Rapid molecular identification of fecal origin-colonies growing on Enterococcus spp.-specific culture methods
The mEI, Chromocult enterococci, and m-Enterococcus culture-based methods used to assess water quality by the detection of Enterococcus spp. were first compared in terms of sensitivity using (1) 41 different type strains of Enterococcus spp. and (2) environmental colonies identified by 16S rRNA sequ...
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Veröffentlicht in: | Journal of water and health 2017-04, Vol.15 (2), p.239-250 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The mEI, Chromocult
enterococci, and m-Enterococcus culture-based methods used to assess water quality by the detection of Enterococcus spp. were first compared in terms of sensitivity using (1) 41 different type strains of Enterococcus spp. and (2) environmental colonies identified by 16S rRNA sequencing. Then, two specific-rtPCR assays targeting Enterococcus spp. and Enterococcus faecalis/faecium were tested for their ability to confirm the identity of putative enterococcal colonies. The mEI, Chromocult
enterococci, and m-Enterococcus methods detected β-glucosidase activity for 28 (68.3%), 32 (78.0%), and 12 (29.3%) of the 41 reference enterococcal strains tested, respectively. Analysis with environmental colonies showed that mEI and Chromocult
enterococci media had false positive rates of 4.3% and 5.0%, respectively. Finally, the two rtPCR assays showed a specificity of 100%. Only two (2/19) colonies of E. faecium isolated from mEI agar were not detected by the Enterococcus faecium rtPCR assay, for a sensitivity of 89.5%. Our results showed that Chromocult
enterococci medium recovered more E. faecalis/faecium cells than the two other methods. Thus, the use of Chromocult
enterococci combined with the Enterococcus faecalis/faecium rtPCR assay showed the best combination to decrease the high false-positive rate obtained when the entire Enterococcus genus is targeted. |
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ISSN: | 1477-8920 1996-7829 |
DOI: | 10.2166/wh.2016.199 |