Comparison of Rambach agar, SM-ID medium, and Hektoen Enteric agar for primary isolation of non-typhi salmonellae from stool samples

Abstract

Stool samples (n = 504) were streaked simultaneously onto Rambach agar (R agar; E. Merck, Darmstadt, Germany), SM-ID medium (bioMérieux S.A., Montalieu-Vercieu, France), and Hektoen Enteric (HE) agar (BBL Becton-Dickinson, Baltimore, Md.) in order to evaluate the performances of the first two media in comparison with that of the well-established HE agar. Following overnight cultivation at 37 degrees C, 29 samples (5.8%) were positive for non-typhi salmonellae on at least one of the three media. Sensitivities and specificities were 69 and 98%, 79 and 85%, and 100 and 79% for R, SM-ID, and HE agars, respectively. On the basis of the poor sensitivities, R and SM-ID agars are not recommended as primary plating media when screening for non-typhi salmonellae. However, the high specificity of R agar may help to reduce the work load when this medium is used for plating after enrichment.