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

Previous studies showed that temperature and total organic carbon in drinking water would cause chlorine dioxide (ClO(2)) loss in a water distribution system and affect the efficiency of ClO(2) for Legionella control. However, among the various causes of ClO(2) loss in a drinking water distribution system, the loss of disinfectant due to the reaction with corrosion scales has not been studied in detail. In this study, the corrosion scales from a galvanized iron pipe and a copper pipe that have been in service for more than 10 years were characterized by energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The impact of these corrosion scale materials on ClO(2) decay was investigated in de-ionized water at 25 and 45 degrees C in a batch reactor with floating glass cover. ClO(2) decay was also investigated in a specially designed reactor made from the iron and copper pipes to obtain more realistic reaction rate data. Goethite (alpha-FeOOH) and magnetite (Fe(3)O(4)) were identified as the main components of iron corrosion scale. Cuprite (Cu(2)O) was identified as the major component of copper corrosion scale. The reaction rate of ClO(2) with both iron and copper oxides followed a first-order kinetics. First-order decay rate constants for ClO(2) reactions with iron corrosion scales obtained from the used service pipe and in the iron pipe reactor itself ranged from 0.025 to 0.083 min(-1). The decay rate constant for ClO(2) with Cu(2)O powder and in the copper pipe reactor was much smaller and it ranged from 0.0052 to 0.0062 min(-1). Based on these results, it can be concluded that the corrosion scale will cause much more significant ClO(2) loss in corroded iron pipes of the distribution system than the total organic carbon that may be present in finished water.
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PMID:Effect of pipe corrosion scales on chlorine dioxide consumption in drinking water distribution systems. 1788 30

Copper-silver ionisation is gaining popularity worldwide as a water disinfection method. We review the literature that supports the effectiveness and safety of the copper-silver ionisation pertaining to legionella control in water distribution systems. A search between January 1997 and January 2007 was conducted in relevant health databases: Medline, Embase, NHS CRD, Cochrane Library Plus, Web of Knowledge, IME (Spanish Medical Index) and IBECS (Health Sciences Bibliographic Index). Ten published studies were selected according to inclusion and exclusion criteria previously established; most of these were experimental. Legionella levels decrease with the application of any of the procedures used in these studies and the procedures can be combined to obtain better outcomes. No studies containing an economic evaluation were found. We conclude that copper-silver ionisation is an effective method to control legionella, bearing in mind that eradication cannot be achieved by any method in isolation. Maintaining high temperatures in the water system can maximise effectiveness of the method. Copper-silver appears to be safe, as long as ion levels are monitored and kept within international recommended levels. More studies with concurrent control group, long follow-up and economic evaluation are required to properly assess this procedure.
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PMID:Is copper-silver ionisation safe and effective in controlling legionella? 1790 90

A medical centre in Southern Taiwan experienced an outbreak of nosocomial Legionnaires' disease, with the water distribution system thought to be the source of the infection. Even after two superheats and flush, the rate of Legionella positivity in distal sites in hospital wards and intensive care units (ICUs) was 14% and 66%, respectively. Copper-silver ionisation was therefore implemented in an attempt to control Legionella colonisation in both hot- and cold-water systems. Environmental cultures and ion concentration testing were performed to evaluate the efficacy of ionisation. When the system was activated, no significant change in rate of Legionella positivity in the hospital wards (20% vs baseline of 30%) and ICUs (28% vs baseline of 34%) of the test buildings over a three-month period was found, although all Legionella positivity rates were below 30%, an arbitrary target for Legionnaires' disease prevention. When ion concentrations were increased from month 4 to month 7, however, the rate of Legionella positivity decreased significantly to 5% (mean) in hospital wards (P=0.037) and 16% (mean) in ICUs (P=0.037). Legionella positivity was further reduced to 0% in hospital wards and 5% (mean) in ICUs while 50% sites were still positive for Legionella in a control building. Although Legionella was not completely eradicated during the study period, no culture- or urine-confirmed hospital-acquired Legionnaires' disease was reported. Ionisation was effective in controlling Legionella for both hot and cold water, and may be an attractive alternative as a point-of-entry systematic disinfection solution for Legionella.
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PMID:Efficacy of point-of-entry copper--silver ionisation system in eradicating Legionella pneumophila in a tropical tertiary care hospital: implications for hospitals contaminated with Legionella in both hot and cold water. 1819 74

This study was conducted in our 650 bed general hospital, which is situated on the southern outskirts of Milan (Italy). After a first nosocomial case of pneumonia (caused by Legionella pneumophila serogroup 1), we first used a conventional method (heat shock) without success. To solve the problem we then tried a copper-silver ionization system combined with a chlorine dioxide device. During the four years after the installation of these two systems we recorded a significant (p < or = 0.05) reduction in Legionella colonization, and no new cases of Legionnaires' disease were observed. Our results suggest that the Cu-Ag ionization system, combined with a chlorine dioxide device, is a highly promising method for the control of Legionella pneumophila in a hospital water distribution system.
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PMID:Prolonged effect of two combined methods for Legionella disinfection in a hospital water system. 1837 73

The aim of this study was to evaluate the efficacy of copper and silver ions and of free chlorine in different combinations and concentrations (0.4 to 0.8-0.04 to 0.08 mg/l Cu(2+) Ag(+); 0.4 to 0.8-0.04 to 0.08-0.2 mg/l Cu(2+) Ag(+) Cl; 0.4 to 0.8-0.04 to 0.08-2 mg/l Cu(2+) Ag(+) Cl; 0.4 to 0.8-0.04 to 0.08-4 mg/l Cu(2+) Ag(+) Cl; 2-20 mg/l Cl), in inactivating Legionella pneumophila in drinking and distilled water after a contact time of 24-hours. Treatment with chlorine alone at 20 mg/l concentration was found to be the most effective treatment leading to complete killing of bacteria within 4 minutes in all water samples. On the other hand, at 2 mg/l concentration complete inactivation was obtained after 3 hours. The association of copper and silver ions at concentrations of 0.4-0.04 mg/l was found to be less effective and live bacteria could still be identified in all water samples after a 24 hour contact time. When testing copper and silver ions in combination, at concentrations of 0.8-0.08 mg/l and different combinations of the three disinfectants, results varied according to the various concentrations and type of water. The combination of copper and silver with 2 mg/l of chlorine was found to be more effective than 2mg/l of chlorine alone; a synergistic effect can therefore be hypothesized. The physical and chemical properties of drinking water, in particular its chlorine content, may have affected the water disinfection process when disinfecting agents were used in low concentrations. In conclusion, this study confirms the efficacy of shock hyperchlorination in the inactivation of Legionella pneumophila. However, the combination of free chlorine with metal (copper and silver) ions may represent a valid option for reducing the concentration of disinfectants to safer levels for human health and avoiding damage to water distribution systems especially in facilities such as hotels and hospitals.
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PMID:Inactivation of Legionella pneumophila by combined systems of copper and silver ions and free chlorine. 1837 4

Multicopper oxidases have been described to have functions in copper tolerance, manganese oxidation, and iron oxidation in a range of bacteria. The putative cytoplasmic membrane multicopper oxidase from Legionella pneumophila was investigated. The mcoL gene was found to be critical for aerobic extracellular growth under either iron-limiting conditions or in the presence of ferrous Fe(II) iron, as a sole source of this essential metal. The mcoL mutants showed minor growth defects when grown in the presence of Fe(III) as the iron source. In contrast, intracellular growth and survival was not affected by the absence of the mcoL gene regardless of available iron concentration. The evidence presented here could indicate a possible role for mcoL in prevention of the toxic effects of ferrous iron during aerobic conditions. However, a function in high-affinity acquisition of iron could also be possible given the inability of the McoL mutants to grow aerobically under iron-limiting conditions.
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PMID:Functional analysis of the multi-copper oxidase from Legionella pneumophila. 1840 41

Legionnaires' disease (LD) can be nosocomial, community acquired or travel related. The source of Legionella infection is potable water systems that become colonized by the microorganism. Prevention studies involved mainly hospital water systems. Different strategies have been suggested but none are fully successful: engineering modifications, heating of water to temperatures above 59 degrees C, heating and flushing the plumbing with hot water (80 degrees C), water chlorination, silver-copper ionization of the water, UV-light disinfection of water, instant heating in order to avoid hot-water tanks and others. LD is widely underdiagnosed because laboratory methods are specific and suspicion index is usually low; therefore, the appropriate tests are not requested. In addition, all methods present limitations. No randomized controlled trials have been performed to study the treatment of legionellosis but comparative observational studies have been published, mostly involving community-acquired cases. Macrolides and quinolones presented similar results when comparing important outcomes, such as mortality and complications.
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PMID:Nosocomial legionellosis: prevention and management. 1962 57

The presence of Legionella spp. in potable water systems is a major concern to municipal water providers and consumers alike. Despite the inclusion of chlorine in potable supplies and frequent chlorination cycles, the bacterium is a recalcitrant human pathogen capable of causing incidents of Legionnaires' disease, Pontiac fever and community-acquired pneumonia in humans. Using two materials routinely employed for the delivery of potable water as a substratum, copper and stainless steel, the development of Legionella pneumophila biofilms and their response to chlorination was monitored over a three-day and a three-month period, respectively. Preliminary in vitro studies using broth and sterile tap water as culture media indicated that the bacterium was capable of surviving in low numbers for 28 days in the presence of chlorine. Subsequently, biofilms were grown for three days, one month and two months, respectively, on stainless steel and copper sections, which are widely used for the conveyance of potable water. Immediately after exposure to 50mg/L chlorine for 1h, the biofilms yielded no recoverable colonies, but colonies did reappear in low numbers over the following days. Despite chlorination at 50mg/L for 1h, both one- and two-month-old L. pneumophila biofilms were able to survive this treatment and to continue to grow, ultimately exceeding 1x10(6)cfu per disc. This research provides an insight into the resistance afforded to L. pneumophila against high levels of chlorine by the formation of biofilms and has implications for the delivery of potable water.
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PMID:Resistance of Legionella pneumophila serotype 1 biofilms to chlorine-based disinfection. 1978 74

Legionella pneumophila is an intracellular pathogen causing pneumonia-like disease in humans. A 43-kb putative heavy metal efflux gene island was found on the L. pneumophila genome. Large Legionella deletion strains of the metal efflux genes were tested in human THP-1-derived macrophages and amoebal Acanthamoeba castellanii cells and were able to survive and replicate similar to the wild type, suggesting that they do not play a significant role within the intracellular environment. Examination of the sequence of this genomic island revealed that some genes were not accurately annotated and there were no known metal-responsive regulators encoded in this region. Therefore, functional roles of these metal resistance genes were tested by conducting metal resistance assays. Individual genes were cloned in an expression vector and expressed in an appropriate metal-sensitive Escherichia coli background with varying concentrations of the tested metal. Of the 11 efflux systems, a role was determined only for one. A Cu(I)-translocating P(IB)-type ATPase was shown to be encoded by lpg1024. This gene, termed copA, complemented a copper-sensitive (Delta copA) E. coli strain in trans and was able to confer copper resistance.
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PMID:The metal efflux island of Legionella pneumophila is not required for survival in macrophages and amoebas. 1989 45

The study was to determine the efficacy of copper-silver ionization against the formation of Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Acinetobacter baumannii in biofilms and planktonic phases. At concentrations below the EPA limits, ionization has potential to control the three waterborne pathogens, in addition to Legionella, in hospital water systems for nosocomial infection control.
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PMID:Efficacy of copper-silver ionization in controlling biofilm- and plankton-associated waterborne pathogens. 2008 Sep 97


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