Bacterial Population-level Virulence Factors

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Presenter:  Professor Garth D. Ehrlich

Date: Jun 15, 2017

Time: 12:00pm to 1:00pm

Contact person:  Melody Song; Menzies School of Health Research
T: (08) 8946 8485

Location:  Royal Darwin Hospital Campus, Seminar Room 013 (off the foyer of the Menzies Building)


Modern methods of analysis have demonstrated that bacterial growth patterns, ecology, and intra-species heterogeneity are more complex than were envisioned by early microbiologists. Laboratory methods of propagation were developed to study acute, epidemic infections; however, it is now recognized that the phenotype associated with these diseases represents only a minor aspect of what is a very complex bacterial life cycle, which consists of multiple phases including, but not limited to: planktonic, attachment, biofilm, and dispersal. In this study, we establish a new rubric, bacterial plurality, for the understanding of bacterial ecology and evolution with respect to chronic infection. The fundamental tenets of bacterial plurality are that the bacteria within an infecting population display multiple phenotypes and possess multiple genotypes. Phenotypic plurality is embodied in the biofilm paradigm and genotypic plurality is embodied in the concepts of the supra-genome and the distributed genome hypothesis. It is now clear that the ability of bacteria to generate diversity in situ during chronic infections provides bacterial populations the ability to persist in the face of a multi-faceted host response.


Dr Ehrlich is Professor of Microbiology and Immunology at Drexel University College of Medicine, USA.  Dr Ehrlich counts among his major contributions to science the re-writing of much of our understanding of chronic bacterial pathogenesis.  This began with his promulgation of the biofilm paradigm to explain many facets of chronic mucosal microbial infections. This was followed by his advancement of the Distributed Genome Hypothesis to explain the clinical variability among strains within bacterial species. These theoretical constructs together form the bases for his rubric of Bacterial Plurality.  More recently he has used statistical genetics to identify distributed bacterial genes that are associated with virulence.

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