CHARACTERISTICS OF WALL DEFICIENT AND CLASSICAL FORMS OF PROPIONIBACTERIUM ACNES FROM RHEUMATOID ARTHRITI

Diphtheroid bacilli were isolated from 10% of 59 rheumatoid and none of 41 nonrheumatoid synovial fluid cultures. Diphtheroid isolates were biochemically and physiologically identified as Propionibacterium acnes. The six strains were shown to be similar by electron microscopy, buoyant density and antibiotic sensitivity studies. On the basis of combined biotyping and serotyping, P. acnes isolates were subdivided into two sero-biotypes IG and IID. One aerotolerant strain (RA44) exhibited transitional forms of P. acnes.;Enriched Biphasic BYS medium was employed favoring growth of cell wall deficient forms. Morphological variability and buoyant density analysis suggested different growth phases. Stabilized CWDF were biochemically inactive when studied by a modified test procedure and antibiotic tolerant against a battery of antimicrobial agents. Electron and light microscopic observations suggested intracellular involvement of CWDF which may have relevance to the immunopathology in rheumatoid arthritis. Apparent reversion to classical diphtheroids in pre-reduced Chopped Meat Glucose Medium occurred after 1-2 wk incubation in 6 of 59 cases.;Experimental arthritis in 11 day chick embryos was produced with rheumatoid synovial joint fluid cultures containing stabilized CWDF. Joint lesions varied in severity from erythema and edema to flexed and clenched feet. Injection of fresh cultures of P. acnes isolates induced similar lesions in chicks with no notable differences in virulence between sero-biotypes. Cultures from nonrheumatoid joints produced abnormalities in only one case. Staining with fluorescein labeled muramidase revealed CWDF in synovial fluid of both rheumatoid and nonrheumatoid patients showing that a microbial population does exist in this milieu. In a separate experiment, a 6% recovery rate of P. acnes from the joints of infected chicks was experienced. The significance of these results and possible pathologic mechanisms are discussed.