Diagnosis of reactive arthritis

The diagnosis of Reiter's syndrome or reactive arthritis is based on data on previous infection, analysis of clinical features and data of laboratory and instrumental examination methods and the results of etiological diagnosis.

Etiological diagnosis of reactive arthritis

Immunological method:

• detection of chlamydia antigen in epithelial cells obtained as a result of scrapings from the urethra and conjunctiva, synovial fluid (direct immunofluorescence analysis, etc.);
• detection of antibodies to antigens of chlamydia in blood serum and synovial fluid (complement fixation reaction, direct and indirect immunofluorescence):
  • acute phase of chlamydia or exacerbation of the chronic process - IgM antibodies for the first 5 days, IgA antibodies - for 10 days, IgG antibodies - after 2-3 weeks;
  • reinfection or reactivation of primary chlamydial infection - increased levels of IgG antibodies, IgA antibodies, single IgM antibodies;
  • chronic course of chlamydia - permanent titers of IgG and IgA antibodies;
  • asymptomatic course of chlamydia, persistence of pathogen - low titers of IgA antibodies;
  • Chlamydial infection is a low IgG antibody titer.
• detection of antibodies to bacteria of the intestinal group in the blood serum (direct hemagglutination reaction method, complement fixation reaction).

Morphological method - the identification of morphological structures of the pathogen (color preparations, immunofluorescent analysis).

The culture method is the isolation of chlamydia (cell culture, chicken embryos, laboratory animals).

Molecular biological method - identification of the pathogen DNA (PCR, etc.) The method is used to detect a DNA pathogen in the blood and synovial fluid.

Bacteriological study of feces.

Bacteriological examination of urine.

Diagnostic criteria of Reiter's syndrome:

• chronological association of the development of the disease with a previous genitourinary or intestinal infection;
• asymmetric arthritis with a predominant lesion of the joints of the legs, thalalgia, enthesopathy;
• signs of the inflammatory process in the genitourinary tract and eyes;
• detection of antibodies to chlamydia and / or other arthritogenic microorganisms in the blood and / or their antigens in biological materials;
• damage to the skin and mucous membranes;
• availability of HLA-B27.

Differential diagnosis of reactive arthritis

The most frequent diseases requiring differential diagnosis with reactive arthritis are infectious arthritis, diseases associated with infection, accompanied by arthritis, orthopedic pathology and various forms of juvenile idiopathic arthritis.

The diagnosis of reactive arthritis is based on the diagnostic criteria adopted at the III International Meeting on Reactive Arthritis in Berlin in 1995.

According to these criteria, the diagnosis of "reactive arthritis" is valid only if the patient has a typical peripheral arthritis, which proceeds according to the type of asymmetric oligoarthritis with a predominant lesion of the joints of the lower extremities.

Berlin diagnostic criteria for reactive arthritis

Index	Diagnostic Criteria
Peripheral arthritis	Asymmetric Oligoarthritis (lesion up to 4 joints) Primary leg joint damage
Infectious manifestations	Diarrhea Urethritis Time of onset: within 4 weeks before the development of arthritis
Laboratory confirmation of infection	Not necessarily, but it is desirable in the presence of severe clinical manifestations of infection Mandatory in the absence of obvious clinical manifestations of infection
Exclusion criteria	The established cause of the development of mono- or oligoarthritis: spondyloarthropathy; septic arthritis; crystalline arthritis; Lyme disease; streptococcal arthritis

Clinical signs of infection (diarrhea or urethritis), transferred for 2-4 weeks before the development of arthritis, are necessary. Laboratory confirmation in this case is desirable, but not necessary. In the absence of clinical manifestations of infection, its confirmatory laboratory data are taken into account.

Laboratory tests to confirm arthritic infection

Method of examination	Material
Culture analysis	Feces Synovial fluid Detachable from the urethra
Serologic examination - detection of antibodies to arthritogenic microorganisms	Blood Synovial fluid
Polymerase chain reaction - detection of bacterial DNA	Epithelial cells from the urethra Synovial fluid
Immunofluorescence microscopy - detection of bacteria in the synovial membrane	Cells of the synovium

[1], [2], [3], [4], [5], [6]