Genetic analysis of non-hydrogen sulfide-producing Salmonella enterica serovar Typhimurium and Infantis isolates in Japan

The great majority of non-typhoid Salmonella species produce hydrogen sulfide (H2S) from both thiosulfate and sulfite by means of anaerobically induced dissimilatory pathways. Although the H2S production is a characteristic of prime importance in the identification of Salmonella spp., the non producing Salmonella isolates can be occasionally observed and isolated in our institute. In this study, we performed whole genome sequencing of the non-producing serovar Typhimurium and Infantis isolates from poultry meat, indicating that nonsense mutation in the phsA gene encoding thiosulfate reductase subunit could be associated with the non-producing phenotype. In addition, those Typhimurium isolates carry the blaCMY-2 beta-lactamase, showing a reduced susceptibility to cefazolin. It suggests that lack of biomarker regarding H2S production might lead to incorrect identification of such antimicrobial resistant Salmonella enterica isolates.