Review: Other Helicobacter species

This article is a review of the most important, accessible, and relevant literature published between April 2018 and April 2019 in the field of Helicobacter species other than Helicobacter pylori. The initial part of the review covers new insights regarding the presence of gastric and enterohepatic non-H. pylori Helicobacter species (NHPH) in humans and animals, while the subsequent section focuses on the progress in our understanding of the pathogenicity and evolution of these species. Over the last year, relatively few cases of gastric NHPH infections in humans were published, with most NHPH infections being attributed to enterohepatic Helicobacters. A novel species, designated "Helicobacter caesarodunensis," was isolated from the blood of a febrile patient and numerous cases of human Helicobacter cinaedi infections underlined this species as a true emerging pathogen. With regard to NHPH in animals, canine/feline gastric NHPH cause little or no harm in their natural host; however they can become opportunistic when translocated to the hepatobiliary tract. The role of enterohepatic Helicobacter species in colorectal tumors in pets has also been highlighted. Several studies in rodent models have further elucidated the mechanisms underlying the development of NHPH-related disease, and the extra-gastric effects of a Helicobacter suis infection on brain homeostasis was also studied. Comparative genomics facilitated a breakthrough in the evolutionary history of Helicobacter in general and NHPH in particular. Investigation of the genome of Helicobacter apodemus revealed particular traits with regard to its virulence factors. A range of compounds including mulberries, dietary fiber, ginseng, and avian eggs which target the gut microbiota have also been shown to affect Helicobacter growth, with a potential therapeutic utilization and increase in survival.