Campylobacter mustelae, a New Species Resulting from the Elevation of Campylobacter pylori subsp. mustelae to Species Status

The name Campylobacter pylori subsp. mustelae was recently proposed for strains belonging to the genus Campylobacter that were isolated from the gastric mucosa of ferrets because of the high levels of deoxyribonucleic acid relatedness (85 to 100%) of these strains to the type strain of Campylobacter pylori. Subsequent deoxyribonucleic acid relatedness studies done independently in three laboratories by three different methods indicate that the original results were in error. Strains isolated from ferrets in the United States, England, and Australia are members of a single species that is substantially different from C. pylori (10 to 20% relatedness at 50°C and 3 to 10% relatedness at 65°C as determined by the hydroxyapatite method; less than 10% relatedness at 65°C as determined by the nylon membrane blot method; and 30 to 49% relatedness at 66 to 68°C as determined by the spectrophotometric method). The strains isolated from ferrets also differ from human C. pylori strains in their ability to reduce nitrates, their negative leucine arylamidase reaction, their susceptibility to nalidixic acid, and their resistance to cephalothin. The strains from ferrets possess both polar and lateral flagella, whereas only polar flagella have been demonstrated in human C. pylori strains. Thus, the strains isolated from ferrets are members of a species that is distinct from C. pylori, and we propose elevating C. pylori subsp. mustelae to species status as Campylobacter mustelae sp. nov.