A Lothigius1, A Sjöling, A-M Svennerholm, I Bölin. 1. WHO Collaborating Centre for Research on Enterotoxigenic Escherichia coli (ETEC), and Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden. asa.lothigius@microbio.gu.se
Abstract
AIMS: In this study, the main objective was to verify the hypothesis of induction of 'viable but non-culturable' (VBNC) forms of enterotoxigenic Escherichia coli (ETEC) during incubation in water. METHODS AND RESULTS: Six clinically isolated ETEC strains were studied. Viable counts showed culturable ETEC bacteria for up to 3 months in freshwater but only two out of six strains were culturable in seawater at this time point. Although the bacterial cells remained intact, no production or secretion of heat-labile (LT) or heat-stable (ST) enterotoxins was observed using GM1-ELISA methods. However, genes encoding ETEC toxins (STh and LT), colonization factors (CS7 and CS17), gapA and 16S RNA were expressed during 3 months in both sea water and freshwater microcosms as determined by real-time RT-PCR on cDNA derived from the bacteria. CONCLUSIONS: Clinically isolated ETEC strains can survive for long periods in both sea water and freshwater. The bacterial cells remain intact, and the gene expression of virulence genes and genes involved in metabolic pathways are detected after 3 months. SIGNIFICANCE AND IMPACT OF THE STUDY: These results indicate that ETEC bacteria can enter a VBNC state during stressful conditions and suggest that ETEC has the potential to be infectious after long-term incubation in water.
AIMS: In this study, the main objective was to verify the hypothesis of induction of 'viable but non-culturable' (VBNC) forms of enterotoxigenic Escherichia coli (ETEC) during incubation in water. METHODS AND RESULTS: Six clinically isolated ETEC strains were studied. Viable counts showed culturable ETEC bacteria for up to 3 months in freshwater but only two out of six strains were culturable in seawater at this time point. Although the bacterial cells remained intact, no production or secretion of heat-labile (LT) or heat-stable (ST) enterotoxins was observed using GM1-ELISA methods. However, genes encoding ETEC toxins (STh and LT), colonization factors (CS7 and CS17), gapA and 16S RNA were expressed during 3 months in both sea water and freshwater microcosms as determined by real-time RT-PCR on cDNA derived from the bacteria. CONCLUSIONS: Clinically isolated ETEC strains can survive for long periods in both sea water and freshwater. The bacterial cells remain intact, and the gene expression of virulence genes and genes involved in metabolic pathways are detected after 3 months. SIGNIFICANCE AND IMPACT OF THE STUDY: These results indicate that ETEC bacteria can enter a VBNC state during stressful conditions and suggest that ETEC has the potential to be infectious after long-term incubation in water.
Authors: Matthew A Croxen; Robyn J Law; Roland Scholz; Kristie M Keeney; Marta Wlodarska; B Brett Finlay Journal: Clin Microbiol Rev Date: 2013-10 Impact factor: 26.132
Authors: Kelly K Baker; Reid Senesac; Daniel Sewell; Ananya Sen Gupta; Oliver Cumming; Jane Mumma Journal: Environ Sci Technol Date: 2018-08-27 Impact factor: 9.028