Salmonella recovery from chicken bone marrow and cecal counts differ by pathogen challenge method

Area of Science:

• Food safety
• Microbiology
• Poultry science

Background:

• Mechanically separated chicken (MSC) is a vehicle for Salmonella enterica transmission in foodborne disease outbreaks.
• Chicken bone marrow may harbor Salmonella, leading to MSC contamination.

Purpose of the Study:

• To determine if chicken bone marrow is susceptible to Salmonella infection based on challenge method.
• To assess the impact of Salmonella challenge site and inoculation on cecal pathogen levels.

Main Methods:

• 30-day-old chickens (Gallus domesticus) were challenged with S. enterica via oral gavage, endo-tracheal gavage, or transdermal scratch (N=150).
• Salmonella recovery from bone marrow and cecal samples was quantified at 3, 6, and 9 days post-challenge.

Main Results:

• Salmonella recovery rates from bone marrow varied significantly by challenge method (P=0.0015).
• Oral and endo-tracheal gavage yielded 10% and 20% Salmonella recovery from bone marrow, respectively.
• Cecal Salmonella counts differed significantly by challenge method (P=0.032), with oral gavage showing the highest levels (3.0 log10 cfu/g).

Conclusions:

• Chickens can develop short-term systemic Salmonella infections through simulated aerosol, ingestion, or wounding challenges.
• Salmonella presence in chicken bone marrow can compromise food safety standards and increase consumer transmission risk.