In structure these drugs are analogues of p-amino benzoic acid Different types of antimicrobial drugs are as follows:
1. Antibiotics
These are the substances( produced wholly or partially by chemical synthesis) which in low concentrations inhibit the growth of microorganisms or destroy them by intervening in their metabolic processes.
Antibiotics are products of microbial growth and thus, antibiotic therapy has been likened to setting one thief against another ‟.
Antibiotics are of two types:
1. Bactericidal antibiotics have cidal( killing) effect on microbes. For example, penicillin, ofloxacin, amino glycosides, etc.
2. Bacteriostatic antibiotics have a static( inhibitory) effect on microbes. For example, erythromycin, tetracycline, chloramphenicol, etc