| Abstract |
Introduction
According to the estimates of the World Health Organization, 663 million people remain without access to controlled and protected drinking water supplies. Even more, they have no access to safe drinking water, with at least 1.8 billion people using fossil-source water sources. For this reason, since 2004 the WHO has recommended the implementation of water safety plans (WSPs) as the most appropriate means of reducing the contamination of drinking water and the risks to human health from aquatic diseases.
The objectives of this PhD thesis were: a) the sanitary investigation of the water supply networks in large public and private buildings in Crete; b) the control of the microbiological quality of water for human consumption in these and c) the evaluation of the WSPs of large hotels of the Region of Crete and on the other hand the exploration of the possibility of designing and implementing WSPs at major Public Hospitals of Crete.
Methods
Ninety four (94) hotel units in Crete have been selected at which even one case of Legionnaires' Traveler Disease (TALD) had been recorded through the European Legion Disease Surveillance Network (ELDSNet). Of these, 63 applied preventive water quality management measures in the context of the implementation of quality assurance systems (ISO 9000 and ISO 14000) and 31 did not apply any preventative program. Using a specific checklist, the water supply system of the buildings was assessed. A total of 132 hotels were explored throughout Crete from which, 3,311 environmental samples were taken.
In the context of the assessment of the water supply system of the Crete hospitals and the investigation of the possibility of designing water safety plans, a total of eight hospitals were inspected. Of these hospitals, 168 samples of water were taken for microbiological analysis from various clinics and sites. Also, 469 samples of water were taken to control the degree of colonization in Legionella spp. Finally, all the results from the samples of hotels and hospitals were tested using a unique code, linked and analyzed both by single-factorial and multifactorial analysis for the search for risk factors.
Results
According to the results of microbiological analyzes of 3,311 samples taken from 132 hotels, 685 (20.69%), deriving from 83 (62.89%) hotels, were positive (≥ 50 cfu / L) for Legionella spp. (L. pneumophilla serogroups 1-10, 12-14 and non-pneumophilla species (L. anisa, L. erythra, L. tusconensis, L. taurinensis, L. birminghamensis, L. rubrilucens, L. londiniesis). The colonization of the water supply systems of the Hotel units studied has shown a statistically significant correlation (p value <0.0001) with the following risk factors (RR> 1): non-application water safety plans, residual chlorine at a concentration of less than 0.2 mg / L, hotel star rating of less than 4 *, age of buildings and water supply networks.
Of the 168 water samples taken from hospitals for microbiological analysis, Escherichia coli was detected only in one (0.60%) sample of hospital water at a low concentration of 1 cfu / 100 mL. Enterococci were detected in three samples (1.79%) from three Hospitals at low concentrations, namely 1 cfu / 100 mL (2 samples) and 7 cfu / 100 mL. Pseudomonas aeruginosa was detected in 6 (3.57%) samples from three Hospitals in populations ranging from 1 cfu / 250 mL to 650 cfu / 250 mL (median = 160, Std Dev = 214.94). Common aerobic microbes at 37 ° C / 48h were detected in 39 (23.21%) samples from six hospitals at concentrations of 1 to 95 cfu / mL, while total coliforms were detected in 15 (8.93%) samples from 4 hospitals at low concentrations from 1 cfu / 100 mL to 21 cfu / 100 mL. Our study found that the water networks of the hospitals studied were all colonized by Legionella spp. at which, 237/469 (50.5%) of the samples were found positive (≥50 CFU / L).
Conclusions
The current study revealed that most of the water distribution networks of hotels and hospitals studied were found colonized by Legionella spp. posing a potential risk to both clients, patients and visitors, as well as to employees. The contribution of factors related to the construction, maintenance, management and disinfection of water supply networks, as well as, the requirement for the implementation of WSPs in the water supply systems of hotel units and hospitals was, also, computed. Chemical treatment and monitoring of drinking water quality including chlorine disinfection, pH adjustment, and water temperature control of hot water systems are recommended as control measures in WSPs in conjunction with other parameters. Older hotels and hospitals are at a higher risk.
The presence of Legionella spp. in the water distribution networks of both hotels and hospitals is one of the most serious microbiological hazards a WSP must face. The reduction of this risk is therefore a multi-faceted issue that requires both the development of a WSP and its proper implementation. It has also been found that recreational waters, water scenery and watering gardens may serve as Legionella sources and should not be ignored during hotel inspections and the designing of WSPs. Risk assessment, environmental monitoring and disinfection of water systems are the key elements for the prevention of pathogenic micro-organisms.
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