Escherichia albertii : the still unfolding journey of a misdiagnosed pathogen that became a new species and a new member of the family of attaching and effacing enteric bacterial pathogens

SUMMARY Escherichia albertii, initially identified as Hafnia alvei , by the commercial identification biochemical strip, API 20E, was isolated from an infant with diarrhea in Bangladesh in 1989. However, this bacterium was later renamed as a novel species, E. albertii (after M. John Albert, the discoverer) because of its similarities in biochemical and genetic properties to the genus Escherichia , but different from those of any known species in the genus. E. albertii possesses many pathogenic attributes, including a key one, which is the ability to produce attaching and effacing (A/E) lesions in the intestinal mucosa mediated by genes on a 35kb pathogenicity island called the locus of enterocyte effacement. Therefore, it is a member of the family of A/E pathogens. Some of the initially reported enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli (EHEC), Shigella boydii O13, and cytolethal distending toxin II-producing E. coli (CTEC-II) were later confirmed as E. albertii. E. albertii caused sporadic cases of diarrhea and diarrheal outbreaks and rarely extraintestinal infections. E. albertii was also associated with the death of birds in Scotland, UK, and Alaska in the USA. Not only birds (including chickens) but also mammals, including raccoons, seem to be major reservoirs of E. albertii, suggesting that E. albertii is an emerging zoonotic pathogen. Specific detection methods and selective and differential media for E. albertii have been developed for diagnosis. Several E. albertii isolates have been sequenced, revealing key characteristics of the organism. However, there are still many gaps in knowledge that exist regarding this bacterium. In this review, we will describe what is known about some key facets of this bacterium but also directions of future research to fill the knowledge gap.