Comparison of acetate differential agar with sellers citrate-mannitol-agar.

A total of 245 isolates of Escherichia coli (paracolons) were employed in comparing the use of acetate differential agar (ADA) with the simple test described by Sellers to eliminate these organisms from consideration as enteric pathogens. At 18 hr after the media were inoculated, 83% of the isolates produced a positive citrate reaction on Sellers citrate-mannitol-agar (SCM) and 7% gave a positive reaction on ADA. At 24 hr, 92% of the cultures were positive on SCM versus 42% on ADA. At 48 hr, 244 (99.6%) of the isolates were positive on SCM, whereas a 72-hr incubation period was required for equal results with ADA. One isolate failed to grow on either medium.