scholarly journals In vivotransfer of an R factor within the lower gastro-intestinal tract of sheep

1977 ◽  
Vol 79 (2) ◽  
pp. 259-268 ◽  
Author(s):  
M. G. Smith
Keyword(s):  
Antibiotic Treatment ◽  
Intestinal Tract ◽  
Host Cells ◽  
E Coli ◽  
Adult Sheep ◽  
Resistance Determinants ◽  
R Factor ◽  
Short Period ◽  
Gastro Intestinal Tract

SUMMARYThe transfer of an R factor from donorE. coliintroduced into the rumen of adult sheep to strains of the coliform microflora resident post rumen in the lower gastro-intestinal tract was found to be greatly increased when the animals were subjected to a short period of starvation (ca. 24–48 h). This also resulted in coliform organisms containing the resistance determinants of the R factor being excreted for much longer periods, sometimes for months afterwards. As no antibiotic treatment was given to the animals during these experiments, possession of the R factor should have conferred no selective advantages on the host cells and other plasmids could possibly be transferred similarlyin vivoin sheep or other ruminants and perhaps also within the gut of monogastric animals.

scholarly journals In vivotransfer of R factors betweenEscherichia colistrains inoculated into the rumen of sheep

1975 ◽  
Vol 75 (3) ◽  
pp. 363-370 ◽  
Author(s):  
M. G. Smith
Keyword(s):  
Population Density ◽  
Antibiotic Treatment ◽  
Intestinal Tract ◽  
Total Coliform ◽  
Starvation Period ◽  
Experimental Animals ◽  
E Coli ◽  
R Factor ◽  
R Factors

SUMMARYSubstantial transfer of R factors occurredin vivo, under certain conditions, in the rumen of adult sheep in the absence of any antibiotic treatment. A starvation period of 24–48 hr. was required to produce the conditions necessary, when even quite low inocula (ca. 103cells) of donor and recipientE. colicould grow within the rumen and reach a population density sufficient for transfer to take place. The results indicate that under the same conditions R factors may be transferred between organisms in the lower intestinal tract also. Without the starvation period, the inoculation of even massive numbers (1010cells) of the same organisms resulted in almost no detectable transfer.Some of the experimental animals on which a starvation period was imposed became carriers of either the inoculated recipientE. coli, or of R factor bearing coliforms, and these formed 1–10% of the total coliform population of the faeces for at least 6 weeks.

scholarly journals In Vitro and In Vivo Antibacterial Activities of a Novel Glycylcycline, the 9-t-Butylglycylamido Derivative of Minocycline (GAR-936)

1999 ◽  
Vol 43 (4) ◽  
pp. 738-744 ◽  
Author(s):  
P. J. Petersen ◽  
N. V. Jacobus ◽  
W. J. Weiss ◽  
P. E. Sum ◽  
R. T. Testa
Keyword(s):  
Anaerobic Bacteria ◽  
Tetracycline Resistance ◽  
Protective Effects ◽  
Gram Negative ◽  
E Coli ◽  
Resistance Determinants ◽  
Aerobic And Anaerobic ◽  
Ribosomal Protection

ABSTRACT The 9-t-butylglycylamido derivative of minocycline (TBG-MINO) is a recently synthesized member of a novel group of antibiotics, the glycylcyclines. This new derivative, like the first glycylcyclines, theN,N-dimethylglycylamido derivative of minocycline and 6-demethyl-6-deoxytetracycline, possesses activity against bacterial isolates containing the two major determinants responsible for tetracycline resistance: ribosomal protection and active efflux. The in vitro activities of TBG-MINO and the comparative agents were evaluated against strains with characterized tetracycline resistance as well as a spectrum of recent clinical aerobic and anaerobic gram-positive and gram-negative bacteria. TBG-MINO, with an MIC range of 0.25 to 0.5 μg/ml, showed good activity against strains expressing tet(M) (ribosomal protection), tet(A), tet(B),tet(C), tet(D), and tet(K) (efflux resistance determinants). TBG-MINO exhibited similar activity against methicillin-resistant Staphylococcus aureus (MRSA), penicillin-resistant streptococci, and vancomycin-resistant enterococci (MICs at which 90% of strains are inhibited, ≤0.5 μg/ml). TBG-MINO exhibited activity against a wide diversity of gram-negative aerobic and anaerobic bacteria, most of which were less susceptible to tetracycline and minocycline. The in vivo protective effects of TBG-MINO were examined against acute lethal infections in mice caused by Escherichia coli, S. aureus, andStreptococcus pneumoniae isolates. TBG-MINO, administered intravenously, demonstrated efficacy against infections caused byS. aureus including MRSA strains and strains containingtet(K) or tet(M) resistance determinants (median effective doses [ED50s], 0.79 to 2.3 mg/kg of body weight). TBG-MINO demonstrated efficacy against infections caused by tetracycline-sensitive E. coli strains as well asE. coli strains containing either tet(M) or the efflux determinant tet(A), tet(B), ortet(C) (ED50s, 1.5 to 3.5 mg/kg). Overall, TBG-MINO shows antibacterial activity against a wide spectrum of gram-positive and gram-negative aerobic and anaerobic bacteria including strains resistant to other chemotherapeutic agents. The in vivo protective effects, especially against infections caused by resistant bacteria, corresponded with the in vitro activity of TBG-MINO.

scholarly journals Magnesium Sensing Regulates Intestinal Colonization of Enterohemorrhagic Escherichia coli O157:H7

mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
Author(s):  
Yutao Liu ◽  
Runhua Han ◽  
Junyue Wang ◽  
Pan Yang ◽  
Fang Wang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Large Intestine ◽  
Intestinal Tract ◽  
Regulatory System ◽  
Regulatory Pathway ◽  
Content Type ◽  
E Coli ◽  
Low Magnesium ◽  
Enterocyte Effacement

ABSTRACT The large intestinal pathogen enterohemorrhagic Escherichia coli (EHEC) O157:H7 detects host cues to regulate virulence gene expression during colonization and infection. However, virulence regulatory mechanisms of EHEC O157:H7 in the human large intestine are not fully understood. Herein, we identified a virulence-regulating pathway where the PhoQ/PhoP two-component regulatory system senses low magnesium levels and signals to the O island 119-encoded Z4267 (LmiA; low magnesium-induced regulator A), directly activating loci of enterocyte effacement genes to promote EHEC O157:H7 adherence in the large intestine. Disruption of this pathway significantly decreased EHEC O157:H7 adherence in the mouse intestinal tract. Moreover, feeding mice a magnesium-rich diet significantly reduced EHEC O157:H7 adherence in vivo. This LmiA-mediated virulence regulatory pathway is also conserved among several EHEC and enteropathogenic E. coli serotypes; therefore, our findings support the use of magnesium as a dietary supplement and provide greater insights into the dietary cues that can prevent enteric infections. IMPORTANCE Sensing specific gut metabolites is an important strategy for inducing crucial virulence programs by enterohemorrhagic Escherichia coli (EHEC) O157:H7 during colonization and infection. Here, we identified a virulence-regulating pathway wherein the PhoQ/PhoP two-component regulatory system signals to the O island 119-encoded low magnesium-induced regulator A (LmiA), which, in turn, activates locus of enterocyte effacement (LEE) genes to promote EHEC O157:H7 adherence in the low-magnesium conditions of the large intestine. This regulatory pathway is widely present in a range of EHEC and enteropathogenic E. coli (EPEC) serotypes. Disruption of this pathway significantly decreased EHEC O157:H7 adherence in the mouse intestinal tract. Moreover, mice fed a magnesium-rich diet showed significantly reduced EHEC O157:H7 adherence in vivo, indicating that magnesium may help in preventing EHEC and EPEC infection in humans.

scholarly journals Selective enrichment of R−segregants as the main mechanism of ‘curing’ of the R factor by acridine dyes

1971 ◽  
Vol 17 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Masanosuke Yoshikawa
Keyword(s):  
Shigella Flexneri ◽  
Host Cells ◽  
Bacterial Strains ◽  
Initial Inoculum ◽  
Selective Enrichment ◽  
E Coli ◽  
R Factor ◽  
Acridine Dyes ◽  
Increased Sensitivity ◽  
R Factors

SUMMARYBy the use of appropriate strains ofEscherichia coli, Shigella flexneriandSalmonella typhimuriumwith and without an R factor, R100, the mechanism of ‘curing’ of R factor by acridine dyes was examined. This R factor was shown to confer increased sensitivity to acriflavine upon the host cells.E. colistrain W-3630, once infected with R100, has never been observed to segregate R−cells. When mixtures of R+and R−cells of this strain were grown in acriflavine broth, the proportion of R−cells increased and was also correlated with the proportion in the initial inoculum. Other bacterial strains carrying R100segregate R~ cells spontaneously. Growth tests starting with varying proportion of R+and R−cells of these strains in acriflavine broth also gave a marked correlation between the initial and final proportions of R−cells, and indicated that the main cause of ‘curing’ the R factor was the selective enrichment of R−segregants present in the initial inocula or arising spontaneously during growth of the R+culture. These results suggest that the mechanisms underlying the ‘curing’ of F and R factors are different. Tests with several acridine dyes gave results similar to those with acriflavine.

scholarly journals Role of F1C Fimbriae, Flagella, and Secreted Bacterial Components in the Inhibitory Effect of Probiotic Escherichia coli Nissle 1917 on Atypical Enteropathogenic E. coli Infection

2014 ◽  
Vol 82 (5) ◽  
pp. 1801-1812 ◽  
Author(s):  
Sylvia Kleta ◽  
Marcel Nordhoff ◽  
Karsten Tedin ◽  
Lothar H. Wieler ◽  
Rafal Kolenda ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Molecular Mechanisms ◽  
Inhibitory Effect ◽  
Host Cells ◽  
Single Infection ◽  
Content Type ◽  
E Coli ◽  
Initial Adhesion

ABSTRACTEnteropathogenicEscherichia coli(EPEC) is recognized as an important intestinal pathogen that frequently causes acute and persistent diarrhea in humans and animals. The use of probiotic bacteria to prevent diarrhea is gaining increasing interest. The probioticE. colistrain Nissle 1917 (EcN) is known to be effective in the treatment of several gastrointestinal disorders. While bothin vitroandin vivostudies have described strong inhibitory effects of EcN on enteropathogenic bacteria, including pathogenicE. coli, the underlying molecular mechanisms remain largely unknown. In this study, we examined the inhibitory effect of EcN on infections of porcine intestinal epithelial cells with atypical enteropathogenicE. coli(aEPEC) with respect to single infection steps, including adhesion, microcolony formation, and the attaching and effacing phenotype. We show that EcN drastically reduced the infection efficiencies of aEPEC by inhibiting bacterial adhesion and growth of microcolonies, but not the attaching and effacing of adherent bacteria. The inhibitory effect correlated with EcN adhesion capacities and was predominantly mediated by F1C fimbriae, but also by H1 flagella, which served as bridges between EcN cells. Furthermore, EcN seemed to interfere with the initial adhesion of aEPEC to host cells by secretion of inhibitory components. These components do not appear to be specific to EcN, but we propose that the strong adhesion capacities enable EcN to secrete sufficient local concentrations of the inhibitory factors. The results of this study are consistent with a mode of action whereby EcN inhibits secretion of virulence-associated proteins of EPEC, but not their expression.

scholarly journals A Review on the Anti-Inflammatory Activity of Pomegranate in the Gastrointestinal Tract

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Elisa Colombo ◽  
Enrico Sangiovanni ◽  
Mario Dell'Agli
Keyword(s):  
Gastrointestinal Tract ◽  
Clinical Studies ◽  
Intestinal Tract ◽  
Biological Activities ◽  
Inflammatory Activity ◽  
Beneficial Effects ◽  
Anti Inflammatory ◽  
Gastro Intestinal Tract ◽  
Inflammatory Effect

Several biological activities of pomegranate have been widely described in the literature, but the anti-inflammatory effect in the gastrointestinal tract has not been reviewed till now. The aim of the present paper is to summarize the evidence for or against the efficacy of pomegranate for coping with inflammatory conditions of the gastro-intestinal tract. The paper has been organized in three parts: (1) the first one is devoted to the modifications of pomegranate active compounds in the gastro-intestinal tract; (2) the second one considering the literature regarding the anti-inflammatory effect of pomegranate at gastric level; (3) the third part considers the anti-inflammatory effect of pomegranate in the gut.In vivostudies performed on the whole fruit or juice, peel, and flowers demonstrate antiulcer effect in a variety of animal models. Ellagic acid was the main responsible for this effect, although other individual ellagitannins could contribute to the biological activity of the mixture. Different preparations of pomegranate, including extracts from peels, flowers, seeds, and juice, show a significant anti-inflammatory activity in the gut. No clinical studies have been found, thus suggesting that future clinical studies are necessary to clarify the beneficial effects of pomegranate in the gastrointestinal tract.

scholarly journals How the colonic environment influences Enterohaemorrhagic E. coli outer membrane vesicle production, and the interaction between outer membrane vesicles with human host cells

2020 ◽  
Vol 2 (7A) ◽  
Author(s):  
Daniel Yara ◽  
Regis Stentz ◽  
Tom Wileman ◽  
Stephanie Schuller
Keyword(s):  
Outer Membrane ◽  
Bile Salts ◽  
Membrane Vesicle ◽  
Outer Membrane Proteins ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
T84 Cells ◽  
E Coli

Enterohaemorrhagic E. coli (EHEC) may instigate bloody diarrhoea and haemolytic uraemic syndrome (HUS) due to Shiga toxin (Stx) production. Stx has been detected within outer membrane vesicles (OMVs), which are membrane-derived nanosized proteoliposomes. During colonisation, EHEC encounters many environmental surroundings such as the presence of bile salts and carbon dioxide (CO2). Here, the influence of different intestinal cues on EHEC OMV production was studied. OMV yield was quantified by densitometric analysis of outer membrane proteins F/C and A, following OMV protein separation by SDS-PAGE. Compared to cultures in Luria broth, higher OMV yields were attained following culture in human cell growth medium and simulated colonic environmental medium, with further increases in the presence of bile salts. Interestingly, lower yields were attained in the presence of T84 cells and CO2. The interaction between OMVs and different human cells was also examined by fluorescence microscopy. Here, OMVs incubated with cells showed internalisation by semi confluent but not fully confluent T84 cell monolayers. OMVs were internalised into the lysosomes in confluent Vero and Caco-2 cells, with Stx being transported to the Golgi and then the Endoplasmic reticulum. OMVs were detected within polarised Caco-2 cells, with no impact on the transepithelial electrical resistance by 24 hours. These results suggest that the colonic environmental factors influences OMV production in vivo. Additionally, results highlight the discrepancies which arise when using different cells lines to examine the intestine. Nevertheless, coupled with Stx, OMVs may serve as tools of EHEC which are involved in HUS development.

scholarly journals Changes in the distribution of copper and molybdenum after Mo administration and subsequent additional oral or intraperitoneal Cu administration to rats

1982 ◽  
Vol 48 (2) ◽  
pp. 353-364 ◽  
Author(s):  
H. Nederbragt
Keyword(s):  
Intestinal Tract ◽  
Qualitative Difference ◽  
Inbred Rats ◽  
Liver And Kidney ◽  
A Minor ◽  
Gastro Intestinal Tract ◽  
Minor Extent

1. Male WAG/Cpb inbred rats fed on rations containing 1·5 mg copper/kg (deficient) and 6·0 mg Cu/kg (adequate) were supplemented with molybdenum (500 mg/kg diet). Starting at week 0 rats were killed weekly for up to 6 weeks and the caeruloplasmin activity of plasma, the Cu concentration of plasma, liver and kidney and the Mo concentration of liver and kidney were determined. The experiment was repeated with rats fed on diets of the same composition but given additional Cu for periods of 2 weeks. Cu was given orally by increasing dietary Cu to 6·0 mg/kg and 25·0 mg/kg for Cu-deficient and Cu-adequate rats respectively or intraperitoneally by injecting 75 μg and 250 μg every second day to Cu-deficient and Cu-adequate rats respectively.2. After Mo administration to Cu-deficient rats plasma and kidney Cu and liver and kidney Mo increased but caeruloplasmin activity and liver Cu decreased. In Cu-adequate rats plasma, liver and kidney Cu and liver and kidney Mo increased to much higher levels than in Cu-deficient rats. Caeruloplasmin activity was not affected. Fluctuations in plasma Cu and kidney Mo were correlated closely.3. No qualitative difference between the effect of oral or intraperitoneal Cu administered to Mo-treated Cu-deficient or Cu-adequate rats was found. In Cu-deficient Mo-supplemented rats additional Cu increased plasma Cu, caeruloplasmin activity and liver and kidney Cu and Mo. In Cu-adequate Mo-supplemented rats additional Cu decreased plasma Cu and liver and kidney Mo and increased caeruioplasmin activity and kidney Cu and, to a minor extent, liver Cu.4. In view of the assumption that in rats a Cu, Mo and S containing compound, related to Cu-thiomolybdate, may be formed in vivo the results suggest thai Cu binds to the Mo-S part of the compound; when this compound is formed in the gastro-intestinal tract it can not be absorbed and when it is formed at systemic sites it changes the Cu distribution.

scholarly journals Cell-free prediction of protein expression costs for growing cells

2017 ◽  
Author(s):  
Olivier Borkowski ◽  
Carlos Bricio ◽  
Michaela Murgiano ◽  
Guy-Bart Stan ◽  
Tom Ellis
Keyword(s):  
Gene Expression ◽  
Host Cells ◽  
Translation Efficiency ◽  
Heterologous Proteins ◽  
E Coli ◽  
Multiple Processes ◽  
Significant Burden ◽  
The Cost ◽  
The Relationship

Translating heterologous proteins places significant burden on host cells, consuming expression resources leading to slower cell growth and productivity. Yet predicting the cost of protein production for any gene is a major challenge, as multiple processes and factors determine translation efficiency. Here, to enable prediction of the cost of gene expression in bacteria, we describe a standard cell-free lysate assay that determines the relationship betweenin vivoand cell-free measurements and γ, a relative measure of the resource consumption when a given protein is expressed. When combined with a computational model of translation, this enables prediction of thein vivoburden placed on growingE. colicells for a variety of proteins of different functions and lengths. Using this approach, we can predict the burden of expressing multigene operons of different designs and differentiate between the fraction of burden related to gene expression compared to action of a metabolic pathway.

Sign in / Sign up

Export Citation Format

Share Document