Described herein are compounds, and pharmaceutically acceptable salts and prodrugs thereof, which are useful as inhibitors of IMPDH. In certain embodiments, a compound of the invention selectively inhibits a parasitic IMPDH versus a host IMPDH. Further, the invention provides pharmaceutical compositions comprising one or more compounds of the invention. The invention also relates to methods of treating various parasitic and bacterial infections in mammals. Moreover, the compounds may be used alone or in combination with other therapeutic or prophylactic agents, such as anti-virals, anti-inflammatory agents, antimicrobials and immunosuppressants.