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Published on: July 22, 2011
Use of Rambach Propylene Glycol Containing Agar for identification of Salmonella spp
R Gruenewald1, R W Henderson, S Yappow
1Enteric Bacteriology Laboratory, New York City Department of Health, New York 10016.
Abstract:
When grown on Rambach Propylene Glycol Containing Agar (Rambach agar), 216 of 230 (93.9%) Salmonella organisms isolated from patients and 54 of 62 (87.1%) Salmonella stock cultures produced a crimson-colored growth. Of the 14 clinical Salmonella isolates which displayed colors other than crimson, 8 were Salmonella typhi, 2 were Salmonella paratyphi A, and 4 belonged to other commonly isolated serotypes. All eight Salmonella stock cultures which failed to produce a crimson color belonged to rarely isolated serotypes. In contrast, of 83 non-Salmonella stock cultures distributed among 29 bacterial species, none produced a crimson color. These results suggest that while Rambach agar cannot preidentify S. typhi and S. paratyphi A, the medium can be used for the presumptive identification and can assist in the definitive identification of the overwhelming majority of Salmonella isolates.
Insights
Rambach agar effectively identifies most Salmonella species with crimson growth, aiding in presumptive identification. However, it cannot differentiate Salmonella typhi and Salmonella paratyphi A from other serotypes.
Area of Science:
- Microbiology
- Clinical Diagnostics
- Bacteriology
Background:
- Accurate identification of Salmonella is crucial for public health.
- Traditional methods for Salmonella identification can be time-consuming.
- Novel selective and differential agars are continuously developed to improve diagnostic efficiency.
Purpose of the Study:
- To evaluate the efficacy of Rambach agar for the presumptive identification of Salmonella species.
- To determine if Rambach agar can differentiate between common and rare Salmonella serotypes.
- To assess the specificity of Rambach agar against non-Salmonella bacterial species.
Main Methods:
- Salmonella isolates from clinical samples and stock cultures were grown on Rambach agar.
- Colony color and morphology were observed and recorded.
- Non-Salmonella bacterial species were also tested on Rambach agar for specificity assessment.
Main Results:
- 93.9% of clinical and 87.1% of stock Salmonella cultures produced crimson growth on Rambach agar.
- Salmonella typhi and Salmonella paratyphi A isolates, along with some other common serotypes, did not consistently produce crimson color.
- Rarely isolated Salmonella serotypes and all tested non-Salmonella species did not produce crimson growth, indicating high specificity.
Conclusions:
- Rambach agar is a valuable tool for the presumptive identification of the majority of Salmonella isolates.
- The medium assists in the definitive identification of Salmonella by differentiating them from other bacteria.
- Rambach agar has limitations in differentiating specific serotypes like Salmonella typhi and Salmonella paratyphi A.
