RESUMEN
Background: Gastric microbiota is a complex ecosystem, composed by diverse microorganisms, where H pylori and Lactobacillus are relevant species. Aim: To study the probiotic properties of Lactobacillus spp isolated from gastric biopsies of subjects bearing or not H pylori. Materials and Methods: Gastric biopsies from 197 individuals that consulted for gastrointestinal disorders were cultivated in media specific for H pylori and Lactobacillus spp. Probiotic properties of lactobacilli isolates and histological diagnosis of H pylori colonized patients were performed. Results: Among 197 individuals evaluated, Hpylori was detected in 43 percent, Lactobacillus spp in 24 percent, while 8 percent presented both bacteria simultaneously. Forty one percent of the Lactobacillus spp strains produced hydrogen peroxide, S'3 percent presented a highly hydrophobic surface and 32 percent had an inhibitory effect upon Hpylori ATCC 43504, even greater than Lactobacillus LGG or LAL reference strains. The main pathological diagnosis of patients ivas chronic non-atrophic gastritis (73 percent) followed by intestinal metaplasia (19 percent). A similar proportion of both conditions were observed in patients colonized by Lactobacillus spp, while not colonized individuals developed preferentially chronic non-atrophic gastritis (p =0.002). Conclusions: Lactobacillus spp and H pylori were mutually excluded, suggesting a competitive colonization model between probiotic bacteria and pathogens.