The Role of Intracellular Organisms in the Pathogenesis of Inflammatory Arthritis

Box 1

Preliminary classification criteria for reactive arthritis (adapted from Braun et al. [3]).

Major criteria

   (1) Arthritis with 2 of 3 of the following findings.

       (i) Asymmetric

       (ii) Mono- or oligoarthritis

       (iii) Affection predominantly in lower limbs

   (2) Preceding symptomatic infection with 1 or 2 of the following findings.

      (i) Enteritis (diarrhoea for at least 1 day, 3 days, to 6 weeks before the onset of arthritis)

      (ii) Urethritis (dysuria or discharge for at least 1 day, 3 days, to 6 weeks before the onset of arthritis)

Minor criteria, atleast one of the following

   (1) Evidence of triggering infection

      (i) Positive nucleic acid amplification test in the morning urine or urethral/cervical swab for Chlamydia trachomatis

      (ii) Positive stool culture for enteric pathogens associated with ReA

   (2) Evidence of persistent synovial infection (positive immunohistology or PCR for Chlamydia)

Definition of reactive arthritis

Definite ReA: both major criteria and a relevant minor criterion

Probable ReA: (1) both major criteria, but no relevant minor criteria or (2) major criteria 1 and one or more of minor criteria.

Exclusion criteria

Other causes for acute arthritis