Comparative Identification of Rare Salmonella Serovars from Snakes in Poland Using Slide Agglutination and Genomic Analysis, Including a Putatively Novel Serovar IIIb 38:z10:z6

Salmonella is a globally important pathogen and one of the World Health Organization and One Health priority organisms. Reptiles represent environmental reservoirs of Salmonella serovars that can cause reptile-associated salmonellosis (RAS) in humans. Due to distinct biochemical features and uncommon O and H antigen variants, reptile-associated isolates may be difficult to identify using standard microbiological diagnostics. This study analyzed 62 Salmonella isolates obtained from wild and kept snakes in Poland. Samples originated from Natrix natrix, N. tessellata, Coronella austriaca, Zamenis longissimus, Elaphe dione and Nerodia fasciata species. Serovar prediction using SeqSero1.2 was compared with classical slide agglutination. Seventeen serovars were confirmed, with S. enterica subsp. diarizonae (IIIb) 38:r:z being the most frequent. For seven isolates, molecular and serological results were inconsistent. Among three isolates from Coronella austriaca predicted as IIIb 38:z10:z50, three distinct second-phase flagellar phenotypes were detected. Slide agglutination confirmed the presence of serovar 38:z10:z6, which has not been previously listed in the White–Kauffmann–Le Minor scheme or described in the scientific literature. The findings highlight the utility of genetic serovar prediction while emphasizing the need for continuous validation, particularly for the identification of rare or atypical Salmonella serovars associated with reptiles.