Study on the vertical transmission of arthropathic and amyloidogenic Enterococcus faecalis in a flock of brown layer chickens

Enterococcus faecalis-related amyloid arthropathy was diagnosed in a sample of birds from a flock of brown layer parent chickens aged 57 weeks. E,faec alis was isolated from amyloidotic knee joints and from blood samples from lame birds. From this flock a smaller one was kept for production purposes to study the vertical transmission of arthropathic and amyloidogenic E. fae calis, Three batches of non-soiled and thoroughly disinfected eggs, to prev ent egg-shell contamination, were collected for 6 weeks and submitted for i ncubation every 2 weeks, No joint pathology was found in the offspring chic ks (n = 458) monitored for joint disease until 16 or 21 weeks of age. Fresh and candled eggs (infertiles and dead embryos) obtained at day 18 of the i ncubation period had negative results at bacteriological examination of the yolk sac, except one non-hatched egg (late embryonal death in shell) from which E, faecalis was isolated. Genotyping by pulsed-field gel electrophore sis (PFGE) of all E, faecalis isolates obtained from blood and joints (exce pt one) of the parent birds and of the non-hatched egg after Sma I digestio n showed that all isolates were genetically closely related or identical to a known arthropathic and amyloidogenic E.faecalis strain. In this study, v ertical transmission of E.faecalis, although it may occur on a small scale as shown by PFGE, did not seem to play a significant role. Conversely, the chronicity of the condition and the development of an immune response may h ave affected the efficiency of its transmission.