Effect of pH in the survival of Lactobacillus salivarius strain UCO_979C wild type and the pH acid acclimated variant

Background Bacterial acclimation involves cellular changes permitting the survival of a microorganism to prolonged acid pH exposure. The general aim of this work is to support this idea by determining the effect of pH in the survival of the human gastric derived probiotic strain Lactobacillus salivarius UCO_979C-1 (wild type) and L. salivarius UCO_979C-2 (acclimation to pH 2.6), which possesses anti-Helicobacter pylori properties. Results To assess this aim, the exopolysaccharide production through the phenol-sulfuric acid method was evaluated. Moreover, morphological and structural changes by transmission and scanning electron microscopy were observed. The bacterial survival was measured by viable count. The results showed that the acclimated variant strain synthesized higher levels of exopolysaccharide (690 ± 0.03 mg/L) more than the wild type (450 ± 0.12 mg/L). In addition, the acclimated variant preserved the viable count at pH 2.6 for 48 h, whereas the wild type strain decreases after 6 h and was non-viable at 24 h. Conclusion The results suggest that the acid stress acclimation of the strain L. salivarius UCO_979C-1 modified some cellular properties making this strain potentially useful as a gastric probiotic.

Prevalencia de Helicobacter pylori y de genes asociados a virulencia en biopsias gástricas / Prevalence of Helicobacter pylori virulence genes in gastric biopsies in Chilean patients over a 10-year period

Introducción: La detección de genes asociados a virulencia en Helicobacter pylori constituye un buen marcadorgenético para predecir riesgo de enfermedades asociadas a la persistencia del patógeno. Objetivos: Determinar la prevalencia de cagA, vacA, babA2, iceA y dupA en pacientes chilenos, durante 10 años de seguimiento. Métodos: Se analizaron las biopsias gástricas de 1 577 pacientes (183 niños) obtenidas entre enero de 2003 y diciembre de 2007, mediante PCR convencional y cultivo bacteriano. En 374 individuos positivos se investigó la prevalencia de cagA, vacA (s1a, s1b, s2, m1, m2, i1 e i2), babA2, iceA (1 y 2) y dupA. Resultados: La prevalenciade H. pylori en adultos fue 48.7% y un 23.7% de los pacientes presentó más de un cepa bacteriana. La prevalenciapor genes fue: cagA 29.4%, vacAm1 52.7%, vacAm2 61.8%, vacAs1a 46.5%, vacAs1b 28.3%, vacAs2 41.7%, vacAi1 30.9%, vacAi2 12.0%, babA23.5%, iceA1 30.5%, iceA2 61.2% y dupA 28.9%. Se observó un 90% de concordancia en la prevalencia delos genes hpy, cagA, babA2, iceA e iceA2, y un 67.6% para vacAs1a, cuando se comparó biopsia y cultivo como fuente de ADN. Conclusiones: La mayoría de los genes de virulencia han mantenido su prevalencia en el tiempo,excepto vacAm1 y babA2 que la han aumentado. Sin embargo, la prevalencia de babA2 continúa siendo muy baja.

Background: Genes associated with virulence in Helicobacter pylori are good markers for prediction of risk of developing diseases due to persistent infection. Aim: To establish the prevalence of cagA, vacA, babA2,iceA and dupA among Chilean patients over a 10-year period. Methods: 1 577 gastric biopsies (183 children), collected from January 2003 to December 2007, were analyzed by conventional PCR and bacteriological culture. The prevalence of the genes cagA, vacA (s1a, s1b, s2, m1, m2, i1 and i2), babA2, iceA (1 and 2) and dupA were investigated in 374 positive individuals. Results: Prevalence of H. pylori in adults was 48.7%, with 23.7% of them presenting more than one infecting strain. Prevalence of genes was as follows: cagA 29.4%, vacAm152.7%, vacAm2 61.8%, vacAs1a 46.5%, vacAs1b 28.3%, vacAs2 41.7%, vacAi1 30.9%, vacAi2 12.0%, babA2 3.5%, iceA1 30.5%, iceA2 61.2% and dupA 28.9%. Ninety percent of agreement was observed in the prevalence of genes hpy, cagA, babA2, iceA and iceA2, by using DNA from both sources, but was only 67.6% for vacAs1a gene. Conclusion: The results suggest that all the genes conserved their prevalence in this period with the exception of vacAm1 and babA2, in which there was increased prevalence. Nonetheless, the prevalence of the gene babA2 continues to be very low.