In Vitro Incorporation of Helicobacter pylori into Candida albicans Caused by Acidic pH Stress

Abstract

Yeasts can adapt to a wide range of pH fluctuations (2 to 10), while <i>Helicobacter pylori</i>, a facultative intracellular bacterium, can adapt to a range from pH 6 to 8. This work analyzed if <i>H. pylori</i> J99 can protect itself from acidic pH by entering into <i>Candida albicans</i> ATCC 90028. Growth curves were determined for <i>H. pylori</i> and <i>C. albicans</i> at pH 3, 4, and 7. Both microorganisms were co-incubated at the same pH values, and the presence of intra-yeast bacteria was evaluated. Intra-yeast bacteria-like bodies were detected using wet mounting, and intra-yeast binding of anti-<i>H. pylori</i> antibodies was detected using immunofluorescence. The presence of the <i>H. pylori</i> rDNA 16S gene in total DNA from yeasts was demonstrated after PCR amplification. <i>H. pylori</i> showed larger death percentages at pH 3 and 4 than at pH 7. On the contrary, the viability of the yeast was not affected by any of the pHs evaluated. <i>H. pylori</i> entered into <i>C. albicans</i> at all the pH values assayed but to a greater extent at unfavorable pH values (pH 3 or 4, <i>p =</i> 0.014 and <i>p =</i> 0.001, respectively). In conclusion, it is possible to suggest that <i>H. pylori</i> can shelter itself within <i>C. albicans</i> under unfavorable pH conditions.