Scale and detection method impacted Salmonella prevalence and diversity in ponds

Area of Science:

• Environmental Microbiology
• Food Safety Science
• Agricultural Water Quality

Background:

• Effective food safety management in agriculture necessitates understanding foodborne pathogen ecology in water sources.
• Site-specific strategies are essential for mitigating hazards in agricultural water systems.

Purpose of the Study:

• To identify factors associated with Salmonella contamination in Virginia farm ponds.
• To compare Salmonella detection rates between culture-based and culture-independent (CIDT) methods.
• To assess the influence of environmental variables on Salmonella presence in agricultural water.

Main Methods:

• Collected 600 grab samples from 30 sites across nine Virginia ponds.
• Utilized both culture-based and CIDT methods for Salmonella detection.
• Serotyped cultured Salmonella isolates using Kauffman-White classification.
• Collected environmental data and employed mixed-effect models to analyze associations.

Main Results:

• Salmonella detection was significantly higher using CIDT (31%) compared to culture-based methods (13%).
• Culture methods identified 11 Salmonella serovars; 42.1% of CIDT-positive samples were culture-positive.
• Environmental factors like total coliforms, E. coli, temperature, UV, and rain influenced Salmonella detection, with rain increasing detection odds.
• Associations between environmental factors and Salmonella varied significantly between individual ponds.

Conclusions:

• Salmonella detection methods and the scale of analysis (individual pond vs. combined) significantly impact observed water quality.
• Individualized water management plans are crucial, as pond-specific factors influence Salmonella contamination.
• Findings highlight the importance of considering detection methodology and site-specific risks in agricultural water monitoring programs.