Legionella Colonization of Hotel Water Systems in Touristic Places of Greece: Association with System Characteristics and Physicochemical Parameters

Abstract

This study aimed to assess the colonization of hotel water systems in central Greece and Corfu by Legionella, and to investigate the association between physicochemical parameters and Legionella colonization. Standardized hygiene inspection was conducted in 51 hotels, and 556 water samples were analyzed for Legionella spp. Free chlorine concentration, pH, hardness, conductivity, and trace metals were defined in cold water samples. The results of inspections and chemical analyses were associated with the microbiological results using univariate and logistic regression analysis. According to the score of the checklist used for the inspections, 17.6% of the hotels were classified as satisfactory, 15.7% as adequate, and 66.7% as unsatisfactory. Moreover, 74.5% of the hotels were colonized by Legionella spp. and 31.4% required remedial measures according to the European guidelines. Legionella spp. were isolated in 28% of the samples. Unsatisfactory results of inspections were associated with Legionella presence (relative risk (RR) = 7.67, p-value = 0.043). In hot-water systems, <50 °C temperatures increased the risk of Legionella colonization (RR = 5.36, p-value < 0.001). In cold-water systems, free chlorine concentration <0.375 mg/L (odds ratio (OR) = 9.76, p-value = 0.001), pH ≥ 7.45 (OR = 4.05, p-value = 0.007), and hardness ≥321 mgCaCO3/L (OR = 5.63, p-value = 0.003) increased the risk, whereas copper pipes demonstrated a protective role (OR = 0.29, p-value = 0.0024). The majority of the hotels inspected were colonized with Legionella. Supplementary monitoring of the risk factors that were identified should be considered.

Evaluation of Legionella spp. Colonization in Residential Buildings Having Solar Thermal System for Hot Water Production

“…Another issue evidenced by this study is the high temperature of cold water (higher than 20 °C in several cases), which may represent an optimum condition for Legionella spp. growth [ 20 , 21 ].…”

Legionella and Biofilms—Integrated Surveillance to Bridge Science and Real-Field Demands

“…Apart from the complex and often unknown architectures of interconnected pipelines, equipment, pumps, and other hydraulic settings [35] that can potentially disseminate the bacteria by aerosolization, they also have very diverse conditions of the system. Warm temperatures, hydrodynamic patterns (specially stagnation) [35], water quality (pH and hardness) [44][45][46][47], corrosion and scaling (as nutrient sources) [48], and surface materials [49,50] have been linked to Legionella prevalence. Additionally, biocidal programs that are not properly set or managed may promote Legionella colonization in several installations [51][52][53][54].…”

“…These are all critical aspects related to Legionella persistence in man-made systems that contribute to a higher or lower legionellosis risk. The studies considered in Table 1 cover different water settings, including cooling towers [55][56][57], premise plumbing from hospitals [51,52,54,[58][59][60][61][62][63][64] and hotels [45,48,[64][65][66][67][68][69], residential potable water systems [46,70,71], and other facilities [72][73][74][75][76][77][78].…”

Colonization of<em> </em><em>Legionella </em><em>spp. </em>in Hot and Cold Water Networks of Residential Buildings in Pisa District (Tuscany, Italy): A Five-Years Survey

“…Another issue evidenced by this study is the high temperature of cold water (higher than 20°C in several cases), which may represent an optimum condition for Legionella spp. growth [21,22].…”