The effects of silver nitrate on Mycobacterium abscessus biofilms in a simulated antimicrobial showerhead environment

Antimicrobial silver materials for drinking water disinfection have become increasingly popular in building-wide systems (e.g., copper-silver ionization) and point-of-use applications (e.g., silver containing plumbing fixtures) to combat the microbial growth of drinking water associated pathogens th...

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Main Authors: Sarah Pitell, Cheolwoon Woo, Jill Millstone, Janet Stout, Leanne Gilbertson, Sarah-Jane Haig
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-05-01
Series:Frontiers in Public Health
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Online Access:https://www.frontiersin.org/articles/10.3389/fpubh.2025.1572869/full
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author Sarah Pitell
Cheolwoon Woo
Jill Millstone
Jill Millstone
Jill Millstone
Janet Stout
Janet Stout
Leanne Gilbertson
Sarah-Jane Haig
Sarah-Jane Haig
author_facet Sarah Pitell
Cheolwoon Woo
Jill Millstone
Jill Millstone
Jill Millstone
Janet Stout
Janet Stout
Leanne Gilbertson
Sarah-Jane Haig
Sarah-Jane Haig
author_sort Sarah Pitell
collection DOAJ
description Antimicrobial silver materials for drinking water disinfection have become increasingly popular in building-wide systems (e.g., copper-silver ionization) and point-of-use applications (e.g., silver containing plumbing fixtures) to combat the microbial growth of drinking water associated pathogens that can cause infections in the immunocompromised (DWPIs). However, evaluations of various silver-containing treatments suggest that their efficacy is often temporary or incomplete. A potential explanation of these observations is insufficient dosing of silver into the drinking water to reduce these types of microorganisms, which are known to be more resistant to biocides. Instead, sublethal exposure may cause these microorganisms to adapt in ways that increase their resistance to disinfection. In this study, we assessed the effects of different silver concentrations on biofilms of clinically and environmentally isolated Mycobacterium abscessus, a biofilm-forming member of the drinking water microbiota with public health and environmental significance, in a bench-scale system operated to simulated the use patterns of antimicrobial showerheads. We found that high concentrations of silver significantly reduced biofilms cell densities and impacted cellular aggregation behavior, but ultimately made the resulting treated water non-potable due to the concentration of silver needed to solicit these effects. Silver concentrations that were more appropriate for drinking water applications resulting in limited reduction in viable M. abscessus. Additionally, transcriptomic analysis revealed that genes related to stress survival were upregulated in all experimental conditions: genes related to flavoprotein, chaperone, and protease synthesis, ribosome synthesis, and cysteine and methionine metabolism were upregulated in the lower dose condition, and peptidoglycan synthesis and antioxidant production were upregulated in the higher silver dose condition. These expressional changes may enhance survival and pathogenicity traits in M. abscessus after silver exposure. Overall, our findings indicate that silver exposure drives meaningful changes in biofilm behavior and gene expression in M. abscessus isolates, yet does not inactivate M. abscessus under the simulated conditions.
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spelling doaj-art-5af53273b10148e7bca9e6127fc957bc2025-08-20T03:08:26ZengFrontiers Media S.A.Frontiers in Public Health2296-25652025-05-011310.3389/fpubh.2025.15728691572869The effects of silver nitrate on Mycobacterium abscessus biofilms in a simulated antimicrobial showerhead environmentSarah Pitell0Cheolwoon Woo1Jill Millstone2Jill Millstone3Jill Millstone4Janet Stout5Janet Stout6Leanne Gilbertson7Sarah-Jane Haig8Sarah-Jane Haig9Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA, United StatesDepartment of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA, United StatesDepartment of Chemistry, University of Pittsburgh, Pittsburgh, PA, United StatesDepartment of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA, United StatesDepartment of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA, United StatesDepartment of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA, United StatesSpecial Pathogens Laboratory, Pittsburgh, PA, United StatesDepartment of Civil and Environmental Engineering, Duke University, Durham, NC, United StatesDepartment of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA, United StatesDepartment of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA, United StatesAntimicrobial silver materials for drinking water disinfection have become increasingly popular in building-wide systems (e.g., copper-silver ionization) and point-of-use applications (e.g., silver containing plumbing fixtures) to combat the microbial growth of drinking water associated pathogens that can cause infections in the immunocompromised (DWPIs). However, evaluations of various silver-containing treatments suggest that their efficacy is often temporary or incomplete. A potential explanation of these observations is insufficient dosing of silver into the drinking water to reduce these types of microorganisms, which are known to be more resistant to biocides. Instead, sublethal exposure may cause these microorganisms to adapt in ways that increase their resistance to disinfection. In this study, we assessed the effects of different silver concentrations on biofilms of clinically and environmentally isolated Mycobacterium abscessus, a biofilm-forming member of the drinking water microbiota with public health and environmental significance, in a bench-scale system operated to simulated the use patterns of antimicrobial showerheads. We found that high concentrations of silver significantly reduced biofilms cell densities and impacted cellular aggregation behavior, but ultimately made the resulting treated water non-potable due to the concentration of silver needed to solicit these effects. Silver concentrations that were more appropriate for drinking water applications resulting in limited reduction in viable M. abscessus. Additionally, transcriptomic analysis revealed that genes related to stress survival were upregulated in all experimental conditions: genes related to flavoprotein, chaperone, and protease synthesis, ribosome synthesis, and cysteine and methionine metabolism were upregulated in the lower dose condition, and peptidoglycan synthesis and antioxidant production were upregulated in the higher silver dose condition. These expressional changes may enhance survival and pathogenicity traits in M. abscessus after silver exposure. Overall, our findings indicate that silver exposure drives meaningful changes in biofilm behavior and gene expression in M. abscessus isolates, yet does not inactivate M. abscessus under the simulated conditions.https://www.frontiersin.org/articles/10.3389/fpubh.2025.1572869/fullNTMbiofilmCDC reactoropportunistic pathogenMycobacterium abscessus
spellingShingle Sarah Pitell
Cheolwoon Woo
Jill Millstone
Jill Millstone
Jill Millstone
Janet Stout
Janet Stout
Leanne Gilbertson
Sarah-Jane Haig
Sarah-Jane Haig
The effects of silver nitrate on Mycobacterium abscessus biofilms in a simulated antimicrobial showerhead environment
Frontiers in Public Health
NTM
biofilm
CDC reactor
opportunistic pathogen
Mycobacterium abscessus
title The effects of silver nitrate on Mycobacterium abscessus biofilms in a simulated antimicrobial showerhead environment
title_full The effects of silver nitrate on Mycobacterium abscessus biofilms in a simulated antimicrobial showerhead environment
title_fullStr The effects of silver nitrate on Mycobacterium abscessus biofilms in a simulated antimicrobial showerhead environment
title_full_unstemmed The effects of silver nitrate on Mycobacterium abscessus biofilms in a simulated antimicrobial showerhead environment
title_short The effects of silver nitrate on Mycobacterium abscessus biofilms in a simulated antimicrobial showerhead environment
title_sort effects of silver nitrate on mycobacterium abscessus biofilms in a simulated antimicrobial showerhead environment
topic NTM
biofilm
CDC reactor
opportunistic pathogen
Mycobacterium abscessus
url https://www.frontiersin.org/articles/10.3389/fpubh.2025.1572869/full
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