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A High-throughput Platform for the Screening of Salmonella spp./Shigella spp.
Published on: November 7, 2018
Culture methods differ on the isolation of Salmonella enterica serotypes from naturally contaminated swine fecal
Marcos H Rostagno1, Jared K Gailey, H Scott Hurd
1National Animal Disease Center, USDA, Ames, IA 50010, USA.
Abstract:
Four culture methods (A, B, C, and D) were comparatively evaluated for their ability to isolate Salmonella enterica from pooled swine fecal samples (n = 100). None of the methods was able to isolate Salmonella from all positive samples. The relative sensitivity of the culture methods evaluated was 82%, 94%, 95%, and 78% for methods A, B, C, and D, respectively. The comparison of sensitivities showed that methods B and C performed significantly better (P < 0.05) than methods A and D. Although relative sensitivities of methods B and C were equal, from the 89 positive samples concomitantly detected by both, 35 (39.3%) had different serotypes (no match) isolated by each method. On the basis of the results of this study, it was concluded that culture methods differ on the isolation of S. enterica serotypes from naturally contaminated swine fecal samples. Depending on the objective(s) of investigations on the ecology and epidemiology of S. enterica in swine populations, a method or a combination of methods should be considered for more reliable results.
Insights
Comparing four culture methods for isolating Salmonella enterica from swine feces, methods B and C showed significantly higher sensitivity. However, different serotypes were isolated by each method, suggesting a combination may be best for reliable Salmonella detection.
Area of Science:
- Veterinary Microbiology
- Food Safety
- Bacteriology
Background:
- Salmonella enterica is a significant pathogen in swine, posing risks to animal health and food safety.
- Accurate isolation of Salmonella enterica from swine fecal samples is crucial for epidemiological studies and control strategies.
- Various culture methods exist, but their comparative performance in detecting diverse Salmonella serotypes in swine is not fully elucidated.
Purpose of the Study:
- To comparatively evaluate the efficacy of four distinct culture methods (A, B, C, and D) for isolating Salmonella enterica from naturally contaminated swine fecal samples.
- To determine the relative sensitivity and performance differences among the evaluated culture methods.
- To assess the impact of culture method choice on the diversity of isolated Salmonella enterica serotypes.
Main Methods:
- Pooled swine fecal samples (n = 100) were analyzed using four different Salmonella enterica isolation protocols (Methods A, B, C, and D).
- Relative sensitivity of each method was calculated based on the number of positive samples detected.
- Statistical analysis (P < 0.05) was employed to compare the performance of the culture methods.
Main Results:
- No single method achieved 100% isolation from all positive samples.
- Methods B and C demonstrated significantly higher relative sensitivities (94% and 95%, respectively) compared to Methods A (82%) and D (78%).
- Despite similar high sensitivities, 39.3% of concurrently detected positive samples yielded different Salmonella serotypes between Methods B and C, indicating method-specific biases in serotype recovery.
Conclusions:
- Culture methods exhibit variability in isolating Salmonella enterica serotypes from swine feces.
- Methods B and C are superior for overall Salmonella detection sensitivity in swine fecal samples.
- For comprehensive ecological and epidemiological investigations of Salmonella enterica in swine, employing a single method may be insufficient; a combination of methods is recommended for enhanced reliability and broader serotype coverage.
