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Bauer M, Ermolaeva M, Singer M, Wetzker R, Soares MP. Hormesis as an adaptive response to infection. Trends Mol Med 2024:S1471-4914(24)00100-X. [PMID: 38744580 DOI: 10.1016/j.molmed.2024.04.012] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/02/2024] [Accepted: 04/12/2024] [Indexed: 05/16/2024]
Abstract
Hormesis is a phenomenon whereby low-level stress can improve cellular, organ, or organismal fitness in response to a subsequent similar or other stress insult. Whereas hormesis is thought to contribute to the fitness benefits arising from symbiotic host-microbe interactions, the putative benefits of hormesis in host-pathogen interactions have yet to be explored. Hormetic responses have nonetheless been reported in experimental models of infection, a common feature of which is regulation of host mitochondrial function. We propose that these mitohormetic responses could be harnessed therapeutically to limit the severity of infectious diseases.
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Affiliation(s)
- Michael Bauer
- Department of Anesthesiology and Intensive Care Medicine, Jena University Hospital, Jena, Germany; Cluster of Excellence Balance of the Microverse, Friedrich Schiller University Jena, Jena, Germany.
| | - Maria Ermolaeva
- Cluster of Excellence Balance of the Microverse, Friedrich Schiller University Jena, Jena, Germany; Leibniz Institute on Aging - Fritz Lipmann Institute, Jena, Germany
| | - Mervyn Singer
- Bloomsbury Institute of Intensive Care Medicine, University College London, London, UK
| | - Reinhard Wetzker
- Department of Anesthesiology and Intensive Care Medicine, Jena University Hospital, Jena, Germany
| | - Miguel P Soares
- Cluster of Excellence Balance of the Microverse, Friedrich Schiller University Jena, Jena, Germany; Instituto Gulbenkian de Ciência, Oeiras, Portugal
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Zhao Y, Lin K, Zhang H, Zhang Y, Li S, Zhang S, Zhang W, Zhou A, Zhuang Y, Chen J, Wu C, Zhou W, He X, Yue Q, Zhang M, Huang Y, Li L, Hong L, Cai F, Huang L, Ruan Z, Xu S, Zhang Y, Chen X, Chen J, Ye Y, Bian T, Li J, Yin J, Li X, Jiang L, Lei C, Liu J, Zhang Y, Jin J, Ai J, Pan J, Zhang W. Prognostic value of poly-microorganisms detected by droplet digital PCR and pathogen load kinetics in sepsis patients: a multi-center prospective cohort study. Microbiol Spectr 2024; 12:e0255823. [PMID: 38526296 PMCID: PMC11064489 DOI: 10.1128/spectrum.02558-23] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 01/28/2024] [Indexed: 03/26/2024] Open
Abstract
This study aimed to investigate the prognostic value of a novel droplet digital polymerase chain reaction (DDPCR) assay in sepsis patients. In this prospective cohort study, univariable and multivariable Cox regressions were used to assess risk factors for 28-day mortality. We also monitored pathogen load together with clinical indicators in a subgroup of the cohort. A total of 107 sepsis patients with positive baseline DDPCR results were included. Detection of poly-microorganisms [adjusted hazard ratio (HR) = 3.19; 95% confidence interval (CI) = 1.34-7.62; P = 0.009], high Charlson Comorbidity Index (CCI) score (adjusted HR = 1.14; 95% CI = 1.01-1.29; P = 0.041), and Sequential Organ Failure Assessment (SOFA) score (adjusted HR = 1.18; 95% CI = 1.05-1.32; P = 0.005) at baseline were independent risk factors for 28-day mortality while initial pathogen load was not associated (adjusted HR = 1.17; 95% CI = 0.82-1.66; P = 0.385). Among 63 patients with serial DDPCR results, an increase in pathogen load at days 6-8 compared to baseline was a risk factor for 28-day mortality (P = 0.008). Also, pathogen load kinetics were significantly different between day-28 survivors and nonsurvivors (P = 0.022), with a decline overtime only in survivors and an increase from days 3 and 4 to days 6-8 in nonsurvivors. Using DDPCR technique, we found that poly-microorganisms detected and increased pathogen load a week after sepsis diagnosis were associated with poor prognosis.IMPORTANCEThis prospective study was initiated to explore the prognostic implications of a novel multiplex PCR assay in sepsis. Notably, our study was the largest cohort of sepsis with droplet digital polymerase chain reaction pathogen monitoring to date, allowing for a comprehensive evaluation of the prognostic significance of both pathogen species and load. We found that detection of poly-microorganisms was an independent risk factors for 28-day mortality. Also, pathogen load increase 1 week after sepsis diagnosis was a risk factor for 28-day mortality, and differential pathogen load kinetics were identified between day-28 survivors and nonsurvivors. Overall, this study demonstrated that pathogen species and load were highly correlated with sepsis prognosis. Patients exhibiting conditions mentioned above face a more adverse prognosis, suggesting the potential need for an escalation of antimicrobial therapy.Registered at ClinicalTrials.gov (NCT05190861).
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Affiliation(s)
- Yuanhan Zhao
- Department of Infectious Diseases, National Medical Center for Infectious Diseases, Shanghai Key Laboratory of Infectious Diseases and Biosafety Emergency Response, Huashan Hospital, Fudan University, Shanghai, China
- Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Cancer and Basic Medicine (IBMC), Chinese Academy of Sciences, Hangzhou, China
| | - Ke Lin
- Department of Infectious Diseases, National Medical Center for Infectious Diseases, Shanghai Key Laboratory of Infectious Diseases and Biosafety Emergency Response, Huashan Hospital, Fudan University, Shanghai, China
| | - Haocheng Zhang
- Department of Infectious Diseases, National Medical Center for Infectious Diseases, Shanghai Key Laboratory of Infectious Diseases and Biosafety Emergency Response, Huashan Hospital, Fudan University, Shanghai, China
| | - Yanliang Zhang
- Department of Infectious Diseases, The Nanjing Hospital of Chinese Medicine affiliated to Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Shaling Li
- Department of Infectious Diseases, Xiangya Hospital Central South University, Changsha, Hunan, China
| | - Shengguo Zhang
- Department of Infectious Diseases, The Third Affiliated Hospital of Wenzhou Medical University, WenZhou, Zhejiang, China
| | - Wei Zhang
- Society of Clinical Epidemiology and Evidence-Based Medicine, Shanghai Medical Association, Shanghai, China
| | - Aiming Zhou
- Department of Intensive Care Unit, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yangyang Zhuang
- Department of Intensive Care Unit, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Jie Chen
- Department of Intensive Care Unit, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Caixia Wu
- Department of Intensive Care Unit, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Wei Zhou
- Department of Intensive Care Unit, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Xiaoju He
- Department of Infectious Diseases, The Nanjing Hospital of Chinese Medicine affiliated to Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Qiaoyan Yue
- Department of Infectious Diseases, The Nanjing Hospital of Chinese Medicine affiliated to Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Meng Zhang
- Department of Infectious Diseases, The Nanjing Hospital of Chinese Medicine affiliated to Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Yan Huang
- Department of Infectious Diseases, Xiangya Hospital Central South University, Changsha, Hunan, China
| | - Liang Li
- Department of Infectious Diseases, Xiangya Hospital Central South University, Changsha, Hunan, China
| | - Liang Hong
- Department of Infectious Diseases, The Third Affiliated Hospital of Wenzhou Medical University, WenZhou, Zhejiang, China
| | - Fujing Cai
- Department of Infectious Diseases, The Third Affiliated Hospital of Wenzhou Medical University, WenZhou, Zhejiang, China
| | - Lisu Huang
- Department of Infectious Disease, Xinhua Children’s Hospital, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhengshang Ruan
- Department of Infectious Disease, Xinhua Children’s Hospital, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shanshan Xu
- Department of Infectious Disease, Xinhua Children’s Hospital, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yan Zhang
- Department of Anesthesiology and Surgical Intensive Care Unit, Xinhua Children’s Hospital, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaohua Chen
- Department of Infectious Diseases, Shanghai Sixth Hospital, Shanghai Jiaotong University, Shanghai, China
| | - Jie Chen
- Department of Infectious Diseases, Shanghai Sixth Hospital, Shanghai Jiaotong University, Shanghai, China
| | - Ying Ye
- Department of Infectious Diseases, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
| | - Tingting Bian
- Department of Infectious Diseases, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
| | - Jiabin Li
- Department of Infectious Diseases, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
| | - Jun Yin
- Department of Infectious Diseases, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, China
| | - Xiang Li
- Department of Critical Care Medicine, Minhang Hospital, Fudan University, China, Shanghai
| | - Lijing Jiang
- Department of Critical Care Medicine, Minhang Hospital, Fudan University, China, Shanghai
| | - Chen Lei
- Department of Critical Care Medicine, Minhang Hospital, Fudan University, China, Shanghai
| | - Jun Liu
- Department of Laboratory, Wuxi No.5 People’s Hospital Affiliated to Nantong University, Nantong, China
| | - Ying Zhang
- Department of Laboratory, Wuxi No.5 People’s Hospital Affiliated to Nantong University, Nantong, China
| | - Jialin Jin
- Department of Infectious Diseases, National Medical Center for Infectious Diseases, Shanghai Key Laboratory of Infectious Diseases and Biosafety Emergency Response, Huashan Hospital, Fudan University, Shanghai, China
| | - Jingwen Ai
- Department of Infectious Diseases, National Medical Center for Infectious Diseases, Shanghai Key Laboratory of Infectious Diseases and Biosafety Emergency Response, Huashan Hospital, Fudan University, Shanghai, China
| | - Jingye Pan
- Department of Intensive Care Unit, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Wenhong Zhang
- Department of Infectious Diseases, National Medical Center for Infectious Diseases, Shanghai Key Laboratory of Infectious Diseases and Biosafety Emergency Response, Huashan Hospital, Fudan University, Shanghai, China
- Shanghai Huashen Institute of Microbes and Infections, Shanghai, China
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Dunbar R. Why did doctrinal religions first appear in the Northern Subtropical Zone? Evol Hum Sci 2023; 5:e15. [PMID: 37587936 PMCID: PMC10427489 DOI: 10.1017/ehs.2023.13] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 05/01/2023] [Accepted: 05/02/2023] [Indexed: 08/18/2023] Open
Abstract
Doctrinal religions that involve recognised gods, more formal theologies, moral codes, dedicated religious spaces and professional priesthoods emerged in two phases during the Neolithic. Almost all of these appeared in a narrow latitudinal band (the northern Subtropical Zone). I suggest that these developments were the result of a need to facilitate community bonding in response to scalar stresses that developed as community sizes increased dramatically beyond those typical of hunter-gatherer societies. Conditions for population growth (as indexed by rainfall patterns and the difference between pathogen load and the length of the growing season) were uniquely optimised in this zone, creating an environment of ecological release in which populations could grow unusually rapidly. The relationship between latitude, religion and language in contemporary societies suggests that the peculiar characteristics of the northern (but not the southern) Subtropical Zone were especially favourable for the evolution of large scale religions as a way of enforcing community cohesion.
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Affiliation(s)
- R.I.M. Dunbar
- Department of Experimental Psychology, University of Oxford, Radcliffe Observatory Quarter, Oxford OX2 6GG, UK
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Awan ZA, Shoaib A, Schenk PM, Ahmad A, Alansi S, Paray BA. Antifungal potential of volatiles produced by Bacillus subtilis BS-01 against Alternaria solani in Solanum lycopersicum. Front Plant Sci 2023; 13:1089562. [PMID: 36777534 PMCID: PMC9909239 DOI: 10.3389/fpls.2022.1089562] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 12/12/2022] [Indexed: 05/30/2023]
Abstract
Bacterial biocontrol agent/s (BCAs) against plant diseases are eco-friendly and sustainable options for profitable agricultural crop production. Specific beneficial strains of Bacillus subtilis are effective in controlling many fungal diseases including Alternaria blight caused by a notorious pathogen "Alternaria solani". In the present study, the biocontrol attributes of a newfangled strain of B. subtilis (BS-01) have been investigated and its bioactive compounds were also identified against A. solani. The volatile organic compounds (VOCs) produced by BS-01 in organic solvents viz., n-hexane, dichloromethane, and ethyl acetate were extracted and their antifungal efficacy has evaluated against A. solani. Also, the preventive and curative biocontrol method to reduce the fungal load of A. solani was estimated by both foliar and seed applications on infected tomato (Solanum lycopersicum) plants as determined by quantitative PCR assays. Growth chamber bioassay revealed that both foliar and seed application of BS-01 on tomato plants previously or subsequently infected by A. solani significantly reduced the pathogen load on inoculated tomato foliage. Results showed that antifungal bioassays with various concentrations (10-100 mg mL-1) of extracted metabolites produced by BS-01 in ethyl acetate fraction showed the highest inhibition in fungal biomass (extracellular metabolites: 69-98% and intracellular metabolites: 48-85%) followed by n-hexane (extracellular metabolites: 63-88% and intracellular metabolites: 35-62%) and dichloromethane (extracellular metabolites: 41-74% and intracellular metabolites: 42-70%), respectively. The extracted volatile compounds of BS-01 were identified via GC-MS analysis and were found in great proportions in the organic fractions as major potent antifungal constituents including triphenylphosphine oxide; pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl); pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(phenylmethyl); n-hexadecanoic acid; n-tridecan-1-ol; octadecane; octadecanoic acid; eicosane and dodecyl acrylate. Separate or mixture of these bioactive VOCs had the potential to mitigate the tomato early blight disease severity in the field that would act as a sustainable plant protection strategy to generate profitable tomato production.
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Affiliation(s)
- Zoia Arshad Awan
- Faculty of Agricultural Sciences, University of the Punjab, Lahore, Pakistan
| | - Amna Shoaib
- Faculty of Agricultural Sciences, University of the Punjab, Lahore, Pakistan
| | - Peer M. Schenk
- Plant-Microbe Interactions Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, QLD, Australia
| | - Ajaz Ahmad
- Department of Clinical Pharmacy, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Saleh Alansi
- Botany and Microbiology Department, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Bilal Ahamad Paray
- Zoology Department, College of Sciences, King Saud University, Riyadh, Saudi Arabia
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Nusairat B, Odetallah N, Wang JJ. Live Performance and Microbial Load Modulation of Broilers Fed a Direct-Fed Microbials (DFM) and Xylanase Combination. Vet Sci 2022; 9. [PMID: 35324870 DOI: 10.3390/vetsci9030142] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/12/2022] [Accepted: 03/15/2022] [Indexed: 11/24/2022] Open
Abstract
The animal industry, which focuses on producing protein for human consumption, is continuously seeking solutions that can enhance both animal performance and health at a low cost. Several feed additives are currently being used to improve the nutritive value of feed as well as replacing the subtherapeutic levels of antibiotic growth promoters (AGP). This study was designed to investigate the effect of a feed additive that is a blend of multi-strain Bacillus spp. probiotics and a xylanase in a 2 × 2 factorial dietary treatments design, testing two levels of the feed additive blend (0 and 100 g/MT) and two cereal grain types (corn and wheat) on live performance, gut lesions, environmental Clostridium perfringens load, and pathogen load in the digesta of broiler chickens (E. tenella, total aerobic count cells (APC), E. coli, and C. perfringens). Day-old chicks were randomly placed in 10 replicate pens per treatment with 52 birds per replicate and grown to 42 d of age. Data were analyzed by two-way ANOVA. At 42 d, birds fed EnzaPro were heavier (p < 0.0004) than unsupplemented birds. An improvement in FCR (p = 0.03) was observed from 1 to 42 d by approximately two points in both corn- and wheat-based diets supplemented with EnzaPro. In wheat-based diets, supplementing EnzaPro reduced (p < 0.0001) a 21 d lesion score of intestines with a further reduction (p < 0.02) at 42 d. EnzaPro reduced (p < 0.03) litter moisture by approximately 1% compared to non-supplemented EnzaPro in both corn- and wheat-based diets. Pathogen load in digesta (C. perfringens, E. tenella, APC, and E. coli) was reduced (p < 0.0002) when EnzaPro was supplemented in diets. It can be concluded that EnzaPro (a blend of DFM Bacillus spp (1 × 105 CFU/g feed) and xylanase (10 XU/g feed)) may be used in both corn- and wheat-based diets to improve the performance and gut health of broilers.
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Bonacorsi S, Visseaux B, Bouzid D, Pareja J, Rao SN, Manissero D, Hansen G, Vila J. Systematic Review on the Correlation of Quantitative PCR Cycle Threshold Values of Gastrointestinal Pathogens With Patient Clinical Presentation and Outcomes. Front Med (Lausanne) 2021; 8:711809. [PMID: 34631732 PMCID: PMC8496934 DOI: 10.3389/fmed.2021.711809] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 08/19/2021] [Indexed: 02/04/2023] Open
Abstract
Background: Quantitative (q) polymerase chain reaction (PCR) cycle threshold (Ct) values represent the number of amplification cycles required for a positive PCR result and are a proxy of pathogen quantity in the tested sample. The clinical utility of Ct values remains unclear for gastrointestinal infections. Objectives: This systematic review assesses the global medical literature for associations between Ct values of gastrointestinal pathogens and patient presentation and clinical outcomes. Data Sources: MEDLINE, EMBASE, Cochrane library databases: searched January 14-17, 2020. Study Eligibility Criteria: Studies reporting on the presence or absence of an association between Ct values and clinical outcomes in adult and pediatric populations were included. Animal studies, reviews, meta-analyses, and non-English language studies were excluded. Participants: Humans infected with gastrointestinal pathogens, detected with qPCR. Interventions: Diagnostics assessing Ct values. Extracted data were reported narratively. Results: Thirty-three eligible studies were identified; the most commonly studied pathogens were Clostridioides difficile (n = 15), norovirus (n = 10), and rotavirus (n = 9). Statistically significant associations between low C. difficile Ct values and increased symptom severity or poor outcome were reported in 4/8 (50%) studies, and increased risk of death in 1/2 (50%) studies; no significant associations were found between Ct value and duration of symptoms or length of hospital stay. Among studies of norovirus, 5/7 (71%), mainly genogroup II, reported symptomatic cases with significantly lower median Ct values than controls. Significantly lower rotavirus Ct values were also observed in symptomatic cases vs. controls in 3/7 (43%) studies, and associated with more severe symptoms in 2/2 studies. Contradictory associations were identified for non-C. difficile bacterial and parasitic pathogens. Conclusions: In conclusion, some studies reported clinically useful associations between Ct values and patient or healthcare outcomes; additional, well-designed, large-scale trials are warranted based on these findings. Systematic Review Registration: [PROSPERO], identifier [CRD42020167239].
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Affiliation(s)
- Stéphane Bonacorsi
- Department of Microbiology, Robert Debré University Hospital, AP-HP, Paris, France
| | - Benoit Visseaux
- Université de Paris, IAME, INSERM, Paris, France
- Université de Paris, Laboratoire de Virologie, Hôpital Bichat Claude Bernard, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Donia Bouzid
- Université de Paris, IAME, INSERM, Paris, France
- Université de Paris, Service d'Accueil des Urgences, Hôpital Bichat Claude Bernard, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Josep Pareja
- STAT-Dx Life, S.L. (a QIAGEN Company), Medical Affairs, Barcelona, Spain
| | - Sonia N. Rao
- QIAGEN Inc., Medical Affairs, Germantown, MD, United States
| | - Davide Manissero
- QIAGEN Manchester Ltd, Medical Affairs, Manchester, United Kingdom
| | - Glen Hansen
- Microbiology and Molecular Diagnostics, Hennepin County Medical Center, Department of Infectious Diseases, School of Medicine, University of Minnesota, Minneapolis, MN, United States
- Department of Pathology and Laboratory Medicine, School of Medicine, University of Minnesota, Minneapolis, MN, United States
| | - Jordi Vila
- Biomedical Diagnostic Centre, Department of Clinical Microbiology, Institute of Global Health, School of Medicine, Hospital Clinic, University of Barcelona, Barcelona, Spain
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Tardy L, Giraudeau M, Hill GE, McGraw KJ, Bonneaud C. Contrasting evolution of virulence and replication rate in an emerging bacterial pathogen. Proc Natl Acad Sci U S A 2019; 116:16927-32. [PMID: 31371501 DOI: 10.1073/pnas.1901556116] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
With increasing antibiotic resistance, there is a pressing need to understand how host resistance naturally influences bacterial virulence and replication rates. We test this in an infection experiment using 55 isolates of a bacterium, which were collected over the course of the epidemic following its natural emergence in a North American songbird. We demonstrate virulence has increased linearly from outbreak to the present day, encompassing >150,000 bacterial generations. Despite this, bacterial replication rate only increased during the initial spread of host resistance but not thereafter. Thus, contrary to common assumptions, virulence and replication rates can evolve independently, particularly after the initial spread of host resistance. Host resistance through immune clearance is predicted to favor pathogens that are able to transmit faster and are hence more virulent. Increasing pathogen virulence is, in turn, typically assumed to be mediated by increasing replication rates. However, experiments designed to test how pathogen virulence and replication rates evolve in response to increasing host resistance, as well as the relationship between the two, are rare and lacking for naturally evolving host–pathogen interactions. We inoculated 55 isolates of Mycoplasma gallisepticum, collected over 20 y from outbreak, into house finches (Haemorhous mexicanus) from disease-unexposed populations, which have not evolved protective immunity to M. gallisepticum. We show using 3 different metrics of virulence (body mass loss, symptom severity, and putative mortality rate) that virulence has increased linearly over >150,000 bacterial generations since outbreak (1994 to 2015). By contrast, while replication rates increased from outbreak to the initial spread of resistance (1994 to 2004), no further increases have occurred subsequently (2007 to 2015). Finally, as a consequence, we found that any potential mediating effect of replication rate on virulence evolution was restricted to the period when host resistance was initially increasing in the population. Taken together, our results show that pathogen virulence and replication rates can evolve independently, particularly after the initial spread of host resistance. We hypothesize that the evolution of pathogen virulence can be driven primarily by processes such as immune manipulation after resistance spreads in host populations.
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8
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Hubálek Z, Rudolf I. Francisella tularensis prevalence and load in Dermacentor reticulatus ticks in an endemic area in Central Europe. Med Vet Entomol 2017; 31:234-239. [PMID: 28256734 DOI: 10.1111/mve.12229] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [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: 06/24/2016] [Revised: 11/14/2016] [Accepted: 11/17/2016] [Indexed: 06/06/2023]
Abstract
A total of 7778 host-seeking adult Dermacentor reticulatus (Ixodida: Ixodidae) ticks were examined for the prevalence of Francisella tularensis holarctica (Thiotrichales: Francisellaceae) in a natural focus of tularaemia in the floodplain forest-meadow ecosystem along the lower reaches of the Dyje (Thaya) river in South Moravia (Czech Republic) between 1995 and 2013. Ticks were pooled (10 specimens per pool) and their homogenates inoculated subcutaneously in 4-week-old specific pathogen-free mice. Dead mice were sectioned, their spleens cultivated on thioglycollate-glucose-blood agar and impression smears from the spleen, liver and heart blood were Giemsa-stained. Sixty-four pools were positive for F. tularensis: the overall minimum infection rate (MIR) was 0.82%. Overall MIRs for the 4714 female and 3064 male D. reticulatus examined were 0.89 and 0.72%, respectively; MIRs fluctuated across years between 0.0 and 2.43%. The estimated bacterial load in infected ticks varied from 0.84 to 5.34 log10 infectious F. tularensis cells per tick (i.e. from about seven to 220 000 cells). Ticks with low loads were more prevalent; more than 1000 infectious cells were detected in 24 ticks (0.3% of all ticks and 37.5% of infected ticks). Monitoring of D. reticulatus for the presence and cell numbers of F. tularensis may be a valuable tool in the surveillance of tularaemia.
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Affiliation(s)
- Z Hubálek
- Institute of Vertebrate Biology, v.v.i., Medical Zoology Laboratory, Academy of Sciences of the Czech Republic, Brno, Czech Republic
| | - I Rudolf
- Institute of Vertebrate Biology, v.v.i., Medical Zoology Laboratory, Academy of Sciences of the Czech Republic, Brno, Czech Republic
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Rosengaus RB, Moustakas JE, Calleri DV, Traniello JF. Nesting ecology and cuticular microbial loads in dampwood (Zootermopsis angusticollis) and drywood termites (Incisitermes minor, I. schwarzi, Cryptotermes cavifrons). J Insect Sci 2003; 3:31. [PMID: 15841247 PMCID: PMC524670 DOI: 10.1093/jis/3.1.31] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2003] [Accepted: 08/18/2003] [Indexed: 05/24/2023]
Abstract
Termites form one-piece nests in wood that can vary in their moisture content and degree of decomposition, and thus microbial richness. To estimate the microbial load of nests and the potential risk they pose for colony members, we quantified the number of microbes in the nest and on the cuticle of the dampwood termite, Zootermopsis angusticollis, and three drywood termites, Incisitermes minor, I. schwarzi, and Cryptotermes cavifrons. The number of colony forming units (CFUs) cultured from nest material samples and washes of the cuticle of larvae and nymphs were determined. CFUs recorded from nest material was low (fewer than 60 CFUs/g) in the drywood termites and comparatively high in the dampwood species, as more than 800 bacterial and fungal CFUs/g were cultured from the nest material of Z. angusticollis. Similarly, cuticular microbial loads were negligible in the drywood termites sampled, ranging from 0.5 to fewer than 16 CFUs/cm2, whereas approximately 200 CFUs/cm2 were cultured from Z. angusticollis. The nesting and feeding habits of these basal species likely influence colony microbial load and the degree of pathogen exposure, which in turn could favor adaptations to resist disease that vary with termite nesting biology.
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Affiliation(s)
- Rebeca B. Rosengaus
- Department of Biology, Northeastern University, 134 Mugar Life Science Building, Boston, MA 02115-5000, USA
| | - Jacqueline E. Moustakas
- Department of Integrative Biology and Museum of Paleontology, 1101 Valley Life Sciences Building, University of California, Berkeley, CA 94720, USA
| | - Daniel V. Calleri
- Department of Biology, Boston University, 5 Cummington Street, Boston, Ma 02215, USA
| | - James F.A. Traniello
- Department of Biology, Boston University, 5 Cummington Street, Boston, Ma 02215, USA
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