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Aerosol transmission of arthropathic and amyloidogenic Enterococcus faecalis
W J Landman1, K T Veldman, D J Mevius
1Animal Health Service, Poultry Health Center, Deventer, The Netherlands.
Insights
Young chicks exposed to Enterococcus faecalis aerosol developed bacteremia, with one-day-old chicks showing the highest rates. Treatments like formaldehyde gas, Newcastle disease virus vaccine, or corticosteroids did not significantly increase early bacteremia, though chronic cases were observed.
Area of Science:
- Veterinary Microbiology
- Avian Pathology
- Infectious Diseases
Background:
- Enterococcus faecalis can cause disease in poultry.
- Understanding the pathogenesis and risk factors for E. faecalis bacteremia in chicks is crucial for disease prevention.
- Previous studies have focused on specific inoculation routes, but aerosol exposure dynamics require further investigation.
Purpose of the Study:
- To investigate the susceptibility of young brown layer chicks to aerosolized Enterococcus faecalis.
- To evaluate the impact of pre-treatments (formaldehyde gas, Newcastle disease vaccine virus, methylprednisolone) on the development of bacteremia following E. faecalis aerosol exposure.
- To assess the potential for chronic bacteremia and associated pathology.
Main Methods:
- One-day-old and four-day-old brown layer chicks were exposed to an aerosol of an arthropathic and amyloidogenic Enterococcus faecalis strain.
- Pre-treatments included formaldehyde gas, Newcastle disease vaccine virus (NDVV) aerosol, or methylprednisolone injection.
- Positive control group received intramuscular inoculation of E. faecalis.
- Blood cultures were performed at various time points (24 hours, 10 days, 14 days, 66 days) to monitor bacteremia.
- Joint pathology was assessed.
Main Results:
- One-day-old chicks exposed to E. faecalis aerosol showed the highest bacteremia rates (70%-80%) at 24 hours.
- Pre-treatments with formaldehyde gas did not increase bacteremia.
- NDVV aerosol or methylprednisolone treatment in four-day-old chicks resulted in lower bacteremia rates at 24 hours compared to one-day-old chicks.
- Chronic bacteremia was observed in some groups up to 14 days post-exposure.
- No joint pathology was observed in aerosol-exposed groups, unlike the intramuscularly inoculated group.
Conclusions:
- Young chicks, particularly one-day-old, are highly susceptible to aerosolized Enterococcus faecalis, leading to significant bacteremia.
- Pre-treatments evaluated did not enhance early bacteremia following aerosol exposure.
- Aerosol exposure, despite causing chronic bacteremia, did not result in joint pathology in this study.
- Further research is needed to understand the factors influencing chronic bacteremia and the lack of pathology in aerosol-exposed birds.
Abstract:
One-day-old brown layer chicks were exposed to an aerosol of an arthropathic and amyloidogenic Enterococcus faecalis strain alone or after being subjected to treatment with formaldehyde gas (100-200 ppm). Four-day-old chicks were also treated with the same aerosol but after treatment with a Newcastle disease vaccine virus (NDVV) aerosol or intramuscular injection with methylprednisolon at day 1. The same E. faecalis strain was inoculated intramuscularly in day-old chicks as positive control. Bacteremia with time showed that 24 hr after the aerosol the day-old exposed chicks had the highest rate of positive blood cultures (70%-80%). Lower numbers of bacteremic birds at this point in time were found in the chicks treated with E. faecalis aerosol at day 4 (3/10 in the methylprednisolon-treated group and 0/10 in the NDVV-treated group) and the E. faecalis intramuscular-injected group at day 1 (2/10). Formaldehyde gas treatment did not favor the occurrence of bacteremia. NDVV aerosol exposure or injection with corticosteroids did not favor the occurrence of bacteremia 24 hr after E. faecalis aerosol exposure at day 4 either, although 66 days after aerosol, one bird (1/14) treated with NDVV showed bacteremia. A few bacteremic birds were found 10 days after aerosol in the NDVV- and methylprednisolon-treated groups, whereas at 14 days after aerosol, one bacteremic bird was seen in the group subjected to E. faecalis aerosol at day 1, indicating the occurrence of chronic bacteremia. In contrast to the E. faecalis intramuscular-inoculated birds, no joint pathology was seen in the aerosol-exposed groups in spite of the occurrence of chronic bacteremia.
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