Visual display of the Development and application of a plating media for detection of Helicobacter pylori in water

				
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.