A Comparative Study Between Rapid And Conventional Moeller Decarboxylase And Dihydrolase Medium For Identification Of Enterobacteriaceae And Nonfermentative Bacteria

A total of 100 bacterial isolates from various clinical specimens were used to test a rapid method for determining lysine and ornithine decarboxylase activity as well as arginine dihydrolase activity. The conventional Moeller decarboxylase broth was tested in parallel with the rapid method on 84 Enterobacteriaceae and 16 Non-fermentative Gram-negative rods. Both the media were checked at half-hourly or hourly intervals for up to eight hours, with the final reading taken after incubation for 24 hours at 37C. Lysine and ornithine decarboxylase activity were generally detected by the rapid broth in 2 to 4 hours incubation while the arginine decarboxylase and dihydrolase were slower and required 6 to 8 hours, but most of the clinical strains produced arginine decarboxylase within 4 hours. However the Conventional Moeller decarboxylase broth requires about 1 to 4 days for detecting these enzymatic activity. The results obtained by the rapid method were comparable to those of Conventional method in the 100 clinical isolates. The requirement of shorter incubation time for detection of positive reactions make this procedure well suited to a routine clinical laboratory.