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Experimental Corynebacterium pseudotuberculosis infection in lambs
Abstract:
Lambs were inoculated IV with 3.2 X 10(3) colony forming units (CFU) to 3.2 X 10(6) CFU of Corynebacterium pseudotuberculosis from a 6-hour broth culture supplemented with 0.1% sorbitan monooleate. After 28 days, multiple abscesses were observed in the lungs and lymph nodes. The number of abscesses in the lungs correlated with the inoculation dose. Two lambs given 10(5) CFU and 10(6) CFU died. Multiple abscesses occurred in other lambs given 10(6) CFU to 10(4) CFU and few abscesses occurred in lambs given 10(3) CFU. Corynebacterium pseudotuberculosis was isolated from lung abscesses, inoculation site abscesses, and lymph node abscesses, but not from normal tissues. Because this procedure consistently induced abscesses in the lungs, we believe it will be a suitable challenge system for studies on the prevention of caseous lymphadenitis in sheep.
Insights
Intravenous inoculation of Corynebacterium pseudotuberculosis in lambs consistently induced lung and lymph node abscesses. This dose-dependent response suggests a viable challenge model for studying caseous lymphadenitis prevention in sheep.
Area of Science:
- Veterinary Medicine
- Microbiology
- Animal Science
Background:
- Caseous lymphadenitis (CLA) is a contagious disease in sheep and goats caused by Corynebacterium pseudotuberculosis.
- Effective prevention strategies require reliable challenge models to test interventions.
Purpose of the Study:
- To establish a reproducible experimental model for inducing caseous lymphadenitis in lambs using Corynebacterium pseudotuberculosis.
- To evaluate the dose-dependent effects of bacterial inoculation on abscess formation and clinical outcomes.
Main Methods:
- Lambs were intravenously inoculated with varying doses (3.2 x 10^3 to 3.2 x 10^6 CFU) of Corynebacterium pseudotuberculosis.
- Abscess development in lungs and lymph nodes was assessed after 28 days.
- Bacterial isolation was performed from abscesses and normal tissues.
Main Results:
- Intravenous inoculation consistently induced multiple abscesses in the lungs and lymph nodes.
- A positive correlation was observed between the inoculation dose and the number of lung abscesses.
- Mortality occurred in lambs receiving the highest doses (10^5 and 10^6 CFU).
- Corynebacterium pseudotuberculosis was successfully isolated from all observed abscesses.
Conclusions:
- The described intravenous inoculation method provides a consistent and dose-dependent challenge model for Corynebacterium pseudotuberculosis infection in lambs.
- This model is suitable for future research into the prevention and treatment of caseous lymphadenitis in sheep.