Helicobacter pylori is one of the commonest bacterial infections of mankind (Holcombe et al 1992). It is primarily acquired in early life and may be associated with malnutrition (Sullivan et al 1990) and growth retardation in children (Patel et al 1994). Infection is usually life-long, may lead to chronic gastritis, duodenal ulceration (National Institutes of Health 1994) and gastric cancer in later life (Eurogast Study Group 1993).
Several community and environmental studies have suggested that water may play a role in the transmission of H. pylori (Hegarty et al 1999; Hulten et al 1998; Hulten et al 1996; West et al 1992; Klein et al 1991). H. pylori has been cultured from human faeces (Parsonet et al 1999; Thomas et al 1992) and may reach water destined for human consumption. H. pylori has been shown to colonise drinking water biofilms in laboratory studies (Mackay et al 1999). H. pyloriDNA has been amplified from drinking water in Peru (Klein et al 1991) and Sweden (Hulten et al 1998). Helicobacter sp. DNA has been amplified from biofilms removed from the water distribution network in Scotland (Park et al 2001). Water-induced coccoid forms of H. pylori remain infective (She et al 2003) and the presence of H. pylori in drinking water has been linked to human disease in two separate studies (Bunn et al 2002; Baker & Hegarty 2001). Epidemiological associations have been described between H. pylori colonisation and water quality in Peru (Klein et al 1991) and China (Brown et al 2002; Hopkins et al 1993).
In drinking water systems micro-organisms are predominantly associated with surfaces as biofilms. Biofilms consist of both micro- and macro-organisms embedded in an extracellular matrix of polysaccharides of microbial origin (Costerton et al., 1994). Water-borne enteric pathogens such as Escherichia coli (Mackerness et al., 1993) and Campylobacter spp. (Buswell et al., 1998) make use of biofilms as a vector and reservoir, but do not survive for prolonged periods in potable water (Buswell et al., 1998).
A scientific report submitted to the Scottish Official Research Unit in 2002 reported that H. pyloriDNA had been tentatively identified in biofilm samples collected from five sites in the Scottish water distribution network. However these studies were inconclusive since the amplified DNAs were not subjected to sequence analysis for final identification.
The aims of this tender were to determine whether biofilm samples removed from five sites in the Scottish water distribution network contained H. pyloriDNA by PCR amplification and sequence analysis.