Distribution and phenotypic characteristics of Salmonella serotype from 1975 to 2021 in Fujian Province

Abstract

ObjectiveThis study aimed to analyze the serotype and phenotype of human and non-human sourced Salmonella from 1975 to 2021 in Fujian Province retrospectively.MethodsSalmonella isolates were collected from clinical hospitals， public service employee health， circulating fresh food， and the environment from 1975 to 2021 in Fujian Province， and serotypes and variants were distinguished using WHO-recommended Salmonella serotyping methods. Two prediction software were used based on whole genome sequencing， while the same antigen but different isolates or phenotypic variants were identified using biochemical combinations and MALDI-TOF-MS flight mass spectrometry.ResultsThere were 4 693 human- and non-human-sourced Salmonella isolates that contained 21 serogroups of four subspecies （18 from patients， 9 from healthy employees， 17 from food， and 8 from the environment）. Salmonella paratyphoid A， S. typhoid， S. enteritis， S. cholerae， S. typhimurium， S. rosen， and S. stanley were dominant isolates in the 30 total extraintestinal invasive serotypes. There were 96 Salmonella serotypes other than S. typhoid， S. paratyphoid A， and S. paratyphoid B （63 from patients， 51 from healthy employees， 60 from food， and 20 from the environment）， and the top 10 clinical serotypes were S. typhimurium， S. typhoid， S. enteritis， S. derby， S. stanley， S. paratyphoid A， S. anatum， S. wetavreden， S. rosen， and S. london， while the top 10 from food were S. anatum， S. derby， S. typhimurium， S. stanley， S. wetavreden， S. newport， S. enteritis， S. tompson， S. agona， and S. london. Fourteen serotypes （including 10 diphasic serotypes and 4 monophasic serotypes） had monophasic variants. Several serotypes had phenotypic variants such as hydrogen sulfide-negative， fermenter of lactose or sucrose， colony mucus type， and chromogenic type.ConclusionSalmonella are characterized by their biodiversity and multiple sources in Fujian Province. Invasive cases are gradually dominated by non-typhoid Salmonella. Laboratories should enhance their ability to diagnose monophasic variants and phenotypic variants of Salmonella， as well as pet and environmental traceability for scattered outbreaks of infectious diseases.

Keywords

• salmonella serotype
• monophasic variants
• biodiversity
• eco-behavioral infectious diseases
• traceability