title: Rapid molecular identification of fecal origin-colonies growing on Enterococcus spp.-specific culture methods.
abstract: 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.
authors.affiliation: AFM Water Consulting, 1249 d'Édimbourg, Québec City (Québec), Canada G3J 1C8 E-mail: afmwaterconsulting@outlook.com.
authors.forename: Andrée F
authors.initials: AF
authors.lastname: Maheux
authors.affiliation: AFM Water Consulting, 1249 d'Édimbourg, Québec City (Québec), Canada G3J 1C8 E-mail: afmwaterconsulting@outlook.com.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Bouchard
authors.affiliation: Centre de recherche en infectiologie de l'Université Laval, Axe Maladies infectieuses et immunitaires, Centre de recherche du CHU de Québec-Université Laval, Québec City (Québec), Canada.
authors.forename: Ève
authors.initials: È
authors.lastname: Bérubé
authors.affiliation: Centre de recherche en infectiologie de l'Université Laval, Axe Maladies infectieuses et immunitaires, Centre de recherche du CHU de Québec-Université Laval, Québec City (Québec), Canada; Département de microbiologie-infectiologie et d'immunologie, Faculté de médecine, Université Laval, Québec City (Québec), Canada.
authors.forename: Michel G
authors.initials: MG
authors.lastname: Bergeron
mesh_terms: D058491:Bacterial Load / Q000379:methods*; D016983:Enterococcus / Q000302:isolation & purification*; D013293:Enterococcus faecalis / Q000235:genetics / Q000302:isolation & purification; D016984:Enterococcus faecium / Q000235:genetics / Q000302:isolation & purification; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D014871:Water Microbiology; D060753:Water Quality
chemical_list: D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S