Nutritional requirements and antibiotic resistance patterns of Helicobacter species in chemically defined media

The growth of the gastric pathogen Helicobacter pylori in the absence of serum remains challenging, and nutritional requirements have only partially been defined, while almost nothing is known about nutritional requirements of other Helicobacter spp. Although previous data showed that H. pylori grows in the chemically defined medium F-12, but not in other tissue culture media examined, the specific components responsible for growth were not entirely understood. Here we describe the optimization of amino acids, metals, and sodium chloride for H. pylori. Iron, zinc, and magnesium were critical for growth; copper was not required. Optimization of sodium chloride was further beneficial. Nutritional requirements and antibiotic resistance patterns of several other Helicobacter spp. revealed that all except H. felis grew in serum-free, unsupplemented F-12. All Helicobacter spp. were resistant to at least six antimicrobial agents when cultured in the presence of serum. However, in the absence of serum, H. pylori, H. mustelae, and H. muridarum became sensitive to polymyxin B and/or trimethoprim. Much of the data were obtained using a convenient ATP assay to quantify growth. H. pylori has surprisingly few absolute requirements for growth: 9 amino acids, sodium and potassium chloride, thiamine, iron, zinc, magnesium, hypoxanthine, and pyruvate. These data suggest that H. pylori and other Helicobacter spp. are not as fastidious as previously thought. The data also suggest that chemically defined media described herein could yield the growth of a wide range of Helicobacter spp., allowing a more detailed characterization of Helicobacter physiology and interactions with host cells.