Special Issue "Pathogen Legionella pneumophila"

A special issue of Pathogens (ISSN 2076-0817).

Deadline for manuscript submissions: closed (30 September 2016)

Special Issue Editor

Guest Editor
Prof. Dr. Claudiu T. Supuran

Neurofarba Department, Sezione di Scienze Farmaceutiche e Nutraceutiche, Università degli Studi di Firenze, Sesto Fiorentino (Florence) 50019, Italy
Website | E-Mail
Phone: +39-055-4573729/3005
Fax: +39-055-4573385
Interests: drug design; metalloenzymes; carbonic anhydrases; anticancer agents; antiinfectives; sulfonamides; coumarins

Special Issue Information

Dear Colleagues,

 

Legionella pneumophila is a Gram-negative environmental bacterium that normally infects amoebae. It was discovered in 1976 when it provoked a life-threatening pneumonia-like disease in many participants at the 58th Annual Convention of the American Legion in Philadelphia. This condition was subsequently dubbed Legionnaires’ disease, or legionellosis. When the bacterial pathogen was characterized in detail, it was shown that a large number of its subspecies and serovars are widespread in nature. It is now known that L. pneumophila and the related species L. longbeachae are responsible for legionellosis in humans. These pathogens are increasingly spread all over the world through the development of artificial water systems for air conditioning, cooling towers, and aerosolizing devices, among other applications, and they have started to show resistance to the clinically used antibiotics. This issue of the Pathogens will bring together papers in all fields, starting with molecular biology and ending with novel antibiotic development related to L. pneumophila.

Professor Claudiu T. Supuran
Guest Editor

Manuscript Submission Information

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Keywords

  • Legionella pneumophila
  • antibiotic
  • drug resistance
  • pathogenicity
  • invasion
  • bacterial evolution
  • pathogen survival
  • drug development

Published Papers (4 papers)

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Research

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Open AccessArticle Application of Hydrogen Peroxide as an Innovative Method of Treatment for Legionella Control in a Hospital Water Network
Pathogens 2017, 6(2), 15; doi:10.3390/pathogens6020015
Received: 14 February 2017 / Revised: 5 April 2017 / Accepted: 11 April 2017 / Published: 17 April 2017
Cited by 1 | PDF Full-text (1314 KB) | HTML Full-text | XML Full-text
Abstract
Objectives: To evaluate the effectiveness of hydrogen peroxide (HP) use as a disinfectant in the hospital water network for the control of Legionella spp. colonization. Methods: Following the detection of high levels of Legionella contamination in a 136-bed general hospital water network, an
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Objectives: To evaluate the effectiveness of hydrogen peroxide (HP) use as a disinfectant in the hospital water network for the control of Legionella spp. colonization. Methods: Following the detection of high levels of Legionella contamination in a 136-bed general hospital water network, an HP treatment of the hot water supply (25 mg/L) was adopted. During a period of 34 months, the effectiveness of HP on Legionella colonization was assessed. Legionella was isolated in accordance with ISO-11731 and identification was carried out by sequencing of the mip gene. Results: Before HP treatment, L. pneumophila sg 2–15 was isolated in all sites with a mean count of 9950 ± 8279 cfu/L. After one-month of HP treatment, we observed the disappearance of L. pneumophila 2–15, however other Legionella species previously not seen were found; Legionella pneumophila 1 was isolated in one out of four sampling sites (2000 cfu/L) and other non-pneumophila species were present in all sites (mean load 3000 ± 2887 cfu/L). Starting from September 2013, HP treatment was modified by adding food-grade polyphosphates, and in the following months, we observed a progressive reduction of the mean load of all species (p < 0.05), resulting in substantial disappearance of Legionella colonization. Conclusion: Hydrogen peroxide demonstrated good efficacy in controlling Legionella. Although in the initial phases of treatment it appeared unable to eliminate all Legionella species, by maintaining HP levels at 25 mg/L and adding food-grade polyphosphates, a progressive and complete control of colonization was obtained. Full article
(This article belongs to the Special Issue Pathogen Legionella pneumophila)
Figures

Figure 1

Open AccessArticle Combination of Heat Shock and Enhanced Thermal Regime to Control the Growth of a Persistent Legionella pneumophila Strain
Pathogens 2016, 5(2), 35; doi:10.3390/pathogens5020035
Received: 15 March 2016 / Revised: 4 April 2016 / Accepted: 11 April 2016 / Published: 15 April 2016
Cited by 4 | PDF Full-text (1532 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Following nosocomial cases of Legionella pneumophila, the investigation of a hot water system revealed that 81.5% of sampled taps were positive for L. pneumophila, despite the presence of protective levels of copper in the water. A significant reduction of L. pneumophila
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Following nosocomial cases of Legionella pneumophila, the investigation of a hot water system revealed that 81.5% of sampled taps were positive for L. pneumophila, despite the presence of protective levels of copper in the water. A significant reduction of L. pneumophila counts was observed by culture after heat shock disinfection. The following corrective measures were implemented to control L. pneumophila: increasing the hot water temperature (55 to 60 °C), flushing taps weekly with hot water, removing excess lengths of piping and maintaining a water temperature of 55 °C throughout the system. A gradual reduction in L. pneumophila counts was observed using the culture method and qPCR in the 18 months after implementation of the corrective measures. However, low level contamination was retained in areas with hydraulic deficiencies, highlighting the importance of maintaining a good thermal regime at all points within the system to control the population of L. pneumophila. Full article
(This article belongs to the Special Issue Pathogen Legionella pneumophila)
Open AccessArticle Convective Mixing in Distal Pipes Exacerbates Legionella pneumophila Growth in Hot Water Plumbing
Pathogens 2016, 5(1), 29; doi:10.3390/pathogens5010029
Received: 18 January 2016 / Revised: 15 February 2016 / Accepted: 1 March 2016 / Published: 12 March 2016
Cited by 5 | PDF Full-text (1598 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Legionella pneumophila is known to proliferate in hot water plumbing systems, but little is known about the specific physicochemical factors that contribute to its regrowth. Here, L. pneumophila trends were examined in controlled, replicated pilot-scale hot water systems with continuous recirculation lines subject
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Legionella pneumophila is known to proliferate in hot water plumbing systems, but little is known about the specific physicochemical factors that contribute to its regrowth. Here, L. pneumophila trends were examined in controlled, replicated pilot-scale hot water systems with continuous recirculation lines subject to two water heater settings (40 °C and 58 °C) and three distal tap water use frequencies (high, medium, and low) with two pipe configurations (oriented upward to promote convective mixing with the recirculating line and downward to prevent it). Water heater temperature setting determined where L. pneumophila regrowth occurred in each system, with an increase of up to 4.4 log gene copies/mL in the 40 °C system tank and recirculating line relative to influent water compared to only 2.5 log gene copies/mL regrowth in the 58 °C system. Distal pipes without convective mixing cooled to room temperature (23–24 °C) during periods of no water use, but pipes with convective mixing equilibrated to 30.5 °C in the 40 °C system and 38.8 °C in the 58 °C system. Corresponding with known temperature effects on L. pneumophila growth and enhanced delivery of nutrients, distal pipes with convective mixing had on average 0.2 log more gene copies/mL in the 40 °C system and 0.8 log more gene copies/mL in the 58 °C system. Importantly, this work demonstrated the potential for thermal control strategies to be undermined by distal taps in general, and convective mixing in particular. Full article
(This article belongs to the Special Issue Pathogen Legionella pneumophila)

Review

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Open AccessReview Legionella pneumophila Carbonic Anhydrases: Underexplored Antibacterial Drug Targets
Pathogens 2016, 5(2), 44; doi:10.3390/pathogens5020044
Received: 14 May 2016 / Revised: 11 June 2016 / Accepted: 12 June 2016 / Published: 16 June 2016
Cited by 14 | PDF Full-text (1205 KB) | HTML Full-text | XML Full-text
Abstract
Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes which catalyze the hydration of carbon dioxide to bicarbonate and protons. Many pathogenic bacteria encode such enzymes belonging to the α-, β-, and/or γ-CA families. In the last decade, enzymes from some of these pathogens, including
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Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes which catalyze the hydration of carbon dioxide to bicarbonate and protons. Many pathogenic bacteria encode such enzymes belonging to the α-, β-, and/or γ-CA families. In the last decade, enzymes from some of these pathogens, including Legionella pneumophila, have been cloned and characterized in detail. These enzymes were shown to be efficient catalysts for CO2 hydration, with kcat values in the range of (3.4–8.3) × 105 s−1 and kcat/KM values of (4.7–8.5) × 107 M−1·s−1. In vitro inhibition studies with various classes of inhibitors, such as anions, sulfonamides and sulfamates, were also reported for the two β-CAs from this pathogen, LpCA1 and LpCA2. Inorganic anions were millimolar inhibitors, whereas diethyldithiocarbamate, sulfamate, sulfamide, phenylboronic acid, and phenylarsonic acid were micromolar ones. The best LpCA1 inhibitors were aminobenzolamide and structurally similar sulfonylated aromatic sulfonamides, as well as acetazolamide and ethoxzolamide (KIs in the range of 40.3–90.5 nM). The best LpCA2 inhibitors belonged to the same class of sulfonylated sulfonamides, together with acetazolamide, methazolamide, and dichlorophenamide (KIs in the range of 25.2–88.5 nM). Considering such preliminary results, the two bacterial CAs from this pathogen represent promising yet underexplored targets for obtaining antibacterials devoid of the resistance problems common to most of the clinically used antibiotics, but further studies are needed to validate them in vivo as drug targets. Full article
(This article belongs to the Special Issue Pathogen Legionella pneumophila)

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