Biofilm Formation by and Thermal Niche and Virulence Characteristics of Escherichia spp.

Abstract

ABSTRACTIn order to better understand the ecological and virulence characteristics of the various clades ofEscherichia,in vitroandin vivoexperiments were undertaken. Members of the recently described cryptic clades ofEscherichia(clades III, IV, and V) were found to have an enhanced ability to form biofilms compared to strains ofEscherichia coli,E. fergusonii, orE. albertii. Members of the cryptic clades were also able to replicate at a lower temperature (5°C versus 11°C) than strains of the named species ofEscherichia. Neither a strain's maximal growth rate nor its optimal temperature for growth varied with respect to the strain's phylogenetic affiliation.Escherichiastrains not belonging to the speciesE. coliwere positive for a mix of traits thought to enhance a strain's ability to cause either intestinal or extraintestinal disease. However, no non-E. coliEscherichiastrain was virulent in a mouse model of extraintestinal infection. The frequency of resistance to antibiotics was low, and none of the strains tested harbored class 1, 2, or 3 integrons. The results of these experiments support the hypothesis that members of the crypticEscherichiaclades may be better able to persist in the external environment compared toE. coli,E. fergusonii, orE. albertii, isolates.