Biofilms and Helicobacter pylori: Dissemination and persistence within the environment and host

Abstract

The presence of viable Helicobacter pylori (H. pylori) in the environment is considered to contribute to the levels of H. pylori found in the human population, which also aids to increase its genetic variability and its environmental adaptability and persistence. H. pylori form biofilms both within the in vitro and in vivo environment. This represents an important attribute that assists the survival of this bacterium within environments that are both hostile and adverse to proliferation. It is the aim of this paper to review the ability of H. pylori to form biofilms in vivo and in vitro and to address the inherent mechanisms considered to significantly enhance its persistence within the host and in external environments. Furthermore, the dissemination of H. pylori in the external environment and within the human body and its impact upon infection control will be discussed.

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

“…These authors have thus suggested the ability of H. pylori to produce self-inhibiting substances with bacteriostatic activity. It appears, however, that the effect of the apparent inhibition of the bacteria was due to the transition of the microorganisms into the VBNC state, which in the case of H. pylori is connected with spiral-to-coccoid transformation (9,10,14,22,33). Cis-2-tetradecenic acid (C 14 :Δ 2 ), which is produced by X. fastidiosa, is responsible for biofilm formation and autoaggregative behavior associated with the increased synthesis of hemagglutinin-like HxfA/B proteins.…”

“…This is supported by chemotaxis away from AI-2 and protons and towards nutrients (amino acids and metal ions), urea, and HCO 3 -. In addition, the spiral shape enables effective penetration of mucin (6,22,31). After bacterial proliferation in the gastric mucosa, microorganisms enter the stationary phase accompanied by a decrease in AI-2 concentration and an increase in DSFs autoinductive activity.…”

“…The transition of spiral H. pylori forms, exposed to unfavourable environmental conditions, to more resistant coccoid forms is relatively well documented (9,11,22). Still, many controversies have arisen regarding the possibility of reversing bacteria from the VBNC state to the culturable state through a process called resuscitation (24).…”

“…The spherical forms display enhanced survival capabilities as shown by the increased potential for autoaggregation, biofilm formation, and biocide resistance. Furthermore, the coccoid forms are also responsible for creating a carcinogenic environment in the stomach (14,22,31,33). The late form of H. pylori biofilm is associated with low nutrient levels and elevated concentrations of AI-2 (17,31,32).…”

“…Spiral and coccoid forms of H. pylori enter the human stomach. Coccoid forms, which are exposed to stimulatory/ stress-inducing factors that occur in this environment and are induced by AI-2 secreted by the gastric microflora, are converted from the spherical to the spiral form (9)(10)(11)13,14,22,29,48,49). The possible lack of AI-2 stimulation causes H. pylori to remain in the coccoid form with the decreased ability to adhere to and penetrate the mucosa, potentially contributing to the removal of this bacterium from the human body (6).…”