Antagonistic effects of Lactobaccilus casei subspecies casei on Helicobacter pylori

Background: Helicobacter pylori is a gram negative curved bacterium, inhabited in gastric
mucosa where it remains for years. It causes several diseases such as gastritis and peptic ulcer. Its
conventional treatment is antibiotics therapy; however there are other methods under investigation
by probiotic micro organisms like Lactobacilli. It is reported that Lactobacilli supernatant inhibits
H. pylori growth. In the present study, inhibitory effects of a subspecies of Lactobacillus genus, L.
casei casei, on H. pylori growth in a mix culture was investigated.
Materials & Methods: The study was performed in 2002, using a gel stabilized system. This system
consisted of two layers including a solid PYS (peptone yeast extract salt solution) medium
containing 1.5% agar plus 2% glucose at the bottom and a semi-solid PYS medium (0.75% agar
without glucose but certain number of washed bacterial cells) on the top, all in a 30 ml tubes. In
this system, L. casei casei and H. pylori were cultivated alone and in mix cultures. Samples from
cultures were taken by sterile cork borers, each core was sectioned into smaller size, on which
viable counts, pH, glucose concentration and optical density were determined and compared to
each other.
Results: The investigating organism in this system produced growth band in the semi-solid layer.
The growth position (growth bands), number of viable cells, optical density and pH in the mix
culture of H. pylori plus L. casei casei were similar to those in the culture of H. Pylori alone.
Conclusions: The results indicated that, L. casei casei can not prevent H. pylori growth in the mix
culture and is not a good candidate as a probiotic against H. Pylori.