Salmonellosis Outcomes Differ Substantially by Serotype

Abstract

BACKGROUND: Most human infections are caused by closely related serotypes within 1 species of Salmonella. Few data are available on differences in severity of disease among common serotypes. METHODS: We examined data from all cases of Salmonella infection in FoodNet states during 1996-2006. Data included serotype, specimen source, hospitalization, and outcome. RESULTS: Among 46,639 cases, 687 serotypes were identified. Overall, 41,624 isolates (89%) were from stool specimens, 2524 (5%) were from blood, and 1669 (4%) were from urine; 10,393 (22%) cases required hospitalization, and death occurred in 219 (0.5%). The case fatality rate for S. Newport (0.3%) was significantly lower than for Typhimurium (0.6%); Dublin (3.0%) was higher. With respect to invasive disease, 13 serotypes had a significantly higher proportion than Typhimurium (6%), including Enteritidis (7%), Heidelberg (13%), Choleraesuis (57%), and Dublin (64%); 13 serotypes were significantly less likely to be invasive. Twelve serotypes, including Enteritidis (21%) and Javiana (21%), were less likely to cause hospitalization than Typhimurium (24%); Choleraesuis (60%) was significantly more so. CONCLUSIONS: Salmonella serotypes are closely related genetically yet differ significantly in their pathogenic potentials. Understanding the mechanisms responsible for this may be key to a more general understanding of the invasiveness of intestinal bacterial infections.