Scottish Government

EXECUTIVE SUMMARY

The aims of this tender were to determine whether biofilm samples supplied by Scottish Water and removed from five sites in the Scottish water distribution network contained Helicobacter pyloriDNA by PCR amplification and sequence analysis.

Biofilm samples were subjected to DNA extraction followed by H. pylori-specific PCR analysis and sequencing. All biofilm samples previously identified as negative for H. pyloriDNA were found to be negative by PCR. Two out of 15 biofilm samples (removed from two sites in the water distribution network) that had yielded a positive PCR result in previous studies yielded a positive PCR result with our assay. The biofilm samples that yielded a positive PCR reaction for H. pyloriDNA were subjected to sequence analysis to determine their identity. The identity of the sequenced DNA was determined by matching it to published DNA sequences using the BLAST database.

Of the two positive PCR results obtained the percentage sequence match from biofilm sample 1264C to a segment of the 16S r RNA gene of H. pylori was 100% and the top ten matches for the DNA sequence were all for the 16S r RNA gene of H. pylori.

The percentage sequence match obtained from biofilm sample 1264C was 93% but the top ten matches for the DNA sequenced were all for the 16S r RNA gene of H. pylori.

Our results show, using the methods outlined above, that H. pyloriDNA was present in biofilm samples taken from the Scottish drinking water supply. Further work is needed to ascertain both the extent of the presence of H. pylori and its public health significance. A summary of these findings is provided in Table 1.

Table 1: A summary of the PCR and sequencing results obtained in comparison to previous findings