LEADING ARTICLE DIGEST LIUER 01s 2002;39:2-8 Voyage of Helicobacter pylori in human stomach: odyssey of a bacterium V. Ricci R. Zarrillil M. Romano2 hwl Institute of Human Physiology, University of Pavia, Pavia; I Department of Cellular and Molecular Biology and Pathology “L. Califano”, Centre of Experimental Endocrinology and Oncology %. Salvamre” of CNR, “‘Federico II” University, Naples; 2 Department of Internal Medicine, Chair of Gastmentemlogy, Second University of Naples, Neples, Italy. Addme frrs cmrewandme Dr. M. Romano, Dipartimanto di Internistica Clinica e Sperimentale, Cattedra di Gastmentemlogia. Seconda Llniversit8 di Napoli, II Policlinico, Edificio 3, II piano, via Pansini 5, 80131 Napoli, Italy. Fax: +39-081-6666714. E-mail: marco.romano@unina2.it Work carried out in authors’ laboratories was supported in part by grants from Associazione ltaliana per la Ricerca sul Cancro, Byk Gulden, C.I.R.A.N.A.D., and Minister0 dall’Universit8 e dells Ricerca Scientifica e Tecnologica ICOFIN 2000 to L/R. and R.Z.1, Italy. Excellent artwork of M. Berardone is acknowledged. Authors regret that due to space limit8tions meny important papers have not been cited, and apologize for these omissions. Helicobacter pylori (H. pylori) has come a long way since it was first cul- tured from gastric biopsy specimens by Warren and Marshall in 1982 and is now recognized as the major player in a wide spectrum of gastric diseases ranging from asymptomatic gastritis, to peptic ulcer disease, adenocarcino- ma of the distal stomach, and gastric mucosa-associated lymphoid tissue (MALT) lymphoma ’ ?. Thus, H. pylori is now considered as a true bacteri- al pathogen, an organism able to induce disease in an immunocompetent host after developing an infection (i.e., successful and persistent coloniza- tion) 3. Many aspects of this intriguing bacterium, including its genoma, have been unravelled and the complex scenario of the events related to the response of the host to the infection is being clarified. However, several clinically rele- vant questions still remain unanswered. Should we always consider H. py- lori as a pathogen or might this bacterium have also symbiotic features J? Are all H. pylori strains equal? Should we seek and treat H. pylori infection even in asymptomatic subjects, irrespective of the underlying gastric dis- ease? Is H. pylori really protective to the lower oesophagus and proximal stomach while being harmful to the distal stomach? The purpose of this article is far from attempting to find a clue to these is- sues, but will be mainly focused on describing, step by step, what happens once H. pylori has gained access to our stomach. Like any skilled seaman, H. pylori has developed properties enabling it to: 1) successfully sail the hostile sea represented by the gastric lumen, 2) reach a safe harbour where to it can dock firmly and gain access to food and beverages, 3) defend itself from its enemies, 4) create a good and safe environment for a comfortable life. How H. pylori sails the gastric lumen It is now generally accepted that the bug must gain entry to the stomach via the mouth, humans being the principal reservoir. Most of the infections oc- cur during childhood, and seem to be decreasing with improvements in hy- giene practices 5. The person-to-person mode of transmission is supported by the higher incidence of infection among institutionalised children and adults and the clustering of H. pylori infection within families 5. No pre- dominant route of acquisition of H. pylori has been defined. Possibilities in- clude oral-oral, faecal-oral, iatrogenic, and vector transmission, the prepon- derance of each largely depending upon local factors. Data in support of oral-oral transmission are derived from a variety of observations. H. pylori has been isolated from the mouth, even though rarely 6. Moreover, acquisi- tion of H. pylori infection has been described both in a physician following mouth-to-mouth resuscitation of a H. pylori-infected patient ’ and in a bench researcher who put her fingers in her mouth after touching cell cul- tures experimentally colonized with H. pylori x. The possibility of faecal- oral spread of helical replicative forms or of coccoid forms of the bacteri- um remains under debate, but there are few data to support the concept. It has also been hypothesized that H. pylori infection might be transmitted sexually via oral-genital contact, with the human vagina acting as a reser- 2