Novobiocin-brilliant green-glucose agar: new medium for isolation of salmonellae

Abstract

A new medium, called novobiocin-brilliant green-glucose (NBG) agar, was developed for the isolation of Salmonella spp. and evaluated against other conventionally used media including bismuth sulfite, xylose-lysine decarboxylase, brilliant green-sulfa, hektoen enteric, and salmonella-shigella agars. NBG had recovery rates comparable to the other enteric media tested with pure cultures as well as with naturally contaminated amphibian and reptile waters and fecal specimens. However, NBG, hektoen enteric, and salmonella-shigella agars failed to differentiate Salmonella typhi from a fecal specimen even after enrichment in selenite F. Although Citrobacterfreundii could grow and resembled salmonellae on NBG, at no time was the recovery of Salmonella spp. colonies jeopardized by the presence of C. freundii in either seeded or naturally contaminated samples. Confirmation rates of typical colonies from NBG agar also compared favorably to the other media tested; however, bismuth sulfite, although selective, was found to have varied differential characteristics for Salmonella spp. As a result, many more colonies had to be picked, which caused bismuth sulfite agar to have the lowest confirmation rate of the media tested. The distinct advantage that NBG agar offers over the conventional method tested, including bismuth sulfite, is the consistent differential reaction of all Salmonella subgroups including biochemically atypical strains. The medium is inexpensive, easy to prepare, and can be stored for at least 2 weeks at 4°C without loss of selective or differential properties.

Comparison of five plating media for isolation of Salmonella species from human stools

“…In our study, although we used a new formula proposed by the manufacturer, the selectivity did not improve appreciably, overlooking in many cases the isolation of salmonellae. Nevertheless, this medium together with BS has the advantage of being an excellent alternative for the isolation of S. typhi (6), contrary to NBGL, in which this serotype is not detected (4,13), and other media like SS, in which S. typhi can go undetected in some cases (4).…”

“…However, we were not able to include it in the present study because of a lack of funds, since this medium, at least in Spain, is expensive (Ͼ$1 per plate). For NBGL (11), whose forerunner could be considered NBG (4), the detection of Salmonella spp. is based on the production of H 2 S. Other bacteria, e.g., Citrobacter spp., are not able to grow on NBGL because of the high acidity caused by the fermentation of the lactose and/or glycerol contained in the medium.…”

Tracking Salmonella Enteritidis in the Genomics Era: Clade Definition Using a SNP-PCR Assay and Implications for Population Structure

“…The presence of sulfadiazine in the media is effective in inhibiting the growth of E. coli and Proteus and to a large extent Shigella species [31]. In a latter modification of the BGS agar, the replacement of lactose with glucose and of sulfadiazine with novobiocin to create the novobiocin-brilliant green agar (NBG), led to a higher recovery of Salmonella but the medium could not differentiate it from hydrogen sulfide-positive Citrobacter organism [32].…”

Note: Comparison of media for the isolation of lactose‐positive Salmonella

“…Thc fcrmcntation of lactose and the production of H,S are the two biochemical tests a hich are most commonly used in selective culture media for the isolation of Sulmonelli/. Two new media hake recent11 been described which have a similar basis, novobiocin-brilliant green-glucose agar (NBG ; H2S production and glucose fermentation) (Devenish 1986), and novobiocin-brilliant green-& cerol-lactose agar (NBGL; H2S production) (Poisson 1992). Rambach agar (RB ; hlerck, Germany) and SM-ID (SM ; bioMCrieux, France), two recent commercially a\ ailable media, use the production of chromo- (Aspinall et ul.…”