RESUMEN
Legionella is one of the emerging concerns of water quality in built water environments. Premise plumbing systems are among the recognised sources of infection. In the present study, colonisation of hot water networks in health care facilities, schools, hotels, private residences, office and industrial buildings was investigated. Data was analysed in connection with building and premise plumbing characteristics. Over 60% of all buildings were colonised by Legionella; counts were over 1000 CFU/L in 49%. The most prevalent type was Legionella pneumophila serogroup 2-14, isolated from 75% of the positive samples. Centrally produced hot water was found to be a key risk factor (46% of the samples were positive vs. 16% in individual systems); within this group the type of the building was less relevant. Colonisation levels in schools were similar to hotels or hospitals, representing a previously underestimated risk setting. Systems supplied by water from deep groundwater sources were significantly less likely to be colonised than more vulnerable sources (bank-wall filtration, surface water abstraction or karstic water; 28% vs. 51% positive), regardless of the type of treatment applied, including the presence of disinfection. The aggravating effect of larger, more complex and older buildings on colonisation was also confirmed. The present study represents the first baseline analysis, pre-empting regulation or monitoring requirements for Legionella. The prevalence of legionellae and the identified risk factors are indicative for other settings lacking targeted interventions. The statistically confirmed risk factors can serve as indicators for preliminary risk assessment and the prioritisation of interventions.
Asunto(s)
Legionella/aislamiento & purificación , Ingeniería Sanitaria , Microbiología del Agua , Abastecimiento de Agua , Desinfección , Hungría , Legionella/clasificación , Legionella pneumophila/aislamiento & purificación , Purificación del Agua/métodosRESUMEN
Nosocomial legionellosis is a growing concern worldwide. In Hungary, about 20% of the reported cases are health-care associated, but in the absence of legal regulation, environmental monitoring of Legionella is not routinely performed in hospitals. In the present study, 23 hospitals were investigated. The hot water distribution system was colonized by Legionella in over 90%; counts generally exceeded the public health limit value. Hot water temperature was critically low in all systems (<45 °C), and large differences (3-38 °C temperature drop) were observed within buildings, indicating insufficient circulation. Most facilities were older than 30 years (77%); however, new systems (n = 3) were also shown to be rapidly colonized at low hot water temperature. Vulnerable source of drinking water, complex distribution system, and large volume hot water storage increased the risk of Legionella prevalence (OR = 28.0, 27.3, 27.7, respectively). Risk management interventions (including thermal or chemical disinfection) were only efficient if the system operation was optimized. Though the risk factors were similar, in those hospitals where nosocomial legionellosis was reported, Legionella counts and the proportion of L. pneumophila sg 1 isolates were significantly higher. The results of environmental prevalence of legionellae in hospitals suggest that the incidence of nosocomial legionellosis is likely to be underreported. The observed colonization rates call for the introduction of a mandatory environmental monitoring scheme.
Asunto(s)
Infección Hospitalaria/microbiología , Legionella/aislamiento & purificación , Legionelosis/microbiología , Infección Hospitalaria/epidemiología , Microbiología Ambiental , Hospitales/estadística & datos numéricos , Hungría/epidemiología , Legionella/clasificación , Legionella/genética , Legionelosis/epidemiología , PrevalenciaRESUMEN
Hospital tap water is a potential source of pathogenic bacteria associated with nosocomial infections. Infection control should include preventive measures to reduce the risk of waterborne infection. The efficiency of point-of-use water filters in infection control was assessed in the intensive care unit of a Hungarian hospital with long history of nosocomial Pseudomonas aeruginosa cases. All taps in the unit were fitted with disposable point-of-use filters. The incidence of nosocomial P. aeruginosa infections decreased from 2.71 to 0 cases/100 patient days when the filters were in place. Legionnaires' disease was not observed either during or outside the study period. Before the application of the filters, both P. aeruginosa and Legionella sp. were shown to colonize five of the seven taps. Filtration eliminated both bacteria completely, though secondary contamination was observed. Total genome restriction profiling of environmental and clinical P. aeruginosa isolates have shown the ubiquitous presence of a single genotype. The same genotype was detected in five of the seven previous nosocomial cases, which supports the assumption of water-derived infection. The results demonstrate that point-of-use filters are effective and cost-efficient measures in reducing health-care associated infections.