Determinants of Helicobacter pylori seroprevalence in Mexican adolescents

BACKGROUND

Helicobacter pylori infection is one of the most common human infections and is considered to play an etiologic role in several gastroduodenal diseases. In this study we determined the H. pylori seroprevalence among adolescents in Morelos, Mexico, and explored the association between seroprevalence and socioeconomic, dietary and lifestyle variables.

MATERIALS AND METHODS

A cross-sectional study was conducted in 5861 Mexican subjects aged 11-21 years. H. pylori infection was determined by an enzyme-linked immunosorbent assay previously validated in Mexico. A self-administered questionnaire was used to collect information on sociodemographic factors, housing, living conditions and food consumption. Multivariate logistic regression methods were used to obtain odds ratios and 95% confidence intervals.

RESULTS

The overall H. pylori seroprevalence was 47.6%; 40.6% in preadolescents (11-14 years), 48.6% in adolescents (15-17 years), and 59.8% in young adults (18-24 years). A positive association was found between age and H. pylori seroprevalence. Inverse associations were found for availability of drinking water, sewerage, and home appliances at the time of the subject's birth, a proxy variable of socioeconomic status. Intake of milk products and total fats was positively associated with infection.

CONCLUSIONS

This large seroprevalence study showed that H. pylori infection is frequent among adolescents in Mexico. An early acquisition of infection is indirectly suggested. Some variables denoting low socioeconomic status were inversely associated with H. pylori seroprevalence. Associations with intake of milk products and total fats suggest new hypotheses in this field of research.

Substrates' and products' inhibition in fructanase production by a new Kluyveromyces marxianus CF15 from Agave tequilana fructan in a batch reactor

This study focuses on fructanase production in a batch reactor by a new strain isolated from agave juice (K. marxianus var. drosophilarum) employing different Agave tequilana fructan (ATF) concentrations as substrate. The experimental data suggest that the fructanase production may be inhibited or repressed by high substrate (50 g/L) and ethanol (20.7 g/L) concentrations present in culture medium. To further analyze these phenomena an unstructured kinetic mathematical model taking into account substrate and products inhibition was proposed and fitted. The mathematical model considers six reaction kinetics and the ethanol evaporation, and predicts satisfactorily the biomass, fructan, glucose, fructose, ethanol, and fructanase behavior for different raw material initial concentrations. The proposed model is the first to satisfactorily describe the production of fructanase from branched ATF with a new strain of K. marxianus.