Intensive research has revealed that 50% of the world’s population is infected by Helicobacter pylori (H. pylori). However, co-infection of Helicobacter species has not been thoroughly investigated. The literature indicates that non-H. pylori (non-HP) Helicobacter species can be detected in 0.2-6% of human gastric biopsies. Although Helicobacter species are generally host specific, they can jump between host species. The non-HP Helicobacter species detected in humans are thought to be acquired through zoonotic transmission.
Non-HP Helicobacter species may have clinical significance in patients. Studies have shown as association between infection with typically benign Helicobacter and disease in immunocompromised individuals. However, co-infection with H. pylori was not definitively rules out in these cases, In addition, co-infection may result in H. pylori acquiring antibiotic resistance genes given it has a natural competence to uptake foreign DNA. Coinfection could provide a broad gene pool reservoir for recombination leading to unpredictable antibiotic resistant patterns. Further, although it has been assumed that presence of enterohepatic (non-stomach) Helicobacter species in the gut is not clinically significant, they still possess a potential risk for gastric colonization.
How common are these bacteria? We routinely culture antibiotic resistant strains of H. pylori and occasionally fail to culture strains from patients with positive breath, serology and CLO tests. These may actually be other species. The fastidious nature of non-HP Helicobacter may render them difficult to culture in vitro.
In this study we used next generation sequencing technology to perform a targeted sequencing protocol to study the prevalence of non-HP Helicobacter infections. Preliminary results unsurprisingly showed traces of H. pylori in our patients. However, we also detected H. felis, H. acinonychis and H. heilmanii in patients’samples. Some individuals carried co-infections.
The effects of co-infection with different Helicobacter spp. will be important in understanding the pathogenesis, biology and evolution of H. pylori.