Development and evaluation of a new growth medium for Helicobacter pylori

Abstract

The present study was aimed at modifying the original formulation of Commercial Eugon agar (CEA) to develop a new H. pylori growth medium. Initial studies were carried out to determine the number of H. pylori colonies recovered on in-house H. pylori agar (IHPA), IHPA without l-cysteine and sodium sulfite (IHPA-NC), IHPA without l-cysteine (IHPA-C), IHPA without sodium sulfite (IHPA-N) and CEA as the control. Significant differences (P<0.001) in the number of colonies recovered were observed between IHPA-N, IHPA-NC and IHPA-C. Incorporation of sodium sulfite decreased the number of colonies recovered, indicating that sodium sulfite was inhibitory to H. pylori growth. Removal of l-cysteine reduced the number of colonies recovered, suggesting that l-cysteine is necessary for the growth of H. pylori. In the subsequent study, incorporation of K2HPO4 further increased the number of colonies recovered compared with IHPA-N (P<0.001), and 0.25% (w/v) of K 2HPO4 yielded the highest numbers of colonies (P≤0.04). Finally, thirty other H. pylori clinical isolates were evaluated for their growth in the IHPAP-N, a new medium consisting of 1.5% (w/v) pepticase, 0.5% (w/v) peptone, 0.4% (w/v) sodium chloride, 0.03% (w/v) l-cysteine, 0.55% (w/v) dextrose, 0.25% (w/v) K2HPO4 and 1.5% (w/v) agar. The number of colonies recovered in IHPAP-N was significantly (P<0.005) higher than that of CEA. IHPAP-N with 0.25% K2HPO4 and without sodium sulfite were adequate solid media for the growth of H. pylori. © 2009 Federation of European Microbiological Societies.