Detection of H. pylori in biofilms formed in a real drinking water distribution system using petide nucleic acid fluorescence in situ hybridization

Helicobacter pylori has previously been detected in real drinking water distribution systems (DWDS) using PCR based- techniques, but this approach will not discriminate between live and dead cells and their spatial relationship within the biofilm. On the other hand, in situ detection using fluorescence in situ hybridization (FISH) has been used successfully for spatial resolution but only in lab-grown experiments. In the present work, therefore, two flow cells were placed in a by-pass of the DWDS, and coupons were regularly removed for the detection of H. pylori by peptide nucleic acid (PNA) FISH, as well as for the assessment of CFU and total bacteria and visualization under scanning electron and epifluorescence microscopy. Chemical and physical parameters of the water feeding the flow cells were also monitored.Cells exhibiting similar morphology to H. pylori that were PNA FISH positive could be sparsely detected in the coupons. The technique showed promise despite the large morphologicalheterogeneity of microorganismspresent in biofilms and associated autofluorescence.Fundação para a Ciência e a Tecnologia (FCT)European Commission Research Project (SAFER