Submitted to: Letters in Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 24, 2003
Publication Date: April 10, 2003
Citation: Jackson, C.R., Cray, P.J., Hiott, L.M., Hall, M.C. 2003. Anomalies in Species Identification of Enterococci from Veterinary Sources Using a Commercial Biochemical Identification System. Letters in Applied Microbiology. 36(4):245-250 Interpretive Summary: Presently, identification of enterococci is primarily accomplished using a time-consuming biochemical testing scheme. Identification of enterococci from non-human sources is more difficult due to the atypical results usually obtained with those isolates. In order to find an alternative method for identification, the BBL Crystal ID kit was evaluated. Using the kit, species identification of enterococcal isolates appeared to vary depending on number of times the isolate was sub-cultured. Increased sub-culturing increased agreement to the original designation from 59% to 64%. This information will be useful for and used by researchers who utilize this commercial biochemical kit for identification of enterococci isolated from non-human sources.
Technical Abstract: AIMS: A commercial biochemical panel ID kit was used to identify presumptive enterococci isolates of veterinary or agricultural origin obtained during different steps of culture. METHODS AND RESULTS: Fifty isolates identified as enterococci using a genus PCR assay were tested for genus and species identification using the BBL Crystal Identification Gram-Positive ID kit. Following sub-culture of the isolates 3 times, 59% agreement with the original panel ID was obtained. After 4 and 6 sub-cultures, percent agreement increased to 61% and 64%, respectively. Nineteen of the 50 cultures were identified as both Enterococcus faecalis and Enterococcus faecium. CONCLUSIONS: Due to the variability between speciation of isolates following re-culture, additional methods for speciation are warranted. SIGNIFICANCE AND IMPACT OF THE STUDY: This study suggests that the identification of the genus and species of non-human enterococcal isolates can vary greatly during successive passages when using this kit.