Salmonella Infection in Middle-Aged and Older Adults: Incidence and Risk Factors from the 45 and Up Study

Background: Salmonella infection is one of the most common foodborne bacterial pathogens, and causes a significant health burden globally. We investigated the incidence and risk factors for notification and hospitalization due to Salmonella infection in older adults. Materials and Methods: We used the 45 and Up Study, a large-scale Australian prospective study of adults aged ≥45 years, with record linkage to multiple databases for the years 2006-2012 to estimate the incidence of notification and hospitalization for Salmonella infection and estimate hazard ratios using Cox regression. Results: Over a total follow-up of 1,120,242 person-years, 333 adults had laboratory-confirmed Salmonella infection and 101 were hospitalized; the notification and hospitalization incidence were 29.7 (95% confidence interval [CI]: 26.9-33.3) and 9.0 (95% CI: 7.4-10.9) per 100,000 person-years, respectively. The risk of Salmonella infection notification did not differ by age, but risk of hospitalization increased with age. Elderly males had the highest risk of infection-related hospitalization. The risk of notification was higher for those living in rural or remote areas (adjusted hazard ratio [aHR] 1.7, 95% CI 1.3-2.2), those taking proton pump inhibitors (aHR 1.9, 95% CI 1.4-2.4), and those reporting chicken/poultry intake at least seven times per week (aHR 3.2, 95% CI 1.3-7.9). Conclusions: Chicken consumption remains a significant risk factor for Salmonella infection, highlighting the importance of reducing contamination of poultry and improving food safety advice for older people.