Ability ofEscherichia coliO157:H7 isolates to colonize the intestinal tract of conventional adult CD1 mice is transient

2001 ◽  
Vol 47 (1) ◽  
pp. 91-95 ◽  
Author(s):  
J Wayne Conlan ◽  
Sonia L Bardy ◽  
Rhonda KuoLee ◽  
Ann Webb ◽  
Malcolm B Perry
Keyword(s):  
Escherichia Coli ◽  
Mouse Model ◽  
Intestinal Tract ◽  
Vaccine Development ◽  
Escherichia Coli O157 ◽  
Intestinal Colonization ◽  
E Coli ◽  
Cd1 Mice ◽  
A Current

In an attempt to improve upon a current mouse model of intestinal colonization by Escherichia coli O157:H7 used in this laboratory for vaccine development, nine clinical isolates of the pathogen were screened for their ability to persist in the intestinal tract of conventional adult CD-1 mice. None of the test isolates of E. coli O157:H7 were capable of colonizing these mice for a period of more than two weeks. Most of the isolates appeared to be benign for the experimental host, but one isolate was lethal. This virulence correlated with the ability of the latter isolate to produce large quantities of Shiga-like toxin 2 in vitro.

scholarly journals Use of In Vivo-Induced Antigen Technology for Identification of Escherichia coli O157:H7 Proteins Expressed during Human Infection

2005 ◽  
Vol 73 (5) ◽  
pp. 2665-2679 ◽  
Author(s):  
Manohar John ◽  
Indira T. Kudva ◽  
Robert W. Griffin ◽  
Allen W. Dodson ◽  
Bethany McManus ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Vaccine Development ◽  
Human Infection ◽  
Escherichia Coli O157 ◽  
Standard Laboratory ◽  
E Coli ◽  
Phase Culture ◽  
Stool Specimens

ABSTRACT Using in vivo-induced antigen technology (IVIAT), a modified immunoscreening technique that circumvents the need for animal models, we directly identified immunogenic Escherichia coli O157:H7 (O157) proteins expressed either specifically during human infection but not during growth under standard laboratory conditions or at significantly higher levels in vivo than in vitro. IVIAT identified 223 O157 proteins expressed during human infection, several of which were unique to this study. These in vivo-induced (ivi) proteins, encoded by ivi genes, mapped to the backbone, O islands (OIs), and pO157. Lack of in vitro expression of O157-specific ivi proteins was confirmed by proteomic analysis of a mid-exponential-phase culture of E. coli O157 grown in LB broth. Because ivi proteins are expressed in response to specific cues during infection and might help pathogens adapt to and counter hostile in vivo environments, those identified in this study are potential targets for drug and vaccine development. Also, such proteins may be exploited as markers of O157 infection in stool specimens.

Parenteral immunization with a glycoconjugate vaccine containing the O157 antigen of Escherichia coli O157:H7 elicits a systemic humoral immune response in mice, but fails to prevent colonization by the pathogen

1999 ◽  
Vol 45 (4) ◽  
pp. 279-286
Author(s):  
J Wayne Conlan ◽  
Andrew D Cox ◽  
Rhonda KuoLee ◽  
Ann Webb ◽  
Malcolm B Perry
Keyword(s):  
Escherichia Coli ◽  
Intestinal Tract ◽  
Horse Serum ◽  
Convincing Evidence ◽  
Escherichia Coli O157 ◽  
Intestinal Colonization ◽  
E Coli ◽  
Humoral Immune ◽  
Parenteral Immunization ◽  
Glycoconjugate Vaccine

The results of the present study show that whereas both BALB/c and C57BL/6 mice parenterally inoculated with a horse serum albumin - Escherichia coli O157 antigen conjugate vaccine develop systemic, specific antibodies to the carrier protein, only the former mice routinely develop antibodies to the carbohydrate O157 moiety. However, little convincing evidence was found to show that these antibodies transuded into the intestinal tract either naturally or in response to an oral inoculum of the pathogen. Moreover, this vaccination procedure failed to protect mice against intestinal colonization following oral challenge with the pathogen. Thus, the results of this study suggest that parenteral vaccination might be an unsuitable strategy for combatting E. coli O157:H7 organisms located in the gut.Key words: Escherichia coli, glycoconjugate vaccine, mice.

Susceptibility of three strains of conventional adult mice to intestinal colonization by an isolate of Escherichia coli O157:H7

1998 ◽  
Vol 44 (8) ◽  
pp. 800-805 ◽  
Author(s):  
J Wayne Conlan ◽  
Malcolm B Perry
Keyword(s):  
Escherichia Coli ◽  
Vaccine Development ◽  
Immunoglobulin A ◽  
Bacterial Pathogen ◽  
Mouse Strains ◽  
Escherichia Coli O157 ◽  
Intestinal Colonization ◽  
E Coli ◽  
Adult Mice ◽  
Enhanced Resistance

Three mouse strains were assessed for their susceptibility to intestinal colonization by a strain of the enteric bacterial pathogen Escherichia coli O157:H7. Following intragastric inoculation of E. coli O157:H7, the intestines of young adult female CD1, BALB/c, and C57BL/6 mice became colonized, as evidenced by faecal shedding of the pathogen for periods of up to 5 weeks. None of the three mouse strains examined developed overt disease in response to colonization by the organism. Following clearance of the primary inoculum, BALB/c mice, but not CD1 or C57BL/6 mice, appeared to acquire enhanced resistance to recolonization by E. coli O157:H7, as evidenced by a decreased faecal shedding period. This enhanced resistance correlated with the presence and persistence of immunoglobulin A, but not immunoglobulin G, in the serum and faeces directed against the O157 antigen. The implications of these findings to vaccine development against E. coli O157:H7 are discussed.Key words: E. coli O157:H7, CD1 mice, BALB/c mice, C57BL/6 mice, faecal shedding.

Salmonella landau as a live vaccine against Escherichia coli O157:H7 investigated in a mouse model of intestinal colonization

1999 ◽  
Vol 45 (9) ◽  
pp. 723-731 ◽  
Author(s):  
J Wayne Conlan ◽  
Rhonda KuoLee ◽  
Ann Webb ◽  
Malcolm B Perry
Keyword(s):  
Escherichia Coli ◽  
Immune Response ◽  
Mouse Model ◽  
Mucosal Immunity ◽  
Host Resistance ◽  
Mucosal Immune Response ◽  
Escherichia Coli O157 ◽  
Local Immune Response ◽  
Intestinal Colonization ◽  
E Coli

The present study was performed to assess the potential of a humoral mucosal immune response directed against the O157 antigen of Escherichia coli O157:H7 to prevent intestinal colonization by the pathogen. To this end, mice were gavaged with inocula of Salmonella landau, a Salmonella strain that naturally expresses the O157 antigen. Salmonella landau was avirulent for mice. Despite this, mice exposed to S. landau developed high titres of serum and coproantibodies against the O157 antigen. These mice, compared with controls, demonstrated some ability to resist transient intestinal colonization by an oral inoculum of an isolate of E. coli O157:H7. These findings suggest that a local immune response directed against the O157 antigen might increase host resistance to this pathogen.Key words: Salmonella landau, Escherichia coli O157:H7, mucosal immunity, mice.

Effect of Tannins on the In Vitro Growth of Escherichia coli O157:H7 and In Vivo Growth of Generic Escherichia coli Excreted from Steers

2007 ◽  
Vol 70 (3) ◽  
pp. 543-550 ◽  
Author(s):  
BYENG R. MIN ◽  
WILLIAM E. PINCHAK ◽  
ROBIN C. ANDERSON ◽  
TODD R. CALLAWAY
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Bacterial Growth ◽  
Escherichia Coli O157 ◽  
Tannin Extract ◽  
Bacterial Growth Rate ◽  
Linear Effect ◽  
E Coli

The effect of commercially available chestnut and mimosa tannins in vitro (experiment 1) or in vivo (experiment 2) on the growth or recovery of Escherichia coli O157:H7 or generic fecal E. coli was evaluated. In experiment 1, the mean growth rate of E. coli O157:H7, determined via the measurement of optical density at 600 nm during anaerobic culture in tryptic soy broth at 37°C, was reduced (P < 0.05) with as little as 400 μg of either tannin extract per ml of culture fluid. The addition of 200, 400, 600, 800, and 1,200 μg of tannins per ml significantly (P < 0.01) reduced the specific bacterial growth rate when compared with the nontannin control. The specific growth rate decreased with increasing dose levels up to 800 μg of tannins per ml. Bacterial growth inhibition effects in chestnut tannins were less pronounced than in mimosa tannins. Chestnut tannin extract addition ranged from 0 to 1,200 μg/ml, and a linear effect (P < 0.05) was observed in cultures incubated for 6 h against the recovery of viable cells, determined via the plating of each strain onto MacConkey agar, of E. coli O157:H7 strains 933 and 86-24, but not against strain 6058. Similar tests with mimosa tannin extract showed a linear effect (P < 0.05) against the recovery of E. coli O157:H7 strain 933 only. The bactericidal effect observed in cultures incubated for 24 h with the tannin preparations was similar, although it was less than that observed from cultures incubated for 6 h. When chestnut tannins (15 g of tannins per day) were infused intraruminally to steers fed a Bermuda grass hay diet in experiment 2, fecal E. coli shedding was lower on days 3 (P < 0.03), 12 (P = 0.08), and 15 (P < 0.001) when compared with animals that were fed a similar diet without tannin supplementation. It was concluded that dietary levels and sources of tannins potentially reduce the shedding of E. coli from the gastrointestinal tract.

scholarly journals Cooperative Role of Antibodies against Heat-Labile Toxin and the EtpA Adhesin in Preventing Toxin Delivery and Intestinal Colonization by Enterotoxigenic Escherichia coli

2012 ◽  
Vol 19 (10) ◽  
pp. 1603-1608 ◽  
Author(s):  
Koushik Roy ◽  
David J. Hamilton ◽  
James M. Fleckenstein
Keyword(s):  
Escherichia Coli ◽  
Diarrheal Disease ◽  
Vaccine Development ◽  
Enterotoxigenic Escherichia Coli ◽  
Intestinal Colonization ◽  
Content Type ◽  
Heat Labile

ABSTRACTEnterotoxigenicEscherichia coli(ETEC) is an important cause of diarrheal disease in developing countries, where it is responsible for hundreds of thousands of deaths each year. Vaccine development for ETEC has been hindered by the heterogeneity of known molecular targets and the lack of broad-based sustained protection afforded by existing vaccine strategies. In an effort to explore the potential role of novel antigens in ETEC vaccines, we examined the ability of antibodies directed against the ETEC heat-labile toxin (LT) and the recently described EtpA adhesin to prevent intestinal colonizationin vivoand toxin delivery to epithelial cellsin vitro. We demonstrate that EtpA is required for the optimal delivery of LT and that antibodies against this adhesin play at least an additive role in preventing delivery of LT to target intestinal cells when combined with antibodies against either the A or B subunits of the toxin. Moreover, vaccination with a combination of LT and EtpA significantly impaired intestinal colonization. Together, these results suggest that the incorporation of recently identified molecules such as EtpA could be used to enhance current approaches to ETEC vaccine development.

In Vitro Inactivation of Escherichia coli O157:H7 in Bovine Rumen Fluid by Caprylic Acid

2004 ◽  
Vol 67 (5) ◽  
pp. 884-888 ◽  
Author(s):  
THIRUNAVUKKARASU ANNAMALAI ◽  
MANOJ KUMAR MOHAN NAIR ◽  
PATRICK MAREK ◽  
PRADEEP VASUDEVAN ◽  
DAVID SCHREIBER ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Caprylic Acid ◽  
Rumen Fluid ◽  
Bacterial Load ◽  
Anaerobic Bacteria ◽  
Inhibitory Effect ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Bovine Rumen

The antibacterial effect of caprylic acid (35 and 50 mM) on Escherichia coli O157:H7 and total anaerobic bacteria at 39° C in rumen fluid (pH 5.6 and 6.8) from 12 beef cattle was investigated. The treatments containing caprylic acid at both pHs significantly reduced (P < 0.05) the population of E. coli O157:H7 compared with that in the control samples. At pH 5.6, both levels of caprylic acid killed E. coli O157:H7 rapidly, reducing the pathogen population to undetectable levels at 1 min of incubation (a more than 6.0-log CFU/ml reduction). In buffered rumen fluid at pH 6.8, 50 mM caprylic acid reduced the E. coli O157:H7 population to undetectable levels at 1 min of incubation, whereas 35 mM caprylic acid reduced the pathogen by approximately 3.0 and 5.0 log CFU/ml at 8 and 24 h of incubation, respectively. At both pHs, caprylic acid had a significantly lesser (P < 0.05) and minimal inhibitory effect on the population of total anaerobic bacteria in rumen compared with that on E. coli O157:H7. At 24 h of incubation, caprylic acid (35 and 50 mM) reduced the population of total anaerobic bacteria by approximately 2.0 log CFU/ml at pH 5.6, whereas at pH 6.8, caprylic acid (35 mM) did not have any significant (P > 0.05) inhibitory effect on total bacterial load. Results of this study revealed that caprylic acid was effective in inactivating E. coli O157:H7 in bovine rumen fluid, thereby justifying its potential as a preslaughter dietary supplement for reducing pathogen carriage in cattle.

scholarly journals Synthesis of antibiotic loaded polylactic acid nanoparticles and their antibacterial activity against Escherichia coli O157:H7 and methicillin-resistant Staphylococcus aureus

Biomédica ◽  
2017 ◽  
Vol 37 (1) ◽  
pp. 11 ◽  
Author(s):  
Mónica Tatiana Herrera ◽  
Jhon Jhamilton Artunduaga ◽  
Claudia Cristina Ortiz ◽  
Rodrigo Gonzalo Torres
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Antibacterial Activity ◽  
Polylactic Acid ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Escherichia Coli O157 ◽  
Methicillin Resistant ◽  
E Coli

Introducción. Las nanopartículas poliméricas constituyen una herramienta nanotecnológica que podría ayudar a combatir los microorganismos patógenos que han desarrollado resistencia a los antibióticos convencionales.Objetivo. Sintetizar nanopartículas de ácido poliláctico cargadas con ofloxacina y vancomicina, y determinar su actividad antibacteriana frente a Escherichia coli O157:H7 y Staphylococcus aureus resistente a la meticilina (SARM).Materiales y métodos. Las nanopartículas de ácido poliláctico cargadas con ofloxacina y vancomicina se sintetizaron utilizando el método de emulsión y evaporación de solvente. Se caracterizaron mediante dispersión de luz en modo dinámico, electroforesis Doppler con láser y microscopía electrónica de barrido (S-TEM). Se evaluó la actividad antibacteriana in vitro de las nanopartículas de ácido poliláctico con ofloxacina contra E. coli O157:H7 y nanopartículas de ácido poliláctico con vancomicina contra SARM, mediante el método de microdilución en caldo.Resultados. Se obtuvieron nanopartículas poliméricas con tamaños inferiores a 379 nm y carga superficial positiva de hasta 21 mV. Las nanopartículas cargadas con ofloxacina presentaron una concentración inhibitoria mínima (CIM50) de 0,001 μg/ml frente a E. coli O157:H7, valor 40 veces menor que la concentración de antibiótico libre necesaria para lograr el mismo efecto (CIM50=0,04 μg/ml). Para SARM, las nanopartículas mejoraron la potencia farmacológica in vitro de la vancomicina alexhibir una MIC50 de 0,005 μg/ml, comparada con la de 0,5 μg/ml del antibiótico libre.Conclusiones. Se mejoró el efecto antibacteriano de la ofloxacina y la vancomicina incorporadas en la matriz polimérica de ácido poliláctico. Las nanopartículas poliméricas constituirían una alternativa para el control de cepas bacterianas de interés en salud pública.

scholarly journals Contribution and Interaction of Shiga Toxin Genes to Escherichia coli O157:H7 Virulence

Toxins ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 607 ◽  
Author(s):  
Gillian A.M. Tarr ◽  
Taryn Stokowski ◽  
Smriti Shringi ◽  
Phillip I. Tarr ◽  
Stephen B. Freedman ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Population Level ◽  
Escherichia Coli O157 ◽  
Additive Interaction ◽  
Shiga Toxins ◽  
E Coli ◽  
Uremic Syndrome ◽  
Shiga Toxin Genes

Escherichia coli O157:H7 is the predominant cause of diarrhea-associated hemolytic uremic syndrome (HUS) worldwide. Its cardinal virulence traits are Shiga toxins, which are encoded by stx genes, the most common of which are stx1a, stx2a, and stx2c. The toxins these genes encode differ in their in vitro and experimental phenotypes, but the human population-level impact of these differences is poorly understood. Using Shiga toxin-encoding bacteriophage insertion typing and real-time polymerase chain reaction, we genotyped isolates from 936 E. coli O157:H7 cases and verified HUS status via chart review. We compared the HUS risk between isolates with stx2a and those with stx2a and another gene and estimated additive interaction of the stx genes. Adjusted for age and symptoms, the HUS incidence of E. coli O157:H7 containing stx2a alone was 4.4% greater (95% confidence interval (CI) −0.3%, 9.1%) than when it occurred with stx1a. When stx1a and stx2a occur together, the risk of HUS was 27.1% lower (95% CI −87.8%, −2.3%) than would be expected if interaction were not present. At the population level, temporal or geographic shifts toward these genotypes should be monitored, and stx genotype may be an important consideration in clinically predicting HUS among E. coli O157:H7 cases.

scholarly journals Long Polar Fimbriae Contribute to Colonization by Escherichia coli O157:H7 In Vivo

2004 ◽  
Vol 72 (10) ◽  
pp. 6168-6171 ◽  
Author(s):  
Dianna M. Jordan ◽  
Nancy Cornick ◽  
Alfredo G. Torres ◽  
Evelyn A. Dean-Nystrom ◽  
James B. Kaper ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Parent Strain ◽  
Escherichia Coli O157 ◽  
Intestinal Colonization ◽  
E Coli ◽  
Gnotobiotic Piglets

ABSTRACT The contribution of long polar fimbriae to intestinal colonization by Escherichia coli O157:H7 was evaluated in sheep, conventional pigs, and gnotobiotic piglets. E. coli O157:H7 strains with lpfA1 and lpfA2 mutated were recovered in significantly lower numbers and caused fewer attachment and effacement lesions than the parent strain.

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