Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023241 (Legionella)
 6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

German Standards Specification DIN 19,643 is at present under revision for health reasons and because of both negative and positive experiences gathered in practice. To enable adaptation of the standards specification to future developments, a Part I of the specification is being created comprising the demands to be made on the quality of the water and general demands on the construction and operation of swimming pools and tubs and basins in bath houses, e.g. in spas or municipal swimming pools. The subsequent parts of the new specification (Part 2 to Part n) concern the demands to be made on individual combinations of processes; these can be supplemented at any time in accordance with technical progress without requiring revision of the entire standards specification. Essential innovations are the reformulation of the required efficiency of disinfection, the introduction of the parameters Legionella pneumophila, trihalogen methane (THM) and the reduction of the limit value for chloramines. Technically speaking, the new features concern the automatic measurement of the auxiliary parameters of hygiene such as redox potential, pH value and free chlorine, automatic control of disinfectant additions, automatic filter rinsing with fluidization of the filter-bed to a prescribed minimum bed expansion, and the sight-glas at the filter container. The demands made on Jacuzzi and warm water spouted bed besins are integrated into the specification, thus obviating the need for German Standards Specification DIN 19,644.
 ...
PMID:[Update of DIN 19.643--treatment and disinfection of swimming pool and bathing tub water]. 139 75

The susceptibility of Legionella pneumophila to iodination was studied with cultures grown in well water, on rich agar media, and attached to stainless-steel surfaces. Legionella pneumophila grown in water cultures in association with other microorganisms were less sensitive to disinfection by chlorine and iodine than were agar-passaged cultures. Differences in sensitivity to disinfection between water-cultured and agar-grown legionellae were determined by comparing C x T values (concentration in milligrams per litre multiplied by time in minutes to achieve 99% decrease in viability) and CM x T values (concentration in molarity). Iodine (1500x) gave a greater difference in CM x T values than did chlorine (68x). Iodine was 50 times more effective than chlorine when used with agar-grown cultures but was only twice as effective when tested against water-grown Legionella cultures. C x T x S values (C x T multiplied by percent survivors), which take into consideration the percent surviving bacteria, were used to compare sensitivities in very resistant populations, such as those in biofilms. Water cultures of legionellae associated with stainless-steel surfaces were 135 times more resistant to iodination than were unattached legionellae, and they were 210,000 times more resistant than were agar-grown cultures. These results indicate that the conditions under which legionellae are grown can dramatically affect their susceptibility to some disinfectants and must be considered when evaluating the efficacy of a disinfecting agent.
 ...
PMID:Effects of culture conditions and biofilm formation on the iodine susceptibility of Legionella pneumophila. 164 85

The apparent failure of hyperchlorination and continuous dosing with chlorine to eliminate legionellae from a dental teaching hospital water supply prompted a prospective study to evaluate charcoal filters as a means of decontamination. Legionella pneumophila serogroup 10 and L. bozemanii serogroup 2 were isolated from dental units yielding 10(1)-10(3) colony forming units (cfu) ml-1 with total bacterial counts in the range 10(2)-greater than 10(4) cfu ml-1. After chair-side installation of charcoal filters bacterial contamination of the dental unit water was prevented and legionellae were initially not detected, but after 7 days the total count returned to pre-filtration levels of greater than 10(4) cfu ml-1; L. pneumophila serogroup 10 was eliminated but L. bozemanii serogroup 2 persisted. These results suggest that neither chlorination nor charcoal filtration deal adequately with the potential hazard of Legionella spp. in dental water.
 ...
PMID:The efficacy of chlorination and filtration in the control and eradication of Legionella from dental chair water systems. 197 12

Forty eyewash units were sampled for protozoa, bacteria, and fungi. Total heterotrophic bacterial counts on nutrient agar and R2A agar (Difco Laboratories, Detroit, Mich.) ranged from 0 to 10(5) CFU/ml, with Pseudomonas spp. being the most frequently isolated. Total counts of 10(4) and 10(8) cells per ml were obtained with the acridine orange staining procedure. All samples were examined for Legionella spp. by direct fluorescent-antibody staining and by culturing on buffered charcoal-yeast extract agar containing alpha-ketoglutarate and glycine and supplemented with cycloheximide, vancomycin, and polymyxin B. DNA-DNA hybridization was used to confirm identification of the Legionella isolates. Legionellae were detected in 35 of 40 (87.5%) samples by direct fluorescent-antibody staining, with 3 samples yielding both Legionella spp. and amoebae. Amoebae identified as Hartmannella, Vahlkampfia, Acanthamoeba, and Cochliopodium spp. were detected in 19 of 40 (47:5%) samples. Sabouraud dextrose agar was used to obtain a crude estimate of viable fungal populations, pH, hardness, and ammonia, alkalinity, chlorine, copper, and iron contents were recorded for all water samples collected from eyewash stations; 33% of the samples had greater than or equal to 10 mg of CO2 per liter. It is concluded that eyewash stations not regularly flushed and/or cleaned and used to flush traumatized eye tissue may be a source of infection and can contaminate laboratory environments via aerosol transmission.
 ...
PMID:Isolation of amoebae and Pseudomonas and Legionella spp. from eyewash stations. 203 3

The Federal German DIN standard No. 19644 that has been enforced in West Germany since 1989 had to be revised in view of the fact that German legislation is expected to issue an ordinance on swimming pool and public bath water within the framework of the Federal Communicable Diseases Act; furthermore, the need for revision also arose from the solution of the hygienic problems of treatment and disinfection of warm whirlpool water, and from the necessity of modifying several now outdated regulations. It is the aim of public health legislation to prevent health risks of bathers and of attendant staff by Legionella pneumophila in all types of basins with additional water cycles and intake of air (aerosol formation); likewise, adverse health effects of side reaction products of the disinfectant chlorine (i. e. chloroamines and halogenated organic compounds, especially the trihalomethanes) must be avoided. Recent research has shown that these aims can be achieved by altering the mode of running and backwashing filters of all process combinations including those using ozone and introducing an additional absorption on powdered activated carbon, and the process combination of flocculation-filtration-chlorination. Improved treatment would be without effect if turnover rates could not be assessed reliably for basins of irregular geometry--as they are preferably used today--operated with additional water cycles involving intake of air. Lack of costly investigations prompts users to estimate turnover rates on the basis of experience collected with basins of square or rectangular dimensions.
 ...
PMID:[Current status of bath water treatment techniques]. 214 49

The association between Legionella pneumophila and the free-living amoeba Acanthamoeba polyphaga was studied. Intracellular growth of L. pneumophila within amoebic trophozoite was confirmed by kinetic growth experiments, light and electron microscopy. Cysts produced from infected trophozoites were found to protect the legionellas from at least 50 mg/l free chlorine. The ability of L. pneumophila to survive within the cysts of A. polyphaga is suggested as a possible mechanism by which the organism evades disinfection and spreads to colonize new environments.
 ...
PMID:Survival of Legionella pneumophila within cysts of Acanthamoeba polyphaga following chlorine exposure. 219 57

An increase in endemic rate of nosocomial Legionella pneumophila pneumonia prompted an investigation that revealed 16.2% (12/74) of patient care hot-water sites surveyed were culture-positive for L. pneumophila. No positive cultures were recovered from cooling towers, air intakes, or construction areas. Heat flushing of hospital hot-water outlets to temperatures greater than 60 degrees C for 30 min achieved a 66% reduction in positive Legionella cultures. After 4 1/2 months, different serotypes recurred in previously eradicated areas and there were new positive cultures. Continuous supplemental chlorination of the hot-water system (2 parts per million [ppm]) significantly reduced the number of culture-positive samples from 37.4% (43/115) to 7.0% (8/115) after 6 weeks (P less than .005). Of 30 sites surveyed 6 months after hot-water chlorination, 67% (20) were still culture-negative. Of those positive, 70% had less than or equal to 150 L. pneumophila/ml and 90% were from bathtubs. Adverse effects of chlorination on users and plumbing have not been seen. There have been no definite cases of nosocomial L. pneumophila in areas served by supplemental chlorine during the first 17 months of the chlorination project. Technology allowing tighter regulation of chlorine and use of silicates to control corrosion have made continuous hot-water chlorination a safe and effective option in Legionella control.
 ...
PMID:Reduction in Legionella pneumophila through heat flushing followed by continuous supplemental chlorination of hospital hot water. 198 27

Potential sources of Legionella spp. in a university hospital were investigated over 3 years in order to gain better understanding of the ecology and transmission of this organism to hospitalized patients. The survey highlighted the contamination of the hot water system with high concentrations of legionellas (up to 10(6) cfu 1(-1]. Legionella pneumophila serogroup 6 was predominant followed by L. pneumophila serogroup 10. Serogroup 1 and other species (L. longbeachae, L. micdadei) were rarely isolated. Serogroup 6 was also the predominant cause of nosocomial legionellosis in 15 sporadic cases in immunocompromised patients from 1981 to 1987. In light of this problem, several control measures were tried consecutively. A disinfection cycle with 6 ppm free chlorine failed to eradicate legionellas because of difficulties with the plumbing system. Raising the temperature in hot water tanks to 80 degrees C was effective locally, but mixer tanks where cold and hot water (60-65 degrees C) are mingled in order to achieve 45 degrees C became the principal reservoirs. Disconnecting the mixer tanks, maintaining a temperature of 60 degrees C in the heating tanks and accelerating the flow rate in the hot water system proved to be the most useful measures.
 ...
PMID:Legionella spp. in a hospital hot water system: effect of control measures. 256 4

Water disinfection systems utilizing electrolytically generated copper and silver ions (200 and 20, 400 and 40, or 800 and 80 micrograms/liter) and low levels of free chlorine (0.1 to 0.4 mg/liter) were evaluated at room (21 to 23 degrees C) and elevated (39 to 40 degrees C) temperatures in filtered well water (pH 7.3) for their efficacy in inactivating Legionella pneumophila (ATCC 33155). At room temperature, a contact time of at least 24 h was necessary for copper and silver (400 and 40 micrograms/liter) to achieve a 3-log10 reduction in bacterial numbers. As the copper and silver concentration increased to 800 and 80 micrograms/liter, the inactivation rate significantly (P less than or equal to 0.05) increased from K = 2.87 x 10(-3) to K = 7.50 x 10(-3) (log10 reduction per minute). In water systems with and without copper and silver (400 and 40 micrograms/liter), the inactivation rates significantly increased as the free chlorine concentration increased from 0.1 mg/liter (K = 0.397 log10 reduction per min) to 0.4 mg/liter (K = 1.047 log10 reduction per min). Compared to room temperature, no significant differences were observed when 0.2 mg of free chlorine per liter with and without 400 and 40 micrograms of copper and silver per liter was tested at 39 to 40 degrees C. All disinfection systems, regardless of temperature or free chlorine concentration, showed increase inactivation rates when 400 and 40 micrograms of copper and silver per liter was added; however, this trend was significant only at 0.4 mg of free chlorine per liter.
 ...
PMID:Efficacy of copper and silver ions and reduced levels of free chlorine in inactivation of Legionella pneumophila. 261 3

The susceptibility of coliform bacteria and bacterial pathogens to free chlorine residuals was determined before and after incubation with amoebae and ciliate protozoa. Viability of bacteria was quantified to determine their resistance to free chlorine residuals when ingested by laboratory strains of Acanthamoeba castellanii and Tetrahymena pyriformis. Cocultures of bacteria and protozoa were incubated to facilitate ingestion of the bacteria and then were chlorinated, neutralized, and sonicated to release intracellular bacteria. Qualitative susceptibility of protozoan strains to free chlorine was also assessed. Protozoa were shown to survive and grow after exposure to levels of free chlorine residuals that killed free-living bacteria. Ingested coliforms Escherichia coli, Citrobacter freundii, Enterobacter agglomerans, Enterobacter cloacae, Klebsiella pneumoniae, and Klebsiella oxytoca and bacterial pathogens Salmonella typhimurium, Yersinia enterocolitica, Shigella sonnei, Legionella gormanii, and Campylobacter jejuni had increased resistance to free chlorine residuals. Bacteria could be cultured from within treated protozoans well after the time required for 99% inactivation of free-living cells. All bacterial pathogens were greater than 50-fold more resistant to free chlorine when ingested by T. pyriformis. Escherichia coli ingested by a Cyclidium sp., a ciliate isolated from a drinking water reservoir, were also shown to be more resistant to free chlorine. The mechanism that increased resistance appeared to be survival within protozoan cells. This study indicates that bacteria can survive ingestion by protozoa. This bacterium-protozoan association provides bacteria with increased resistance to free chlorine residuals which can lead to persistence of bacteria in chlorine-treated water. We propose that resistance to digestion by predatory protozoa was an evolutionary precursor of pathogenicity in bacteria and that today it is a mechanism for survival of fastidious bacteria in dilute and inhospitable aquatic environments.
 ...
PMID:Survival of coliforms and bacterial pathogens within protozoa during chlorination. 322 66


1 2 3 4 5 6 7 8 9 10 Next >>