Non-Helicobacter pylori Helicobacter Species Associated with Human Disease: a Primer for the Clinical Microbiology Laboratory

Non-Helicobacter pylori Helicobacter species represent a broad list of 34 organisms, with only 14 convincingly associated with human infections. Additionally, a significant number of these species were discovered only in the last 10 years. Major limitations in our knowledge of these organisms and their clinical relevance adds to the difficulty of culturing and characterizing the species consistently in the clinical laboratory. Further complicating the clinical correlations of these species is the inconsistency in nomenclature exhibited in published studies, which serves as a barrier to creating a universal knowledge base in clinical microbiology laboratories. This article focuses on gastric and enterohepatic Helicobacter species, with particular attention devoted to Helicobacter heilmannii and Helicobacter cinaedi. Additional information is discussed for other, less common species for which clinical associations have been consistently reported.