Arthropathic and amyloidogenic Enterococcus faecalis infections in brown layers: A study on infection routes

Intravenous, intra-articular and intraperitoneal inoculation of 6-week-old brown-layer pullets with an arthropathic and amyloidogenic strain of Enterococcus faecalis resulted in amyloid arthropathy, while intramuscular, oral and intratracheal inoculation did not. Oral inoculation of 1-day-old chickens did not cause any pathology. However, intramuscular inoculation with 10⁶ colony forming units resulted in severe growth retardation and arthritis in 60% of the birds, and amyloid arthropathy in approximately 40%. In egg transmission studies, neither egg dipping nor inoculation of the air chamber with E. faecalis reproduced the condition, although a few chicks became septicaemic. Yolk sac inoculation of 6-day-old embryos caused embryonic death within 2 days. In contrast, egg albumen inoculation with E. faecalis led to arthritis in one of six of the progeny, indicating the possibility that vertical transmission of E. faecalis by the oviductal route could lead to arthritis. The presence of antibodies to E. faecalis was confirmed by enzyme-linked immunosorbent assay in 14/15 of experimental birds that had developed arthritis.