• Korean Journal of Microbiology
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• v.45 no.2
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• pp.126-132
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• 2009

Legionella spp. is the causative agent of Legionellosis, which induces a potentially fatal form of pneumonia. With a concentrated performance during the summer of 2008, we secured 73 isolates from the water systems of 25 wards in Seoul. We analysed serotypes, pathogenic genes (Dot/Icm), and patterns of pulsed-field gel electrophoresis (PFGE) in an attempt to confirm relationships among them. Different from the previous year's pattern (2007), among the isolates, 69 were Legionella pneumophila and 4 were Legionella spp. The serotype distribution of Legionella pneumophila was sg1 43, sg6 9, sg5 8, sg3 8, and sg2 1. The serotype for the 4 Legionella spp. was Legionella nautarum. Most of the Legionella pneumophila had several pathogenic genes. On the other hand, the 4 Legionella spp. were defective in pathogenicity in genomic terms. The PFGE patterns of the serotypes showed a tendency for diversity of Legionella pneumophila and a close correlation with genetic pathogenicity.

• Tuberculosis and Respiratory Diseases
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• v.68 no.2
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• pp.74-79
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• 2010

Background: Legionella pneumophila has been recognized as an important cause of pneumonia. However, limited data are available in the literature regarding legionella pneumonia in Korea. The objective of this study was to compare epidemiological data and clinical presentation of legionella pneumonia and pneumococcal pneumonia. Methods: We retrospectively compared clinical, radiological, and laboratory data, antimicrobial treatment, and treatment outcomes between 28 cases of legionella pneumonia and 56 cases of pneumococcal pneumonia. Diagnoses of both legionella and pneumococcal pneumonia were based on commercial urinary antigen tests. Results: Legionella pneumonia patients included 23 men and 5 women, with a mean age of 61.6 years (range 36~88). Fifteen were smokers and 26 had some underlying diseases. Legionella pneumonia occurred more frequently in healthcare-associated settings than pneumococcal pneumonia (42.9% vs 21.4%, respectively, p=0.040). There were no significant differences in clinical signs and symptoms. Compared to patients with pneumococcal pneumonia, patients with legionella pneumonia presented more frequently with anemia (39.3% vs 8.9%, p=0.001), increased C-reactive protein (57.1% vs 30.4%, p=0.018) and increased alkaline phosphatase (46.4% vs 16.1%, p=0.003). Also, legionella pneumonia patients more often showed pleural effusion on simple chest X-rays (50.0% vs 12.5%, p<0.001). Conclusion: Legionella pneumonia and pneumococcal pneumonia can not be distinguished by clinical manifestations alone. However, legionella pneumonia occurred as a healthcare-associated pneumonia more frequently and was more often associated with anemia and increased CRP and alkaline phosphatase levels.

• Proceedings of the Korean Environmental Health Society Conference
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• 2004.06a
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• pp.197-201
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• 2004

This study was to determine the prevalence of Legionella species in public spas and to know that the presence of Legionella was correlated with other microbiological parameters. A total of 81 water samples were collected from 30 different public spas and sudatoriums so called zzimzilbang in Korea. Although Legionella was not detected in the influent water and the cold tub water, of the 38 samples of hot and warm water taken from public tubs, 11(28.8%) were found to be positive for Legionella spp. All of the isolates were identified as a species L. pneumophila serogroups 1 and 2-14 by latex agglutination. And HPC concentrations in all spas water isolated Legionella were above the level of $10^4\;cfu/ml$.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.360-368
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• 2013

Recently interactive water fountains are gaining popularity in making public facilities in South Korea. The total number of interactive fountains is rapidly growing at the rate of >50% annually. In this study, we performed quantitative microbial risk assessment to estimate infection risks in children by Legionella spp. while playing in interactive fountains. The exposure dose for a given concentration of Legionella in water was calculated using water-aerosol partition rate of Legionella, exposure duration, inhalation rate, and deposit rate of aerosols in the lungs following inhalation. The dose was converted to infection risk by using the dose-response function developed for L. pneumophila. High weight and/or old children, i.e., 12-year children, running around in fountains were the highest risk group by showing >0.05 infection probability for fountain waters containing ${\geq}10^4$ CFU/L Legionella. The result supported the current guideline by Korea Centers for Disease Control and Prevention, which permits use of water with < $10^3$ CFU/L Legionella cells for all purposes. However, the results still warrant further evaluation of the guideline to accommodate risks for children because the dose-response relationship in the model was developed for healthy adults. Further risk assessment studies need to be conducted by employing dose-response model for children who generally carries weaker immune system than adults.

• BMB Reports
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• v.55 no.7
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• pp.316-322
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• 2022

Ubiquitin is relatively modest in size but involves almost entire cellular signaling pathways. The primary role of ubiquitin is maintaining cellular protein homeostasis. Ubiquitination regulates the fate of target proteins using the proteasome- or autophagy-mediated degradation of ubiquitinated substrates, which can be either intracellular or foreign proteins from invading pathogens. Legionella, a gram-negative intracellular pathogen, hinders the host-ubiquitin system by translocating hundreds of effector proteins into the host cell's cytoplasm. In this review, we describe the current understanding of ubiquitin machinery from Legionella. We summarize structural and biochemical differences between the host-ubiquitin system and ubiquitin-related effectors of Legionella. Some of these effectors act much like canonical host-ubiquitin machinery, whereas others have distinctive structures and accomplish non-canonical ubiquitination via novel biochemical mechanisms.

• Journal of Environmental Science International
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• v.17 no.6
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• pp.581-589
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• 2008

This study was carried out to evaluate the effect of water quality of cooling tower on Legionella pneumophila disinfection using Ru/Ti electrode. The influences of parameters such as pH, turbidity, $CaCO_3$ and TOC were investigated using laboratory scale batch reactor. Oxidants such as free Cl, $ClO_2,\;H_2O_2\;and\;O_3$ were measured. The results showed that all of the water quality parameters of cooling tower had deteriorated disinfection of Legionella pneumophila. When the turbidity, $CaCO_3$ and TOC was increased, oxidants which was generated during electrolysis was decreased. pH, free Cl, $ClO_2\;and\;H_2O_2$ concentration were decreased with the increase of pH, whereas $O_3$ concentration was increased with the increase of pH. The order of effect of water quality on the disinfection performance for Legionella pneumophila was turbidity > $CaCO_3$ > TOC > pH. To obtain the safety standard (1000 CFU/L), the simultaneous increase current and NaCl dosage was needed.

• Journal of Environmental Health Sciences
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• v.14 no.1
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• pp.23-32
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• 1988

A study was carried out to find distribution of Legionella spp. in hot water supplying systems of buildings in Seoul. Water samples were taken from the hot water taps in three research institute buildings during the period from the 2nd to 27th February, 1987. And all of the three buildings were supplied with hot water from the same central hot water tank. GVPC BCYEa and blood agar were used for the isolation of Legionella pneurnophila and slide agglutination test (SAT) was performed to identify their strain types. Main findings were as follows 1. 44 samples taken from hot tap-water revealed 20% of positive culture and 44 samples taken from hot water spouts revealed 11% of positive culture. 2. The 78% of positive samples taken from hot water was obtained from 25.1$\circ$C~45.0$\circ$C temperature range. 3. Only, Legionella pneumophila serogroup 3 was identified and most of them has been than 2$\mu$m in length. 4. The densities of the Legionella pneurnophila isolated from hot water samples were within the range of $1.0\times 10^2$ to $1.1\times 10^3$ CFU/l and their densities isolated from hot water spouts were either 1 CFU/plate or 2 CFU/plate.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.424-428
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• 2013

To identify risk factors for Legionella contamination, water quality variables routinely measured in examination of natural and city waters were meta-analyzed for significance of correlation to Legionella incidences. For evaluation of abundance of Escherichia coli as a risk factor, which is currently used as an indicator of Legionella contamination in an official guideline in Korea, odds ratio (OR) of above-cutoff total coliform counts for Legionella presence/absence was used as the effect size in the meta-analysis. The OR was estimated as 1.05 (0.36-3.12, 95% CI), and the probability of having identical odds reached 0.92. Also, ORs from individual studies showed significant heterogeneity (P=0.008), which contributed to 63% of total variance of the ORs. In the case of heterotrophic plate count (HPC), the OR for Legionella presence/absence was 2.72 (2.04-3.63) with highly significant deviation from identical odds (P<0.0001). ORs from different studies were seemingly homogeneous ($Q_{df=8}$=12.7, P=0.12). Turbidity and concentrations of chlorine, iron ion and cupper ion were other routine variables that could be considered as risk factors. However, statistical measures from different studies were not uniform enough to develop an appropriate effect size while the number of studies reporting the variables was also small (3-5). In conclusion, HPC appeared to be appropriate as indicator of Legionella contamination, rather than fecal bacteria contamination. HPC may imply abundance of habitats (amoebas and biofilms) of Legionella in water. This result warrants further studies for standardizing protocols and cutoff values to infer Legionella risks from HPC.

• Journal of Yeungnam Medical Science
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• v.5 no.1
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• pp.77-84
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• 1988

The principal mode of the transmission of Legionnaires disease is a inthalation of the cooling tower water droplets in which Legionellae exist. As a central cooling system is popularized in many public buildings and large buildings nowadays, the number of cooling towers is rapidly increasing. Therefore the possibility of an outbreak of Legionnaires disease is likely increased. To determine the presence of Legionella in cooling tower water as the first step for the prevention of Legionnaires disease, 48 samples of cooling tower water were taken from 24 buildings in Taegu city in july and september 1987. Three samples out of 24 water samples In September yielded Legionella but it was not isolated in the samples of July. Isolated 3 Legionellas were identified as Legionella peumophila. It seems that Legionella from the cooling tower will be isolated more frequently in late summer than early because central cooling system is stopped operation during winter season which is cool. As based on our survey, Legionnaires disease can occur in Taegu city and if it happens it is most likely due to L. pneumophila.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.613-619
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• 2007

This study has carried out a performance of dimensionally stable anode for the purpose of disinfection of Legionella pneumophila in water. Three kinds of electrode were prepared by plating and thermal deposition, which were coated by the oxides of Pt, Ru and Ir on Ti metal surface, respectively. The order of disinfection performance for Legionella pneumophila was Ru/Ti > Ir/Ti > Pt/Ti. Free Cl and $ClO_2$ generation of Ir/Ti electrode was higher than that of two electrodes. However, the concentrations of generated $H_2O_2$ and $O_3$ of the Ru/Ti electrode were highest among the three electrodes. The higher NaCl concentration was, the more oxidants was generated and disinfection effect was increased. However, optimum NaCl dosage was 0.0125% due to the regulation on the conductivity and $Cl^-$ concentration for the cooling water quality of air conditioning and refrigeration equipment. With the increase of current, oxidants was more generated and following disinfection effect was increased. The increase of electrode distance reduced oxidants generation due to the low electric power, and their disinfection effect was decreased accordingly.