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Reens AL, Cosetta CM, Saur R, Trofimuk O, Brooker SL, Lee ML, Sun AK, McKenzie GJ, Button JE. Tunable control of B. infantis abundance and gut metabolites by co-administration of human milk oligosaccharides. Gut Microbes 2024; 16:2304160. [PMID: 38235736 PMCID: PMC10798361 DOI: 10.1080/19490976.2024.2304160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 01/08/2024] [Indexed: 01/19/2024] Open
Abstract
Precision engineering of the gut microbiome holds promise as an effective therapeutic approach for diseases associated with a disruption in this microbial community. Engrafting a live biotherapeutic product (LBP) in a predictable, controllable manner is key to the consistent success of this approach and has remained a challenge for most LBPs under development. We recently demonstrated high-level engraftment of Bifidobacterium longum subsp. infantis (B. infantis) in adults when co-dosed with a specific prebiotic, human milk oligosaccharides (HMO). Here, we present a cellular kinetic-pharmacodynamic approach, analogous to pharmacokinetic-pharmacodynamic-based analyses of small molecule- and biologic-based drugs, to establish how HMO controls expansion, abundance, and metabolic output of B. infantis in a human microbiota-based model in gnotobiotic mice. Our data demonstrate that the HMO dose controls steady-state abundance of B. infantis in the microbiome, and that B. infantis together with HMO impacts gut metabolite levels in a targeted, HMO-dependent manner. We also found that HMO creates a privileged niche for B. infantis expansion across a 5-log range of bacterial inocula. These results demonstrate remarkable control of both B. infantis levels and the microbiome community metabolic outputs using this synbiotic approach, and pave the way for precision engineering of desirable microbes and metabolites to treat a range of diseases.
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Affiliation(s)
| | | | | | | | | | - Martin L. Lee
- Prolacta Bioscience, Duarte, CA, USA
- Department of Biostatistics, University of California Los Angeles Fielding School of Public Health, Los AngelesCA, USA
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Button JE, Cosetta CM, Reens AL, Brooker SL, Rowan-Nash AD, Lavin RC, Saur R, Zheng S, Autran CA, Lee ML, Sun AK, Alousi AM, Peterson CB, Koh AY, Rechtman DJ, Jenq RR, McKenzie GJ. Precision modulation of dysbiotic adult microbiomes with a human-milk-derived synbiotic reshapes gut microbial composition and metabolites. Cell Host Microbe 2023; 31:1523-1538.e10. [PMID: 37657443 DOI: 10.1016/j.chom.2023.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 06/13/2023] [Accepted: 08/07/2023] [Indexed: 09/03/2023]
Abstract
Manipulation of the gut microbiome using live biotherapeutic products shows promise for clinical applications but remains challenging to achieve. Here, we induced dysbiosis in 56 healthy volunteers using antibiotics to test a synbiotic comprising the infant gut microbe, Bifidobacterium longum subspecies infantis (B. infantis), and human milk oligosaccharides (HMOs). B. infantis engrafted in 76% of subjects in an HMO-dependent manner, reaching a relative abundance of up to 81%. Changes in microbiome composition and gut metabolites reflect altered recovery of engrafted subjects compared with controls. Engraftment associates with increases in lactate-consuming Veillonella, faster acetate recovery, and changes in indolelactate and p-cresol sulfate, metabolites that impact host inflammatory status. Furthermore, Veillonella co-cultured in vitro and in vivo with B. infantis and HMO converts lactate produced by B. infantis to propionate, an important mediator of host physiology. These results suggest that the synbiotic reproducibly and predictably modulates recovery of a dysbiotic microbiome.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Martin L Lee
- Prolacta Bioscience, Duarte, CA 91010, USA; Department of Biostatistics, University of California Los Angeles, Fielding School of Public Health, Los Angeles, CA 90095, USA
| | - Adam K Sun
- Prolacta Bioscience, Duarte, CA 91010, USA
| | - Amin M Alousi
- Department of Stem Cell Transplantation, Division of Cancer Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Christine B Peterson
- Department of Biostatistics, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Andrew Y Koh
- Department of Pediatrics, Division of Hematology/Oncology, The University of Texas Southwestern Medical Center, Dallas, TX 75235, USA; Harold C. Simmons Comprehensive Cancer Center, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | | | - Robert R Jenq
- Department of Genomic Medicine, Division of Cancer Medicine, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
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Button JE, Autran CA, Reens AL, Cosetta CM, Smriga S, Ericson M, Pierce JV, Cook DN, Lee ML, Sun AK, Alousi AM, Koh AY, Rechtman DJ, Jenq RR, McKenzie GJ. Dosing a synbiotic of human milk oligosaccharides and B. infantis leads to reversible engraftment in healthy adult microbiomes without antibiotics. Cell Host Microbe 2022; 30:712-725.e7. [PMID: 35504279 DOI: 10.1016/j.chom.2022.04.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 03/11/2022] [Accepted: 04/07/2022] [Indexed: 11/30/2022]
Abstract
Predictable and sustainable engraftment of live biotherapeutic products into the human gut microbiome is being explored as a promising way to modulate the human gut microbiome. We utilize a synbiotic approach pairing the infant gut microbe Bifidobacterium longum subspecies infantis (B. infantis) and human milk oligosaccharides (HMO). B. infantis, which is typically absent in adults, engrafts into healthy adult microbiomes in an HMO-dependent manner at a relative abundance of up to 25% of the bacterial population without antibiotic pretreatment or adverse effects. Corresponding changes in metabolites are detected. Germ-free mice transplanted with dysbiotic human microbiomes also successfully engraft with B. infantis in an HMO-dependent manner, and the synbiotic augments butyrate levels both in this in vivo model and in in vitro cocultures of the synbiotic with specific Firmicutes species. Finally, the synbiotic inhibits the growth of enteropathogens in vitro. Our findings point to a potential safe mechanism for ameliorating dysbioses characteristic of numerous human diseases.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Adam K Sun
- Prolacta Bioscience, Duarte, CA 91010, USA
| | - Amin M Alousi
- Department of Stem Cell Transplantation, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Andrew Y Koh
- Department of Pediatrics, Division of Hematology/Oncology, The University of Texas Southwestern Medical Center, Dallas, TX 75235, USA; Harold C. Simmons Comprehensive Cancer Center, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | | | - Robert R Jenq
- Department of Genomic Medicine, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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Swaminathan G, Citron M, Xiao J, Norton JE, Reens AL, Topçuoğlu BD, Maritz JM, Lee KJ, Freed DC, Weber TM, White CH, Kadam M, Spofford E, Bryant-Hall E, Salituro G, Kommineni S, Liang X, Danilchanka O, Fontenot JA, Woelk CH, Gutierrez DA, Hazuda DJ, Hannigan GD. Vaccine Hyporesponse Induced by Individual Antibiotic Treatment in Mice and Non-Human Primates Is Diminished upon Recovery of the Gut Microbiome. Vaccines (Basel) 2021; 9:vaccines9111340. [PMID: 34835271 PMCID: PMC8619314 DOI: 10.3390/vaccines9111340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/19/2021] [Accepted: 10/29/2021] [Indexed: 11/16/2022] Open
Abstract
Emerging evidence demonstrates a connection between microbiome composition and suboptimal response to vaccines (vaccine hyporesponse). Harnessing the interaction between microbes and the immune system could provide novel therapeutic strategies for improving vaccine response. Currently we do not fully understand the mechanisms and dynamics by which the microbiome influences vaccine response. Using both mouse and non-human primate models, we report that short-term oral treatment with a single antibiotic (vancomycin) results in the disruption of the gut microbiome and this correlates with a decrease in systemic levels of antigen-specific IgG upon subsequent parenteral vaccination. We further show that recovery of microbial diversity before vaccination prevents antibiotic-induced vaccine hyporesponse, and that the antigen specific IgG response correlates with the recovery of microbiome diversity. RNA sequencing analysis of small intestine, spleen, whole blood, and secondary lymphoid organs from antibiotic treated mice revealed a dramatic impact on the immune system, and a muted inflammatory signature is correlated with loss of bacteria from Lachnospiraceae, Ruminococcaceae, and Clostridiaceae. These results suggest that microbially modulated immune pathways may be leveraged to promote vaccine response and will inform future vaccine design and development strategies.
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Affiliation(s)
- Gokul Swaminathan
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
- Correspondence: (G.S.); (G.D.H.)
| | - Michael Citron
- Infectious Diseases and Vaccine Research, MRL, Merck & Co., Inc., West Point, PA 19486, USA; (M.C.); (J.X.); (D.C.F.); (T.M.W.)
| | - Jianying Xiao
- Infectious Diseases and Vaccine Research, MRL, Merck & Co., Inc., West Point, PA 19486, USA; (M.C.); (J.X.); (D.C.F.); (T.M.W.)
| | - James E. Norton
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
| | - Abigail L. Reens
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
| | - Begüm D. Topçuoğlu
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
| | - Julia M. Maritz
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
| | - Keun-Joong Lee
- Pharmacokinetics, Pharmacodynamics & Drug Metabolism, MRL, Merck & Co. Inc., Rahway, NJ 07065, USA; (K.-J.L.); (G.S.)
| | - Daniel C. Freed
- Infectious Diseases and Vaccine Research, MRL, Merck & Co., Inc., West Point, PA 19486, USA; (M.C.); (J.X.); (D.C.F.); (T.M.W.)
| | - Teresa M. Weber
- Infectious Diseases and Vaccine Research, MRL, Merck & Co., Inc., West Point, PA 19486, USA; (M.C.); (J.X.); (D.C.F.); (T.M.W.)
| | - Cory H. White
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
| | - Mahika Kadam
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
| | - Erin Spofford
- Safety Assessment and Laboratory Animal Research, MRL, Merck & Co. Inc., Boston, MA 02115, USA; (E.S.); (E.B.-H.)
| | - Erin Bryant-Hall
- Safety Assessment and Laboratory Animal Research, MRL, Merck & Co. Inc., Boston, MA 02115, USA; (E.S.); (E.B.-H.)
| | - Gino Salituro
- Pharmacokinetics, Pharmacodynamics & Drug Metabolism, MRL, Merck & Co. Inc., Rahway, NJ 07065, USA; (K.-J.L.); (G.S.)
| | - Sushma Kommineni
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
| | - Xue Liang
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
| | - Olga Danilchanka
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
| | - Jane A. Fontenot
- New Iberia Research Center, University of Louisiana at Lafayette, Lafayette, LA 70503, USA;
| | - Christopher H. Woelk
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
| | - Dario A. Gutierrez
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
| | - Daria J. Hazuda
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
- Infectious Diseases and Vaccine Research, MRL, Merck & Co., Inc., West Point, PA 19486, USA; (M.C.); (J.X.); (D.C.F.); (T.M.W.)
| | - Geoffrey D. Hannigan
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA 02141, USA; (J.E.N.J.); (A.L.R.); (B.D.T.); (J.M.M.); (C.H.W.); (M.K.); (S.K.); (X.L.); (O.D.); (C.H.W.); (D.A.G.); (D.J.H.)
- Correspondence: (G.S.); (G.D.H.)
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Reens AL, Cabral DJ, Liang X, Norton JE, Therien AG, Hazuda DJ, Swaminathan G. Immunomodulation by the Commensal Microbiome During Immune-Targeted Interventions: Focus on Cancer Immune Checkpoint Inhibitor Therapy and Vaccination. Front Immunol 2021; 12:643255. [PMID: 34054810 PMCID: PMC8155485 DOI: 10.3389/fimmu.2021.643255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 04/22/2021] [Indexed: 12/11/2022] Open
Abstract
Emerging evidence in clinical and preclinical studies indicates that success of immunotherapies can be impacted by the state of the microbiome. Understanding the role of the microbiome during immune-targeted interventions could help us understand heterogeneity of treatment success, predict outcomes, and develop additional strategies to improve efficacy. In this review, we discuss key studies that reveal reciprocal interactions between the microbiome, the immune system, and the outcome of immune interventions. We focus on cancer immune checkpoint inhibitor treatment and vaccination as two crucial therapeutic areas with strong potential for immunomodulation by the microbiota. By juxtaposing studies across both therapeutic areas, we highlight three factors prominently involved in microbial immunomodulation: short-chain fatty acids, microbe-associate molecular patterns (MAMPs), and inflammatory cytokines. Continued interrogation of these models and pathways may reveal critical mechanistic synergies between the microbiome and the immune system, resulting in novel approaches designed to influence the efficacy of immune-targeted interventions.
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Affiliation(s)
- Abigail L. Reens
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA, United States
| | - Damien J. Cabral
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA, United States
| | - Xue Liang
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA, United States
| | - James E. Norton
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA, United States
| | - Alex G. Therien
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA, United States
| | - Daria J. Hazuda
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA, United States
- Infectious Disease and Vaccine Research, Merck & Co., Inc., West Point, PA, United States
| | - Gokul Swaminathan
- Exploratory Science Center, Merck & Co., Inc., Cambridge, MA, United States
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Reens AL, Crooks AL, Su CC, Nagy TA, Reens DL, Podoll JD, Edwards ME, Yu EW, Detweiler CS. A cell-based infection assay identifies efflux pump modulators that reduce bacterial intracellular load. PLoS Pathog 2018; 14:e1007115. [PMID: 29879224 PMCID: PMC6007937 DOI: 10.1371/journal.ppat.1007115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 06/19/2018] [Accepted: 05/21/2018] [Indexed: 12/20/2022] Open
Abstract
Bacterial efflux pumps transport small molecules from the cytoplasm or periplasm outside the cell. Efflux pump activity is typically increased in multi-drug resistant (MDR) pathogens; chemicals that inhibit efflux pumps may have potential for antibiotic development. Using an in-cell screen, we identified three efflux pump modulators (EPMs) from a drug diversity library. The screening platform uses macrophages infected with the human Gram-negative pathogen Salmonella enterica (Salmonella) to identify small molecules that prevent bacterial replication or survival within the host environment. A secondary screen for hit compounds that increase the accumulation of an efflux pump substrate, Hoechst 33342, identified three small molecules with activity comparable to the known efflux pump inhibitor PAβN (Phe-Arg β-naphthylamide). The three putative EPMs demonstrated significant antibacterial activity against Salmonella within primary and cell culture macrophages and within a human epithelial cell line. Unlike traditional antibiotics, the three compounds did not inhibit bacterial growth in standard microbiological media. The three compounds prevented energy-dependent efflux pump activity in Salmonella and bound the AcrB subunit of the AcrAB-TolC efflux system with KDs in the micromolar range. Moreover, the EPMs display antibacterial synergy with antimicrobial peptides, a class of host innate immune defense molecules present in body fluids and cells. The EPMs also had synergistic activity with antibiotics exported by AcrAB-TolC in broth and in macrophages and inhibited efflux pump activity in MDR Gram-negative ESKAPE clinical isolates. Thus, an in-cell screening approach identified EPMs that synergize with innate immunity to kill bacteria and have potential for development as adjuvants to antibiotics.
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Affiliation(s)
- Abigail L. Reens
- Department of Molecular, Cellular, & Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
| | - Amy L. Crooks
- Department of Molecular, Cellular, & Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
| | - Chih-Chia Su
- Department of Pharmacology, Case Western Reserve, Cleveland OH, United States of America
| | - Toni A. Nagy
- Department of Molecular, Cellular, & Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
| | - David L. Reens
- Department of Physics, University of Colorado Boulder, Boulder, CO, United States of America
- JILA, National Institutes of Standards and Technology and University of Colorado Boulder, Boulder, CO, United States of America
| | - Jessica D. Podoll
- Department of Molecular, Cellular, & Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
| | - Madeline E. Edwards
- Department of Molecular, Cellular, & Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
| | - Edward W. Yu
- Department of Pharmacology, Case Western Reserve, Cleveland OH, United States of America
| | - Corrella S. Detweiler
- Department of Molecular, Cellular, & Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
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Hull NM, Reens AL, Robertson CE, Stanish LF, Harris JK, Stevens MJ, Frank DN, Kotter C, Pace NR. Molecular analysis of single room humidifier bacteriology. Water Res 2015; 69:318-327. [PMID: 25574772 DOI: 10.1016/j.watres.2014.11.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 11/14/2014] [Accepted: 11/15/2014] [Indexed: 06/04/2023]
Abstract
Portable, single-room humidifiers are commonly used in homes for comfort and health benefits, but also create habitats for microbiology. Currently there is no information on home humidifier microbiology aside from anecdotal evidence of infection with opportunistic pathogens and irritation from endotoxin exposure. To obtain a broader perspective on humidifier microbiology, DNAs were isolated from tap source waters, tank waters, and biofilm samples associated with 26 humidifiers of ultrasonic and boiling modes of operation in the Front Range of Colorado. Humidifiers sampled included units operated by individuals in their homes, display models continuously operated by a retail store, and new humidifiers operated in a controlled laboratory study. The V1V2 region of the rRNA gene was amplified and sequenced to determine the taxonomic composition of humidifier samples. Communities encountered were generally low in richness and diversity and were dominated by Sphingomonadales, Rhizobiales, and Burkholderiales of the Proteobacteria, and MLE1-12, a presumably non-photosynthetic representative of the cyanobacterial phylum. Very few sequences of potential health concern were detected. The bacteriology encountered in source waters sampled here was similar to that encountered in previous studies of municipal drinking waters. Source water bacteriology was found to have the greatest effect on tank water and biofilm bacteriology, an effect confirmed by a controlled study comparing ultrasonic and boiler humidifiers fed with tap vs. treated (deionized, reverse osmosis, 0.2 μm filtered) water over a period of two months.
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Affiliation(s)
- Natalie M Hull
- Dept. of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | - Abigail L Reens
- Dept. of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | - Charles E Robertson
- Dept. of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | - Lee F Stanish
- Dept. of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | - J Kirk Harris
- Dept. of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Mark J Stevens
- Dept. of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Daniel N Frank
- Dept. of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Cassandra Kotter
- Dept. of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Norman R Pace
- Dept. of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA.
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