Hygiene monitoring biosensing systems in hospital environments

This thesis concerns the monitoring of biogenic impurities and hygiene in hospital environments by means of biosensing systems. The objective is to find biosensing systems applicable in hospital environments and able to identify pathogens that cause nosocomial infections, on surfaces, in the air and water. In the first part of the thesis, nosocomial infections were investigated, along with their prevalence, mortality, financial aspects and the most common microorganisms causing them. Furthermore. existing national and international nosocomial infection surveillance programmes, as well as organisations and journals associated with this field, were pinned down. Collaboration with the Meilahti Helsinki University Central Hospital enabled examination of their nosocomial infection status and familiarisation with their current prevention practices. The most important is good hand hygiene, trailed by, among others, pressurisation and filtration of air; limited use of tap water; and good overall cleanliness. Products that monitor or test the hygiene level are not in routine use. Three areas, where biosensing systems could be of use in a hospital, were identified. These are the ventilation system, the water distribution system and cleaning. The second part of the thesis discusses biosensing systems. Various methods were mapped in an overview of this field, comprising electrochemical, optical, microelectromechanical, nucleic acid- and cell-based systems. Based on this, the most promising methods – laser- and light-emitting diode-induced fluorescence and biocavity lasing – were explored further. These have the potential to detect microbes eminently fast, even in real time. Use of the fluorescence method to verify the functioning of filters in the ventilation system has been evaluated, as well as the biocavity laser's potential to validate the purity of water and the cleanliness of surfaces in conjunction with cleaning. Rapid biosensing systems based on the aforementioned novel