In Reply The gram-negative pathogen H pylori is specifically adapted to colonize the mucus layer of the human gastric mucosa. It therefore differs from other gram-negative bacteria in several respects. First, despite the induction of a strong local immune response in the gastric mucosa of colonized individuals, the bacterium establishes chronic infection lasting up to several decades. Second, it persists strictly as an extracellular pathogen. Third, due to the different lipid A acetylation of its lipopolysaccharide, it induces 500- to 1000-fold lower endotoxic activity compared with bacteria such as Salmonella typhimurium or Escherichia coli. Fourth, even in strongly immunosuppressed patients, H pylori never causes septicemia. Therefore, the immune response to infection by H pylori maintains a balance between host and pathogen as well as the innate and the adaptive immune systems.
Mayerle J, Kuipers EJ, Lerch MM. Genetic Variants Associated With Susceptibility to Helicobacter pylori—Reply. JAMA. 2013;310(9):976-977. doi:10.1001/jama.2013.194772