Some clinical, immunological and bacteriological observations in a case of pyogenic arthritis due to bacteroides fragilis.

A case of recurrent pyogenic arthritis in a knee joint and abscess formation of the lower limb is described. The infection occurred in a 70-year-old male patient treated with steroids for rheumatoid arthritis. A strain of Bacteroides fragilis was repeatedly isolated both from the knee joint and the abscess. The isolated strain was used as antigen in tube agglutination tests and significant titre changes were observed during the course of the disease. The isolated strain was initially sensitive to doxycycline but developed resistance to this drug during therapy. The sensitivity to lincomycin remained unaffected.