacterial strains may be able to enzymatically destroy the antibacterial drug. The best example is the beta-lactamase enzyme that is found in bacteria that are resistant to beta-lactam drugs (penicillins and cephalosporins).54,86 As previously discussed, bacteria containing this enzyme can destroy certain penicillin and cephalosporin drugs, thus rendering the drug ineffective against these strains. 

Antibacterial drugs that affect cell wall synthesis include two large femilies,the penicillins and cephalosporins, and two individual drugs, bacitracin and vancomycin. 

Benzylpenicillin Penicillin notatum, P. chrysogenum Antibacterial drug... 

Bubonic plague no longer causes the great dread that it once did, because there are now several very effective antibacterial drugs that can destroy the bacillus. These include streptomycin, chloramphenicol and the tetracyclines, but not the penicillins or related drugs. Nonetheless, the sheer scale of the loss of life in the pre-antibiotic era provides a timely reminder of how much we have grown to depend upon these magic bullets . 

Historically important not used or not now important as an antibacterial drug. b Report on therapeutic efficacy of crude penicillin. c Produced by biosynthetic methods not utilized until 1953. dUsed primarily or exclusively in animals. 

Antibacterial drugs that inhibit cell wall synthesis penicillins, cephalosporins and vancomycin... 

Figure 2 Semisynthetic bulk drugs Ampicillin (antibacterial) from penicillin G. Modifications of biosynthetic structures are often created to improve the in vivo attributes of the original compound, utilizing the biosynthesis product as the starting material containing most, if not all, of the structural complexity that provides the basic biological activity. Similarly, codeine (analgesic), although found in opium from Papaver plants, is most economically made by methylation of morphine, which is more efficiently isolated from opium.

During World War II chemists contributed to the Allied effort by developing and producing antibacterials (sulfa drugs, penicillin), antimalarials, and synthetic buna-S (GR-S) rubber. They contributed to the purification of uranium 235 and plutonium 239 as well as the development of conventional explosives needed for the Manhattan Project. 

The outstanding success of penicillin, in both local and systemic bacterial infections, followed from its high selectivity, the reason for which is discussed in Section 13.1. The mammalian toxicity is so low that it has come to be regarded as the most innocuous of all antibacterial drugs (however, a small proportion of patients become sensitized to it). In 1948, Brotzu found (in a sewage outfall on the Sardinian coast) another mould, Cephalosporium, which gave rise to the related cephalosporin series of antibiotics (see Section 13.2). 

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