An antimicrobial such as isoniazid that is only effective against mycobacterium would be considered to be a drug.

Anti-bacterial drug

Explanation:

An antimicrobial such as isoniazid that is only effective against mycobacterium would be considered to be an anti-bacterial drug.

Mycobacterium is a pathogenic micro organisms which belongs to the class called Bacteria. Others include virus, Protozoa and fungi.

Since the drug is only effect against mycobacterium which is a bacteria it is called anti bacterial drug. Drugs which are effective against virus, Protozoa and fungi are known as antiviral, antiprotozoal and antifungal respectively.

its probably to later but whats the question