title: A modified MacConkey agar for selective enumeration of necrotoxigenic E. coli O55 and probiotic E. coli Nissle 1917.
abstract: An agar selective enumeration of necrotoxigenic Escherichia coli O55 (NTEC2) and probiotic E. coli Nissle 1917, using modified MacConkey agar, was developed to study bacterial interference between these E. coli strains in a gnotobiotic piglet model. Replacement of lactose with saccharose in the agar enables the direct visual enumeration of red colonies of E. coli O55 and yellow colonies of E. coli Nissle 1917 that are co-cultured in the same Petri dish. A total of 336 colonies (168 for each color) were subjected to strain-specific PCR identification with LNA probes. Sensitivity, specificity, and positive and negative predictive values were 96.43%, 95.83%, 95.86% and 96.41% respectively in E. coli O55, and 98.21%, 97.02%, 97.06% and 98.19% respectively in E. coli Nissle 1917. Color-based enumeration of both E. coli strains in colonic contents and mesenteric lymph nodes homogenates of gnotobiotic piglets demonstrated the applicability of this method for the gnotobiotic piglet model of enteric diseases.
authors.affiliation: Laboratory of Gnotobiology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Doly 183, 549 22 Novy Hradek, Czech Republic.
authors.forename: Alla
authors.initials: A
authors.lastname: Splichalova
authors.affiliation: Laboratory of Gnotobiology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Doly 183, 549 22 Novy Hradek, Czech Republic. Electronic address: splichal@gnotobio.cz.
authors.forename: Igor
authors.initials: I
authors.lastname: Splichal
authors.affiliation: Biological Research Department, Ardeypharm GmbH, Loerfeldstrasse 20, 58313 Herdecke, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Sonnenborn
authors.affiliation: Department of Microbiology, Nutrition and Dietetics, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamycka129, 165 21 Prague 6- Suchdol, Czech Republic.
authors.forename: Vojtech
authors.initials: V
authors.lastname: Rada
mesh_terms: D000362:Agar / Q000737:chemistry; D000818:Animals; D015169:Colony Count, Microbial / Q000295:instrumentation / Q000379:methods*; D003116:Color; D003470:Culture Media / Q000737:chemistry* / Q000378:metabolism; D004926:Escherichia coli / Q000145:classification / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology; D006801:Humans; D019936:Probiotics / Q000008:administration & dosage / Q000737:chemistry*; D013552:Swine
chemical_list: D003470:Culture Media; D000362:Agar
keywords: Cytotoxic necrotizing factor; E. coli Nissle 1917; E. coli O55; LNA probes; MacConkey agar; NTEC