V2 regions of 16S ribosomal RNA used as a molecular marker for the speciesidentification of streptococci in peripheral blood and synovial fluid frompatients with psoriatic arthritis

Objective. To detect the 16S ribosomal RNA (rRNA) of 3 streptococcal specie s in the peripheral blood and synovial fluid of patients with psoriatic art hritis (PsA). Methods, Reverse transcription-polymerase chain reaction (RT-PCR) detection targets bacterial 16S rRNA, which is present in bacteria at high copy numb ers, The 3 species-specific primers for group A streptococci (GAS; Streptoc occus pyogenes), group B streptococci (GBS; Streptococcus agalactiae), and Streptococcus pneumoniae were designed from the fragments of highly variabl e V2 regions of 16S rRNA, Total RNA was prepared from,whole peripheral bloo d sand joint fluid obtained from patients with PsA and rheumatoid arthritis (RA). All positive PCR reactions were then sequenced with a Pharmacia ALF DNA sequencing system. Results. Our data in 19 PsA patients showed that 7 peripheral blood samples were positive for GAS (P = 0.006 versus GAS-positive RA patients [n = 0] b y Fisher's exact test), and 2 were also positive for GBS, One synovial flui d sample from a PsA patient was positive for GAS. S pneumoniae was absent f rom all specimens. Seventeen patients with RA were PCR negative for the 3 s treptococcal species. Peripheral blood from a patient with inflammatory bow el disease was positive for GAS. Conclusion. The presence of GAS 16S rRNA in the peripheral blood and synovi al fluid of patients with PsA supports the concept that PsA is a reactive a rthritis to certain streptococci.