Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS, USA
Erysipelothrix rhusiopathiae is a non-sporeforming gram-positive rod that is widespread in the environment and is often associated with turkeys and swine in commercial farms. The organism is responsible for the annual loss of millions of dollars in the turkey and swine industry in Japan. The organism causes erysipeloid in certain occupational groups including fishermen, butchers and others handling animal products. Erysipeloid is a slow spreading, painful, erythematous swelling of the skin. In marine mammals Erysipelothrix rhusiopathiae is known to cause a characteristic rhomboidal skin lesion and more importantly a fatal form of septicemia. Several reference strains of Erysipelothrix rhusiopathiae and Erysipelothrix tonsillarum were obtained from the ATCC. Five environmental isolates of Erysipelothrix, each implicated in the deaths of marine mammals, were obtained from various marine mammal sources. All isolates were analyzed by a variety of biochemical, immunologic, and molecular methods. Four of the five environmental isolates matched one of the biochemical patterns established by the reference isolates (the Shedd I isolate was positive for maltose fermentation). The polymerase chain reaction detected the presence of an Erysipelothrix species specific 407 bp ribosomal RNA gene fragment in all of the isolates tested. Furthermore, the isolates produced different plasmid profiles. The immunostaining of Western blotted Frasch extracted proteins with the IgG fraction of rabbit antisera produced against heat killed and Frasch extracted cultures of the Erysipelothrix isolates (NRaD and Shedd I) revealed the presence of many shared bacterial antigens among the isolates tested. Although a few differences were observed between the five isolates and between each isolate and the reference strains, all of the environmental isolates were determined to be Erysipelothrix rhusiopathiae.