Use of Presumpto Plates to identify anaerobic bacteria.

Identification of anaerobic bacteria requires special media and growth conditions that contribute to a higher cost per identification than that for aerobic isolates. Newer rapid methods streamline the identification process, but confirmation to the species level is often difficult. The Presumpto Plate method for the identification of commonly encountered anaerobes consists of three quadrant plates, each containing four conventional media, that result in the generation of 21 test parameters: growth on Lombard-Dowell medium; production of indole, indole derivative, catalase, lecithinase, and lipase; proteolysis of milk, H2S, and esculin; growth on 20% bile; precipitate on bile; DNase, glucose, casein, starch, and gelatin hydrolysis; and fermentation of lactose, mannitol, and rhamnose. Identification charts were developed by using the results from 2,300 anaerobic isolates. Because conventional media were used, there was a high degree of agreement between the Presumpto Plate method and the reference method when testing commonly encountered anaerobes. The Presumpto Plate method is as accurate as commercially available enzyme systems for the identification of many anaerobic species but is less expensive to perform.