A population-based study on the incidence, risk factors and outcome of Salmonella bloodstream infections in South Sweden 2012-2022

Abstract

Abstract Introduction: Invasive infections caused by Salmonella are a significant global health concern. This population-based study aimed to comprehensively analyze invasive Salmonella infections in South Sweden, focusing on incidence, clinical presentation, risk factors, and outcomes. Methods This population-based observational cohort study, conducted from 2012 to 2022, included all patients with Salmonella bloodstream infections (BSI) in the Skåne region, South of Sweden. A control group consisted of patients with positive stool cultures/PCR for Salmonella but without BSI. Data were collected following a predefined study protocol and systematically reviewed. Standardized statistical analyses assessed patient characteristics, clinical presentation, and outcomes. Results Between 2012 and 2022, 149 patients with Salmonella BSI were identified, with the majority having non-typhoidal Salmonella (NTS) infections (95%). A declining trend in the incidence of Salmonella BSI was observed, with the highest incidence in 2012 (1.5 per 100,000 person-years) and the lowest in 2020 (0.3 per 100,000 person-years). Patients with BSI were more likely to be older, have comorbidities, be immunosuppressed, and use proton pump inhibitors (PPIs). Additionally, BSI patients presented with fewer gastrointestinal symptoms, had a higher respiratory rate, lower saturation, and higher clinical scores, suggesting a more septic presentation. Salmonella BSI patients had significantly longer hospital stays and higher 30-day, 90-day, 180-day, and 365-day mortality rates compared to the control group. Conclusion Invasive Salmonella infections are rare but have a substantial impact on patients in South Sweden. The absence of classic gastroenteritis symptoms increases the risk of Salmonella bloodstream infection. This study highlights the importance of distinguishing between clinical presentations to guide appropriate treatment. The declining trend in incidence, particularly associated with international travel, necessitates further investigation to understand contributing factors.