Assignment 2 : Introduction

Helicobacter pylori eradication by lactic acid bacteria

Stage1

Helicobacter pylori is a curve rod-shaped, Gram-negative, microaerophilic bacterium usually presented in the human stomach. It is a major cause of chronic gastritis and peptic ulcer disease. H. pylori is believed to associate with an increased risk of gastric carcinoma (Heavey and Rowland, 2004). It is classified to Class I (definite) biological carcinogen in humans by the International Agency for Research into Cancer (IARC) and the World Health Organization (WHO) (Park et al., 2004). The prevalence of H. pylori infection is high as 80% in developing countries and up to 40% in developed countries (Cover and Blaser, 1995; Dubois, 1995). At present, a combination therapies consisting of acid suppression drugs (proton pump inhibitors) and antibiotics (amoxicillin, clarithromycin, or nitroimidazoles) are used as a treatment for H. pylori eradication (Hamilton-Miller, 2003). However, antibiotic-based therapy would not be cost effective, cause side effect and would lead to widespread of antibiotic resistance (Michetti, 2001). For these reasons, this regimen is not recommended and the alternative strategies are developed to decrease H. pylori colonization.

Stage 2

Many studies reported that some strains of lactic acid bacteria showed antagonistic effect against H. pylori. Tsai et al. (2004) found that Enterococcus faecium TM39 isolated from infant faeces was able to inhibit the growth of H. pylori. Colonization of H. pylori could be reduced by ingestion of probiotic product containing Lactobacillus johnsonii La1 (Cruchet et al., 2003). In addition, chitosan microsphere containing the precipitant produced by L. casei ATCC 393 displayed growth inhibition and anti-adhesive activity on H. pylori (Ko et al., 2011).

Stage 3

However, the potential uses of probiotics especially, lactic acid bacteria to inhibit H. pylori infections, characterization of antimicrobial metabolites produced and their responsible mechanisms, are less documented.

Stage 4 & 5

Therefore, the objectives of this study was to select the most effective lactic acid bacteria for H. pylori eradication as well as to characterize the predominant antimicrobial metabolites secreted by selected strain. The final purpose was to evaluate the potential use of selected strain for H. pylori eradication in food products. Lactic acid bacteria may represent an approach to establish a harmless relationship with H. pylori. Approaches based on simple dietary changes are likely to meet public acceptance and may prove safer and cheaper than complex drug regimens.

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