A medical microbiologist is expert in the isolation and identification of microbial agents that cause infectious disease. Viruses, bacteria and fungi, as well as parasites, are identified and, where possible, tested for susceptibility to appropriate antimicrobial agents. Source: American Board of Medical Specialties, 2007. www.abms.org [7/1/2007: definiton added, source added; 7/1/2011: modified source]