Legionella chlorination

This review aimed to evaluate the contamination rate of dental unit waterlines (DUWL) with Pseudomonas aeruginosa and Legionella pneumophila in several countries in the Middle East.Literature search was conducted in databases such as PubMed, Scopus, Web of Science, and Google Scholar to gather studies published from the beginning of 2000 to 30th April 2020. Medical Subject Headings (MeSH) terms were; "Legionellosis"; "Legionnaire", "Legionellosis", "L. pneumophila", "dent", "dental", "dentistry", "Dental Unit Waterlines", "dental water", "DUWL", "Middle East", "P...

This study assessed the bacterial community composition of a drinking water system (DWS) serving a mid-sized city (120,000 inhabitants) in Brazil. Water samples, including raw and treated water, were collected at seven points throughout the DWS. DNA was extracted and analysed using high-throughput sequencing (Ion Torrent). Free chlorine and turbidity were measured in situ. Results showed that the highest relative abundance of 16S rRNA genes was from phyla Proteobacteria, followed by Bacteroidetes and Actinobacteria...

The bacterium Legionella pneumophila is a ubiquitous microorganism naturally present in water environments. The actual presence of this opportunistic premise plumbing pathogen in recreational swimming pools and hot tubs in the northwestern part of Croatia has not been investigated. This study aimed to analyze the presence of the opportunistic pathogen L. pneumophila in public swimming pool water in Primorje-Gorski Kotar County (N = 4587) over a four-year period (2018-2021). Additionally, the second aim was to investigate the connection between the presence of L...

BACKGROUND: Legionnaires' disease is a notifiable condition in New South Wales (NSW), Australia; clinicians and laboratories are required to report the disease to NSW Health. We describe the investigation of a sporadic case associated with the use of a communal spa pool in the case's apartment building complex and the use of whole genome sequencing to examine relatedness between clinical and environmental Legionella pneumophila serogroup 1 (Lp1) strains. METHODS: In February 2018, a confirmed case of Lp1 infection was notified in a man in his 60s hospitalised with pneumonia...

Urban villages are unique residential neighborhoods in urban areas in China. Roof tanks are their main form of water supply, and water quality deterioration might occur in this system because of poor hygienic conditions and maintenance. In this study, water samples were seasonally collected from an urban village to investigate the influence of roof tanks as an additional water storage device on the variation in the microbial community structure and pathogenic gene markers. Water stagnation in the roof tank induced significant decreases in chlorine (p < 0...

INTRODUCTION: Legionella disease can manifest as severe respiratory tract infection with a high mortality rate and is sometimes associated with a hospital outbreak by a contaminated water supply. A patient with breast cancer admitted about a month before. High fever was observed 18 days after admission and the Legionella antigen test showed the positive result. METHODS: Due to the incidence of Legionella infection, we demonstrated the active surveillance of Legionella contamination in the entire hospital...

In dental clinics, the infections may be acquired through contaminated devices, air, and water. Aerosolized water may contain bacteria, grown into the biofilm of dental unit waterlines (DUWLs). We evaluated a disinfection method based on water osmosis and chlorination with chlorine dioxide (O-CD), applied to DUWL of five dental clinics. Municipal water was chlorinated with O-CD device before feeding all DUWLs. Samplings were performed on water/air samples in order to research total microbial counts at 22-37 °C, Pseudomonas aeruginosa , Legionella spp...

Disinfection is essential for the microbial safety of reclaimed water. Traditional chlorine disinfection leads to secondary problems such as disinfection by-products and chlorine-resistant bacteria. Ferrate (Fe(VI)) is a novel green disinfectant. However, research on the disinfection characteristics of Fe(VI) remains insufficient. This study compared the disinfection efficacy between Fe(VI) and chlorine in secondary effluent, including the inactivation efficiency of coliforms and heterotrophic bacteria and the control effect on typical chlorine-resistant bacteria...

INTRODUCTION: There is growing interest in the public health and transport sectors in research into exposure to biological hazards, considering not only the risks arising from inter-human contagion, but also those related to exposure to the flight environment itself. The aim of this paper is to report data from an investigation into the water and air-conditioning systems of commercial aircraft for the presence of Legionella contamination, with a total of 645 water samples taken during the period 2007-2021...

BackgroundLegionnaires' disease is a respiratory illness often associated with hotels and travel. Spain is a major tourist destination and one of the European countries with most cases of Legionnaires' disease , both community- and travel-associated. However, the prevalence of Legionella in tourist facilities is unknown.AimThe present investigation aimed to survey the tourist facilities in the Balearic Islands, Spain, for Legionella prevalence.MethodsWe visited tourist facilities in the Balearic Islands in two different periods (2006-2010 and 2015-2018) and took water samples following national and international guidelines...

Legionella occurrence monitoring is not required by United States Environmental Protection Agency (USEPA) drinking water regulations, and few occurrence studies exist for Legionella in source water or distribution systems. Legionella occurrence was monitored in Las Vegas Valley (Las Vegas, Nevada, USA) drinking water sources, including non-treated surface water, seasonal groundwater (61 wells, before and after chlorination), finished water (after treatment at water treatment facilities), and chlorinated distribution system water (at 9 reservoirs and 75 sample locations throughout the network)...

Opportunistic pathogens (OPs), such as Pseudomonas spp., Legionella spp., and mycobacteria, have been detected in biofilms in drinking water distribution systems and water storage tanks and pose potential risks to finished drinking water quality and safety. Emerging UV technologies, such as UV light emitting diodes (LEDs) and krypton chloride (KrCl*) excimers, could provide an alternative to chemical-based secondary disinfection (i.e., chlorine or chloramines) for controlling biofilm-bound OPs. UV systems offer long lifetimes, ability to select wavelength, small size with high power density, and limited-to-no disinfection by-product formation...

In premise plumbing, microbial water quality may deteriorate under certain conditions, such as stagnation. Stagnation results in a loss of disinfectant residual, which may lead to the regrowth of microorganisms, including opportunistic pathogens. In the present study, microbial regrowth was investigated at eight faucets in a building over four seasons in one year. Water samples were obtained before and after 24 h of stagnation. In the first 100‍ ‍mL after stagnation, total cell counts measured by flow cytometry increased 14- to 220-fold with a simultaneous decrease in free chlorine from 0...

Legionella spp. is the etiological agent of the serious respiratory pneumonia known as Legionnaires' disease. This respiratory illness is frequently associated with travel and tourist resorts. Spain is an important tourist destination, and one of the top European countries concerning Legionnaires' disease cases, both community and travel associated. Still, the colonization of Legionella in our hotels remains scarce. Here, we surveyed 204 hotels in the Canary Islands, Spain, for five years (2015-2019), to determine the Legionella prevalence...

A local preschool installed NSF/ANSI 42 and 53 certified point-of-use (POU) filters in its classroom sinks and drinking fountains to protect children from the possibility of elevated lead (Pb) levels in drinking water. We examined the effects of these filters during flowing water and immediately following stagnation periods on Pb, chlorine, and bacterial concentrations in the field and the laboratory. Before and after typical school stagnation periods, we collected samples from filtered classroom sinks, a filtered drinking fountain and nearby unfiltered sinks for a year...

A meta-analysis of existing and available Illumina 16S rRNA datasets from drinking water source, treatment and drinking water distribution systems (DWDS) were collated to compare changes in abundance and diversity throughout. Samples from bulk water and biofilm were used to assess principles governing microbial community assembly and the value of amplicon sequencing to water utilities. Individual phyla relationships were explored to identify competitive or synergistic factors governing DWDS microbiomes. The relative importance of stochasticity in the assembly of the DWDS microbiome was considered to identify the significance of source and treatment in determining communities in DWDS...

The main function of quartz sand in drinking water treatment has been to remove turbidity, while the microbial effect of its solid-liquid interface has been ignored. In order to solve the limitations of control of the disinfection by-products (DBPs) and opportunistic pathogens (OPs) in common quartz sand, the common quartz sand was modified to iron sand. The maximum DBPs formation potential of typical nitrogenous disinfection by-products (N-DBPs) and carbonaceous disinfection by-products was determined using gas chromatography-ECD...

A one-day water sampling and flushing study was conducted for three schools in Maricopa County that experienced prolonged building inactivity due to the COVID-19 pandemic: an elementary school, middle school, and high school. Grab samples were taken at hand washing sinks, water fountains, and hose bibbs before and after flushing. Samples were analyzed for free chlorine, UVA254, copper, lead, total trihalomethanes, pH, conductivity, temperature, and Legionella species. All three schools experienced an increase in free chlorine post-flush...

Water-based opportunistic pathogens (OPs) are a leading cause of drinking-water-related disease outbreaks, especially in developed countries such as the United States (US). Physicochemical water quality parameters, especially disinfectant residuals, control the (re)growth, presence, colonization, and concentrations of OPs in drinking water distribution systems (DWDSs), while the relationship between OPs and those parameters remain unclear. This study aimed to quantify how physicochemical parameters, mainly monochloramine residual concentration, hydraulic residence time (HRT), and seasonality, affected the occurrence and concentrations of four common OPs (Legionella, Mycobacterium, Pseudomonas, and Vermamoeba vermiformis) in four full-scale DWDSs in the US...

Secondary water supply systems (SWSSs) are characterized by long water stagnation and low levels of chlorine residuals, which may pose a high microbial risk to terminal users. In this study, the SWSSs of 12 residential neighborhoods in a metropolitan area of 5 million people in southeastern China were seasonally investigated to assess their microbial risks by determining more than 30 physicochemical and biological parameters. Although the microbiological quality of SWSS water met the requirements of the standards for drinking water quality of China, it did deteriorate in various aspects...