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Kumar A, Yang T, Chakravorty S, Majumdar A, Nairn BL, Six DA, Marcondes Dos Santos N, Price SL, Lawrenz MB, Actis LA, Marques M, Russo TA, Newton SM, Klebba PE. Fluorescent sensors of siderophores produced by bacterial pathogens. J Biol Chem 2022; 298:101651. [PMID: 35101443 PMCID: PMC8921320 DOI: 10.1016/j.jbc.2022.101651] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 11/25/2022] Open
Abstract
Siderophores are iron-chelating molecules that solubilize Fe3+ for microbial utilization and facilitate colonization or infection of eukaryotes by liberating host iron for bacterial uptake. By fluorescently labeling membrane receptors and binding proteins, we created 20 sensors that detect, discriminate, and quantify apo- and ferric siderophores. The sensor proteins originated from TonB-dependent ligand-gated porins (LGPs) of Escherichia coli (Fiu, FepA, Cir, FhuA, IutA, BtuB), Klebsiella pneumoniae (IroN, FepA, FyuA), Acinetobacter baumannii (PiuA, FepA, PirA, BauA), Pseudomonas aeruginosa (FepA, FpvA), and Caulobacter crescentus (HutA) from a periplasmic E. coli binding protein (FepB) and from a human serum binding protein (siderocalin). They detected ferric catecholates (enterobactin, degraded enterobactin, glucosylated enterobactin, dihydroxybenzoate, dihydroxybenzoyl serine, cefidericol, MB-1), ferric hydroxamates (ferrichromes, aerobactin), mixed iron complexes (yersiniabactin, acinetobactin, pyoverdine), and porphyrins (hemin, vitamin B12). The sensors defined the specificities and corresponding affinities of the LGPs and binding proteins and monitored ferric siderophore and porphyrin transport by microbial pathogens. We also quantified, for the first time, broad recognition of diverse ferric complexes by some LGPs, as well as monospecificity for a single metal chelate by others. In addition to their primary ferric siderophore ligands, most LGPs bound the corresponding aposiderophore with ∼100-fold lower affinity. These sensors provide insights into ferric siderophore biosynthesis and uptake pathways in free-living, commensal, and pathogenic Gram-negative bacteria.
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Affiliation(s)
- Ashish Kumar
- Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA
| | - Taihao Yang
- Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA
| | - Somnath Chakravorty
- Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA; Department of Medicine, Jacobs School of Medicine & Biomedical Sciences, University of Buffalo School of Medicine, Buffalo, New York, USA
| | - Aritri Majumdar
- Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA
| | - Brittany L Nairn
- Department of Biological Sciences, Bethel University, St. Paul, Minnesota, USA
| | - David A Six
- Department of Biology, Venatorx Pharmaceuticals, Inc, Malvern, Pennsylvania, USA
| | - Naara Marcondes Dos Santos
- Departamento de Microbiologia, Instituto de Ciencias Biomedicas, Universidade de São Paulo, São Paulo, Brazil
| | - Sarah L Price
- Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Matthew B Lawrenz
- Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, Kentucky, USA
| | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, Ohio, USA
| | - Marilis Marques
- Departamento de Microbiologia, Instituto de Ciencias Biomedicas, Universidade de São Paulo, São Paulo, Brazil
| | - Thomas A Russo
- Department of Medicine, Jacobs School of Medicine & Biomedical Sciences, University of Buffalo School of Medicine, Buffalo, New York, USA
| | - Salete M Newton
- Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA
| | - Phillip E Klebba
- Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, Kansas, USA.
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Louge Uriarte EL, González Pasayo RA, Massó M, Carrera Paez L, Domínguez Moncla M, Donis N, Malena R, Méndez A, Morrell E, Giannitti F, Armendano JI, Faverin C, Centrón D, Parreño V, Odeón AC, Quiroga MP, Moreira AR. Molecular characterization of multidrug-resistant Escherichia coli of the phylogroups A and C in dairy calves with meningitis and septicemia. Microb Pathog 2022; 163:105378. [PMID: 34982979 DOI: 10.1016/j.micpath.2021.105378] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 12/21/2021] [Accepted: 12/28/2021] [Indexed: 11/19/2022]
Abstract
Escherichia coli is an important cause of septicemia (SEPEC) and neonatal meningitis (NMEC) in dairy calves. However, the diversity of virulence profiles, phylogroups, antimicrobial resistance patterns, carriage of integron structures, and fluoroquinolone (FQ) resistance mechanisms have not been fully investigated. Also, there is a paucity of knowledge about the virulence profiles and frequency of potential SEPEC in feces from calves with or without diarrhea. This study aimed to characterize the virulence potential, phylogroups, antimicrobial susceptibility, integron content, and FQ-resistance mechanisms in Escherichia coli isolated from calves with meningitis and septicemia. Additionally, the virulence genes (VGs) and profiles of E. coli isolated from diarrheic and non-diarrheic calves were compared between them and together with NMEC and SEPEC in order to identify shared profiles. Tissue and fluid samples from eight dairy calves with septicemia, four of which had concurrent meningitis, were processed for bacteriology and histopathology. Typing of VGs was assessed in 166 isolates from diverse samples of each calf. Selected isolates were evaluated for antimicrobial susceptibility by the disk diffusion test. Phylogroups, integron gene cassettes cartography, and FQ-resistance determinants were analyzed by PCR, sequencing, and bioinformatic tools. Furthermore, 109 fecal samples and 700 fecal isolates from dairy calves with or without diarrhea were evaluated to detect 19 VGs by uniplex PCR. Highly diverse VG profiles were characterized among NMEC and SEPEC isolates, but iucD was the predominant virulence marker. Histologic lesions in all calves supported their pathogenicity. Selected isolates mainly belonged to phylogroups A and C and showed multidrug resistance. Classic (dfrA17 and arr3-dfrA27) and complex (dfrA17-aadA5::ISCR1::blaCTX-M-2) class 1 integrons were identified. Target-site mutations in GyrA (S83L and D87N) and ParC (S80I) encoding genes were associated with FQ resistance. The VGs detected more frequently in fecal samples included f17G (50%), papC (30%), iucD (20%), clpG (19%), eae (16%), and afaE-8 (13%). Fecal isolates displaying the profiles of f17 or potential SEPEC were found in 25% of calves with and without diarrhea. The frequency of E. coli VGs and profiles did not differ between both groups (p > 0.05) and were identical or similar to those found in NMEC and SEPEC. Overall, multidrug-resistant E. coli isolates with diverse VG profiles and belonging to phylogroups A and C can be implicated in natural cases of meningitis and septicemia. Their resistance phenotypes can be partially explained by class 1 integron gene cassettes and target-site mutations in gyrA and parC. These results highlight the value of antimicrobial resistance surveillance in pathogenic bacteria isolated from food-producing animals. Besides, calves frequently shed potential SEPEC in their feces as commensals ("Trojan horse"). Thus, these bacteria may be disseminated in the farm environment, causing septicemia and meningitis under predisposing factors.
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Affiliation(s)
- Enrique L Louge Uriarte
- Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Innovación para la Producción Agropecuaria y Desarrollo Sostenible, INTA-Consejo Nacional de Investigaciones Científicas y Técnicas (IPADS, INTA-CONICET), Ruta 226 km 73.5, Balcarce, 7620, Buenos Aires, Argentina.
| | - Ramón A González Pasayo
- Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Innovación para la Producción Agropecuaria y Desarrollo Sostenible, INTA-Consejo Nacional de Investigaciones Científicas y Técnicas (IPADS, INTA-CONICET), Ruta 226 km 73.5, Balcarce, 7620, Buenos Aires, Argentina
| | - Mariana Massó
- Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas (IMPaM, UBA-CONICET), Ciudad Autónoma de Buenos Aires, C1121ABG, Argentina
| | - Laura Carrera Paez
- Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas (IMPaM, UBA-CONICET), Ciudad Autónoma de Buenos Aires, C1121ABG, Argentina
| | - Manuel Domínguez Moncla
- Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas (IMPaM, UBA-CONICET), Ciudad Autónoma de Buenos Aires, C1121ABG, Argentina
| | - Nicolás Donis
- Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas (IMPaM, UBA-CONICET), Ciudad Autónoma de Buenos Aires, C1121ABG, Argentina
| | - Rosana Malena
- Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Innovación para la Producción Agropecuaria y Desarrollo Sostenible, INTA-Consejo Nacional de Investigaciones Científicas y Técnicas (IPADS, INTA-CONICET), Ruta 226 km 73.5, Balcarce, 7620, Buenos Aires, Argentina
| | - Alejandra Méndez
- Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Innovación para la Producción Agropecuaria y Desarrollo Sostenible, INTA-Consejo Nacional de Investigaciones Científicas y Técnicas (IPADS, INTA-CONICET), Ruta 226 km 73.5, Balcarce, 7620, Buenos Aires, Argentina
| | - Eleonora Morrell
- Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Innovación para la Producción Agropecuaria y Desarrollo Sostenible, INTA-Consejo Nacional de Investigaciones Científicas y Técnicas (IPADS, INTA-CONICET), Ruta 226 km 73.5, Balcarce, 7620, Buenos Aires, Argentina
| | - Federico Giannitti
- Instituto Nacional de Investigación Agropecuaria (INIA), Ruta 50 km 11, Estación Experimental La Estanzuela, Semillero, 70006, Colonia, Uruguay
| | - Joaquín I Armendano
- Departamento de Fisiopatología, Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires, Paraje Arroyo Seco s/n, Tandil, 7000, Argentina
| | - Claudia Faverin
- Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Innovación para la Producción Agropecuaria y Desarrollo Sostenible, INTA-Consejo Nacional de Investigaciones Científicas y Técnicas (IPADS, INTA-CONICET), Ruta 226 km 73.5, Balcarce, 7620, Buenos Aires, Argentina
| | - Daniela Centrón
- Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas (IMPaM, UBA-CONICET), Ciudad Autónoma de Buenos Aires, C1121ABG, Argentina
| | - Viviana Parreño
- Incuinta, Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Virología e Innovaciones Tecnológicas, INTA-Consejo Nacional de Investigaciones Científicas y Técnicas (IVIT, INTA-CONICET), Castelar, 1712, Buenos Aires, Argentina
| | - Anselmo C Odeón
- Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Innovación para la Producción Agropecuaria y Desarrollo Sostenible, INTA-Consejo Nacional de Investigaciones Científicas y Técnicas (IPADS, INTA-CONICET), Ruta 226 km 73.5, Balcarce, 7620, Buenos Aires, Argentina
| | - María Paula Quiroga
- Instituto de Investigaciones en Microbiología y Parasitología Médica, Facultad de Medicina, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas (IMPaM, UBA-CONICET), Ciudad Autónoma de Buenos Aires, C1121ABG, Argentina.
| | - Ana Rita Moreira
- Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Innovación para la Producción Agropecuaria y Desarrollo Sostenible, INTA-Consejo Nacional de Investigaciones Científicas y Técnicas (IPADS, INTA-CONICET), Ruta 226 km 73.5, Balcarce, 7620, Buenos Aires, Argentina
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Liu C, Sun Z, Shali S, Mei Z, Chang S, Mo H, Xu L, Pu Y, Guan H, Chen GC, Qi Q, Quan Z, Qi J, Yao K, Dai Y, Zheng Y, Ge J. The gut microbiome and microbial metabolites in acute myocardial infarction. J Genet Genomics 2021; 49:569-578. [PMID: 34974193 DOI: 10.1016/j.jgg.2021.12.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 12/11/2021] [Accepted: 12/12/2021] [Indexed: 01/22/2023]
Abstract
Emerging evidence has highlighted the role of the gut microbiome in human health. However, the integrative role of the gut microbiome and microbial metabolites in acute myocardial infarction (AMI) remains unclear. The current study profiled the microbial community through 16S rRNA gene sequencing and shotgun metagenomic sequencing, and measured fecal short-chain fatty acids and circulating choline pathway metabolites among 117 new-onset AMI cases and 78 controls. Significant microbial alternations were observed in AMI patients compared with controls (P = 0.001). The abundances of nine species (e.g., Streptococcus salivarius, Klebsiella pneumoniae) were positively associated, and one species (Roseburia hominis) was inversely associated with AMI status and severity. A gut microbial score at disease onset was associated with the risk of major adverse cardiovascular events in 3.2 years (hazard ratio [95% CI]: 2.01 [1.04-4.24]) in AMI patients. The molar proportions of fecal acetate and butyrate were higher, and the circulating levels of choline and carnitine were lower in AMI patients than in controls. In addition, disease classifiers showed that AMI cases and controls had a more distinct pattern in taxonomical composition than in pathways or metabolites. Our findings suggested that microbial composition and functional potentials were associated with AMI status and severity.
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Affiliation(s)
- Chenglin Liu
- State Key Laboratory of Genetic Engineering, School of Life Sciences and Human Phenome Institute, Fudan University, Shanghai 200433, China
| | - Zhonghan Sun
- State Key Laboratory of Genetic Engineering, School of Life Sciences and Human Phenome Institute, Fudan University, Shanghai 200433, China
| | - Shalaimaiti Shali
- Department of Cardiology, Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Fudan University, 1609 Xietu Road, Shanghai 200032, China
| | - Zhendong Mei
- State Key Laboratory of Genetic Engineering, School of Life Sciences and Human Phenome Institute, Fudan University, Shanghai 200433, China; Ministry of Education Key Laboratory of Contemporary Anthropology, Fudan University, Shanghai 200433, China
| | - Shufu Chang
- Department of Cardiology, Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Fudan University, 1609 Xietu Road, Shanghai 200032, China
| | - Hanjun Mo
- Department of Cardiology, Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Fudan University, 1609 Xietu Road, Shanghai 200032, China
| | - Lili Xu
- Department of Cardiology, Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Fudan University, 1609 Xietu Road, Shanghai 200032, China
| | - Yanni Pu
- State Key Laboratory of Genetic Engineering, School of Life Sciences and Human Phenome Institute, Fudan University, Shanghai 200433, China
| | - Huihui Guan
- State Key Laboratory of Genetic Engineering, School of Life Sciences and Human Phenome Institute, Fudan University, Shanghai 200433, China
| | - Guo-Chong Chen
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Qibin Qi
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Zhexue Quan
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Ji Qi
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Kang Yao
- Department of Cardiology, Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Fudan University, 1609 Xietu Road, Shanghai 200032, China
| | - Yuxiang Dai
- Department of Cardiology, Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Fudan University, 1609 Xietu Road, Shanghai 200032, China.
| | - Yan Zheng
- State Key Laboratory of Genetic Engineering, School of Life Sciences and Human Phenome Institute, Fudan University, Shanghai 200433, China; Department of Cardiology, Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Fudan University, 1609 Xietu Road, Shanghai 200032, China.
| | - Junbo Ge
- Department of Cardiology, Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Fudan University, 1609 Xietu Road, Shanghai 200032, China
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Enterobactin-Specific Antibodies Induced by a Novel Enterobactin Conjugate Vaccine. Appl Environ Microbiol 2019; 85:AEM.00358-19. [PMID: 30877122 DOI: 10.1128/aem.00358-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 03/12/2019] [Indexed: 01/01/2023] Open
Abstract
Enterobactin (Ent)-mediated high-affinity iron acquisition is critical for Gram-negative bacteria to survive in the host. Given the bacteriostatic effect of lipocalin resulting from its potent Ent-binding ability, immune intervention directly targeting Ent is promising for iron-dependent pathogen control. Recently, an Ent conjugate vaccine was reported, but it still has several significant weaknesses. In this study, we sought to develop an innovative Ent conjugate vaccine that can induce a high level of antibodies directed against Ent and to provide solid evidence demonstrating siderophore-binding capacity of Ent-specific antibodies. Using a simple method, we successfully conjugated purified Ent to different carriers, including keyhole limpet hemocyanin (KLH), bovine serum albumin, and CmeC, a vaccine candidate for Campylobacter control. Subcutaneous immunization of rabbits with the KLH-Ent conjugate triggered a strong systemic IgG immune response with an up to 16,384-fold increase in IgG titer directed against whole conjugate and an up to 4,096-fold increase in the level of specific anti-Ent IgG. To evaluate the ability of Ent-specific IgG to bind to the Ent derivatives present in vivo, various Ent derivatives were chemically synthesized and a unique enzyme-linked immunosorbent assay method was developed. The Ent-specific IgG also displayed exceptional reactivity to ferric Ent, a linear trimer of Ent, and different salmochelins. Growth assays further demonstrated that the Ent-specific antibodies significantly inhibited Ent-dependent growth of Campylobacter spp. and Escherichia coli Collectively, this study reports an efficient method to prepare a new type of Ent conjugate vaccines for inducing a high level of Ent-specific antibodies, which can bind to various Ent derivatives and display lipocalin-like bacteriostatic features.IMPORTANCE Ent-mediated high-affinity iron acquisition is a universal and critical contributor for Gram-negative pathogens to survive and infect hosts. Published information has supported an innovative immune intervention strategy that directly targets Ent to starve pathogens by limiting the availability of iron to be utilized. Compared to a recently published Ent conjugate, there are three advantages of the vaccine described in this study: ease of preparation, induction of high titer of anti-Ent IgG, and the ability of Ent-specific antibodies to bind various Ent derivatives, including the salmochelins that help enteric pathogens evade sequestration of siderophores by host lipocalins. In addition, the Ent-specific antibodies were demonstrated to function similarly to lipocalin to interfere with the Ent-dependent growth of Campylobacter and E. coli under iron-restricted conditions. This study has significant potential for broader applications to prevent and control various Gram-negative infections in humans and animals.
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Pi H, Jones SA, Mercer LE, Meador JP, Caughron JE, Jordan L, Newton SM, Conway T, Klebba PE. Role of catecholate siderophores in gram-negative bacterial colonization of the mouse gut. PLoS One 2012; 7:e50020. [PMID: 23209633 PMCID: PMC3510177 DOI: 10.1371/journal.pone.0050020] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 10/16/2012] [Indexed: 11/20/2022] Open
Abstract
We investigated the importance of the production of catecholate siderophores, and the utilization of their iron (III) complexes, to colonization of the mouse intestinal tract by Escherichia coli. First, a ΔtonB strain was completely unable to colonize mice. Next, we compared wild type E. coli MG1655 to its derivatives carrying site-directed mutations of genes for enterobactin synthesis (ΔentA::Cm; strain CAT0), ferric catecholate transport (Δfiu, ΔfepA, Δcir, ΔfecA::Cm; CAT4), or both (Δfiu, ΔfepA, ΔfecA, Δcir, ΔentA::Cm; CAT40) during colonization of the mouse gut. Competitions between wild type and mutant strains over a 2-week period in vivo showed impairment of all the genetically engineered bacteria relative to MG1655. CAT0, CAT4 and CAT40 colonized mice 101-, 105-, and 102-fold less efficiently, respectively, than MG1655. Unexpectedly, the additional inability of CAT40 to synthesize enterobactin resulted in a 1000-fold better colonization efficiency relative to CAT4. Analyses of gut mucus showed that CAT4 hyperexcreted enterobactin in vivo, effectively rendering the catecholate transport-deficient strain iron-starved. The results demonstrate that, contrary to prior reports, iron acquisition via catecholate siderophores plays a fundamental role in bacterial colonization of the murine intestinal tract.
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Affiliation(s)
- Hualiang Pi
- Department of Chemistry and Biochemistry, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
| | - Shari A. Jones
- Department of Microbiology and Plant Biology, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
| | - Lynn E. Mercer
- Department of Chemistry and Biochemistry, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
| | - Jessica P. Meador
- Department of Microbiology and Plant Biology, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
| | - Joyce E. Caughron
- Department of Microbiology and Plant Biology, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
| | - Lorne Jordan
- Department of Chemistry and Biochemistry, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
- Department of Biochemistry, Kansas State University, Manhattan, Kansas, United States of America
| | - Salete M. Newton
- Department of Biochemistry, Kansas State University, Manhattan, Kansas, United States of America
| | - Tyrrell Conway
- Department of Microbiology and Plant Biology, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
| | - Phillip E. Klebba
- Department of Biochemistry, Kansas State University, Manhattan, Kansas, United States of America
- * E-mail:
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The ttpC gene is contained in two of three TonB systems in the human pathogen Vibrio vulnificus, but only one is active in iron transport and virulence. J Bacteriol 2012; 194:3250-9. [PMID: 22505675 DOI: 10.1128/jb.00155-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The TonB system of proteins is required for the energy-dependent active transport of iron-bound substrates across the outer membrane of gram-negative bacteria. We have identified three TonB systems within the human pathogen Vibrio vulnificus. The TonB1 system contains the TonB1, ExbD1, and ExbB1 proteins, whereas both the TtpC2-TonB2 and TtpC3-TonB3 systems contain an additional fourth protein, TtpC. Here we report that TtpC3, although highly related to TtpC2, is inactive in iron transport, whereas TtpC2 is essential for the function of the TtpC2-TonB2 system in V. vulnificus. This protein, together with TonB2, is absolutely required for both the uptake of endogenously produced iron-bound siderophores as well as siderophores produced from other organisms. Through complementation we show that V. vulnificus is capable of using different TtpC2 proteins from other Vibrio species to drive the uptake of multiple siderophores. We have also determined that aerobactin, a common bacterial siderophore involved in virulence of enteric bacteria, can only be brought into the cell using the TtpC2-TonB2 system, indicating an important evolutionary adaptation of TtpC2 and TonB2. Furthermore, in the absence of TonB1, TtpC2 is essential for a fully virulent phenotype as demonstrated using 50% lethal dose (LD(50)) experiments in mice.
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Purification of Legiobactin and importance of this siderophore in lung infection by Legionella pneumophila. Infect Immun 2009; 77:2887-95. [PMID: 19398549 DOI: 10.1128/iai.00087-09] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
When cultured in a low-iron medium, Legionella pneumophila secretes a siderophore (legiobactin) that is both reactive in the chrome azurol S (CAS) assay and capable of stimulating the growth of iron-starved legionellae. Using anion-exchange high-pressure liquid chromatography (HPLC), we purified legiobactin from culture supernatants of a virulent strain of L. pneumophila. In the process, we detected the ferrated form of legiobactin as well as other CAS-reactive substances. Purified legiobactin had a yellow-gold color and absorbed primarily from 220 nm and below. In accordance, nuclear magnetic resonance spectroscopy revealed that legiobactin lacks aromatic carbons, and among the 13 aliphatics present, there were 3 carbonyls. When examined by HPLC, supernatants from L. pneumophila mutants inactivated for lbtA and lbtB completely lacked legiobactin, indicating that the LbtA and LbtB proteins are absolutely required for siderophore activity. Independently derived lbtA mutants, but not a complemented derivative, displayed a reduced ability to infect the lungs of A/J mice after intratracheal inoculation, indicating that legiobactin is required for optimal intrapulmonary survival by L. pneumophila. This defect, however, was not evident when the lbtA mutant and its parental strain were coinoculated into the lung, indicating that legiobactin secreted by the wild type can promote growth of the mutant in trans. Legiobactin mutants grew normally in murine lung macrophages and alveolar epithelial cells, suggesting that legiobactin promotes something other than intracellular infection of resident lung cells. Overall, these data represent the first documentation of a role for siderophore expression in the virulence of L. pneumophila.
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Choi EY, Lee S, Oh HM, Kim YD, Choi EJ, Kim SH, Kim SW, Choi SC, Jun CD. Involvement of protein kinase Cdelta in iron chelator-induced IL-8 production in human intestinal epithelial cells. Life Sci 2006; 80:436-45. [PMID: 17097691 DOI: 10.1016/j.lfs.2006.09.044] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2006] [Revised: 08/27/2006] [Accepted: 09/26/2006] [Indexed: 11/28/2022]
Abstract
We have shown that the bacterial iron chelator, deferoxamine (DFO), triggers inflammatory signals, including the production of CXC chemokine IL-8, in human intestinal epithelial cells (IECs) by activating ERK1/2 and p38 kinase pathways. In the present study, we show that PKCdelta, one of the novel protein kinase C (PKC) isoforms, involves in signal transduction pathways leading to DFO-induced IL-8 production. Pretreatment of human intestinal epithelial HT-29 cells with rottlerin showed remarkable inhibition of DFO-induced IL-8 production. In contrast, other PKC inhibitors such as Gö6976, Gö6983, GF109203X, and staurosporine revealed less or no inhibitory effects on DFO-induced IL-8 production, suggesting a potential role of PKCdelta. Accordingly, DFO caused phosphorylation of PKCdelta in the Thr505 and Ser643 residues in HT-29 cells. Transfection of dominant-negative PKCdelta vector inhibited DFO-induced PKCdelta phosphorylation as well as IL-8 promoter activity. In addition, suppression of endogenous PKCdelta by siRNA significantly reduced DFO-induced IL-8 production. Collectively, these results suggest that PKCdelta plays a pivotal role in signaling pathways leading to iron chelator-induced IL-8 production in human IECs.
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Affiliation(s)
- Eun-Young Choi
- Department of Life Science, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
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Ewers C, Schüffner C, Weiss R, Baljer G, Wieler LH. Molecular characteristics of Escherichia coli serogroup O78 strains isolated from diarrheal cases in bovines urge further investigations on their zoonotic potential. Mol Nutr Food Res 2005; 48:504-14. [PMID: 15538707 DOI: 10.1002/mnfr.200400063] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We investigated the virulence properties and clonal relationship of 21 Escherichia coli strains of serogroup O78 isolated from diarrhoeic cattle and calves. Isolates were screened for 18 genes representing virulence features of different Escherichia coli pathotypes. None of the strains harboured enterotoxin-genes estIa/Ib, eltIa/Ib, or Shiga toxin (stx) genes, genes involved in adhesion (eae, f5, f41) hemolysin gene hlyA or invasion gene ipaC. With a high prevalence we detected enterotoxin astA (61.9%), genes involved in iron acquisition, like fyuA, irp (each 57.1%) and iucD (81.0%), and the operon sequence of Colicin V plasmids (38.1%). Some strains possessed toxin genes cdt-IIIB and cnf1/2 (both 14.3%), the invasion gene tia (23.8%), and the serine protease encoding gene espP (23.8%). Moreover, we could show that E. coli O78 strains under investigation were able to adhere to and invade MDBK-cells with varying efficiencies. The results indicate that the closely related O78 strains, constituting two major PFGE-clusters, harbor various virulence features for bovine intestinal disease but cannot be grouped into one of the common E. coli intestinal pathogenic or other pathotypes according to their virulence gene pattern. Nevertheless, the ability to adhere, invade or harbor toxin genes lets us suggest that O78 strains isolated from diarrheal cases in bovines urges further investigations on the zoonotic potential of these strains.
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Affiliation(s)
- Christa Ewers
- Institut für Mikrobiologie und Tierseuchen, Freie Universität Berlin, Berlin, Germany.
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10
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Crost C, Harel J, Berthiaume F, Garrivier A, Tessier MC, Rakotoarivonina H, Martin C. Influence of environmental cues on transcriptional regulation of foo and clp coding for F165(1) and CS31A adhesins in Escherichia coli. Res Microbiol 2004; 155:475-82. [PMID: 15249065 DOI: 10.1016/j.resmic.2004.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2004] [Accepted: 02/16/2004] [Indexed: 10/26/2022]
Abstract
F165(1) (foo) and CS31A (clp) are bacterial adhesins synthesized by Escherichia coli strains associated with diarrhea and septicemia in piglets and calves. They belong to the P-regulatory family and as such are subject to a phase variation control mediated by Lrp (leucine responsive regulatory protein) and regulators homologous to PapI. Analysis of expression of transcriptional fusions between the fooB or fooI promoters and lacZ showed that Lrp is an activator of foo and fooI transcription, whereas it represses clp transcription. Furthermore, foo phase variation leads to a large majority of phase-ON cells, whereas clp phase variation leads to a majority of phase-OFF cells. We compared the influence of several environmental cues on foo and clp expression, with special attention to the effects of leucine and alanine known to be mediated by Lrp. Inhibition or significant repression of foo and clp transcription was observed at low temperature, in LB medium, and in the presence of glucose, alanine, or leucine. Glucose repression of foo but not of clp was totally relieved by addition of cAMP. Osmolarity and pH had little effect. Alanine but not leucine, and LB medium inhibited foo and clp phase variation, locking cells in the OFF phase. Low temperature inhibited clp phase variation and altered the switch frequency of foo phase variation, leading to more phase-OFF cells. Glucose altered the phase variation of both operons, increasing the number of phase-OFF cells in the population. The regulation pattern of foo and clp is consistent with F165(1) and CS31A production in low nutrient environments, even at moderately acidic pH or high osmolarity.
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Affiliation(s)
- Cécile Crost
- INRA de Clermont-Ferrand-Theix, Unité de Microbiologie, Saint-Genès-Champanelle, France
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11
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Schamberger GP, Diez-Gonzalez F. Characterization of colicinogenic Escherichia coli strains inhibitory to enterohemorrhagic Escherichia coli. J Food Prot 2004; 67:486-92. [PMID: 15035362 DOI: 10.4315/0362-028x-67.3.486] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A previously identified set of anti-Escherichia coli O157:H7 colicinogenic E. coli were characterized to assess the suitability of these isolates as a preharvest food safety intervention in cattle. This collection of 23 E. coli strains were screened for virulence factors, antibiotic resistance, type of colicin(s) present, and their ability to inhibit other pathogenic E. coli. With the use of PCR, pathogen genes were detected in six of the 23 colicinogenic E. coli. When the nonpathogenic strains were assessed for antibiotic resistance, four strains showed resistance to at least one antibiotic. The remaining set of 14 strains were evaluated for the presence of previously identified colicins. Seven colicins (B, El, E2/E7, E7, Ia/Ib, K, and M) were detected. One half of the strains possessed multiple types of colicins. The most commonly detected colicins were B, E2/E7, and M, which were found in six strains each. DNA sequencing was also performed in order to classify the E2/E7 colicins separately from E7 colicins. The 14 colicinogenic E. coli also were evaluated for their ability to inhibit 10 different non-O157 pathogenic E. coli. Six of the colicinogenic E. coli were capable of inhibiting all 10 pathogens, and the remaining eight strains could each inhibit between six to eight of the pathogenic E. coli. This strain collection has great potential for inhibiting E. coli O157:H7 in cattle.
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Affiliation(s)
- Gerry P Schamberger
- Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Avenue, St. Paul, Minnesota 55108, USA
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12
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Dozois CM, Daigle F, Curtiss R. Identification of pathogen-specific and conserved genes expressed in vivo by an avian pathogenic Escherichia coli strain. Proc Natl Acad Sci U S A 2003; 100:247-52. [PMID: 12506201 PMCID: PMC140941 DOI: 10.1073/pnas.232686799] [Citation(s) in RCA: 180] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Escherichia coli is a diverse bacterial species that comprises commensal nonpathogenic strains such as E. coli K-12 and pathogenic strains that cause a variety of diseases in different host species. Avian pathogenic E. coli strain chi7122 (O78:K80:H9) was used in a chicken infection model to identify bacterial genes that are expressed in infected tissues. By using the cDNA selection method of selective capture of transcribed sequences and enrichment for the isolation of pathogen-specific (non-E. coli K-12) transcripts, pathogen-specific cDNAs were identified. Pathogen-specific transcripts corresponded to putative adhesins, lipopolysaccharide core synthesis, iron-responsive, plasmid- and phage-encoded genes, and genes of unknown function. Specific deletion of the aerobactin siderophore system and E. coli iro locus, which were identified by selective capture of transcribed sequences, demonstrated that these pathogen-specific systems contribute to the virulence of strain chi7122. Consecutive blocking to enrich for selection of pathogen-specific genes did not completely eliminate the presence of transcripts that corresponded to sequences also present in E. coli K-12. These E. coli conserved genes are likely to be highly expressed in vivo and contribute to growth or virulence. Overall, the approach we have used simultaneously provided a means to identify novel pathogen-specific genes expressed in vivo and insight regarding the global gene expression and physiology of a pathogenic E. coli strain in a natural animal host during the infectious process.
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Affiliation(s)
- Charles M Dozois
- Department of Biology, Washington University, Campus Box 1137, One Brookings Drive, St. Louis, MO 63130, USA
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13
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Yamamoto S, Okujo N, Miyoshi S, Shinoda S, Narimatsu S. Siderophore production of Vibrio parahaemolyticus strains from different sources. Microbiol Immunol 2000; 43:909-12. [PMID: 10553685 DOI: 10.1111/j.1348-0421.1999.tb01227.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Vibrio parahaemolyticus strains isolated from different sources were assayed for their ability to produce a siderophore, vibrioferrin, under iron-limited growth conditions. The mean value +/- standard error of mean (microM vibrioferrin in spent culture supernatant/optical density at 660 nm) was 832.3 +/- 66.9 for clinical isolates (n=44), which was significantly higher (P<0.01) than those for food isolates (461.0 +/- 66.5; n=37) and coastal isolates (378.8 +/- 37.2; n=26). This suggests that greater productivity of vibrioferrin by clinical isolates may be associated with a selective advantage for survival and proliferation under conditions of iron-limitation such as in the intestine [corrected].
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Affiliation(s)
- S Yamamoto
- Faculty of Pharmaceutical Sciences, Okayama University, Japan
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14
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Keller R, Pedroso MZ, Ritchmann R, Silva RM. Occurrence of virulence-associated properties in Enterobacter cloacae. Infect Immun 1998; 66:645-9. [PMID: 9453621 PMCID: PMC113501 DOI: 10.1128/iai.66.2.645-649.1998] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Enterobacter cloacae is not a primary human pathogen but has been considered to be an important cause of nosocomial infections. Even so, there are almost no reports on its ability to produce recognized virulence-associated properties. In this study, we show that most of the E. cloacae strains examined were resistant to serum bactericidal activity and were able to produce aerobactin and mannose-sensitive hemagglutinin, and all of them could adhere to and invade HEp-2 cells. Since E. cloacae is part of the normal intestinal floras of many individuals, we believe that infectious disease due to endogenous E. cloacae might be a result of both host predisposing factors and the bacterial virulence determinants that we have detected in this survey.
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Affiliation(s)
- R Keller
- Departamento de Microbiologia, Imunologia, e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, SP, Brazil
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15
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Bertin Y, Martin C, Oswald E, Girardeau JP. Rapid and specific detection of F17-related pilin and adhesin genes in diarrheic and septicemic Escherichia coli strains by multiplex PCR. J Clin Microbiol 1996; 34:2921-8. [PMID: 8940423 PMCID: PMC229434 DOI: 10.1128/jcm.34.12.2921-2928.1996] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The F17-related adhesins are prevalent in Escherichia coli strains isolated from calves with diarrhea or septicemia and from lambs with nephropathy. The F17 family includes the F17a, F17b, F17c, and F111 fimbriae produced by bovine E. coli strains and the G agglutinin produced by human uropathogenic E. coli strains. An easy and inexpensive multiplex PCR method was developed to detect all the F17-related fimbriae and to identify four subtypes of structural subunit genes and two distinct subfamilies of adhesin genes by only two runs of amplification. A strict correlation was observed between the phenotypic assays and the multiplex PCR method when 166 pathogenic E. coli strains isolated from intestinal content of calves or lambs were tested. Genes encoding the F17c structural subunit and the subfamily II adhesins were prominent among the bovine and ovine isolates, and the capsule-like CS31A antigen was strictly associated with the F17c fimbriae. The F17b subtype fimbriae were prominent among the bovine isolates producing the CNF2 toxin, whereas the F17a subtype fimbriae were associated with the bovine isolates producing neither the CS31A antigen nor the CNF2 toxin. Five bacterial strains possessed two distinct and complete F17-related fimbrial gene clusters, and two of them produced two F17-related fimbriae at the bacterial cell surface. The related fimbrial gene clusters are probably organized in mosaic operons consisting of F17-related pilin and adhesin genes, and horizontal gene transfer may occur among E. coli strains isolated form different animal species.
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Affiliation(s)
- Y Bertin
- Laboratoire de Microbiologie, Centre de Recherche de Clermont-Ferrand-Theix, St Genès-Champanelle, France.
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16
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Bertin Y, Girardeau JP, Darfeuille-Michaud A, Contrepois M. Characterization of 20K fimbria, a new adhesin of septicemic and diarrhea-associated Escherichia coli strains, that belongs to a family of adhesins with N-acetyl-D-glucosamine recognition. Infect Immun 1996; 64:332-42. [PMID: 8557360 PMCID: PMC173764 DOI: 10.1128/iai.64.1.332-342.1996] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Bovine septicemic Escherichia coli 31A agglutinates bovine, rabbit, and human erythrocytes and adheres in vitro to the brush border of bovine or ovine intestinal epithelial cells and to the human colon carcinoma Caco-2 cell line. The adhesion and hemagglutination of E. coli 31A are mediated by a chromosome-encoded fimbrial adhesin serologically distinct from known fimbrial adhesins found in enterotoxigenic and septicemic bovine E. coli strains. By electron microscopy studies the fimbriae designated 20K were observed as fine flexible filaments (diameter, 3 nm) and the purified major fimbrial subunit appeared with an apparent molecular mass of 20,000 Da. Western blot (immunoblot) analysis, N-terminal sequence alignment, and amino acid composition revealed a high homology with the N-acetyl-D-glcosamine-specific G fimbria of human uropathogenic E. coli and with fimbriae belonging to the F17 family produced by bovine enterotoxigenic and invasive E. coli strains. Immunological study revealed that 20K fimbria was closely related to G fimbria and represents a serological variant of F17 fimbria. Hemagglutination and adhesion inhibition assays demonstrated that 20K, G, and F17 fimbriae bind to an N-acetyl-D-glucosamine-containing receptor, but each probably binds to different oligosaccharide sequences or different receptors on host tissues. 20K fimbriae were produced by a limited group of clonally related strains with the unusual m-inositol-positive phenotype and appeared highly associated with the plasmid-mediated virulence factor. An examination of natural occurrence of 20K fimbriae among a large collection of human and animal pathogenic E. coli showed that 20K fimbria is the prominent adhesin among bovine septicemic E. coli isolated from European countries.
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MESH Headings
- Acetylglucosamine/metabolism
- Adhesins, Escherichia coli/chemistry
- Adhesins, Escherichia coli/genetics
- Adhesins, Escherichia coli/metabolism
- Amino Acid Sequence
- Animals
- Antigens, Bacterial/chemistry
- Artiodactyla
- Bacterial Adhesion
- Base Sequence
- Cross Reactions
- Diarrhea/microbiology
- Escherichia coli/chemistry
- Escherichia coli/immunology
- Escherichia coli/ultrastructure
- Fimbriae, Bacterial/chemistry
- Fimbriae, Bacterial/genetics
- Fimbriae, Bacterial/metabolism
- Fimbriae, Bacterial/ultrastructure
- Humans
- Intestines/microbiology
- Molecular Sequence Data
- Protein Binding
- Receptors, Immunologic/antagonists & inhibitors
- Receptors, Immunologic/metabolism
- Sepsis/microbiology
- Sequence Homology, Amino Acid
- Species Specificity
- Tumor Cells, Cultured
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Affiliation(s)
- Y Bertin
- Laboratoire de Microbiologie, Institut National de la Recherche Agronomique, Saint-Genès-Champanelle, France
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17
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Abstract
1. After a long barren period, the study of bacterial pathogenicity is now one of the most popular subjects in microbiology. This is because bacterial diseases remain a major problem in public health despite the advent of antibiotics, and the subject is a fertile field for the application of genetics and molecular biology. 2. Pathogenicity is a multifactorial property. The biological requirements are abilities to: infect mucous surfaces; enter the host through those surfaces; multiply in the environment of the host; interfere with host defences; and damage the host. Each requirement has many facets all of which can be accomplished by a variety of processes. 3. The molecular determinants of the five requirements for pathogenicity can be identified and the relation between their structure and function obtained by a seven step procedure. Genetic manipulation and observations on organisms grown in vivo play major roles in this procedure. Other vital aspects are the availability of good animal models and the design of biological tests for virulence determinants in vitro that are pertinent to the situation in vivo. 4. A survey of the state of studies on bacterial pathogenicity has highlighted some areas of immense erudition and exposed others that need more attention in the future. Research is often at the highest level of molecular biology for: adherence to and entry of epithelial cells; interference with humoral and phagocytic defences; toxins; and direct induction of cytokines and inflammation. The major gaps are: the determinants of competition with commensals on mucous surfaces; spread into deeper tissues; the host supplied nutrients and metabolism underlying growth rate in vivo; the determinants of interference with the immune response in important chronic diseases and carrier states; the determinants of immunopathological reactions that cause damage in chronic disease; and the determinants of change from carrier to invasive state. Areas that are receiving some attention but are worthy of more are: moving through mucus to gain access to mucous surfaces; opportunistic infections; the determinants of mixed infections; and the determinants of host and tissue susceptibility to infection. 5. Current interest in the regulation of production of virulence determinants and the influence on it of environmental factors has raised speculation on the role these factors play in vivo. However, it has not yet provided much information on the host factors specifically involved in particular bacterial infections. The individualistic concept of community, as a relative latecomer to discussions of animal community, is sometimes misconstrued as holding that communities are random assemblages of organisms without biotic interactions among species. Nevertheless, it has increasingly been accepted as supported by studies of diverse taxa and habitats. However, many other ecologists continue to argue for integrated, biotically controlled and evolved communities.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- H Smith
- Medical School, University of Birmingham, UK
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18
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Le Roy D, Crouzier C, Dho-Moulin M, Dumont AS, Bouchet A, Lafont JP, Andremont A. Results of passive and active immunization directed against ferric aerobactin in experimental enterobacterial infections in mice and chickens. Res Microbiol 1995; 146:167-74. [PMID: 7652210 DOI: 10.1016/0923-2508(96)80894-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Production of aerobactin has been reported to be a virulence factor in members of the family Enterobacteriaceae. To investigate the protection afforded by humoral immunity directed towards aerobactin in infectious diseases caused by aerobactin-producing strains, we tested the efficacy of mAbAERO1, a murine monoclonal antibody directed to ferric aerobactin, which, in vitro, was found to impair the growth of aerobactin-dependent strains of Enterobacteriaceae under iron-limited conditions. The mortality of mice experimentally infected with the aerobactin-producing strains Escherichia coli V2019 (LD50 = 3.5 x 10(5) CFU/mice) or Klebsiella pneumoniae Caroli (LD50 = 1.3 CFU/mice) was not reduced when 1 mg of mAbAERO1 was injected intravenously 1 h before or 1 h after bacterial challenge. Nor was mortality reduced after challenge with either E. coli V2019 or K. pneumoniae Caroli, even though the active immunization of mice with purified FeAero (ferric aerobactin) conjugated with thyroglobulin as followed by a rise in systemic anti-FeAero antibodies. Lastly, chicks born of hens immunized with FeAero showed evidence of antibody transmission towards FeAero, but were not protected when challenged with E. coli MT78, an aerobactin-producing strain highly virulent for chickens. Therefore, under the experimental conditions tested, humoral immunity against aerobactin appeared to play only a minor role in protection against infections caused by aerobactin-producing members of the family Enterobacteriaceae. However, other experimental models should be tested to confirm these observations.
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Affiliation(s)
- D Le Roy
- Laboratoire d'Ecologie microbienne, Institut Gustave-Roussy, Villejuif, France
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19
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Bouchet A, Valvano MA, Dho-Moulin M, Le Roy D, Andremont A. Immunological variants of the aerobactin-cloacin DF13 outer membrane protein receptor IutA among enteric bacteria. Infect Immun 1994; 62:3017-21. [PMID: 8005691 PMCID: PMC302915 DOI: 10.1128/iai.62.7.3017-3021.1994] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Mouse monoclonal antibodies (MAbs) were generated against a 76-kDa IutA receptor of pathogenic avian Escherichia coli 15972. Six of the eight IutA-specific MAbs isolated (AB1 to AB6) were shown to be directed toward membrane-exposed conformational epitopes, although they did not interfere with the uptake of ferric aerobactin and cloacin DF13 as assessed by competition experiments with purified ligands. The two remaining IutA MAbs (AB9 and AB10) recognized linear epitopes buried in the IutA molecule. The panel of IutA MAbs was used to characterize IutA variants occurring in strains of E. coli, Klebsiella pneumoniae, Enterobacter spp., and Shigella spp., resulting in the identification of four immunological groups of IutAs. MAb AB9 defined an epitope conserved in all IutA variants. In addition, the panel of IutA MAbs served to identify the presence of IutA in wild-type bacteria grown in the presence of diphenylamine to reduce the expression of O-specific polysaccharide.
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Affiliation(s)
- A Bouchet
- Laboratoire d'Ecologie Microbienne, Institut Gustave Roussy, Villejuif, France
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20
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Stojiljkovic I, Cobeljic M, Hantke K. Escherichia coli K-12 ferrous iron uptake mutants are impaired in their ability to colonize the mouse intestine. FEMS Microbiol Lett 1993; 108:111-5. [PMID: 8472918 DOI: 10.1111/j.1574-6968.1993.tb06082.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The streptomycin-treated mouse colonization model was used to investigate the role of the Fe2+ uptake system (Feo) of Escherichia coli K12 in the colonization of the mouse intestine. Mutants impaired in the uptake of Fe2+ ions were shown to be deficient also in their colonization ability. Both enterochelin-producing and enterochelin-nonproducing Escherichia coli feo mutants were unable to colonize the mouse intestine. These results demonstrated that Fe(II) is an essential source of iron for E. coli grown in the intestine.
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Affiliation(s)
- I Stojiljkovic
- Mikrobiologie II, Tübingen, FRG, Institute for Preventive Medicine, Beograd, Crnotravska, Yugoslavia
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21
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Le Roy D, Bouchet A, Saulnier P, Pecquet S, Andremont A. Comparison of chemical assay, bioassay, enzyme-linked immunosorbent assay, and dot blot hybridization for detection of aerobactin in members of the family Enterobacteriaceae. Appl Environ Microbiol 1993; 59:942-4. [PMID: 8481015 PMCID: PMC202216 DOI: 10.1128/aem.59.3.942-944.1993] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
In order to determine the best strategy for detection of aerobactin in members of the family Enterobacteriaceae, we compared the results of three phenotypic assays, including a chemical assay, a cross-feeding bioassay, and an enzyme-linked immunosorbent assay (ELISA), with the results of a dot blot hybridization assay using a specific probe for the aerobactin genes. The sensitivity and specificity of the ELISA were better than those of the chemical and cross-feeding assays, but the results of dot blot hybridization were the most reproducible. However, none of the Serratia and Enterobacter cloacae strains which produced aerobactin hybridized with the probe. We concluded that the best strategy for aerobactin detection is a two-step procedure that combines screening by dot blot hybridization with an ELISA for negative strains.
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Affiliation(s)
- D Le Roy
- Laboratoire d'Ecologie Microbienne, Institut Gustave-Roussy, Chatenay-Malabry, France
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