R
Roger P. Johnson
Researcher at Public Health Agency of Canada
Publications - 113
Citations - 6010
Roger P. Johnson is an academic researcher from Public Health Agency of Canada. The author has contributed to research in topics: Escherichia coli & Salmonella. The author has an hindex of 36, co-authored 113 publications receiving 5361 citations. Previous affiliations of Roger P. Johnson include Health Canada & University of Guelph.
Papers
More filters
Journal ArticleDOI
Associations between virulence factors of Shiga toxin-producing Escherichia coli and disease in humans.
Patrick Boerlin,Patrick Boerlin,Scott A. McEwen,Franziska Boerlin-Petzold,Jeff Wilson,Roger P. Johnson,Roger P. Johnson,Carlton L. Gyles +7 more
TL;DR: Multivariate analysis revealed an interaction between the eae andstx2 genes, thus supporting the hypothesis of the synergism between the adhesin intimin and Shiga toxin 2, and a true lack of biological significance of the hemolysin in humans or in disease cannot be excluded.
Book ChapterDOI
Enumeration of bacteriophages by double agar overlay plaque assay.
Andrew M. Kropinski,Andrew M. Kropinski,Amanda Mazzocco,Thomas E. Waddell,Erika J. Lingohr,Roger P. Johnson +5 more
TL;DR: This chapter describes the classical overlay protocol, which is fundamental to many protocols in phage biology, genetics, and molecular biology.
Journal ArticleDOI
Probiotics affect virulence-related gene expression in Escherichia coli O157:H7.
TL;DR: It is shown here that L. acidophilus La-5 secretes a molecule(s) that either acts as a QS signal inhibitor or directly interacts with bacterial transcriptional regulators, controlling the transcription of EHEC O157 genes involved in colonization.
Journal ArticleDOI
Distribution of core oligosaccharide types in lipopolysaccharides from Escherichia coli.
Karen L. Amor,David E. Heinrichs,Emilisa Frirdich,Kim Ziebell,Roger P. Johnson,Chris Whitfield +5 more
TL;DR: Unique sequences in the waa (core OS biosynthesis) gene operon were used to develop a PCR-based system that facilitated unequivocal determination of the core OS types in isolates of E. coli.
Journal ArticleDOI
Escherichia coli O157:H7 diarrhoea associated with well water and infected cattle on an Ontario farm.
S. G. Jackson,R. B. Goodbrand,Roger P. Johnson,V. G. Odorico,David Alves,Kris Rahn,Jeff Wilson,M. K. Welch,Rasik Khakhria +8 more
TL;DR: Hydgeological investigation revealed the design and location of the well would allow manure-contaminated surface water to flow into the well and demonstrates that cattle farm well water is a potential source of E. coli O157:H7 which may not be identified by standard screening for E. bacteria in water.