title: Staphylococcal enterotoxin C in synovial fluid of patients with rheumatoid arthritis.
abstract: BACKGROUND
  In the previous studies using the commercial ELISA kit, the existence of staphylococcal superantigens has been reported in synovial fluid of patients with rheumatoid arthritis (RA).
  
  
  OBJECTIVE
  This study aimed to design molecular methods to detect staphylococcal enterotoxin C in synovial fluid of patients with rheumatoid arthritis.
  
  
  METHODS
  In this experimental study, Staphylococcus aureus strain producing enterotoxin C was used as the reference strain. The polymerase chain reaction (PCR) was set up by design a specific pair of primers. Besides bacterial culture, 50 synovial fluid samples of patients with rheumatoid arthritis were subjected to DNA extraction, and then PCR amplification was carried out according to the protocol. All samples were examined by ELISA method for enterotoxin C. The data were descriptively analyzed.
  
  
  RESULTS
  The results of bacterial culture were negative for all samples. The results showed that 66% (33 cases) of samples contained entC gene and only 46% (23 cases) have also enterotoxin C. The interesting finding was that the results of ELISA and PCR were the same and have shown only 22 positive cases (44%samples) for staphylococcal enterotoxin C.
  
  
  CONCLUSIONS
  Based on the findings of this study, S. aureus enterotoxin C (SEC) has been detected in synovial fluid of patients with rheumatoid arthritis by PCR and ELISA methods. These valuable findings may describe the exact etiology of the RA and as well as change the methods of its diagnosis and treatment. This is the first research, which has shown the staphylococcal entC gene in synovial fluid of RA patients. However, S. aureus strains can produce more than 20 types of enterotoxins. Therefore, its involvement on rheumatoid arthritis pathogenesis makes an important challenge in the future. In this regard, further investigation on the other enterotoxins is necessary.
authors.affiliation: Department of Medical Microbiology, Faculty of Medicine, Baqiyatallah University of Medical Sciences, Tehran, IR Iran.
authors.forename: Ramezan Ali
authors.initials: RA
authors.lastname: Ataee
authors.affiliation: Research Center of Microbial, Baqiyatallah University of Medical Sciences, Tehran, IR Iran.
authors.forename: Mohammad Hosein
authors.initials: MH
authors.lastname: Ataee
authors.affiliation: Department of Rheumatology, Baqiyatallah University of Medical Sciences, Tehran, IR Iran.
authors.forename: Gholam Hosein
authors.initials: GH
authors.lastname: Alishiri
authors.affiliation: Department of Medical Microbiology, Microbial Research Center, Baqiyatallah University of Medical Sciences, Tehran, IR Iran.
authors.forename: Davoud
authors.initials: D
authors.lastname: Esmaeili
keywords: PCR, ELISA; Rheumatoid Arthritis; Staphylococcal Enterotoxin C; Synovial Fluid