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Query: UMLS:C0023241 (Legionella)
 6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This section is designed to provide a brief summary of some of the findings. A good deal of work has been conducted by Mr N. L. Pavey and the team at BSRIA, Bracknell. The BSRIA publications are an excellent source of further information. Ultraviolet radiation: UV radiation of wavelength 254 nm destroys bacteria by a mechanism of damaging nucleic acids by producing thymine dimers which disrupt DNA replication [Gavdy and Gavdy, 1980]. L. pneumophila has been reported as sensitive to UV dosages of 2,500-7,000 uW.s/cm2 [Antopol & Ellner, 1979; Knudson, 1985]. Antopol and Ellner [1979] examined the susceptibility of L. pneumophila to UV dosage. Their results indicated that 50% of the organisms were killed by 380 uWs/cm2 and 90% were killed by 920 uWs/cm2. Kills of 99 and 99.9% were obtained using 1,840 and 2,760 uWs/cm2 respectively. Muraca et al [1987] showed that continuous UV irradiation resulted in a 5 logarithm decrease in waterborne L. pneumophila in a circulating system. Gilpin [1984] reported that in laboratory buffer solutions, exposure to 1 uW of UV radiation per cm2 achieved a 50% kill of L longbeachae in 5 minutes, L. gormanii in 2-30 minutes and L pneumophila in 17 minutes. Exposure times for 99% kills for L. longbeachae, L pneumophila and L. Gormanii were 33, 48 and 63 minutes respectively. The same research worker conducted experiments using a 3 litre circulating water system, connected to a stainless steel housing containing a UV source. The UV lamp output was 7 ergs/mm2 per second per 100 cm at 254 nm. L. pneumophila was killed within 15 seconds, that is within their first pass through the system. Continuous disinfection with UV has the advantages of imparting no taste, odour or harmful chemical by-products and requires minimal operation and maintenance [Muraca et al 1988]. Keevil et al [1989] state that UV irradiation fails to clear systems of biofilm because of poor penetration into microflocs of the micro-organisms. Copper/silver ionisation: A recent study of full scale hot water test rigs incorporating copper-silver ionisation systems has been reported by Pavey, 1996. Copper and silver ions were introduced into the water by electrolysis. One of the principal mechanisms of biocidal action of these ions is thought to be cell penetration. The positively charged copper ions form electrostatic bonds with negatively charged sites on the cell wall. The cell membrane is thus distorted, allowing ingress of silver ions which attack the cell by binding at specific sites to DNA, RNA, respiratory enzymes and cellular protein, causing catastrophic failure of the life support systems of the cell. Silver and copper ion concentrations of 40 and 400 ug/L respectively were effective against planktonic Legionellae in cold water systems and hot water systems containing soft water. In hard water, the ionisation was ineffective due to the inability to control silver ion concentrations. This was caused by scaling of the electrodes and silver ion complexation by the high concentration of dissolved solids. Bosch et al [1993] had earlier extended the application of copper-silver disinfection to human enteric viruses in water, such as adenovirus, rotavirus, hepatitis A virus, and poliovirus. Their work showed that copper and silver ions in the presence of reduced levels of free chlorine did not ensure the total elimination of viral pathogens from water. In the case of an amoeba, Naegleria fowleria [responsible for primary amoebic meningoencephalitis], Cassells et al [1995] have demonstrated that a combination of silver and copper ions were ineffective at inactivating the amoebae at 80 and 800 ug/L respectively. However addition of 1.0 mg/L free chlorine produced a synergistic effect, with superior inactivation relative to either chlorine or silver-copper in isolation. A similar synergy was reported by Yahya et al [1989] in their study of Staphylococcus sp. and Pseudomonas aeruginosa. Yahya et al [1992] also suggested an additive or synergistic effect in the inactivation of coliphage MS-2 and poliovirus. Other techniques: There are a number of other techniques. We have conducted trials of most of these in the control of Legionella sp., but these fall out of the scope of this article, and as such less emphasis has been placed on them here. Ozonation: Ozone [O3] is an oxidising gas, generated electrically from oxygen [O2]. L. pneumophila can be killed at < 1 mg/L of ozone [Edelstien et al 1982]. Muraca et al [1987] found that 1-2 mg/L of continuous ozone over a six hour contact time, produced a 5 logarithm decrease of L. pneumophila. The effectiveness of ozone treatment against a range of bacteria and coliphages has been studied Botzenhart et al [1993]. E. coli was least resistant to ozone, followed by MS 2-coliphage and PhiX 174-coliphage, with L. pneumophila and Bacillus subtilis spores being the most resistant. (ABSTRACT TRUNCATED)
Health Estate 2001 Jun
PMID:Reviewing efficacy of alternative water treatment techniques. 1144 90

A profile of the work of David Harper, global authority on Legionnaire's disease in engineering terms, whose investigations into new-build hospital water systems have uncovered a number of risk factors which could expose patients to the Legionella bacterium.
Health Estate 2005 Aug
PMID:Awareness needed of Legionella risk. 1611 50

Legionella presents an ongoing cause for concern in any sector where duty of care responsibilities prevail. Jo Wolters, microbiologist and sector head of TA-Aqua+ at Tour & Andersson, describes a recently developed method of legionella prevention and control.
Health Estate 2007 Mar
PMID:'Gatekeeper' unit defeats legionella. 1743 5

The long-awaited report from the Health & Safety Executive (HSE) into the Barrow Legionella outbreak has now been published and is in the public domain. Its conclusions and recommendations clearly recognise that the outbreak cannot, and should not, be attributed purely to one group or to the individuals working within one department. Moreover, the failings which contributed to the outbreak stretched from the lowest levels to the top of the council organisation. Develop Training's Tony Green explains how correct training can prevent future outbreaks.
Health Estate 2007 Jun
PMID:Proper training key to defeating Legionella. 1772 51

At a recent presentation at the PCT headquarters in Oldham, Dr Tom Makin, of the Department of Medical Microbiology, Royal Liverpool University Hospitals, described the problems associated with Legionella pneumophila. Health Estate Journal reports.
Health Estate 2007 Nov
PMID:Legionella infection prevention studied. 1806 15

Recent Legionella outbreaks have done nothing to reassure the general public and "customers" of the healthcare sector that there is no risk from the disease. Here Jo Welters, microbiologist and sector head of TA-Aqua+ at hydronic balancing specialist Tour & Andersson, discusses the relevance of a new method for tackling Legionella prevention and the means of removing the current risks associated with the bacteria.
Health Estate 2009 Jan
PMID:Stopping Legionella in its tracks. 1919

Although only around 400 cases are reported annually to the U.K.'s Health Protection Agency (HPA), climate change, and thus warmer cold water supplies entering hospitals, the bacterium's apparent ability to mutate, and the considerable challenge of properly monitoring, and successfully identifying and addressing, all potential infection sources on a large hospital estate mean an increasing risk of hospital patients acquiring the potentially deadly waterborne infection, Legionnaires' disease. This was the warning from a top U.K. microbiologist at a recent "waterborne infection masterclass" organised by specialist water filtration product supplier Pall Medical in Antwerp. Jonathan Baillie reports.
Health Estate 2010 Mar
PMID:Fighting the waterborne menace. 2036 31

In a follow-up to last month's "Fighting the waterborne menace" article (HEJ--March 2010), Dr. Tom Makin, directorate manager, medical microbiology, at the Royal Liverpool and Broadgreen University Hospitals Trust, and Martin Pride, new business development, at Kemper U.K. & Ireland, examine how Legionella has become a significant potential issue in hospital water systems, and discuss a novel, venturi-based engineering system co-developed by Kemper and a German university, and recently successfully trialled at a Liverpool hospital, which ensures constant water circulation, significantly reducing the risk of both biofilm, and consequently Legionella, build-up.
Health Estate 2010 Apr
PMID:Venturi system could be major breakthrough. 2044 80

Selection of heat rejection equipment has traditionally entailed a choice between the higher energy consumption of an air-cooled solution, and the high water consumption of a water-cooled solution. This paper examines advancement in heat rejection technology and the way it can be applied to air conditioning and refrigeration plant in healthcare and other facilities. It also examines field difficulties encountered in pipework design as the knowledge and experience levels of engineers designing systems with remote condensers diminish. With plant larger than 1,000 kW, the only option previously has been water-cooled solutions using an array of cooling towers, or perhaps an evaporative condenser, since air-cooled plant involved massive volumes of chemical refrigerant, which posed a problem ecologically. An additional hurdle was problems associated with limitations on pipe lengths for refrigeration plant. The advent of adiabatically pre-cooled closed circuit coolers and air-cooled condensers has introduced an alternative to cooling towers that offers the potential for "water-cooled performance" from an air-cooled solution with no serious threat of Legionella contamination. However, each application needs to be considered on a case-by-case basis. The paper examines, in detail, the impact of adiabatic pre-cooling, with recent examples of its application in sub-tropical Brisbane providing evidence of the potential performance achievable.
Health Estate 2010 Sep
PMID:The 'fine line' of heat rejection. 2088 4

In a presentation given at a recent IHEEM seminar, "Total water management within healthcare premises", held at London's Royal Society of Arts, David Harper, one of the UK's leading independent experts in Legionella, waterborne contamination prevention, and emergency response, described how the bacterium and its effects were first "discovered", offered valuable advice on how to minimise the risk of its growth and spread, and highlighted some of the alarming findings he had seen throughout a long career in the field, much of it spent providing guidance and advice to hospitals and other healthcare facilities both on Legionella, and a range of other water health and hygiene matters.
Health Estate 2011 Feb
PMID:Legionella--fighting a resourceful foe. 2142 11


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