Hafnia alvei

Hafnia is a genus of Gram-negative, facultatively anaerobic, rod-shaped bacteria in the family Enterobacteriaceae. H. alvei is a commensal of the human gastrointestinal tract and not normally pathogenic, but may cause disease in immunocompromised patients. It is often resistant to multiple antibiotics, including the aminopenicillins. The name comes from Hafnia, the Latin name for Copenhagen. Hafnia alvei is used as a lactic ferment by the dairy industry and more recently as a probiotic included in a dietary supplement product. The genus Hafnia is one of more than 40 genera that currently comprise the family Enterobacteriaceae. Although Møller originally described this genus in 1954, the legitimacy of this group was constantly challenged over the next two decades, often being referred to by synonyms such as “Enterobacter alvei”, “Enterobacter aerogenes subsp. hafniae” and “Enterobacter hafniae” but it is mostly referenced by its current name, Hafnia alvei, in the literature. In 1977, a study concluded that at the end of Camembert manufacturing Hafnia alvei remains as the dominant species. Hafnia alvei is a psychrotrophic strain, which can develop at low temperatures, meaning that it doesn’t stop growing during the storage phase of cheese unlike E. coli. In 1983, Enterobacteriaceae were discovered in freshly produced Camembert: 51% of the identified Enterobacteriaceae were Hafnia alvei strains compared to only 9% of Escherichia coli. These authors also showed that Hafnia alvei grew to a high concentration in cheese (up to 107 CFU/g), in both raw milk and pasteurised milk cheeses.