Exoproducts of the Escherichia coli strain H22 inhibiting some enteric pathogens both in vitro and in vivo

A spontaneous mutant of Escherichia coli (strain AB2847), selected for resistance to the aminoglycoside antibiotic neamine, shows severe restriction of amber suppressors in vivo. Ribosomes isolated from the mutant exhibit only low misreading in vitro in the presence of the antibiotic. Genetic and biochemical analyses indicate that the neamine-resistant phenotype is the result of two distinct mutations. The first, res3128, appears to affect the gene (strA) coding for the ribosomal protein S12. Although it leads to a restrictive phenotype it does not, however, confer resistance to streptomycin. The second mutation, X3128, is located between the sirA and AROB loci and is lethal when segregated from the res3128 mutation. It may affect the ribosome at the level of a post-translational modification.

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Ciprofloxacin Treatment Failure in a Murine Model of Pyelonephritis Due to an AAC(6′)-Ib-cr-Producing Escherichia coli Strain Susceptible to CiprofloxacinIn Vitro

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01489-13 ◽

2013 ◽

Vol 57 (12) ◽

pp. 5830-5835 ◽

Cited By ~ 25

Author(s):

T. Guillard ◽

E. Cambau ◽

F. Chau ◽

L. Massias ◽

C. de Champs ◽

...

Keyword(s):

Escherichia Coli ◽

Murine Model ◽

Resistance Mechanism ◽

Bacterial Count ◽

Coli Strain ◽

Content Type ◽

E Coli ◽

Fixed Concentration

ABSTRACTAAC(6′)-Ib-cr is a plasmid-mediated quinolone resistance mechanism described worldwide forEscherichia coli. Since it confersin vitroonly a low level of resistance to ciprofloxacin, we evaluated its impact on thein vivoactivity of ciprofloxacin. Isogenic strains were obtained by transferring plasmid p449, harboringaac(6′)-Ib-cr, into the quinolone-susceptible strainE. coliCFT073-RR and its D87GgyrAmutant. MICs were 0.015, 0.06, 0.25, and 0.5 μg/ml againstE. colistrains CFT073-RR, CFT073-RR/p449, CFT073-RR GyrAr, and CFT073-RR GyrAr/p449, respectively. Bactericidal activity was reduced at 1× the MIC for the three resistant derivatives, while at a fixed concentration of 0.5 μg/ml, 99.9% killing was observed for all strains exceptE. coliCFT073-RR GyrAr/p449. In the murine model of pyelonephritis, an optimal regimen of ciprofloxacin (10 mg/kg of body weight twice a day [b.i.d.]) significantly decreased the bacterial count in the kidneys of mice infected withE. coliCFT073 (1.6 versus 4.3 log10CFU/g of kidney compared to untreated controls;P= 0.0001), while no significant decrease was observed forE. coliCFT073-RR/p449 (2.7 versus 3.1 log10CFU/g;P= 0.84),E. coliCFT073-RR GyrAr(4.2 versus 4.1 log10CFU/g;P= 0.35), orE. coliCFT073-RR GyrAr/p449 (2.9 versus 3.6 log10CFU/g;P= 0.47). While pharmacokinetic and pharmacodynamic (PK/PD) parameters accounted for ciprofloxacin failure againstgyrA-containing mutants, this was not the case for theaac(6′)-Ib-cr-containing strains, suggesting anin situhydrolysis of ciprofloxacin in the latter case.

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No genotoxicity is detectable for Escherichia coli strain Nissle 1917 by standard in vitro and in vivo tests

European Journal of Microbiology and Immunology ◽

10.1556/1886.2019.00025 ◽

2020 ◽

Vol 10 (1) ◽

pp. 11-19

Author(s):

Silke Dubbert ◽

Birgit Klinkert ◽

Michael Schimiczek ◽

Trudy M. Wassenaar ◽

Rudolf von Bünau

Keyword(s):

Escherichia Coli ◽

Ames Test ◽

Mutagenic Activity ◽

Dna Strand Breaks ◽

Coli Strain ◽

Strand Breaks ◽

Genotoxic Potential ◽

Dna Strand

Probiotic Escherichia coli strain Nissle 1917 (EcN) has a long history of safe use. However, the recently discovered presence of a pks locus in its genome presumably producing colibactin has questioned its safety, as colibactin has been implicated in genotoxicity. Here, we assess the genotoxic potential of EcN. Metabolic products were tested in vitro by the Ames test, a mutagenicity assay developed to detect point mutation-inducing activity. Live EcN were tested by an adapted Ames test. Neither the standard nor the adapted Ames test resulted in increased numbers of revertant colonies, indicating that EcN metabolites or viable cells lacked mutagenic activity. The in vivo Mammalian Alkaline Comet Assay (the gold standard for detecting DNA-strand breaks) was used to determine potentially induced DNA-strand breaks in cells of the gastro-intestinal tract of rats orally administered with viable EcN. Bacteria were given at 109–1011 colony forming units (CFU) per animal by oral gavage on 2 consecutive days and daily for a period of 28 days to 5 rats per group. No significant differences compared to negative controls were found. These results demonstrate that EcN does not induce DNA-strand breaks and does not have any detectable genotoxic potential in the test animals.

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Antioxidants capabilities in correction of gentamicin-induced nephrotoxicity in experimental infection

Kazan medical journal ◽

10.17750/kmj2015-572 ◽

2016 ◽

Vol 97 (4) ◽

pp. 572-578 ◽

Cited By ~ 1

Author(s):

A G Miroshnichenko ◽

V M Brukhanov ◽

I Ye Gossen ◽

V Yu Perfilyev

Keyword(s):

Escherichia Coli ◽

Ascorbic Acid ◽

Klebsiella Pneumoniae ◽

Optical Density ◽

Experimental Infection ◽

Coli Strain ◽

Bacterial Suspension ◽

Bacterial Peritonitis

Aim. To assess the antioxidants effectiveness (ascorbic acid, methylethylpiridinol, N-acetylcysteine) in reducing the gentamicin-induced nephrotoxicity in experimental infection caused by Escherichia coli or Klebsiella pneumoniae.Methods. The experiment was divided into two parts. In the first part, the effect of antioxidants on the sensitivity of bacteria to gentamicin in vitro according to changing the optical density of the bacterial suspension, in the second part - nephroprotective activity of antioxidants and their effects on antibiotic activity in experimental bacterial peritonitis were evaluated.Results. All antioxidants significantly reduce the sensitivity of E. coli to gentamicin in vitro, and the level of effect is directly proportional to the antioxidant concentration. Methylethylpiridinol has the most pronounced antagonistic action against gentamicin. It is found that methylethylpiridinol at a concentration of 4 mmol/l enhances development of Escherichia coli strain by 7 times by the 6th hour of incubation. Ascorbic acid and N-acetylcysteine have a similar probacterial activity profile. In the incubation mixtures containing a strain of Klebsiella pneumoniae, a similar pattern of increase in bacterial biomass optical density was observed with maximum values in the presence of the highest concentrations of antioxidants. In experimental infection, antioxidants reduce the activity of gentamicin against Escherichia coli and Klebsiella pneumoniae, without reducing the antibiotic nephrotoxicity.Conclusion. Ascorbic acid, methylethylpiridinol and N-acetylcysteine reduce the antibacterial activity of gentamicin against Escherichia coli and Klebsiella pneumoniae in vitro and in vivo, in a dose of 80 mg/kg they do not reduce gentamicin nephrotoxicity in bacterial peritonitis in rats; their use in the course of treatment with gentamicin is not only irrational, but also contraindicated.

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Determinants of activity in glutaredoxins: an in vitro evolved Grx1-like variant of Escherichia coli Grx3

Biochemical Journal ◽

10.1042/bj20100289 ◽

2010 ◽

Vol 430 (3) ◽

pp. 487-495 ◽

Cited By ~ 4

Author(s):

Tobias H. Elgán ◽

Anne-Gaëlle Planson ◽

Jon Beckwith ◽

Peter Güntert ◽

Kurt D. Berndt

Keyword(s):

Escherichia Coli ◽

Quantum Coherence ◽

Structural Changes ◽

Dynamic Properties ◽

Coli Strain ◽

Structural Basis ◽

Genes Encoding ◽

Hydrogen Deuterium

The Escherichia coli glutaredoxins 1 and 3 (Grx1 and Grx3) are structurally similar (37% sequence identity), yet have different activities in vivo. Unlike Grx3, Grx1 efficiently reduces protein disulfides in proteins such as RR (ribonucleotide reductase), whereas it is poor at reducing S-glutathionylated proteins. An E. coli strain lacking genes encoding thioredoxins 1 and 2 and Grx1 is not viable on either rich or minimal medium; however, a M43V mutation in Grx3 restores growth under these conditions and results in a Grx1-like protein [Ortenberg, Gon, Porat and Beckwith (2004) Proc. Natl. Acad. Sci. U.S.A. 101, 7439–7944]. To uncover the structural basis of this change in activity, we have compared wild-type and mutant Grx3 using CD and NMR spectroscopy. Ligand-induced stability measurements demonstrate that the Grx3(M43V/C65Y) mutant has acquired affinity for RR. Far-UV CD spectra reveal no significant differences, but differences are observed in the near-UV region indicative of tertiary structural changes. NMR 1H-15N HSQC (heteronuclear single quantum coherence) spectra show that approximately half of the 82 residues experience significant (Δδ>0.03 p.p.m.) chemical shift deviations in the mutant, including nine residues experiencing extensive (Δδ≥0.15 p.p.m.) deviations. To test whether the M43V mutation alters dynamic properties of Grx3, H/D (hydrogen/deuterium) exchange experiments were performed demonstrating that the rate at which backbone amides exchange protons with the solvent is dramatically enhanced in the mutant, particularly in the core of the protein. These data suggest that the Grx1-like activity of the Grx3(M43V/C65Y) mutant may be explained by enhanced intrinsic motion allowing for increased specificity towards larger substrates such as RR.

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Безопасность соединений из группы терпенов ментанового ряда in vitro и in vivo

Экспериментальная и клиническая фармакология ◽

10.30906/0869-2092-2020-83-4-24-30 ◽

2020 ◽

Vol 83 (4) ◽

pp. 24-30

Author(s):

Ирина Владимировна Акулина ◽

Светлана Ивановна Павлова ◽

Ирина Семеновна Степаненко ◽

Назира Сунагатовна Карамова ◽

Александр Владиславович Сергеев ◽

...

Keyword(s):

Escherichia Coli

Проведено токсикологическое исследование соединений с антибактериальными свойствами из группы терпенов ментанового ряда в условиях in vitro и in vivo: лимонена (B34), его производного (+)-1,2-оксида лимонена (B60) и серосодержащего монотерпенового соединения 2-(1’-гидрокси-4’-изопренил-1’-метилциклогексил-2’-тио)метилэтаноата (B65). В условиях in vitro (культура опухолевых клеток HeLa) изучаемые монотерпены в диапазоне концентраций 2 – 200 мкг/мл обладали цитотоксичностью. Ингибирующая концентрация (ИК50) для B34 составила 231 (167 – 295) мкг/мл, для B60 – 181 (105 – 257) мкг/мл, ИК50 B65 – 229 (150 – 308) мкг/мл. Исследование генотоксичности показало, что B34 и B65 в диапазоне концентраций 50 – 1000 мкг/мл не индуцируют SOS мутагенез в клетках Escherichia coli PQ37, тогда как B60 в концентрациях 500 и 1000 мкг/мл проявляет генотоксичность. In vivo в остром эксперименте на беспородных мышах установлена низкая токсичность B34 и его производных при различных путях введения. Наименьший показатель острой токсичности имеет B65, в связи с чем дополнительно на крысах проведено изучение его хронической токсичности. Ежедневное внутрижелудочное введение B65 в разовых дозах, составляющих 1/10 и 1/20 ЛД50 (1000 мг/кг и 500 мг/кг), в течение 1 мес не вызывало гибели животных, значимых нарушений общего состояния, изменения динамики массы тела, морфопатологических изменений. Внутрижелудочное введение B65 крысам в высокой токсической дозе 2000 мг/кг (1/5 ЛД50) в течение месяца вызывает патоморфологические изменения структуры печени.

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Low endotoxin E. coli strain-derived plasmids reduced rAAV vector-mediated immune responses both in vitro and in vivo.

Molecular Therapy — Methods & Clinical Development ◽

10.1016/j.omtm.2021.06.009 ◽

2021 ◽

Author(s):

Qingyun Zheng ◽

Tianyi Wang ◽

Xiangying Zhu ◽

Xiao Tian ◽

Chen Zhong ◽

...

Keyword(s):

Immune Responses ◽

Coli Strain ◽

Raav Vector ◽

E Coli

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Antagonism of Ultraviolet-Light Mutagenesis by the Methyl-Directed Mismatch-Repair System of Escherichia coli

Genetics ◽

10.1093/genetics/154.2.503 ◽

2000 ◽

Vol 154 (2) ◽

pp. 503-512 ◽

Cited By ~ 1

Author(s):

Hongbo Liu ◽

Stephen R Hewitt ◽

John B Hays

Keyword(s):

Escherichia Coli ◽

Mismatch Repair ◽

Excision Repair ◽

Spontaneous Mutation ◽

Repair System ◽

Uv Mutagenesis ◽

Repair Protein ◽

Mismatch Repair System

Abstract Previous studies have demonstrated that the Escherichia coli MutHLS mismatch-repair system can process UV-irradiated DNA in vivo and that the human MSH2·MSH6 mismatch-repair protein binds more strongly in vitro to photoproduct/base mismatches than to “matched” photoproducts in DNA. We tested the hypothesis that mismatch repair directed against incorrect bases opposite photoproducts might reduce UV mutagenesis, using two alleles at E. coli lacZ codon 461, which revert, respectively, via CCC → CTC and CTT → CTC transitions. F′ lacZ targets were mated from mut+ donors into mutH, mutL, or mutS recipients, once cells were at substantial densities, to minimize spontaneous mutation prior to irradiation. In umu+ mut+ recipients, a range of UV fluences induced lac+ revertant frequencies of 4–25 × 10−8; these frequencies were consistently 2-fold higher in mutH, mutL, or mutS recipients. Since this effect on mutation frequency was unaltered by an Mfd− defect, it appears not to involve transcription-coupled excision repair. In mut+ umuC122::Tn5 bacteria, UV mutagenesis (at 60 J/m2) was very low, but mutH or mutL or mutS mutations increased reversion of both lacZ alleles roughly 25-fold, to 5–10 × 10−8. Thus, at UV doses too low to induce SOS functions, such as Umu2′D, most incorrect bases opposite occasional photoproducts may be removed by mismatch repair, whereas in heavily irradiated (SOS-induced) cells, mismatch repair may only correct some photoproduct/base mismatches, so UV mutagenesis remains substantial.

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Exploring Galleria mellonella larval model to evaluate antibacterial efficacy of Cecropin A (1-7)- Melittin against multi-drug resistant enteroaggregative Escherichia coli

Pathogens and Disease ◽

10.1093/femspd/ftab010 ◽

2021 ◽

Author(s):

Jess Vergis ◽

S V S Malik ◽

Richa Pathak ◽

Manesh Kumar ◽

Nitin V Kurkure ◽

...

Keyword(s):

Escherichia Coli ◽

Galleria Mellonella ◽

In Vivo Model ◽

Drug Resistant ◽

Physiological Concentration ◽

Microbial Drug Resistance ◽

Cecropin A ◽

Screening And Identification

Abstract High throughput in vivo laboratory models is need for screening and identification of effective therapeutic agents to overcome microbial drug-resistance. This study was undertaken to evaluate in vivo antimicrobial efficacy of short-chain antimicrobial peptide- Cecropin A (1–7)-Melittin (CAMA) against three multi- drug resistant enteroaggregative Escherichia coli (MDR-EAEC) field isolates in a Galleria mellonella larval model. The minimum inhibitory concentration (MIC; 2.0 mg/L) and minimum bactericidal concentration (MBC; 4.0 mg/L) of CAMA were determined by microdilution assay. CAMA was found to be stable at high temperatures, physiological concentration of cationic salts and proteases; safe with sheep erythrocytes, secondary cell lines and commensal lactobacilli at lower MICs; and exhibited membrane permeabilisation. In vitro time-kill assay revealed concentration- and time-dependent clearance of MDR-EAEC in CAMA-treated groups at 30 min. CAMA- treated G. mellonella larvae exhibited an increased survival rate, reduced MDR-EAEC counts, immunomodulatory effect and proved non-toxic which concurred with histopathological findings. CAMA exhibited either an equal or better efficacy than the tested antibiotic control, meropenem. This study highlights the possibility of G. mellonella larvae as an excellent in vivo model for investigating the host-pathogen interaction, including the efficacy of antimicrobials against MDR-EAEC strains.

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