Dublin's Professor Fanning Speaks About Molecular Identification Methods for Cronobacter spp.
Editor’s Note: We next are going to hear from Professor Seamus Fanning of University College Dublin, addressing Molecular identification methods for Cronobacter. He also spoke at the Dublin conference on Cronobacter.
Biography: Seamus Fanning is the Professor of Food Safety & Zoonoses and the Director of the Centre for Food Safety, University College Dublin. Professor Fanning is an editor of Research in Microbiology and a member of the editorial board of the Journal of Food Protection.
Professor Fanning received an Honours BSc in Biochemistry from NUI, Cork, where he also completed his PhD in Microbiology and Molecular Genetics. Current research interests include the application of molecular methods to Food Safety to control zoonotic microorganisms associated with human disease. A significant part of this work relates to the characterization of the genetic mechanisms contributing to the emergence of multiple drug resistance (MDR); the role of membrane bound efflux pumps in MDR and virulence and how these phenotypes are regulated at a local and global level.
Also, in the past few years the UCD Centre for Food Safety has published several papers describing the detection and characterization of Cronobacter. Professor Fanning is a member of the Microbiology Sub-Committee of the Food Safety Authority of Ireland (FSAI), the Scientific Advisory Committee of safe food and was recently appointed by the European Food Safety Authority (ESFA) to a working group to provide expert opinion on the emergence of antibiotic resistance in food. He also served as a member on the FAO/WHO expert panel on Enterobacter sakazakii in follow-up formula.
Summary: Molecular identification methods for Cronobacter spp.
Historically the ancestry of the genus Enterobacter can best be described as nebulus and confusing. In the 1970’s and 1980’s considerable movement of species, originally assigned to this genus occurred, and these re-designations arose because of initial misplacements, based on older phenotypic and morphological approaches to describing taxonomy.
Currently the genus Enterobacter comprises a large and heterogenous group of organisms within the Enterobacteriaceae family being accounted for by 16 distinct species. Enterobacter sakazakii (E. sakazakii) is one of these species and the only member of the genus recognised as a food-borne pathogen. Following a revision of Enterobacter taxonomy, a new genus Cronobacter was devised which is synonymous with E. sakazakii. Cronobacter consists of a least five distinct species and an additional genomospecies, Cronobacter sakazakii (C. sakazakii), C. dublinensis, C. malonaticus, C. muytjensii, C. turicensis and C. genomospecies I. A further three sub-species of C. dublinensis are also recognised. Correct identification of these organisms is important in order to improve our understanding of the broader epidemiology of the members of this new genus.
In recent years there have been rapid improvements in the provision of microbiologically-based culture approaches to isolate and identify these organisms. A number of molecular identification methods have also been proposed, however the recent recognition of multiple species that share less than 70 percent DNA-DNA similarity has important implications for the sensitivity and specificity of these methods. In this paper, three examples of the application of molecular-based detection strategies for the identification of Cronobacter will be presented.
These will include strategies to identify the genus, specific targets that are thought to be related to pathogenicity and the development of a molecular-based approach to begin to define the O-serotypes of C. sakazakii. Although by no means complete, these examples will illustrate some of the current and future challenges to enable a more refined and reliable molecular-based approach to the identification of all Cronobacter spp.
The development of appropriate molecular methods will facilitate not only a rapid identification of an isolate, but in addition complement the more traditional microbiological-based methods.
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