The epidemiology of extraintestinal non-typhoid Salmonella in Israel: The effects of patients' age and sex

Extraintestinal disease occurs in 5-8% of non-typhoid Salmonella enterica (NTS) infections and is more likely to be associated with hospitalization and death. The study examined the epidemiology of extraintestinal NTS infections in Israel and the possible effects of patients' age and sex. NTS isolates passively submitted to the National Salmonella Reference Center during 1996-2006 were the source for the study cohort. Poisson regression models were used to assess incidence trends over the study years and to evaluate the effects of patients' age and sex on the incidence of extraintestinal NTS manifestations. A total of 36,822 stool and 1,415 (3.7%) patient-unique NTS isolates from blood (74.1%), urine (18.3%), and other sources (3.7%) were studied. Serotypes Enteritidis, Virchow, and Typhimurium accounted for 66.3% of the isolates. Analysis showed a highly significant quadratic (U-shaped) relationship between patients' age and the incidence of extraintestinal isolation (p < 0.001), with increasing risk in the two extremes of age. Differences between the incidence of blood and urine sources were significant in patients <10 and ≥60 years old (relative risk [RR] = 5.88, 95% confidence interval [CI] 3.36-10.30, p < 0.001 and RR = 1.66, 95% CI 1.09-2.53, p = 0.017, respectively). Males ≥60 years of age were more likely than females of the same age to have bacteremia (RR = 1.90, 95% CI 1.39-2.61, p > 0.001) and less likely to have urinary NTS isolation (RR = 0.50, 95% CI 0.28-0.89, p = 0.018). Serotype Virchow had the highest incidence in patients <10 years of age, while serotype Enteritidis had the highest incidence in patients ≥60 years old. The study revealed a complex effect of patients' age and sex on the epidemiology of extraintestinal NTS manifestations.