Penicillins organism specificity

How do antibiotics act Some, like penicillin, block specific enzymes. Peptide antibiotics often form complexes with metal ions (Fig. 8-22) and disrupt the control of ion permeability in bacterial membranes. Polyene antibiotics interfere with proton and ion transport in fungal membranes. Tetracyclines and many other antibiotics interfere directly with protein synthesis (Box 29-B). Others intercalate into DNA molecules (Fig. 5-23 Box 28-A). There is no single mode of action. The search for suitable antibiotics for human use consists in finding compounds highly toxic to infective organisms but with low toxicity to human cells. 

Treatment — There is no specific treatment for C. perfringens toxins, even though the organism is susceptible to penicillin, which is the drug of choice for a naturally acquired infection. Recent laboratory data indicate that clindamycin and rifampin may suppress toxin formation. Available polyvalent antitoxins contain antibodies to several toxins that have been used in treatment, but not enough data exist to prove efficacy.3... 

When prescribing one of the penicillin G depot formulations, practitioners must individualize treatment to clinical and microbial conditions. Some long-acting formulations may not maintain adequate plasma and tissue concentrations to treat specific organisms or infections. For acute streptococcal meningitis, the goal is rapid... 

Clavulanic acid is produced by Streptomyces clavuligerus and is structurally related to penicillins. This naturally occurring compound is a specific and irreversible inhibitor of a wide range of bacterial -lactamases and, therefore, can enhance the activity of penicillins and cephalosporins against many resistant organisms. Potassium clavulanate can be administered both orally and perenter-ally in combination with antibiotics sensitive to the action of -lactamases. 

The CHARM inhibition assay (CIA), Charm farm test (CFT), and Valio TlOl test are all simple multiresidue screening tests based on microbial inhibition (34, 35). The CIA test is actually a disc assay using Bacillus stearothermophilus and specially formulated agar media to increase the sensitivity to sulfonamides. The CFT is a tube assay using the same test organism in a specific formulation, which, along with the nutrients, is in a tablet form. To roughly identify penicillins and sulfonamides with the CIA and CFT tests, positive samples should be reanalyzed after the addition of penicillinase and p-aminobenzoic acid. 

Penicillin and other beta-lactam agents exert their effects by binding to specific enzymatic proteins within the bacterial cell wall. These enzymatic proteins, known as penicillin-binding proteins (PBPs), are responsible for the normal synthesis and organization of the bacterial cell wall. In particular, PBPs help manufacture the peptidoglycans, which are essential for... 

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