HETEROGENEITY IN PHENOTYPIC AND GENOTYPIC CHARACTERISTICS AMONG STRAINS OF HAFNIA-ALVEI

Hafnia alvei is an emerging human pathogen associated with sporadic ca ses and outbreaks of diarrhea. Bangladeshi isolates of H. alvei posses s the Escherichia coli attaching and effacing (eaeA) gene and demonstr ate an attaching and effacing phenotype. In the present study we exami ned 11 Canadian H. alvei isolates and strain 19982 from Bangladesh to determine if the formation of attaching and effacing lesions is a prop erty shared among multiple isolates. Attaching and effacing lesions we re detected by induction of tyrosine kinase protein phosphorylation an d cytoskeletal rearrangements in infected tissue culture epithelial ce lls with immunofluorescence microscopy and by the examination of infec ted cells with transmission electron microscopy. The presence of the e aeA gene was examined by PCR and colony blot hybridization. Profiles o f outer membrane protein extracts, chromosomal macrorestriction fragme nts, and plasmids were also examined. Accumulation of host phosphotyro sine proteins and rearrangement of the cytoskeletal protein alpha-acti nin were both observed in HEp-2 cells infected with H. alvei 19982. In contrast, none of the other II clinical H. alvei isolates demonstrate d 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 poss ess the eaeA gene. The outer membrane protein profiles of all of the C anadian isolates were identical but differed from that of H. alvei 199 82. Pulsed-field gel electrophoresis and plasmid profile analyses of t he clinical H. alvei isolates differed substantially from those of the Bangladeshi strain. These results indicate that there is heterogeneit y among H. alvei strains with respect to signal transduction, attachin g and effacing adhesion, outer membrane constituents, and genotype. Ep idemiological studies on enteropathogenic H. alvei thus need to go bey ond simple species designations and require specific identification of the virulent clones.