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. 2017 Apr 17;6(2):15.
doi: 10.3390/pathogens6020015.

Application of Hydrogen Peroxide as an Innovative Method of Treatment for Legionella Control in a Hospital Water Network

Beatrice Casini  1 , Francesco Aquino  2 , Michele Totaro  3 , Mario Miccoli  4 , Irio Galli  5 , Laura Manfredini  6 , Carlo Giustarini  7 , Anna Laura Costa  8 , Benedetta Tuvo  9 , Paola Valentini  10 , Gaetano Privitera  11 , Angelo Baggiani  12
Affiliations

Application of Hydrogen Peroxide as an Innovative Method of Treatment for Legionella Control in a Hospital Water Network

Beatrice Casini et al. Pathogens. .

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 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; Legionellapneumophila 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.

Keywords: Legionella; disinfection; hospital; hydrogen peroxide.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Legionella pneumophila sg1 (Lp1), Legionella pneumophila sg2-15 (Lp2-15), Legionella spp. (L spp.) loads (cfu/L) detected in the four different sampling sites in the hospital. Intensive Care Unit (ICU), Emergency Department (ED), Oncology (ONCO), Obstetrics and Gynecology (OBST-GYN), Recirculation point (RIC) during the period of hydrogen peroxide (HP) disinfection (from July 2013 to June 2016).
Figure 2
Figure 2
Legionella loads (cfu/L) detected in each of the four sampling sites in the hospital: Intensive Care Unit (ICU), Emergency Department (ED), Oncology (ONCO), Obstetrics and Gynecology (OBST-GYN), Recirculation point (RIC) during the period from July 2013 to June 2016.
See this image and copyright information in PMC

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