Answer:
Anti-bacterial drug
Step-by-step 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.