Disclosed are compounds and pharmaceutically acceptable salts thereof, which are useful as inhibitors of IMPDH. In certain embodiments, a compound selectively inhibits a parasitic IMPDH versus a host IMPDH. Also disclosed are pharmaceutical compositions comprising one or more compounds of the invention. Related methods of treating various parasitic and bacterial infections in mammals are disclosed. 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.