The Emergence of Streptococcus gallolyticus as a Pathogen in Turkeys

Streptococcus gallolyticus, formerly known as Streptococcus bovis, is a Gram-positive coccus bacterium that is a facultative anaerobe. Although it was previously considered a commensal bacterium that caused secondary disease because of a stressor, S. gallolyticus can now be considered a causative agent of disease associated with a variety of infections in both humans and animals. Streptococcus gallolyticus has become an emerging pathogen in the poultry industry, particularly in turkey poults, causing acute mortality, usually without any premonitory signs. In the southern portion of the United States, there has been an influx of S. gallolyticus infections occurring predominately in July and August. A majority of turkey poults most susceptible to this disease range in age between 1.5 and 2.5 wk of age. It is suggested that virulence capability relies on accessory genome components that may not be core to all S. gallolyticus strains. In this review, we aim to provide an overview of the nomenclature changes, identification, and emergence of S. gallolyticus in turkeys.