Thermophilic bacteria: a new cause of human disease.

We studied a group of 31 bacterial isolates from clinical specimens, received by the Centers for Disease Control since 1961, which have been denoted thermophilic for their unusual ability to grow at 50 degrees C. Microbiological characteristics were determined for the group, and an assessment of their clinical significance was made based on retrospective chart review. These bacteria are all gram-negative, nonfermentative, nonsporulating rods, most of which grow better at 42 or 50 degrees C than at 35 degrees C. Some of the bacteria could be implicated as the etiological agents for meningitis, endocarditis, and septicemia. Thermophilic bacteria should be considered potential pathogens when isolated from appropriate clinical specimens.