[Isolation of DNA-cytosine methyltransferases from E. coli B (RII), E. coli K12 and E. coli K12 (RII). Analysis of nucleotide sequences analyzed in vitro].
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Catalysis↗
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[DNA modification in vitro by E. coli C and E. coli MRE 600 DNA-cytosine-methyltransferases: increased resistance of bacteriophage λ DNA to the RII restriction system].
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Coliphages↗
[Sensitivity and repair of the DNA-membrane complexes of E. coli and B/r E. coli B/s-1 bacteria irradiated with gamma-quanta].
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DNA Repair↗
Treatment of infantile E. coli gastroenteritis with specific bovine anti-E. coli milk immunoglobulins.
A milk immunoglobulin concentrate (MIC) containing antibodies to enteropathogenic E. coli strains was prepared by hyperimmunisation of pregnant cows and using the milk obtained during the first 6 to 8 days of lactation. The sterile concentrate contained 70 to 80% protein and 35 to 40% immunoglobulin. The antibacterial activity was measured by bacterial passive agglutination, bacteriostatic activity in vitro, phagocytic clearance in vivo, and a protection test in mice. Though differences in titers were observed, adequate immunologic activity was demonstrated by these tests. Clinical studies were performed with 60 patients (aged 10 days to 18 months) suffering from diarrhoea with isolation of enteropathogenic E. coli. They were treated for 10 days with MIC and stool cultures were done prior to, during, and 2, 3 and 4 days after termination of treatment. Among 51 patients infected with E. coli strains incorporated in the vaccine, stool cultures became negative in 43 (84.3%) after treatment with MIC and 8 remained positive. Nine patients infected with strains O 78:K80(B-) and O 114:K--(B-)--which were not included in the vaccine used for immunisation--served as controls. Only one patient in this group became negative. If all patients receiving antibiotics for non intestinal infections during the treatment period are omitted the results remained unaltered: MIC was effective in 32 out of 38 patients (84.2%). These differences were highly significant. These results provide evidence that treatment with specific MIC is effective in eliminating enteropathogenic E. coli from the intestine.
Animals↗
Affinity labelling of phenylalanyl-tRNA synthetase from E. coli MRE-600 by E. coli tRNAphe containing photoreactive group.
The photoinduced reaction of phenylalanyl-tRNA synthetase (E.C.6.1.1.20) from E.coli MRE-600 with tRNAphe containing photoreative p-N3-C6H4-NHCOCH2-group attached to 4-thiouridine sU8 (azido-tRNAphe) was investigated. The attachment of this group does not influence the dissociation constant of the complex of Phe-tRNAphe with the enzyme, however it results in sevenfold increase of Km in the enzymatic aminoacylation of tRNAphe. Under irradiation at 300 nm at pH 5.8 the covalent binding of [14C]-Phe-azido-tRNAphe to the enzyme takes place 0.3 moles of the reagent being attached per mole of the enzyme. tRNA prevents the reaction. Phenylalanine, ATP,ADP,AMP, adenosine and pyrophosphate (2.5 xx 10(-3) M) don't affect neither the stability of the tRNA-enzyme complex nor the rate of the affinity labelling. The presence of the mixture of either phenylalanine or phenylalaninol with ATP as well as phenylalaninol adenylate exhibits 50% inhibition of the photoinduced reaction. Therefore, the reaction of [14C]-Phe-azido-tRNA with the enzyme is significantly less sensitive to the presence of the ligands than the reaction of chlorambucilyl-tRNA with the reactive group attached to the acceptor end of the tRNA studied in 1. It has been concluded that the kinetics of the affinity labelling does permit to discriminate the influence of the low molecular weight ligands of the enzyme on the different sites of the tRNA enzyme interaction.
Adenine Nucleotides↗
[Flagellar antigens of E. coli serologically interrlelated to H40, 41 and H41, 42, 43 flagellar antigens of Citrobacter. New H-antigeny E. coli i Citrobacter].
The authors confirmed the reference of the test strains H13 (P6c) and H22 (A231a) of the international collection of E. coli to Citrobacter; their antigenic formula was established. As shown, strains P6c possessed a variety of the H-antigen which was not described in Citrobacter earlier, designated as H41a, 97. Three types of flagellar antigens characterized by the presence of an interrelationship with the partial factor H41 of the flagellar Citrobacter antigens were revealed in E. coli; the partial composition of H-antigenic components common for E. coli and Citrobacter was studied. Two of three new varieties of the E. coli H-antigen revealed was characterized by a cross correlation and a relation to the standard H19 E. coli antigen. The strain with the third variety of the H-antigen was capable of forming the H-antigenic mutants which acquired the antigenic component identical to the standard H16 E. coli antigen. E. coli strain is recommended for the replacement of the strain P6c in the International collection of E. coli.
Agglutinins↗
On the process of cellular division in Escherichia coli: a mutant of E. coli lacking a murein-lipoprotein.
A mutant of E. coli lacking a specific outer membrane lipoprotein was found. Both the free and the bound form have been lost in this mutant. No material that cross-reacted with antiserum against lipoprotein was detected by the Ouchterlony test. The mutant was defective in producing mRNA active for lipoprotein synthesis. The mutation leading to the loss of lipoprotein synthesis, referred to as lpo, seems to have arisen during production of an F'. The map position of lpo was at 36.5 min on the E. coli K12 map, in the order man, uidA, lpo, aroD, pps. The lpo mutant grew and divided normally and remained susceptible to bacteriophages lambda, phi80, P1, P2, the T series, and f1, f2, and MS2 in its male derivatives. The mutant was hypersensitive to EDTA and cationic dves and somewhat sensitive to detergents. There was considerable leakage of periplasmic enzymes but passive transport of beta-galactoside was unchanged. These physiological characteristics of the mutant suggest that lipoprotein is involved in maintaining the integrity of the outer envelope structure, by bridging the outer membrane and murein, but not in the vital processes of growth and division.
Cell Division↗
Enterotoxigenic E. coli in humans.
E. coli strains isolated from persons having diarrhoeal disease were tested for the production of TS enterotoxin. The production of TSE was demonstrated in 2.5% in a series of 80 strains isolated from children under one year of age, having acute diarrhoea. TSE was produced by 8.4% of E. coli strains out of 59 strains isolated from patients over one year of age. Among these strains, an interesting E. coli strain was isolated from the patient T. J., which produced TSE for more than 15 months. The production of TLE was tested though not proved in all strains by experiment on an isolated intestinal loop of an adult rabbit. The test on suckling mice so far appears to be the most suitable test for the demonstration of TSE. The results were considered positive when the index (the ratio of the weight of the whole intestine to the weight of the rest of the body) was higher than 0.08 while indices up to 0.078 were considered negative. E. coli strains with indices of intermediate values and strains with temporary production of TSE, occurring particularly in very small children, deserve special attention. The height of the indices was not influenced by a 30-minute exposure at 60 degrees C, but a decrease in the values of the indices was observed after boiling for a period of 15 min. The occurrence of E. coli strains producing TSE is evidently small in humans in European countries but, without doubt, they are important in the aetiology of diarrhoeal diseases.
Animals↗
Fever produced in the rat by intracerebral E. coli endotoxin.
E. coli endotoxin introduced into the brain ventricles or into various brain areas raises the body temperature of conscious rats. Endotoxin-sensitive sites were found within the anterior hypothalamus and the lower brainstem. The increase in temperature (delta T) after microinjection of endotoxin into the anterior hypothalamic nucleus was dose-dependent. Endotoxin injected into the ventricles produced monophasic hyperthermia, but microinjections into the anterior hypothalamus produced monophasic or biphasic types of hyperthermia. The second and third microinjections of endotoxin into the anterior hypothalamic nucleus subsequently caused higher responses in delta T, but not in the rate of temperature change. The effects of the fourth and furter microinjections were the same as those of the third, and no tolerance developed for 24 days. The observations of behaviour, vegetative reactions, skin temperature, and carbon dioxide production indicated that the rise in the rat body temperature induced by endotoxin represents fever and that the heat is gained, at an ambient temperature of 22 degrees C, mainly through skin vessel vasoconstriction. Aspirin abolished and reversed fever induced by endotoxin, while hydrocortisone was without effect.
Animals↗
Large-scale genome analysis of bovine commensal Escherichia coli reveals that bovine-adapted E. coli lineages are serving as evolutionary sources of the emergence of human intestinal pathogenic strains.
How pathogens evolve their virulence to humans in nature is a scientific issue of great medical and biological importance. Shiga toxin (Stx)-producing Escherichia coli (STEC) and enteropathogenic E. coli (EPEC) are the major foodborne pathogens that can cause hemolytic uremic syndrome and infantile diarrhea, respectively. The locus of enterocyte effacement (LEE)-encoded type 3 secretion system (T3SS) is the major virulence determinant of EPEC and is also possessed by major STEC lineages. Cattle are thought to be the primary reservoir of STEC and EPEC. However, genome sequences of bovine commensal E. coli are limited, and the emerging process of STEC and EPEC is largely unknown. Here, we performed a large-scale genomic comparison of bovine commensal E. coli with human commensal and clinical strains, including EPEC and STEC, at a global level. The analyses identified two distinct lineages, in which bovine and human commensal strains are enriched, respectively, and revealed that STEC and EPEC strains have emerged in multiple sublineages of the bovine-associated lineage. In addition to the bovine-associated lineage-specific genes, including fimbriae, capsule, and nutrition utilization genes, specific virulence gene communities have been accumulated in stx- and LEE-positive strains, respectively, with notable overlaps of community members. Functional associations of these genes probably confer benefits to these E. coli strains in inhabiting and/or adapting to the bovine intestinal environment and drive their evolution to highly virulent human pathogens under the bovine-adapted genetic background. Our data highlight the importance of large-scale genome sequencing of animal strains in the studies of zoonotic pathogens.
Animals↗
Scanning electron microscopy of abomasium and intestine of gnotoxenic calves infected either with rotavirus, coronarivus or enteropathogenic Escherichia coli or with rotavirus and E. coli.
Neonatal calf diarrhoea induced with several agents of infection was studied by scanning electron microscopy. In a gnotoxenic calf infected with E. coli K99+ Ent+, slight lesions of the small intestine were observed and desquamation or puffiness of microvilli occurred. In rotavirus-infected calves, the abomasum was covered with abudant mucous film and appeared to be desquamated. In the small intestine, no desquamation of epithelium was observed. Inoculation of the rotavirus and E. coli induced severe diarrhoea. The whole digestive tract, even the abomasum and colon, was eroded. Coronavirus induced marked lesions in all levels of the intestine. These results demonstrate unequivocally the pathogenic properties of the three infectious agnets, the synergistic effect of E. coli and rotavirus. Furthermore, the importance of the abomasum in neonatal diarrhoea is emphasized.
Abomasum↗
Cascade control of E. coli glutamine synthetase. I. Studies on the uridylyl transferase and uridylyl removing enzyme(s) from E. coli.
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Bacterial Proteins↗
[Dynamics of biologically active enterotoxin release by E. coli].
Accumulation of E. coli enterotoxin in the Finkelshtein's culture medium in growing the cells in a 30-litre reactor was studied. Accumulation of active highly molecular enterotoxin occurred in the course of a 6-hour cultivation of E. coli, strain P-99 (O141: K85ab; K88ab: H4) in the fluid medium under aeration. Oxygen utilization, synthesis and release into the nutrient medium of pyruvic acid, and protein accumulation were observed. The preparation obtained was stable to the lyophylic drying, contained thermolabile and thermostable toxins and marked edema of mouse limbs. The data obtained were of significance for the industrial production of active enterotoxin preparations.
Bacterial Proteins↗
Site-specific cleavage of DNA by E. coli DNA gyrase.
E. coli DNA gyrase, which catalyzes the supercoiling of DNA, cleaves DNA site-specifically when oxolinic acid and sodium dodecylsulfate are added to the reaction. We studied the structure of the gyrasecleaved DNA because of its implications for the reaction mechanism and biological role of gyrase. Gyrase made a staggered cut, creating DNA termini with a free 3' hydroxyl and a 5' extension that provided a template primer for DNA polymerase. The cleaved DNA was resistant to labeling with T4 polynucleotide kinase even after treatment with proteinase K. Thus the denatured enzyme that remains attached to cleaved DNA is covalently bonded to both 5' terminal extensions. The 5' extensions of many gyrase cleavage fragments from phi X174, SV40 and Col E1 DNA were partially sequenced using repair with E. coli DNA polymerase I. No unique sequence existed within the cohesive ends, but G was the predominant first base incorporated by DNA polymerase I. The cohesive and sequences of four gyrase sites were determined, and they demonstrated a four base 5' extension. The dinucleotide TG, straddling the gyrase cut on one DNA strand, provided the only common bases within a 100 bp region surrounding the cleavage sites. Analysis of other cleavage fragments showed that cutting between a TG doublet is common to most, or all, gyrase cleavages. Other bases common to some of the sequenced sites were clustered nonrandomly around the TG doublet, and may be variable components of the cleavage sequence. This diverse recognition sequence with common elements is a pattern shared with several other specific nucleic acid-protein interactions.
Base Sequence↗
Occurrence of antibiotic-resistant E. coli and antibiotic resistance genes from culturable bacteria in drinking water sources along the Upper Mahaweli River, Sri Lanka.
Antibiotic-resistant Escherichia coli (AR-E. coli) and antibiotic resistance genes (ARGs) in aquatic environments pose a serious threat to public health. However, their presence in river water in South Asian countries is not well established. The present study investigated AR-E. coli and ARGs from culturable bacteria in drinking water sources from 14 drinking water treatment plants situated along the Upper Mahaweli River, a tropical central hill-country river system in Sri Lanka. A total of 167 E. coli isolates were tested against ten antibiotics using the Kirby-Bauer method, and genomic DNA from culturable bacteria in 45 water samples were screened for 11 ARGs using PCR. Overall, 60.48% E. coli isolates exhibited resistance to at least one antibiotic and multidrug resistance was detected in 27.54%. Highest resistance was for amoxicillin (47.31%), tetracycline (26.95%), and co-trimoxazole (24.55%) and four antibiotics showed seasonal variation. ARGs, dominated by blaTEM (80.0%), tetA (66.67%), and tetM and qnrS (62.22%) were detected in 42.42% PCR assays (n = 210). Multiple antibiotic resistance index varied from 0.00 to 0.80, with 44.91% exceeding the 0.2 threshold value, and the antibiotic resistance index varied from 0.00 to 0.32, with eight above the threshold (≥ 0.2). Hierarchical cluster analysis grouped majority of drinking water sources into the intermediate category while few were categorized under low (Kotagala and Thalawakelle-Galkanda) and high (Haragama, Paradeka, and Nawalapitiya), reflecting the variability of anthropogenic interference. Results highlight the risk associated with AR-E. coli and ARGs from culturable bacteria in one of Sri Lanka's key drinking water sources. Proactive interventions ensuring long-term safety of drinking water sources are urgently needed to safeguard public health.
Sri Lanka↗
Simultaneous detection of salmonellae, Escherichia coli type I (E. coli) and other enterobacteriaceae in dehydrated foods for infants and children.
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Child, Preschool↗
Interaction of membrane aminophospholipids of E. coli with fluorodinitrobenzene and trinitrobenzenesulfonate.
E. coli cells were reacted with TNBS in bicarbonate-NaCl buffer, pH 8.5 (buffer A) and in phosphate-NaCl buffer, pH 7.0 (buffer B). In buffer A, DNP-GPE is the major product when FDNB is used. DNP-PE and DNP-LPE are formed in lesser amounts. Phospholipase A activity is high in buffer A. When TNBS is used, the labeling of the lipid components is less than with FDNB and more TNP-PE is formed relative to TNP-GPE. This data suggests that the phospholipases which are located primarily on the outer L-membrane of the cell wall act to a lesser extent on TNP-PE than on DNP-PE. E. coli cells were prelabeled with TNBS and FDNB in buffer A, washed and incubated in buffer A. The endogenous labeled DNP-PE gradually decreased with time with a concomitant increase in DNP-LPE and DNP-GPE due to phospholipase A activity. In contrast, the endogenous labeled TNP-PE also decreased with time as did the endogenous labeled TNP-LPE but a new orange lipid was produced. This lipid is believed to be a derivative of TNP-PE in which one of the nitro groups has been reduced to an amino group by nitroreductase. E. coli cells were prelabeled with TNBS and FDNB in buffer A, washed and incubated in buffer B. Under these conditions with both TNBS and FDNB there is an increase in TNP-PE and DNP-PE with a concomitant decrease in TNP-LPE, TNP-GPE, DNP-LPE and DNP-GPE. These results show that at neutral pH acylation occurs to regenerate TNP-PE and DNP-PE. E. coli cells were incubated with exogenous DNP-GPE or TNP-GPE in buffer A. The DNP-GPE and TNP-GPE were rapidly hydrolyzed by a phosphodiesterase to DNP-ethanolamine and TNP-ethanolamine. An orange derivative was formed which was provisionally identified as a derivative of DNP-ethanolamine or TNP-ethanolamine in which a nitro group has been reduced to an amino group by nitroreductase. The phospholipases and acylating enzymes present in the cell wall of E. coli are active on the dinitrophenyl and trinitrophenyl derivatives of PE and LPE and may act in concert to model and repair the plasma membrane.
Binding Sites↗
Investigating the zoonotic origins of ESBL-producing E. coli in community-acquired urinary tract infections in Ecuador.
Extended-spectrum β-lactamase-producing Escherichia coli (ESBL-producing E. coli) pose a growing global health threat. Although Latin America has been identified as a global hotspot of antimicrobial resistance, the zoonotic contribution to drug-resistant infections in the region remains poorly defined. We analyzed 137 clinical ESBL-producing E. coli isolates from urinary tract infections (UTIs) in Quito, Ecuador, applying a Bayesian latent class model informed by host-associated mobile genetic elements to estimate the fraction of infections attributable to food-animal sources. We estimated that 25.5% (35/137) of UTI isolates were putative zoonotic cases. This proportion rose to 42.5% after excluding ST131-H30, a human-associated pandemic lineage. Putative zoonotic isolates were enriched for animal-associated β-lactamase genes (e.g., blaTEM-1B, blaCTX-M-65), lacked human-associated markers such as blaOXA-1, and exhibited diverse antimicrobial resistance gene profiles resembling those observed among food-animal isolates. These isolates were also enriched for ColV-associated virulence genes typically linked to avian pathogenic E. coli. Putative zoonotic strains contributed substantially to third-generation cephalosporin-resistant UTIs in Quito, Ecuador, challenging assumptions derived from high-income settings that such infections are driven predominantly by human-to-human transmission. These findings highlight the importance of integrated One Health surveillance and mitigation, particularly in low- and middle-income countries where gaps in water, sanitation, and hygiene (WASH) may interact with antimicrobial use in food production to amplify antimicrobial resistance transmission.IMPORTANCEESBL-producing E. coli have rapidly emerged as a major global antimicrobial resistance threat. In Latin America, cephalosporins are commonly used in food-animal production, fueling the emergence of ESBL-producing E. coli. In low- and middle-income countries, excessive antimicrobial use driven by poorly regulated over-the-counter sales, combined with inadequate water, sanitation, and hygiene (WASH) infrastructure, can facilitate antimicrobial-resistant pathogen transmission from food animals to humans. Using a novel statistical-genomic approach, we found that over one in four cephalosporin-resistant UTIs in Quito, Ecuador, may be caused by E. coli strains originating from food animals. Our findings highlight the public health risks associated with antimicrobial use in food-animal production and the role of environmental and infrastructure-related vulnerabilities. As global demand for animal protein continues rising in middle-income countries, controlling zoonotic antimicrobial resistance transmission becomes increasingly urgent for protecting human health through integrated One Health strategies.
ESBL-producing E. coli↗