title: Juvenile spondyloarthropathies associated with Mycoplasma pneumoniae infection.
abstract: BACKGROUND
  Reactive arthritis (ReA) has been sporadically reported as triggered by Mycoplasma pneumoniae. This study examined the potential relationship between the acute M. pneumoniae infection and juvenile spondyloarthropathy (jSpA) in children.
  
  
  METHODS
  Twelve patients with ReA secondary to acute M. pneumoniae were examined. M. pneumoniae-specific IgM, IgG and IgA antibodies were serologically confirmed by enzyme-linked immunosorbent assay (ELISA) tests (Savyon Diagnost., Israel). Due to the early appearance and relatively short life time of M. pneumoniae-specific IgM antibodies, their detection allowed the diagnosis of acute infection using single serum sample, confirmed by parallel serum in 7 of 12 patients. Specific IgM and IgG titers higher than 10 U/l were considered positive and those higher than 50 U/l as highly positive. Specific IgA antibodies were detected in only one patient.
  
  
  RESULTS
  Four patients were female and eight were male. The mean age at onset was 9 years, and the mean duration of follow-up was 24.1 months (range 18-32). The mean number of involved joints was 2.8, and the knee joints were involved in 7 of 12 patients. The mean recovery time was 4.5 weeks (range 1-28) in eight reactive arthritis (ReA) cases; three patients developed enthesitis-related arthritis, and in one patient, genuine juvenile ankylosing spondylitis (jAS) was diagnosed. Two patients were HLA-B27-positive, and one patient was HLA-B7/B27-positive. Six patients had preceding respiratory symptoms, and five were treated with antibiotics.
  
  
  CONCLUSIONS
  Our findings provide clear evidence of ReA diagnosis following an acute M. pneumoniae infection that in four patients progressed to chronic jSpA. Our results suggest that detecting M. pneumoniae-specific antibodies in serological screening of jSpA patients might be useful. It is presently unclear whether antibiotic treatment would change the disease course in those patients.
authors.affiliation: Department of Pediatrics, Division of Pediatric Rheumatology/Immunology, Children's Hospital Zagreb, Klaiceva 16, 10 000, Zagreb, Croatia. miroslav.harjacek@zg.htnet.hr
authors.forename: Miroslav
authors.initials: M
authors.lastname: Harjacek
authors.forename: Jelena
authors.initials: J
authors.lastname: Ostojic
authors.forename: Oktavija
authors.initials: O
authors.lastname: Djakovic Rode
mesh_terms: D017668:Age of Onset; D016918:Arthritis, Reactive / Q000097:blood / Q000150:complications* / Q000175:diagnosis*; D002648:Child; D002908:Chronic Disease; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D009177:Mycoplasma pneumoniae / Q000276:immunology*; D011019:Pneumonia, Mycoplasma / Q000097:blood / Q000150:complications*; D000091402:Prohibitins; D012698:Serologic Tests; D025242:Spondylarthropathies / Q000097:blood / Q000150:complications* / Q000175:diagnosis*
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; C000717331:PHB2 protein, human; D000091402:Prohibitins