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Method for isolation of both lactose-fermenting and – non-fermenting Escherichia albertii strains from stool samples

Author:
Maheux, Andrée F., Brodeur, Stéphanie, Bérubé, Ève, Boudreau, Dominique K., Abed, Jehane Y., Boissinot, Maurice, Bissonnette, Luc, Bergeron, Michel G.
Source:
Journal of microbiological methods 2018 v.154 pp. 134-140
ISSN:
0167-7012
Subject:
Escherichia albertii, bacteria, feces, fermentation, isolation techniques, lactose, pathogenicity, phenotype, polymerase chain reaction, species identification
Abstract:
Initially, Escherichia albertii has been described as a non-lactose fermenting bacterium and methods used to isolate it were first based on this phenotypic property. However, a recent study showed a variable lactose fermentation phenotype for E. albertii suggesting that this microorganism could have been underestimated by previous studies using isolation methods based on lactose fermentation. In this study, we present a method for the isolation and identification of both lactose fermenting and non-fermenting-E. albertii cells in stool samples, said method combining culture and isolation on mEA agar, an indole test, as well as an E. albertii-specific PCR assay for formal species identification. The ability of the procedure to detect E. albertii strains was verified using 19 E. albertii strains and 132 non-E. albertii strains representing 88 species of different origins majoritary belonging to the Enterobacteriaceae family. All indole-positive white colonies grown on mEA agar were subjected to E. albertii-specific PCR amplification; all E. albertii strains tested were detected with this assay and none of the non-E. albertii strains tested was detected. To demonstrate the ability of the procedure to directly detect E. albertii in stool samples, E. albertii-inoculated stools were tested and for all inoculated samples, E. albertii colonies were easily detected and identified. The present study provides a method enable to recover both lactose-fermenting and -non-fermenting E. albertii strains from clinical samples. This method could help to provide a better portrait of the prevalence and pathogenicity of E. albertii in clinical samples.
Agid:
6144261