Assessment of optimal atmospheric conditions for growth of Helicobacter pylori

The number and diameter of colonies of Helicobacter pylori isolates growing on agar plates were determined to compare five methods that produce a culture atmosphere. No catalyst was applied. No significant difference was found between two hydrogen-based kits that have a different capacity for production of H2. These hydrogen-based methods were significantly better than all others evaluated, including one kit that produces ascorbic acid that binds with oxygen. Growth was significantly improved when the atmosphere outside the plastic incubation jars was enriched with 10% CO2, but carbon dioxide enrichment alone (i.e., no reduction of the oxygen concentration) gave a very poor yield. The colony diameter was a sensitive and reliable measure of atmospheric conditions, as the mean intra- and interobserver difference between repeated readings was < or = 0.1 mm for 82% and < or = 0.2 mm for 95% of the isolates.