Campylobacter and Salmonella infections are the most common contributors to the incidence of reactive arthritis related to foodborne illness, judging from results of a population-based study in two states.
Dr. John M. Townes of Oregon Health and Science University, Portland, and associates conducted telephone interviews with residents of Minnesota and Oregon who had culture-confirmed Campylobacter, Escherichia coli O157, Salmonella, Shigella, and Yersinia infections reported to the Centers for Disease Control and Prevention's Foodborne Disease Active Surveillance Network between 2002 and 2004. Parents or legal guardians provided proxy interviews for those younger than 18 years of age. The researchers invited participants who reported new onset joint pain, joint swelling, back pain, heel pain, and morning stiffness lasting 3 days or more within 8 weeks of culture to complete a detailed questionnaire and physical examination.
Overall, 6,379 culture-confirmed infections were reported to FoodNet in Minnesota and Oregon between 2002 and 2004. The majority were caused by Campylobacter (53%) and Salmonella (30%), followed by E. coli O157 (9%), Shigella (7%), and Yersinia (1%). A total of 4,468 subjects (70%) were interviewed within 2 months of specimen collection. Of these, 575 (13%) reported having new onset of rheumatologic symptoms suggestive of reactive arthritis, which the investigators defined as a history or physical examination findings consistent with monoarthritis, oligoarthritis, dactylitis, enthesitis, or inflammatory back pain without other rheumatologic explanation. The adjusted odds ratio for having these symptoms was higher for subjects aged 18 years and older (OR 2.5), females (OR 1.5), and those who had signs of severe illness including fever, chills, headache, bloody stools, and persistent diarrhea at the time of screening (OR of these symptoms ranged from 1.6 to 2.8). Risk of having new onset of rheumatologic symptoms was not associated with antibiotic use or HLA-B27 (Ann. Rheum. Dis. 2008 Feb. 13 [doi:10.1136/ard.2007.083451
In a subset of 54 patients who met the criteria for the diagnosis of reactive arthritis based on history and physical examinations, Campylobacter was the most common organism of infection (33 cases), followed by Salmonella (17 cases), Shigella (2 cases), E. coli O157 (1 case), and Yersinia (1 case). Most cases were adults (96%) and female (67%). Enthesitis was the most frequent finding on physical exam (48 cases). Arthritis was seen in 10 cases. The incidence of reactive arthritis following culture-confirmed infections of Campylobacter, E. coli O157, Salmonella, Shigella, and Yersinia was estimated to be from 0.6 to 3.1 cases per 100,000 persons.
The researchers acknowledged certain limitations of the study, including the fact that “it is difficult to prove that the rheumatologic symptoms described by our subjects are truly attributable to the antecedent infections,” they reported. “However, by examining a subset of those with subjective symptoms, we were able to provide objective confirmation that the true illness was present, and was not related to alternate rheumatologic diagnoses.”
They also noted the small number of patients in the subset analysis and pointed out there is no universal definition of reactive arthritis. “We elected to include enthesitis and inflammatory back pain in our case definition,” stated the researchers, who had no relevant conflicts. “Including only those with frank arthritis would obviously have resulted in a substantially lower estimate of the incidence.”
The study was supported by the Centers for Disease Control and Prevention and the Oregon Health and Science University General Clinical Research Center.