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Journal of Clinical Microbiology, 12 1996, 2973-2979, Vol 34, No. 12
A Ismaili, B Bourke, JC de Azavedo, S Ratnam, MA Karmali and PM Sherman
Hafnia alvei is an emerging human pathogen associated with sporadic cases
and outbreaks of diarrhea. Bangladeshi isolates of H. alvei possess the
Escherichia coli attaching and effacing (eaeA) gene and demonstrate an
attaching and effacing phenotype. In the present study we examined 11
Canadian H. alvei isolates and strain 19,982 from Bangladesh to determine
if the formation of attaching and effacing lesions is a property shared
among multiple isolates. Attaching and effacing lesions were detected by
induction of tyrosine kinase protein phosphorylation and cytoskeletal
rearrangements in infected tissue culture epithelial cells with
immunofluorescence microscopy and by the examination of infected cells with
transmission electron microscopy. The presence of the eaeA gene was
examined by PCR and colony blot hybridization. Profiles of outer membrane
protein extracts, chromosomal macrorestriction fragments, and plasmids were
also examined. Accumulation of host phosphotyrosine proteins and
rearrangement of the cytoskeletal protein alpha-actinin were both observed
in HEp-2 cells infected with H. alvei 19,982. In contrast, none of the
other 11 clinical H. alvei isolates demonstrated either of these responses,
nor did they form attaching and effacing lesions under electron microscopy.
Consistent with the absence of the attaching and effacing phenotype, these
clinical isolates did not possess the eaeA gene. The outer membrane protein
profiles of all the Canadian isolates were identical but differed from that
of H. alvei 19,982. Pulsed-field gel electrophoresis and plasmid profile
analyses of the clinical H. alvei isolates differed substantially from
those of the Bangladeshi strain. These results indicate that there is
heterogeneity among H. alvei strains with respect to signal transduction,
attaching and effacing adhesion, outer membrane constituents, and genotype.
Epidemiological studies on enteropathogenic H. alvei thus need to go beyond
simple species designations and require specific identification of the
virulent clones.
Copyright © 1996 by the American Society for Microbiology. All rights reserved.
Heterogeneity in phenotypic and genotypic characteristics among strains of Hafnia alvei
Division of Gastroenterology and Nutrition, Hospital for Sick Children, Toronto, Ontario, Canada.
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