An infection may be described as "opportunistic" if it develops as a result of disease or therapy interfering with the body's resistance. Opportunistic infections are usually severe, with hematogenic dissemination and a high mortality. Many of the organisms concerned have little or no pathogenicity in ordinary circumstances; some are familiar pathogens. Among the organisms in the author's series were bacteria (for example, various gram-negative bacilli, Staphylococcus albus, Mima, commensal corynebacteria, lactobacilli), fungi (for example, Candida, Geotrichum, Torulopsis, Trichophyton, Aspergillus, Penicillium, Rhizopus), viruses (herpes simplex, cytomegalovirus, varicella-zoster), and protozoa (Pneumocystis, Toxoplasma). Multiple infections are frequent.
Litle has been learned of the