Proposal of Salmonella paratyphi sp. nov., nom. rev. and Request for an Opinion to conserve the specific epithet paratyphi in the binary combination Salmonella paratyphi as nomen epitheton conservandum

This paper proposes elevating Salmonella paratyphi to independent species status, reviving a name that had lost standing in bacterial nomenclature. Historically, the organism causing paratyphoid fever was first described as 'Bacterium paratyphi' in 1902 but was later reclassified as a subspecies within S. choleraesuis (specifically S. choleraesuis subsp. choleraesuis serovar Paratyphi A). The authors argue that S. paratyphi should be recognized as a distinct species due to its public health significance as a contagious pathogen causing typhoid-like illness in humans, citing nomenclatural rules regarding perilous names. They support this proposal using DNA–DNA hybridization data showing distinct genetic relationships and biochemical/serological characteristics that differentiate S. paratyphi from other Salmonella species. The type strain NCTC 5702T is designated for the species. The authors request formal conservation of the specific epithet paratyphi in the binary combination Salmonella paratyphi to maintain consistency with medical and clinical microbiology literature, where this organism is widely recognized as a distinct human pathogen.

Key findings

• S. paratyphi is proposed as a separate species, elevated from subspecies status within S. choleraesuis, to reflect its distinct public health importance as a typhoid-fever-like pathogen
• DNA–DNA hybridization and biochemical/serological testing differentiate S. paratyphi from other Salmonella species, supporting independent species designation
• The revival of the name S. paratyphi addresses nomenclatural confusion and applies Rule 56a(5) regarding perilous names—organisms causing serious disease or economic harm
• Strain NCTC 5702T is designated as the type strain with antigenic formula 1,2,12:a:−
• Recognizing S. paratyphi as a distinct species avoids confusion with other serovars carrying the Paratyphi designation that do not cause paratyphoid fever