IDENTIFICATION OF SALMONELLA SPP WITH RAMBACH AGAR IN CONJUNCTION WITH THE 4-METHYLUMBELLIFERYL CAPRYLATE (MUCAP) FLUORESCENCE TEST

The utility of Rambach agar to identify Salmonella spp. was examined r elative to its usefulness in clinical microbiology. Forty-four of 54 ( 82%) salmonella organisms isolated from faecal cultures and 66 of 82 ( 84%) salmonella stock cultures produced bright red colour colonies aft er 24 h incubation at 37-degrees-C whereas 48 of 54 (89%) salmonellae isolated from faecal cultures, and 74 of 82 (90%) salmonella stock cul tures, yielded the bright red colour when the incubation time was exte nded to 48 h. Apart from Salmonella typhi and Salmonella paratyphi A t he sensitivity of Rambach agar to detect salmonella strains belonging to five serogroups was 83% and 92% after 24 and 48 h of incubation, re spectively. In contrast, other members of the family Enterobacteriacea e tested failed to give the bright red colour, except for one strain o f Pseudomonas aeruginosa and another of Acinetobacter baumannii. The n on-salmonella strains either gave a different colour - blue, green or orange - or were colourless. To supplement the use of Rambach agar in the detection of Salm. typhi and Salm. paratyphi A and other late or n egative acid-producing salmonella species on this medium, the 4-methyl umbelliferyl caprylate fluorescence (MUCAP) test was carried out, and this showed positive results with all the salmonella strains tested. T hese results suggest that while Rambach agar can not pre-identify Salm . typhi and Salm. paratyphi A, the use of a simple and rapid (MUCAP) t est in combination would make it very useful to identify all Salmonell a spp. after 24 h incubation.