Pathogenesis of Enterococcal Spondylitis Caused by Enterococcus cecorum in Broiler Chickens

Abstract

Enterococcal spondylitis (ES) is a disease of commercial broiler chickens, with a worldwide distribution. Symmetrical hind limb paralysis typical of ES results from infection of the free thoracic vertebra (FTV) by pathogenic strains of Enterococcus cecorum . To determine the pathogenesis of ES, birds with natural and experimental ES were studied over time. In natural disease, case birds (n = 150) from an affected farm and control birds (n = 100) from an unaffected farm were evaluated at weeks 1-6. In control birds, intestinal colonization by E. cecorum began at week 3. In case birds, E. cecorum was detected in intestine and spleen at week 1, followed by infection of the FTV beginning at week 3. E. cecorum isolates recovered from intestine, spleen, and FTV of case birds had matching genotypes, confirming that intestinal colonization with pathogenic strains precedes bacteremia and infection of the FTV. Clinical intestinal disease was not required for E. cecorum bacteremia. In 1- to 3-week-old case birds, pathogenic E. cecorum was observed within osteochondrosis dissecans (OCD) lesions in the FTV. To determine whether OCD of the FTV was a risk factor for ES, 214 birds were orally infected with E. cecorum, and the FTV was evaluated histologically at weeks 1-7. Birds without cartilage clefts of OCD in the FTV did not develop ES; while birds with OCD scores ≥3 were susceptible to lesion development. These findings suggest that intestinal colonization, bacteremia, and OCD of the FTV in early life are crucial to the pathogenesis of ES.

Occurrence of Enterococcus spp. in poultry in Poland based on 2014–2015 data

“…However, E. cecorum may cause enterococcal spondylitis, femoral head necrosis, arthritis. Infection with E. cecorum can constitute a serious health problem, usually for commercial broiler chickens and broiler breeder flocks (2,7,12). Recently, E. cecorum-associated disease was reported in Pekin ducks and in racing pigeons (9).…”

Vertebral Osteomyelitis in Broilers: A Review

“…E. cecorum was also isolated from a broiler flock with pericarditis, hepatitis, femoral head necrosis and/ or VO and the authors concluded that bacteremia and generalized infection seem to be important steps in the pathogenesis of the infection caused by this bacterium in broilers (Jung & Rautenschlein, 2014). This was also suggested by Borst et al (2017), who observed that E. cecorum isolates recovered from the intestine, spleen, and free thoracic vertebra (FTV) of broilers in natural cases of VO had matching genotypes, confirming that intestinal colonization with pathogenic strains precedes bacteremia and infection of the FTV.…”

“…Some evidences suggest that the higher incidence of enterococci-associated diseases in poultry may be due to horizontal spread of dominant E. cecorum clones that exhibit high pathogenicity (Kense & Landman, 2011;Boerlin et al, 2012). However, the source of pathogenic E. cecorum remains unknown (Borst et al, 2017). Moreover, bacterial strains with genotypes similar to those isolated from VO cases were rarely recovered from the ceca of birds with VO and the presence of these isolates was not statistically associated with a higher risk of disease (Borst et al, 2012).…”

“…Field observations showed that the disease occurred in successive flocks, suggesting the persistence of E. cecorum on the farm (Herdt et al, 2009;Kense & Landman, 2011). According to Borst et al (2017), persistence of E. cecorum in the environment between flocks is unproven, although the repeated outbreaks on affected farms may be associated to environmental contamination by pathogenic E. cecorum.…”

Incidence of Bacterial Chondronecrosis with Osteomyelitis (Femoral Head Necrosis) Induced by a Model of Skeletal Stress and its Correlation with Subclinical Necrotic Enteritis

“…Bacteria that translocated when the intestines were compromised could have already been eliminated from the spleen. On the other hand, a field study of E. cecorum-derived spinal BCO found that bacterial presence in the spleen persisted, with increasing incidence, for several weeks [37]. In general, however, the timing of pathogenic events preceding BCO (translocation, bacteremia, colonization of bone tissue, etc.)…”