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6 spectrum that includes E. coli, Acinetobacter, Flavobactrum, Pasteurella, and Ochrobactrum, as well as inhibition of molds. The growth of H. pylori was not enhanced by the presence of the various concentrations of ferrous sulfate, sodium pyruvate, or porcine mucin applied. Therefore these components were omitted from the final formulation. However, more rapid colony formation on HPSPA media was attributed to the presence of Special Peptone and calf serum with iron, so these remained as nutritional components. Increasing the levels of vancomycin or Cefsulodin above 10 mg/L resulted in retarding the growth of Helicobacter, as did increasing trimethoprim above 5 mg/L. Conversely, reducing below these levels allowed background contamination. Therefore these concentrations (as contained in the selective supplement) were considered optimal. Increasing the level of amphotericin B from 5 to 7.5 mg/L was adequate to broaden the spectrum to inhibit all apparent background bacteria. The addition of polymyxin B at 3500 International Units (IU) appreciably reduced the occurrence of mold contaminants while having little deleterious effects on H. pylori colony development. The novel color indicator system to differentiate H. pylori among non-urease producers greatly enhanced the utility of the media (Figure 1). Colony growth and subsequent urease production reduced urea to ammonium and bicarbonate, thus neutralizing a discreet area around each colony. This area of neutralization was marked by a zone of red around the colony as pH of the media changed from about 6.0 to >7.5. Incorporating the color indicator accelerated presumptive identification of H. pylori colonies by at least 12 hours (from 84 down to 72 hours). The final formulation of HP agar is listed in Table 4. FIGURE 1. Helicobacter pylori on HP or Brain Heart Infusion agar plates.