Secretory immune response and clinical sequelae of Salmonella infection in a point source cohort

To determine the kinetic isotypic serum and secretory immune response to Salmonella enteritidis in a cohort of individuals exposed to the organism in a single food source outbreak of dysentery. To determine the clinical outcome and immunogenetics of the exposed cohort and to correlate these features with the immune response.

Following a single point source outbreak of Salmonella enteritidis, a cohort of dysenteric individuals were ascertained using a reactive arthritis screening questionnaire (QUEST). Serum and stimulated saliva samples were obtained at 6, 12, and 24 months following the outbreak of dysentery; examinations were conducted at the same time. Two unexposed control groups were ascertained: (1) general rheumatology clinic patients and (2) well nonarthritic family practice patients. An ELISA to determine quantitative IgA responses to Salmonella enteritidis lipopolysaccharide (LPS) was performed.

Eleven of the 84 exposed individuals with dysentery developed reactive arthritis (ReA) of reactive enthesitis (ReE). There was a prolonged salivary IgA anti-LPS response in both the ReA/ReE and DYS (dysentery alone) patients compared with unexposed controls. A ratio of salivary IgA anti-LPS/serum IgA anti-LPS > 1 was associated with a good outcome (remission) of ReA, whereas a ratio < 1 was associated with chronic disease.

There is a more prolonged humoral immune response to Salmonella LPS in exposed individuals than hitherto described. A risk factor in the prolongation of ReA is the inability to mount an appropriate specific salivary (secretory) immune response.