Antibacterial drugs narrow-spectrum

Antibacterial agents may be classified according to the class of target microorganism. Accordingly, antibacterial agents that inhibit only bacteria are described as narrower medium-spectrum, whereas those that also inhibit mycoplasma, rickettsia, and chlamydia (so-called atypical bacteria) are described as broad-spectrum. The spectrum of activity of common antibacterial drugs is shown in Table 1.1. 

Nalidixic acid (ND) (NeGram) (Fig. 7-1), the prototype of this family of drugs, was synthesized as the result of the discovery that an impurity, isolated during the preparation of the anti-malarial chloroquine,2 had significant antibacterial activity. It was introduced into therapy in 1964. The antibacterial spectrum, however, was relatively narrow and did not include... 

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