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Coe GL, Krout IN, Munro-Ehrlich M, Beamish CR, Vorojeikina D, Colman DR, Boyd EJ, Walk ST, Rand MD. Assessing the role of the gut microbiome in methylmercury demethylation and elimination in humans and gnotobiotic mice. Arch Toxicol 2023; 97:2399-2418. [PMID: 37392210 PMCID: PMC10913183 DOI: 10.1007/s00204-023-03548-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 06/14/2023] [Indexed: 07/03/2023]
Abstract
The risk of methylmercury (MeHg) toxicity following ingestion of contaminated foodstuffs (e.g., fish) is directly related to the kinetics of MeHg elimination among individuals. Yet, the factors driving the wide range of inter-individual variability in MeHg elimination within a population are poorly understood. Here, we investigated the relationship between MeHg elimination, gut microbiome demethylation activity, and gut microbiome composition using a coordinated human clinical trial and gnotobiotic mouse modeling approach together with metagenomic sequence analysis. We first observed MeHg elimination half-lives (t1/2) ranging from 28 to 90 days across 27 volunteers. Subsequently, we found that ingestion of a prebiotic induced changes in the gut microbiome and mixed effects (increased, decrease, and no effect) on elimination in these same individuals. Nonetheless, elimination rates were found to correlate with MeHg demethylation activity in cultured stool samples. In mice, attempts to remove the microbiome via generation of germ-free (GF) animals or through antibiotic (Abx) treatment both diminished MeHg demethylation to a similar extent. While both conditions substantially slowed elimination, Abx treatment resulted in significantly slower elimination than the GF condition, indicating an additional role for host-derived factors in supporting elimination. Human fecal microbiomes transplanted to GF mice restored elimination rates to that seen in control mice. Metagenomic sequence analysis of human fecal DNA did not identify genes encoding proteins typically involved in demethylation (e.g., merB, organomercury lyase). However, the abundance of several anaerobic taxa, notably Alistipes onderdonkii, were positively correlated with MeHg elimination. Surprisingly, mono-colonization of GF free mice with A. onderdonkii did not restore MeHg elimination to control levels. Collectively, our findings indicate the human gut microbiome uses a non-conventional pathway of demethylation to increase MeHg elimination that relies on yet to be resolved functions encoded by the gut microbes and the hostClinical Trial NCT04060212, prospectively registered 10/1/2019.
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Affiliation(s)
- Genevieve L Coe
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Ian N Krout
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Mason Munro-Ehrlich
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Catherine R Beamish
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Daria Vorojeikina
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Daniel R Colman
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Eric J Boyd
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Seth T Walk
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Matthew D Rand
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
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2
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Bazzi W, Abou Fayad AG, Nasser A, Haraoui LP, Dewachi O, Abou-Sitta G, Nguyen VK, Abara A, Karah N, Landecker H, Knapp C, McEvoy MM, Zaman MH, Higgins PG, Matar GM. Heavy Metal Toxicity in Armed Conflicts Potentiates AMR in A. baumannii by Selecting for Antibiotic and Heavy Metal Co-resistance Mechanisms. Front Microbiol 2020; 11:68. [PMID: 32117111 PMCID: PMC7008767 DOI: 10.3389/fmicb.2020.00068] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 01/14/2020] [Indexed: 12/29/2022] Open
Abstract
Acinetobacter baumannii has become increasingly resistant to leading antimicrobial agents since the 1970s. Increased resistance appears linked to armed conflicts, notably since widespread media stories amplified clinical reports in the wake of the American invasion of Iraq in 2003. Antimicrobial resistance is usually assumed to arise through selection pressure exerted by antimicrobial treatment, particularly where treatment is inadequate, as in the case of low dosing, substandard antimicrobial agents, or shortened treatment course. Recently attention has focused on an emerging pathogen, multi-drug resistant A. baumannii (MDRAb). MDRAb gained media attention after being identified in American soldiers returning from Iraq and treated in US military facilities, where it was termed "Iraqibacter." However, MDRAb is strongly associated in the literature with war injuries that are heavily contaminated by both environmental debris and shrapnel from weapons. Both may harbor substantial amounts of toxic heavy metals. Interestingly, heavy metals are known to also select for antimicrobial resistance. In this review we highlight the potential causes of antimicrobial resistance by heavy metals, with a focus on its emergence in A. baumanni in war zones.
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Affiliation(s)
- Wael Bazzi
- Department of Experimental Pathology, Immunology and Microbiology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
- Center for Infectious Diseases Research, American University of Beirut, Beirut, Lebanon
- World Health Organisation (WHO) Collaborating Center for Reference and Research on Bacterial Pathogens, Beirut, Lebanon
| | - Antoine G. Abou Fayad
- Department of Experimental Pathology, Immunology and Microbiology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
- Center for Infectious Diseases Research, American University of Beirut, Beirut, Lebanon
- World Health Organisation (WHO) Collaborating Center for Reference and Research on Bacterial Pathogens, Beirut, Lebanon
| | - Aya Nasser
- Department of Experimental Pathology, Immunology and Microbiology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
- Center for Infectious Diseases Research, American University of Beirut, Beirut, Lebanon
- World Health Organisation (WHO) Collaborating Center for Reference and Research on Bacterial Pathogens, Beirut, Lebanon
| | - Louis-Patrick Haraoui
- Department of Microbiology and Infectious Diseases, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Omar Dewachi
- Rutgers, The State University of New Jersey, Newark, NJ, United States
| | | | - Vinh-Kim Nguyen
- The Graduate Institute of International and Developmental Studies, Geneva, Switzerland
| | - Aula Abara
- Department of Infection, Imperial College London, London, United Kingdom
| | - Nabil Karah
- Department of Molecular Biology, Umea University, Umea, Sweden
| | - Hannah Landecker
- Department of Sociology and Institute for Society and Genetics, University of California, Los Angeles, Los Angeles, CA, United States
| | - Charles Knapp
- Civil and Environmental Engineering, University of Strathclyde, Glasgow, United Kingdom
| | - Megan M. McEvoy
- Institute for Society and Genetics, University of California, Los Angeles, Los Angeles, CA, United States
| | - Muhammad H. Zaman
- Department of Biomedical Engineering, Boston University, Boston, MA, United States
| | - Paul G. Higgins
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
- German Centre for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
| | - Ghassan M. Matar
- Department of Experimental Pathology, Immunology and Microbiology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
- Center for Infectious Diseases Research, American University of Beirut, Beirut, Lebanon
- World Health Organisation (WHO) Collaborating Center for Reference and Research on Bacterial Pathogens, Beirut, Lebanon
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3
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Fernández-Bravo A, Figueras MJ. An Update on the Genus Aeromonas: Taxonomy, Epidemiology, and Pathogenicity. Microorganisms 2020; 8:microorganisms8010129. [PMID: 31963469 PMCID: PMC7022790 DOI: 10.3390/microorganisms8010129] [Citation(s) in RCA: 228] [Impact Index Per Article: 57.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/10/2020] [Accepted: 01/14/2020] [Indexed: 02/07/2023] Open
Abstract
The genus Aeromonas belongs to the Aeromonadaceae family and comprises a group of Gram-negative bacteria widely distributed in aquatic environments, with some species able to cause disease in humans, fish, and other aquatic animals. However, bacteria of this genus are isolated from many other habitats, environments, and food products. The taxonomy of this genus is complex when phenotypic identification methods are used because such methods might not correctly identify all the species. On the other hand, molecular methods have proven very reliable, such as using the sequences of concatenated housekeeping genes like gyrB and rpoD or comparing the genomes with the type strains using a genomic index, such as the average nucleotide identity (ANI) or in silico DNA–DNA hybridization (isDDH). So far, 36 species have been described in the genus Aeromonas of which at least 19 are considered emerging pathogens to humans, causing a broad spectrum of infections. Having said that, when classifying 1852 strains that have been reported in various recent clinical cases, 95.4% were identified as only four species: Aeromonas caviae (37.26%), Aeromonas dhakensis (23.49%), Aeromonas veronii (21.54%), and Aeromonas hydrophila (13.07%). Since aeromonads were first associated with human disease, gastroenteritis, bacteremia, and wound infections have dominated. The literature shows that the pathogenic potential of Aeromonas is considered multifactorial and the presence of several virulence factors allows these bacteria to adhere, invade, and destroy the host cells, overcoming the immune host response. Based on current information about the ecology, epidemiology, and pathogenicity of the genus Aeromonas, we should assume that the infections these bacteria produce will remain a great health problem in the future. The ubiquitous distribution of these bacteria and the increasing elderly population, to whom these bacteria are an opportunistic pathogen, will facilitate this problem. In addition, using data from outbreak studies, it has been recognized that in cases of diarrhea, the infective dose of Aeromonas is relatively low. These poorly known bacteria should therefore be considered similarly as enteropathogens like Salmonella and Campylobacter.
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de Araújo LCA, da Purificação-Júnior AF, da Silva SM, Lopes ACS, Veras DL, Alves LC, Dos Santos FB, Napoleão TH, Dos Santos Correia MT, da Silva MV, Oliva MLV, de Oliveira MBM. In vitro evaluation of mercury (Hg 2+) effects on biofilm formation by clinical and environmental isolates of Klebsiella pneumoniae. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 169:669-677. [PMID: 30500736 DOI: 10.1016/j.ecoenv.2018.11.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/05/2018] [Accepted: 11/09/2018] [Indexed: 06/09/2023]
Abstract
The increase in urbanization and industrialization has contributed to the contamination of different environments by means of xenobiotic compounds, such as heavy metals, causing changes in microbial communities. Among these metals, the Mercury (Hg2+) is one the most prevalent toxic metals for the environment The present study aimed to evaluate the effect of mercury on the formation of biofilm by environmental (collected from urban stream water) and clinical isolates of Klebsiella pneumoniae. In addition, antibiotic resistance, virulence factors, and genetic diversity were investigated. Taxonomic identity of eight isolates (one reference, two clinical, and five environmental isolates) was performed by MALDI-TOF-MS, while the antibiotic susceptibility profile was assessed by the disc diffusion method. The ability to form biofilms was evaluated by culture on Congo red agar and by crystal violet staining. Biofilm structure was analyzed by scanning electron microscopy. The hydrophobicity profile and the presence of the virulence genes cps, fimH, and mrkD was investigated. The presence of merA and its relationship with antimicrobial resistance were also assessed. The identity of all isolates was confirmed by MALDI-TOF-MS, and different profiles of resistance to mercury and antibiotics as well as of biofilm formation were identified for the clinical and environmental isolates. All isolates were hydrophilic and positive for the virulence genes cps, fimH, and mrkD; only the clinical isolate K36-A2 was positive for merA. The diversity of the isolates was confirmed by ERIC-PCR, which revealed high heterogeneity among the isolates. In conclusion, the data demonstrate that the investigated isolates present different responses to exposure to Hg2+ and correspond to distinct populations of K. pneumoniae disseminated in the investigated environment. The data obtained in this work will aid in understanding the mechanisms of survival of this pathogen under adverse conditions.
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Affiliation(s)
| | | | - Sivoneide Maria da Silva
- Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco, Pernambuco, Brazil
| | - Ana Catarina Souza Lopes
- Departamento de Medicina Tropical, Centro de Ciências da Saúde, Universidade Federal de Pernambuco, Pernambuco, Brazil
| | - Dyana Leal Veras
- Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães, Fundação Oswaldo Cruz, Pernambuco, Brazil
| | - Luiz Carlos Alves
- Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães, Fundação Oswaldo Cruz, Pernambuco, Brazil
| | - Fábio Brayner Dos Santos
- Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhães, Fundação Oswaldo Cruz, Pernambuco, Brazil
| | - Thiago Henrique Napoleão
- Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco, Pernambuco, Brazil
| | | | - Márcia Vanusa da Silva
- Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco, Pernambuco, Brazil
| | - Maria Luiza Vilela Oliva
- Departamento de Bioquímica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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Ahmad M. Mercuric resistant bacteria Aeromonas exhibits neurologic toxic effects on the developmental motor reflexes, and brain oxidative stress in mice offspring. Microb Pathog 2017; 114:169-175. [PMID: 29197524 DOI: 10.1016/j.micpath.2017.11.063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 11/20/2017] [Accepted: 11/28/2017] [Indexed: 10/18/2022]
Abstract
Mercury and its derivatives even in small concentration may cause a major human health problem. Though not reported in detail, there are various aquatic bacterial species that produce small quantities of methyl mercury (MM) growing under aerobic conditions. Consumption of food derived from sources contaminated with such bacteria within therapeutic doses and exposure to different forms of MM compounds through such sources may induce substantial toxic effects. In the present study, the perinatal oral exposure of pregnant mice to two strains of mercury resistant bacteria (MRB), Aeromonas KSU5 MRB and KSU6 MRB resulted in a significant reduction in postnatal body weight gain, delays in the opening of the eyes and appearance in the body hair fuzz, and deficits in the developing sensory motor reflexes in the mice pups during their weaning period on post-natal day (PD)7, PD14 and PD21. A significant and MM producing concentration-dependent disturbance in the levels of neurotransmitters like dopamine (DA) and serotonin (5-HT); non-enzymatic oxidative stress (OS) indices like thiobarbituric acid-reactive substances (TBARS) and total reduced glutathione (GSH); and enzymatic OS indices like glutathione S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) were observed in the forebrain region of the offspring at weaning period (PD7, PD14, and PD21), at adolescent age (PD30), and at adult age (PD36). Thus, perinatal exposure to MRB can affect developing fetus, raising the concerns for it's potential neurotoxic hazards. A reduced exposure to mercury during pregnancy is of crucial importance in preventing mercury-induced neurotoxicity in the offspring.
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Affiliation(s)
- Mohammad Ahmad
- College of Nursing, King Saud University, Riyadh, Saudi Arabia.
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6
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Jan AT, Azam M, Choi I, Ali A, Haq QMR. Analysis for the presence of determinants involved in the transport of mercury across bacterial membrane from polluted water bodies of India. Braz J Microbiol 2016; 47:55-62. [PMID: 26887227 PMCID: PMC4827696 DOI: 10.1016/j.bjm.2015.11.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 06/14/2015] [Indexed: 11/03/2022] Open
Abstract
Mercury, which is ubiquitous and recalcitrant to biodegradation processes, threatens human health by escaping to the environment via various natural and anthropogenic activities. Non-biodegradability of mercury pollutants has necessitated the development and implementation of economic alternatives with promising potential to remove metals from the environment. Enhancement of microbial based remediation strategies through genetic engineering approaches provides one such alternative with a promising future. In this study, bacterial isolates inhabiting polluted sites were screened for tolerance to varying concentrations of mercuric chloride. Following identification, several Pseudomonas and Klebsiella species were found to exhibit the highest tolerance to both organic and inorganic mercury. Screened bacterial isolates were examined for their genetic make-up in terms of the presence of genes (merP and merT) involved in the transport of mercury across the membrane either alone or in combination to deal with the toxic mercury. Gene sequence analysis revealed that the merP gene showed 86-99% homology, while the merT gene showed >98% homology with previously reported sequences. By exploring the genes involved in imparting metal resistance to bacteria, this study will serve to highlight the credentials that are particularly advantageous for their practical application to remediation of mercury from the environment.
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Affiliation(s)
- Arif Tasleem Jan
- School of Biotechnology, Yeungnam University, Gyeongsan 712-749, Republic of Korea.
| | - Mudsser Azam
- Department of Biosciences, Jamia Millia Islamia, New Delhi 110025, India
| | - Inho Choi
- School of Biotechnology, Yeungnam University, Gyeongsan 712-749, Republic of Korea
| | - Arif Ali
- Department of Biosciences, Jamia Millia Islamia, New Delhi 110025, India
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Piotrowska M, Popowska M. Insight into the mobilome of Aeromonas strains. Front Microbiol 2015; 6:494. [PMID: 26074893 PMCID: PMC4444841 DOI: 10.3389/fmicb.2015.00494] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 05/05/2015] [Indexed: 11/13/2022] Open
Abstract
The mobilome is a pool of genes located within mobile genetic elements (MGE), such as plasmids, IS elements, transposons, genomic/pathogenicity islands, and integron-associated gene cassettes. These genes are often referred to as “flexible” and may encode virulence factors, toxic compounds as well as resistance to antibiotics. The phenomenon of MGE transfer between bacteria, known as horizontal gene transfer (HGT), is well documented. The genes present on MGE are subject to continuous processes of evolution and environmental changes, largely induced or significantly accelerated by man. For bacteria, the only chance of survival in an environment contaminated with toxic chemicals, heavy metals and antibiotics is the acquisition of genes providing the ability to survive in such conditions. The process of acquiring and spreading antibiotic resistance genes (ARG) is of particular significance, as it is important for the health of humans and animals. Therefore, it is important to thoroughly study the mobilome of Aeromonas spp. that is widely distributed in various environments, causing many diseases in fishes and humans. This review discusses the recently published information on MGE prevalent in Aeromonas spp. with special emphasis on plasmids belonging to different incompatibility groups, i.e., IncA/C, IncU, IncQ, IncF, IncI, and ColE-type. The vast majority of plasmids carry a number of different transposons (Tn3, Tn21, Tn1213, Tn1721, Tn4401), the 1st, 2nd, or 3rd class of integrons, IS elements (e.g., IS26, ISPa12, ISPa13, ISKpn8, ISKpn6) and encode determinants such as antibiotic and mercury resistance genes, as well as virulence factors. Although the actual role of Aeromonas spp. as a human pathogen remains controversial, species of this genus may pose a serious risk to human health. This is due to the considerable potential of their mobilome, particularly in terms of antibiotic resistance and the possibility of the horizontal transfer of resistance genes.
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Affiliation(s)
- Marta Piotrowska
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw Warsaw, Poland
| | - Magdalena Popowska
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw Warsaw, Poland
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