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Serologic testing for reactive arthritis
1St. Boniface Arthritis Research Unit, Medical Microbiology Department, St. Boniface General Hospital, Winnipeg, Manitoba.
Summary
Quantitative antibody tests for Salmonella enteritidis lipopolysaccharide (LPS) show promise for diagnosing reactive arthritis (ReA). IgA anti-LPS is highly specific, distinguishing past Salmonella exposure in ReA patients.
Area of Science:
- Immunology
- Microbiology
- Rheumatology
Background:
- Reactive arthritis (ReA) can follow Salmonella enteritidis infections.
- Accurate diagnostic markers for post-Salmonella ReA are needed.
- Salmonella enteritidis lipopolysaccharide (LPS) is a key antigen involved in the immune response.
Purpose of the Study:
- To evaluate the diagnostic accuracy of quantitative serum antibody responses to Salmonella enteritidis LPS for post-Salmonella ReA.
- To determine the sensitivity and specificity of IgG and IgA anti-LPS antibodies.
Main Methods:
- Serum samples were collected from individuals with and without ReA following a Salmonella enteritidis outbreak.
- Quantitative isotypic antibodies to Salmonella enteritidis LPS were measured using ELISA.
- Receiver operator characteristic (ROC) curves were used to assess diagnostic performance.
Main Results:
- Both IgG and IgA anti-LPS antibodies were elevated in ReA patients compared to controls.
- IgG anti-LPS demonstrated 88% sensitivity and 94% specificity.
- IgA anti-LPS showed 75% sensitivity and 100% specificity at an optimal cutoff.
Conclusions:
- Quantitative IgA anti-LPS antibody levels are highly specific for identifying prior Salmonella LPS exposure in ReA patients.
- These antibody measurements can aid in distinguishing ReA from other conditions in patients with a history of Salmonella infection.