tellurium and Escherichia-coli-Infections

The contamination of food and potable water with microorganisms may cause food-borne and water-borne diseases. The common contaminants include Escherichia coli (E. coli), Salmonella sp. etc. The conventional methods for monitoring the water quality for the presence of bacterial contaminants are time-consuming, expensive, and not suitable for rapid on-spot detection in field conditions. In the current study, super paramagnetic iron oxide nanoparticles (SPIONs) were synthesized and conjugated with E. coli specific Aptamer I to detect E. coli cells qualitatively as well as quantitatively. The sludge consisting of E. coli- SPION complex was separated via magnetic separation. The presence of E. coli cells was confirmed with the help of standard techniques and confocal laser scanning microscopy (CLSM) employing Aptamer II conjugated CdTe-MPA quantum dots (QDs). Finally, an ATmega 328P prototype biosensor based on Aptamer II conjugated CdTe MPA QDs exhibited quantitative and qualitative abilities to detect E.coli. This prototype biosensor can even detect low bacterial counts (up to 1 × 10

Topics: Biosensing Techniques; Cadmium Compounds; Escherichia coli; Escherichia coli Infections; Humans; Magnetite Nanoparticles; Quantum Dots; Tellurium

Nanocolumnar titanium coatings have been fabricated in two sputtering systems with very different characteristics (a laboratory setup and semi-industrial equipment), thus possessing different morphologies (150 nm long columns tilted 20° from the normal and 300 nm long ones tilted 40°, respectively). These coatings exhibit similar antibacterial properties against Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) bacteria. When a synergic route is followed and these coatings are functionalized with tellurium (Te) nanorods, the antibacterial properties are enhanced, especially for the long nanocolumns case. The biocompatibility is preserved in all the nanostructured coatings.

Topics: Anti-Bacterial Agents; Coated Materials, Biocompatible; Escherichia coli; Escherichia coli Infections; Humans; Nanostructures; Nanotubes; Staphylococcal Infections; Staphylococcus aureus; Tellurium; Titanium

Detection of Shiga toxin-producing Escherichia coli (STEC) has evolved significantly since the introduction of sorbitol-MacConkey agar. This study compares four chromogenic media (CHROMagar™ STEC, Rainbow® O157 agar, CHROMagar™ O157, and Colorex® O157) in their identification of non-O157 STEC. When 161 non-O157 STEC were directly inoculated onto each medium, detection rates on CHROMagar™ STEC, Rainbow® O157 agar, CHROMagar™ O157 and Colorex® O157 were 90%, 70%, 3.7% and 6.8%, respectively. Tellurite minimal inhibitory concentrations (MICs) correlated with growth on CHROMagar™ STEC as 20 of 22 isolates with poor or no growth had MICs ≤1μg/mL. Stool spiking experiments revealed that CHROMagar™ STEC had the highest recovery of the six most common non-O157 STEC, ranging from 30% (in mucoid stool) to 98% (in watery stool). When using clinical stool samples, CHROMagar™ STEC had a sensitivity, specificity, positive predictive value, and negative predictive value of 84.6%, 87%, 13.9%, and 99.6%, respectively.

Topics: Anti-Bacterial Agents; Bacteriological Techniques; Chromogenic Compounds; Culture Media; Escherichia coli Infections; Humans; Microbial Sensitivity Tests; Predictive Value of Tests; Sensitivity and Specificity; Shiga-Toxigenic Escherichia coli; Tellurium

Tellurite (Tel)-amended selective media and resistance (Tel-R) are widely used for detecting Shiga toxin-producing Escherichia coli (STEC) from foodstuffs. Tel-R of 81 O157 and non-O157 STEC strains isolated from animal, food and human was thus investigated. Variations of STEC tellurite minimal inhibitory concentration (MIC) values have been observed and suggest a multifactorial and variable tellurite resistome between strains. Some clinically-relevant STEC were found highly susceptible and could not be recovered using a tellurite-based detection scheme. The ter operon was highly prevalent among highly Tel-R STEC but was not always detected among intermediately-resistant strains. Many STEC serogroup strains were found to harbor sublines showing a gradient of MIC values. These Tel-R sublines showed statistically significant log negative correlations with increasing tellurite concentration. Whatever the tellurite concentration, the highest number of resistant sublines was observed for STEC belonging to the O26 serogroup. Variations in the number of these Tel-R sublines could explain the poor recovery of some STEC serogroups on tellurite-amended media especially from food products with low levels of contamination. Comparison of tellurite MIC values and distribution of virulence-related genes showed Tel-R and virulence to be related.

Topics: Adhesins, Bacterial; Animals; Culture Media; Drug Resistance, Bacterial; Escherichia coli Infections; Escherichia coli O157; Escherichia coli Proteins; Food Microbiology; Humans; Microbial Sensitivity Tests; Operon; Polymerase Chain Reaction; Serogroup; Shiga-Toxigenic Escherichia coli; Tellurium; Virulence

The sequencing of highly virulent Escherichia coli O104:H4 strains isolated during the outbreak of bloody diarrhea and hemolytic uremic syndrome in Europe in 2011 revealed a genome that contained a Shiga toxin encoding prophage and a plasmid encoding enteroaggregative fimbriae. Here, we present the draft genome sequence of a strain isolated in Sweden from a patient who had travelled to Tunisia in 2010 (E112/10) and was found to differ from the outbreak strains by only 38 SNPs in non-repetitive regions, 16 of which were mapped to the branch to the outbreak strain. We identified putatively adaptive mutations in genes for transporters, outer surface proteins and enzymes involved in the metabolism of carbohydrates. A comparative analysis with other historical strains showed that E112/10 contained Shiga toxin prophage genes of the same genotype as the outbreak strain, while these genes have been replaced by a different genotype in two otherwise very closely related strains isolated in the Republic of Georgia in 2009. We also present the genome sequences of two enteroaggregative E. coli strains affiliated with phylogroup A (C43/90 and C48/93) that contain the agg genes for the AAF/I-type fimbriae characteristic of the outbreak population. Interestingly, C43/90 also contained a tet/mer antibiotic resistance island that was nearly identical in sequence to that of the outbreak strain, while the corresponding island in the Georgian strains was most similar to E. coli strains of other serotypes. We conclude that the pan-genome of the outbreak population is shared with strains of the A phylogroup and that its evolutionary history is littered with gene replacement events, including most recently independent acquisitions of antibiotic resistance genes in the outbreak strains and its nearest neighbors. The results are summarized in a refined evolutionary model for the emergence of the O104:H4 outbreak population.

Topics: Adaptation, Biological; Adhesins, Bacterial; Anti-Bacterial Agents; Disease Outbreaks; Drug Resistance, Bacterial; Enterohemorrhagic Escherichia coli; Escherichia coli Infections; Gene Order; Genes, Bacterial; Genome, Bacterial; Hemolytic-Uremic Syndrome; Humans; Mutation; Phylogeny; Plasmids; Polymorphism, Single Nucleotide; Prophages; Quantitative Trait Loci; Recombination, Genetic; Shiga Toxin; Tellurium; Tunisia; Virulence

We prepared four differently shaped Te nanomaterials (NMs) as antibacterial reagents against Escherichia coli. By controlling the concentrations of hydrazine (N(2)H(4)) as reducing agent, NaCl, and temperature, we prepared Te nanowires, nanopencils, nanorices, and nanocubes. These four Te NMs resulted in a live/dead ratio of E. coli cells of less than 0.1, which is smaller than that of Ag nanoparticles. The order of antibacterial activity against E. coli is nanocubes ≈ nanorices > nanopencils ≈ nanowires. This is in good agreement with the concentration order of tellurite (TeO(3)(2-)) ions released from Te NMs in E. coli cells, revealing that TeO(3)(2-) ions account for the antibacterial activity of the four Te NMs. We found that spherical Te nanoparticles (32 nm in diameter) with TeO(3)(2-) ions were formed in the E. coli cells. Compared to Ag nanoparticles that are commonly used as antibacterial reagents, Te NMs have higher antibacterial activity and lower toxicity. Thus, Te NMs hold great practical potential as a new and efficient antibacterial agent.

Topics: Animals; Anti-Bacterial Agents; Cell Line; Cell Survival; Escherichia coli; Escherichia coli Infections; Humans; Nanostructures; Tellurium

We investigate the antimicrobial activity and cytotoxicity to mammalian cells of conjugates of the peptide antibiotic polymyxin B (PMB) to Au nanoparticles and CdTe quantum dots. Au nanoparticles fully covered with PMB are identical in antimicrobial activity to the free drug alone, whereas partially-conjugated Au particles show decreased effectiveness in proportion to the concentration of Au. CdTe-PMB conjugates are more toxic to Escherichia coli than PMB alone, resulting in a flattening of the steep PMB dose-response curve. The effect is most pronounced at low concentrations of PMB, with a greater effect on the concentration required to reduce growth by half (IC50) than on the concentration needed to inhibit all growth (minimum inhibitory concentration, MIC). The Gram positive organism Staphylococcus aureus is resistant to both PMB and CdTe, showing minimal increased sensitivity when the two are conjugated. Measurement of reactive oxygen species (ROS) generation shows a significant reduction in photo-generated hydroxyl and superoxide radicals with CdTe-PMB as compared with bare CdTe. There is a corresponding reduction in toxicity of QD-PMB versus bare CdTe to mammalian cells, with nearly 100% survival in fibroblasts exposed to bactericidal concentrations of QD-PMB. The situation in bacteria is more complex: photoexcitation of the CdTe particles plays a small role in IC50 but has a significant effect on the MIC, suggesting that at least two different mechanisms are responsible for the antimicrobial action seen. These results show that it is possible to create antimicrobial agents using concentrations of CdTe quantum dots that do not harm mammalian cells.

Topics: Animals; Anti-Bacterial Agents; Cadmium Compounds; Cell Survival; Escherichia coli; Escherichia coli Infections; Fibroblasts; Gold; Mice; Nanoparticles; NIH 3T3 Cells; Polymyxin B; Quantum Dots; Tellurium

In this study, the cooperative antibacterial efficiency of CdTe quantum dots (QDs) and rocephin against Escherichia coli (E. coli) was investigated. Colony-forming capability assay and diameter of inhibition zone (DIZ) measurement showed the antibiotic action of CdTe QDs-rocephin complex was better than the superposition of pure CdTe QDs and rocephin. The fractional inhibitory concentration index (FICI) indicated that CdTe QDs-rocephin complex could achieve great cooperative antimicrobial effects. The infrared ray (IR) spectrum, photoluminescence (PL) spectrophotometry, and detection of reactive oxygen species (ROS) indicated that CdTe QDs and rocephin formed a stable antimicrobial group through electrostatic attraction and hydrogen bonds and then killed the E. coli together. Meanwhile, the fluorescence intensity of CdTe QDs and the optical density (OD) value of E. coli showed a good linear relationship. Thus, dynamic monitoring to total bacterial concentration in the antibacterial process was realized by the CdTe QDs.

Topics: Anti-Bacterial Agents; Cadmium Compounds; Ceftriaxone; Escherichia coli; Escherichia coli Infections; Humans; Microbial Sensitivity Tests; Quantum Dots; Tellurium

Tellurite-containing media are widely used for the screening and isolation of Shiga toxin-producing Escherichia coli (STEC) O157:H7, but tellurite resistance among non-O157 STEC is poorly characterized. Therefore, we investigated 202 STEC strains representing 61 different serotypes from humans, animals or food for the presence of ter genes by PCR and their correlation with tellurite resistance, by assessing growth on cefixime-tellurite sorbitol MacConkey agar. All strains were screened for terC, terE and terF as markers for the ter gene cluster. Of the 202 strains, 127 contained terC and terE and were tellurite-resistant, but only 121 of these also contained terF. All 72 non-sorbitol-fermenting O157:H7 and O157:NM (non-motile) strains contained terC, terE and terF and expressed tellurite resistance. In contrast, all eight sorbitol-fermenting STEC O157:NM were terC-, terE- and terF-negative and tellurite-sensitive. Among non-O157 STEC, terC, terE and terF were found in all seven O145:NM, four O111:H8/NM, 17 of 18 O26:H11/NM and in 21 strains of 14 other serotypes. The strong correlation between the presence of ter genes and the ability to grow on tellurite-containing media suggest that the ter genes encode tellurite resistance in the vast majority of these strains. The presence of the ter gene cluster was significantly (P<0.00001) associated with the presence of eae genes. We conclude that the use of tellurite-containing media in screening for STEC will allow the detection of STEC O26, O111, O145 and non-sorbitol-fermenting O157, but most strains (in this study 74.3%) from other serotypes will be missed.

Topics: Adhesins, Bacterial; Animals; Cattle; Cefixime; Culture Media; DNA-Binding Proteins; Drug Resistance, Bacterial; Escherichia coli Infections; Escherichia coli O157; Escherichia coli Proteins; Food Microbiology; Genes, Bacterial; Goats; Hemolytic-Uremic Syndrome; Humans; Meat; Milk; Multigene Family; Shiga Toxin; Tellurium

A total of 66 (98.5%) of 67 enterohemorrhagic Escherichia coli (EHEC) O157:H7 strains had increased potassium tellurite (Te) MICs (32 to 1,024 microg/ml), grew on Te-containing media, and possessed Te resistance (ter) genes, whereas 83 (96.5%) of 86 sorbitol-fermenting (SF) EHEC O157:NM strains had Te MICs of

Topics: Culture Media; Drug Resistance, Bacterial; Escherichia coli Infections; Escherichia coli O157; Escherichia coli Proteins; Humans; Microbial Sensitivity Tests; Phenotype; Sorbitol; Tellurium

In this study, five abattoirs in Istanbul were visited between January 2000 and April 2001. During these visits, 330 cattle were selected by a systematic sampling method. Cattle were examined clinically and breed, age, and sex were recorded. Rectal swabs were taken immediately after slaughter. Immunomagnetic separation was performed, and sorbitol-negative colonies were selected on sorbitol MacConkey agar with cefixime and tellurite (CT-SMAC agar). These colonies were checked for 4-methylenebelliferyl-beta-D-glucuronide, indol, rhamnose, and urease activity and motility. Serotypes of bacteria were determined by using antisera specific for Escherichia coli O157 and H7. All cattle selected were clinically healthy. Of 88 sorbitol-negative colonies selected on CT-SMAC agar, isolates from only 14 (4.2%) cattle reacted with anti-O157, and 13 of these isolates also reacted with anti-H7. E. coli O157:H7 was isolated from all breeds, but the numbers of isolates were largest for Holstein and Swiss Brown cows. E. coli O157:H7 was most frequently isolated from 2-year-old cattle. Similarly, it was most frequently isolated from male cattle. E. coli O157:H7 was isolated from cattle slaughtered in four of the five abattoirs studied.

Topics: Abattoirs; Age Factors; Animals; Cattle; Cattle Diseases; Cefixime; Culture Media; Escherichia coli Infections; Escherichia coli O157; Female; Glucuronidase; Immunomagnetic Separation; Male; Prevalence; Sex Factors; Sorbitol; Tellurium; Turkey

Culture on cefixime, tellurite, and sorbitol-MacConkey agar after HCl treatment facilitated the growth of 410 (94%) of 436 eae-positive Shiga toxin-producing Escherichia coli (STEC) strains and 17 (16%) of 107 eae-negative STEC strains. This selectivity was closely related to acid resistance in E. coli and tellurite resistance in eae-positive STEC strains.

Topics: Adhesins, Bacterial; Animals; Bacterial Outer Membrane Proteins; Bacterial Toxins; Carrier Proteins; Cattle; Culture Media; Drug Resistance, Microbial; Escherichia coli; Escherichia coli Infections; Escherichia coli Proteins; Humans; Hydrochloric Acid; Microbial Sensitivity Tests; Shiga Toxins; Tellurium; Virulence