Salmonella infection induces changes in joints of mice inoculated by the oral route

NOTO LLANA M; CACCURI RL; GIACOMODONATO MN; SARNACKI SH; CERQUETTI MC

Estambul, Turquia

Congreso; XII International Congress of Bacteriology and Applied Microbiology; 2008

IUMS

Reactive arthritis (ReA) is a synovitis that overcomes generally after a gastrointestinal or urogenital tract infection. In some developing countries 33% of the ReA cases appeared after an intestinal infection produced by Salmonella enterica serovar. Enteritidis. Currently, there is no suitable animal model for the study of ReA following gastrointestinal infections. In this work, we analyzed the capacity of S. Enteritidis to induce osteoarticular lesions in BALB/c mice. Animals were intragastrically (ig) inoculated with 2 doses of 5x107 UFC of a termosensitive mutant C/2/2 of S. Enteritidis. Previously, these animals were inoculated with zymosan in the knee, in order to produce a lesion. Another group was ig inoculated with the wild type (wt) strain of S. Enteritidis, in doses varying between 102 and 104 UFC/animal. At different times knee samples were taken. Bacteria were not recovered from the joints at any time studied. Histological assessment was performed using an established scoring system (0= normal joint, 1= simple hyperplasia of the synovial membrane, 2= synovitis with inflammatory infiltrate, 3= perisynovitis, 4= inflammatory infiltrate in joint cavity). Results showed that zymosan inoculation generates simple hyperplasia (index between 0 and 1) in days 14, 20, 43 and 75.Treatment with the attenuated strain exacerbated these histological changes, reaching an index between 2 and 3 (p<0.01 with respect to their controls). In joints without previous damage, the infection with the mutant produced minor changes. The joints of those animals inoculated only with the wt strain in a low dose showed a score between 2 and 3 at 25 and 42 days post challenge (p<0.01 compared to their controls). Specific antibodies against whole Salmonella were investigated in knee homogenates by Ouchterlony assay, although they were not detected.  Histological changes were observed early after infection. Six hours after inoculation, the wt strain caused mild focal hyperplasia and pericapsulitis, and 24 h later patches of threefold-layer hyperplasia were observed in the synovial membrane. Modifications induced by the mutant strain were less evident. Our results show that the experimental infection with S. Enteritidis administered ig, generates ReA. High doses of attenuated strain of S. Enteritidis induce the reactivation of preexistent lesions, whereas low doses of the wt strain produce inflammatory changes in healthy joints.