[Characteristic and influencing factors of Salmonella serotypes among asymptomatic workers in Yulin, Guangxi Zhuang Autonomous Region, 2013-2023]

Abstract

Objective: To investigate the diversity, temporal dynamics and influencing factors of serotypes of Salmonella among asymptomatic workers in Yulin, Guangxi Zhuang Autonomous Region, from 2013 to 2023, and provide reference for controlling the hidden transmission of Salmonella and for disease prevention among healthy populations. Methods: Anal rectal swabs were collected from asymptomatic workers in Yulin from 2013 to 2023 for the isolation and identification of Salmonella. The diversity of serotypes of Salmonella was evaluated by using Shannon index, while the isolation rates and composition ratio of different serotypes were compared with χ² test. Spearman correlation analysis was used to evaluate the correlation of natural and social factors with serotype isolation rates for more than eight years, and stepwise multiple linear regression analysis were used to evaluate the impact of social factors on the serotype isolation rates for more than 8 years. Results: A total of 8 073 strains of Salmonella were isolated from 2013 to 2023, with an overall isolation rate of 18.88‰ During the 11-year period, 135 serotypes of Salmonella were identified, and the serotype diversity increased first and then decreased. The serotype with the highest isolation rate was Salmonella Typhimurium (3.04‰), followed by Salmonella Rissen (1.70‰), Salmonella Corvallis (1.41‰), Salmonella Agona (1.36‰), Salmonella Derby (1.22‰), and Salmonella London (1.02‰), accounting for 51.67% of the total Salmonella serotypes isolated. There was no significant trend in isolation rate of Salmonella over the years (χ²=0.67, P=0.415); however, season significantly influenced the isolation rate, with lower rate being observed in winter and higher rate in summer (χ²=615.91, P<0.001). The isolation rate of different serotypes of Salmonella was influenced by social and natural factors, showing a positive correlation with temperature, precipitation, and poultry consumption and production levels. Conclusions: The serotypes of Salmonella carried by asymptomatic workers were complex and diverse in Yulin, Guangxi Zhuang Autonomous Region, from 2013 to 2023, and the isolation rates of multi-serotypes increased from 2013 to 2023. Higher isolation rate was observed in summer and the isolation rate was widely influenced by natural factors such as temperature and precipitation, as well as social factors such as economic conditions. It is necessary to pay attention to the Salmonella serotype carriage in healthy population, and strengthen monitoring of both healthy individuals and pathogenic bacteria.