Clonal relatedness of Salmonella isolates associated with invasive infections in captive and wild-caught rattlesnakes

This study examines the serotype distribution and clonal relatedness among Salmonella isolates obtained from healthy and diseased snakes. Isolates from extraintestinal body sites were obtained through routine diagnostic lab submissions from snakes in two facilities that had experienced a high prevalence of osteomyelitis in Crotalus species. Gastrointestinal isolates were predominantly from fecal samples collected from healthy snakes of both crotalid and non-crotalid species in one facility. PFGE macrorestriction analysis of Salmonella isolates confirmed the clonal and species-restricted nature of Salmonella serotype IIIa 56: z4, z23: - in one facility. Fourteen of 15 isolates from suspected osteomyelitis lesions in wild-caught snakes at the second facility were also from Salmonella subgroup IIIa (serotype IIIa 18: z4, z23: -) and appeared to be closely related by PFGE. Evaluation of a PCR assay for the spvC gene in 209 isolates demonstrated that this method consistently distinguished isolates of subgroup IIIa from those of subgroup IIIb. The data presented establish that Salmonella of subgroup IIIb are abundant and regularly associated with gastrointestinal shedding in snakes but that Salmonella in subgroup IIIa disproportionately cause infections in bone or other extraintestinal sites.