Helicobacter - Non-pylori Helicobacter Species

Non-pylori Helicobacter Species

Recently, new gastric (Helicobacter suis and Helicobacter baculiformis) and enterohepatic (Helicobacter equorum) species have been reported. Helicobacter pylori is of primary importance for medicine; however, non-pylori Helicobacter species (NPHS), which naturally inhabit mammals (except humans) and birds, have been detected in human clinical specimens. NPHS encompass two (gastric and enterohepatic) groups, showing different organ specificity. Importantly, some species such as Helicobacter hepaticus, Helicobacter mustelae and, probably, Helicobacter bilis exhibit carcinogenic potential in animals. NPHS harbour many virulence genes and may cause diseases not only in animals but also in humans. Gastric NPHS such as H. suis (most often), Helicobacter felis, Helicobacter bizzozeronii and Helicobacter salomonis have been associated with chronic gastritis and peptic ulcers in humans and, importantly, with higher risk for MALT lymphoma compared to H. pylori. Enterohepatic species e.g., H. hepaticus, H. bilis and Helicobacter ganmani have been detected by PCR in but still not isolated from specimens of patients with hepatobiliary diseases. Moreover, NPHS may be associated with Crohn's disease, inflammatory bowel disease and ulcerative colitis. The significance of avian helicobacters (Helicobacter pullorum, Helicobacter anseris and Helicobacter brantae) also has been evaluated extensively. NPHS such as Helicobacter cinaedi and Helicobacter canis can cause severe infections, mostly in immunocompromised patients with animal exposure. Briefly, the role of NPHS in veterinary and human medicine is increasingly recognised. However, despite the growing interest in the possible association between NPHS and the chronic hepatobiliary or intestinal diseases in humans, more studies are still required to prove the suggested association. Several other topics such as isolation of still uncultured species, antibiotic resistance and treatment regimens for NPHS infections and, last but not least, NPHS pathogenesis and possible carcinogenesis in humans should be additionally evaluated.