Abstract

The influence of temperature on bacterial virulence has been studied worldwide from the viewpoint of climate change and global warming. The bacterium enteroaggregative Escherichia coli (EAEC) is the causative agent of watery diarrhea and shows an increasing incidence worldwide. Its pathogenicity is associated with the virulence factors aggregative adherence fimbria type I and II (AAFI and AAFII), encoded by aggA and aafA in EAEC strains 17-2 and 042, respectively. This study focused on the effect of temperature increases from 29 °C to 40 °C on fimbrial gene expression using real-time PCR, and on its virulence using an aggregative adherence assay and biofilm formation assay. Incubation at 32 °C caused an up-regulation in both EAEC strains 17-2 and strain 042 virulence gene expression. EAEC strain 042 cultured at temperature above 32 °C showed down-regulation of aafA expression except at 38 °C. Interestingly, EAEC cultured at a high temperature showed a reduced adherence to cells and an uneven biofilm formation. These results provide evidence that increases in temperature potentially affect the virulence of pathogenic EAEC, although the response varies in each strain.

Highlights

  • IntroductionTemperature is known to affect the growth and virulence of bacteria [5], and some studies have suggested a potential association between temperature and water-borne diarrheal diseases, which are a major cause of childhood mortality

  • Climate change has been described as a potential threat to the global population, especially to human health, and previous research has examined the effects of climate change parameters, such as precipitation, humidity, atmospheric pressure and temperature, on particular diseases and mortality [1,2,3].Surface water temperature was reported to be increasing both in temperate and tropical zones [4].Temperature is known to affect the growth and virulence of bacteria [5], and some studies have suggested a potential association between temperature and water-borne diarrheal diseases, which are a major cause of childhood mortality

  • enteroaggregative E. coli (EAEC) strains demonstrated markedly different expression trends, the higher expression level was observed in EAEC strain 17-2

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Summary

Introduction

Temperature is known to affect the growth and virulence of bacteria [5], and some studies have suggested a potential association between temperature and water-borne diarrheal diseases, which are a major cause of childhood mortality. The pathogenic enteroaggregative E. coli (EAEC) is the causative agent of diarrhea worldwide, especially among immunocompromised patients and children [8]. Patients exposed to EAEC from fecalcontaminated water sources can develop watery diarrhea symptoms caused by the attachment of bacteria to intestinal epithelial cells using fimbria and the release of toxins to destroy host cells [1,4,5,6,7,8]

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