Photorhabdus asymbiotica: Shedding Light on a Human Pathogenic Bioluminescent Bacterium

Photorhabdus asymbiotica is a gram-negative bacillus of the family Enterobacteriaceae. The bacterium displays the curious property of bioluminescence – the production of light without heat. It is recognized as a human pathogen in the United States and Australia, where it causes both locally invasive soft tissue infection and disseminated disease. In Australia, P. asymbiotica is vectored by the soil nematode Heterorhabditis gerrardi. The vector in the U.S. has not yet been identified, but it is likely to also be a Heterorhabditid nematode. Although it grows readily on conventional culture media, clinical microbiology laboratories may misidentify this pathogenic bacterium because of an over-reliance on commercial rapid identification systems.