Helicobacter pylori free‐living and biofilm modes of growth: behavior in response to different culture media

Abstract

The physiological behavior of Helicobacter pylori in different growth conditions was investigated to approach its growth standardization. H. pylori free-living and biofilm modes of growth were assessed in four different liquid culture media (Brucella broth, brain heart infusion broth and Ham's F-12 supplemented with 2% fetal calf serum and Ham's F-12 without serum). Free-living growth was monitored during 72 h in each medium and characterized for bacterial density, culturability, viability and morphology. The biofilm formation in the same media was evaluated for biomass production, colony forming unit (CFU) counts and microscopic visualization. Afterward, using Ham's F-12, the effect of amoxicillin and clarithromycin at sub- minimum inhibitory concentrations (sub-MICs) was evaluated on H. pylori biofilm formation and luxS gene expression. Differences in the free-living growth were observed between the media supplemented with serum and Ham's F-12 without serum. Biofilm formation was significantly dependent on the growth media used. Ham's F-12 seems to be a good medium to support both growth phenotypes of H. pylori. Moreover, sub-MICs of antibiotics increased the biofilm formation and affected the luxS gene expression. Optimizing the growth conditions of H. pylori, especially in the biofilm mode, will be helpful to perform more accurate in-depth studies that will allow increasing the knowledge about H. pylori biofilm, which should be a target to eradicate resistant infection.

Antibacterial and Antibiofilm Activities of Tryptoquivalines and Meroditerpenes Isolated from the Marine-Derived Fungi Neosartorya paulistensis, N. laciniosa, N. tsunodae, and the Soil Fungi N. fischeri and N. siamensis

“…These results are in agreement with those obtained in the biomass quantification for the same experimental conditions. However, this result is not unexpected since there are several reports of the increase in biofilm formation in both Gram-positive and Gram-negative bacteria in the presence of sub-inhibitory concentrations of antibiotics [18,19,20]. Interestingly, the BIC value of aszonapyrone A ( 4a ) was found to be higher than 12× MIC against mature biofilms of both S. aureus B1 (BIC > 96 µg/mL) and E. faecalis W1 (BIC > 192 µg/mL).…”

Characterization of Key Helicobacter pylori Regulators Identifies a Role for ArsRS in Biofilm Formation

“…While it is unclear exactly what drives biofilm formation in H. pylori, protection from antibiotics and host defenses during infection (35,38,39) and/or protection in putative environmental reservoir (40-43) have been proposed. Basic characterization has shown that in vitro biofilm formation is varied across strains (32) and appears to be induced under conditions, such as serum/nutrient starvation (44,45). Initial investigations of the extracellular polymeric substances (EPS) matrix observed in in vitro biofilms revealed the presence of lipids, amino acids, and monosaccharides.…”

A proposed role for diffusible signal factors in the biofilm formation and morphological transformation of Helicobacter pylori

“…The biofilm formation capacity was two-to three-fold better than in wild type strains with a functional luxS gene. The study investigating the effect of sub-MIC concentrations of antibiotics revealed the reduced expression of H. pylori luxS gene compared to the control bacteria not treated with antibiotic (20). These results suggest that there is an alternative way to control physiological changes in H. pylori exposed to environmental stress and that this system is associated with biofilm formation and conversion of bacteria to the coccoid form.…”