Cholesterol incorporation into membrane protects H. pylori against stresses. Culture of spiral H. pylori in brucella broth (BBR) containing 250 µM cholesterol produced mucoid colonies with coccoid bacteria (m-coccoids). Since H. pylori do not metabolize cholesterol as a carbon source, we examined the possible role of cholesterol or its water-soluble impurity cholesterol sulfate as signaling molecules. Cultures of spiral H. pylori in BBR containing 50–250 µM cholesterol were examined for bacterial growth and morphology. After 72 h microaerobic incubation, a 50-µL volume of each culture was surface-inoculated on brucella blood agar (BBA). After 72 h, cultures of H. pylori in 150 and 250 µM cholesterol produced m-coccoids on BBA. Compared with spiral H. pylori, m-coccoids exhibited enhanced motility, flagellation, biofilm formation, expression of signaling genes, hom B, lep A and lux S and resistance to 65 °C, pH 2–4, 10% NaCl, oxygen, antibiotics and atorvastatin (ATV). Looking for the time point when spiral H. pylori turned into m-coccoids, ATV was added every 6 h to cultures of spiral H. pylori in BBR containing 250 µM cholesterol up to 72 h. A 50-µL volume from each tube was inoculated on BBA for bacterial morphology and colony characteristics. Cultures of spiral H. pylori with ATV added before 54 h produced pinpoint colonies however those with ATV added after 54–72 h produced m-coccoids. Cholesterol sulfate may have activated signaling systems in H. pylori that resulted in spiral transformation into m-coccoids with resistance to stresses. Cholesterol sulfate availability in stomach may be among the reasons for selective colonization of H. pylori.
Godini et al. (Sat,) studied this question.