An agent used against anaerobic bacteria as well as Protozoa is

An agent used against anaerobic bacteria as well as Protozoa is Metronidazole.
Metronidazole is one of the mainstay drugs for the treatment of anaerobic infections. It is approved by the US Food and Drug Administration for the treatment of anaerobic and protozoal infections.
Metronidazole has activity against protozoans like Entamoeba histolytica, Giardia lamblia and Trichomonas vaginalis, for which the drug was first approved as an effective treatment.