scholarly journals Antimicrobial Polymeric Composites with Embedded Nanotextured Magnesium Oxide

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2183
Author(s):  
Nemanja Aničić ◽  
Mario Kurtjak ◽  
Samo Jeverica ◽  
Danilo Suvorov ◽  
Marija Vukomanović
Keyword(s):  
Magnesium Oxide ◽  
Degradation Kinetics ◽  
Multidrug Resistant ◽  
E Coli ◽  
Structural And Functional Properties ◽  
Controllable Release ◽  
Interphase Interactions ◽  
And Control ◽  
Mgo Surface ◽  
Harmful Effects

Nanotextured magnesium oxide (MgO) can exhibit both antibacterial and tissue regeneration activity, which makes it very useful for implant protection. To successfully combine these two properties, MgO needs to be processed within an appropriate carrier system that can keep MgO surface available for interactions with cells, slow down the conversion of MgO to the less active hydroxide and control MgO solubility. Here we present new composites with nanotextured MgO microrods embedded in different biodegradable polymer matrixes: poly-lactide-co-glycolide (PLGA), poly-lactide (PLA) and polycaprolactone (PCL). Relative to their hydrophilicity, polarity and degradability, the matrices were able to affect and control the structural and functional properties of the resulting composites in different manners. We found PLGA matrix the most effective in performing this task. The application of the nanotextured 1D morphology and the appropriate balancing of MgO/PLGA interphase interactions with optimal polymer degradation kinetics resulted in superior bactericidal activity of the composites against either planktonic E. coli or sessile S. epidermidis, S. aureus (multidrug resistant-MRSA) and three clinical strains isolated from implant-associated infections (S. aureus, E. coli and P. aeruginosa), while ensuring controllable release of magnesium ions and showing no harmful effects on red blood cells.

Mechanistic and structural diversity between cytochrome bd isoforms of Escherichia coli

2021 ◽  
Vol 118 (50) ◽  
pp. e2114013118
Author(s):  
Tamara N. Grund ◽  
Melanie Radloff ◽  
Di Wu ◽  
Hojjat G. Goojani ◽  
Luca F. Witte ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pathogenic Bacteria ◽  
Reduction Rate ◽  
Structural Diversity ◽  
Multidrug Resistant ◽  
E Coli ◽  
Structural And Functional Properties ◽  
Oxygen Reductase ◽  
General Architecture ◽  
Structural Insights

The treatment of infectious diseases caused by multidrug-resistant pathogens is a major clinical challenge of the 21st century. The membrane-embedded respiratory cytochrome bd-type oxygen reductase is a critical survival factor utilized by pathogenic bacteria during infection, proliferation and the transition from acute to chronic states. Escherichia coli encodes for two cytochrome bd isoforms that are both involved in respiration under oxygen limited conditions. Mechanistic and structural differences between cydABX (Ecbd-I) and appCBX (Ecbd-II) operon encoded cytochrome bd variants have remained elusive in the past. Here, we demonstrate that cytochrome bd-II catalyzes oxidation of benzoquinols while possessing additional specificity for naphthoquinones. Our data show that although menaquinol-1 (MK1) is not able to directly transfer electrons onto cytochrome bd-II from E. coli, it has a stimulatory effect on its oxygen reduction rate in the presence of ubiquinol-1. We further determined cryo-EM structures of cytochrome bd-II to high resolution of 2.1 Å. Our structural insights confirm that the general architecture and substrate accessible pathways are conserved between the two bd oxidase isoforms, but two notable differences are apparent upon inspection: (i) Ecbd-II does not contain a CydH-like subunit, thereby exposing heme b595 to the membrane environment and (ii) the AppB subunit harbors a structural demethylmenaquinone-8 molecule instead of ubiquinone-8 as found in CydB of Ecbd-I. Our work completes the structural landscape of terminal respiratory oxygen reductases of E. coli and suggests that structural and functional properties of the respective oxidases are linked to quinol-pool dependent metabolic adaptations in E. coli.

scholarly journals Virulence Characteristics and Antibiotic Resistance Profiles of Shiga Toxin-Producing Escherichia coli Isolates from Diverse Sources

Antibiotics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 587
Author(s):  
Momna Rubab ◽  
Deog-Hwan Oh
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Shiga Toxin ◽  
Multidrug Resistant ◽  
Control Measures ◽  
Diffusion Method ◽  
Shiga Toxins ◽  
E Coli ◽  
And Control ◽  
High Degree

Shiga toxin-producing Escherichia coli (STEC) is an enteric pathogen that causes several gastrointestinal ailments in humans across the world. STEC’s ability to cause ailment is attributed to the presence of a broad range of known and putative virulence factors (VFs) including those that encode Shiga toxins. A total of 51 E. coli strains belonging to serogroups O26, O45, O103, O104, O113, O121, O145, and O157 were tested for the presence of nine VFs via PCR and for their susceptibility to 17 frequently used antibiotics using the disc diffusion method. The isolates belonged to eight different serotypes, including eight O serogroups and 12 H types. The frequency of the presence of key VFs were stx1 (76.47%), stx2 (86.27%), eae (100%), ehxA (98.03%), nleA (100%), ureC (94.11%), iha (96.07%), subA (9.80%), and saa (94.11%) in the E. coli strains. All E. coli strains carried seven or more distinct VFs and, among these, four isolates harbored all tested VFs. In addition, all E. coli strains had a high degree of antibiotic resistance and were multidrug resistant (MDR). These results show a high incidence frequency of VFs and heterogeneity of VFs and MDR profiles of E. coli strains. Moreover, half of the E. coli isolates (74.5%) were resistant to > 9 classes of antibiotics (more than 50% of the tested antibiotics). Thus, our findings highlight the importance of appropriate epidemiological and microbiological surveillance and control measures to prevent STEC disease in humans worldwide.

scholarly journals Microbial Contamination of Chicken Litter Manure and Antimicrobial Resistance Threat in an Urban Area Setting in Cameroon

Antibiotics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 20
Author(s):  
Marie Paule Ngogang ◽  
Tambo Ernest ◽  
Jennifer Kariuki ◽  
Mohamed Moctar Mouliom Mouiche ◽  
Jeanne Ngogang ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Multidrug Resistant ◽  
Diffusion Method ◽  
Dilution Method ◽  
Salmonella Spp ◽  
E Coli ◽  
Chicken Litter ◽  
Convenience Sampling ◽  
And Control ◽  
Broth Dilution

We conducted a pilot study to assess microbiological safety of chicken litter, an affordable organic and main fertilizer used in Cameroon and worldwide. A convenience sampling of 26 farms was done and a questionnaire was administered. Samples of litter were aseptically collected. E. coli and Salmonella spp. were isolated using CLSI standards. Antibiotic susceptibility testing was performed using the disc diffusion method and a micro broth dilution method for colistin. In broiler farms, 90% of participating farmers gave antibiotic prophylaxis. The prevalence of E. coli and Salmonella spp. was 59.1% and 15.5%, respectively. All E. coli isolates were multidrug resistant as well as 36.4% for Salmonella spp. No resistance was found against cefepime and imipenem. All Salmonella spp. tested were found sensitive to colistin while 26.7% of E. coli spp. were colistin resistant. Contamination of chicken litter may be an underestimated source of antimicrobial resistance (AMR) transmission towards animals, humans and the environment with multidrug resistant E. coli and Salmonella spp. This shows the need and opportunity for a One Health approach in AMR surveillance and control in Cameroon. Continued surveillance in chicken litter would enable monitoring of AMR risks and trends.

scholarly journals Limited MDR efflux pump overexpression among multidrug-resistant Escherichia coli of ST131

2021 ◽  
Author(s):  
Johannes Camp ◽  
Sabine Schuster ◽  
Martina Vavra ◽  
Tobias Schweigger ◽  
John W. A. Rossen ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Efflux Pump ◽  
Principal Component ◽  
Efflux Pumps ◽  
Multidrug Resistant ◽  
Gram Negative Bacteria ◽  
E Coli ◽  
Enhanced Expression ◽  
And Control ◽  
Increased Susceptibility

Gram-negative bacteria partly rely on efflux pumps to facilitate growth under stressful conditions and to increase resistance to a wide variety of commonly used drugs. In recent years E. coli ST131 has emerged as a major cause of extraintestinal infection frequently exhibiting an MDR phenotype. The contribution of efflux to MDR in emerging E. coli MDR clones however, is not well studied. We characterized strains from an international collection of clinical MDR-E. coli isolates by MIC testing with and without the addition of the AcrAB-TolC efflux inhibitor 1-(1-naphthylmethyl)-piperazine (NMP). MIC data for 6 antimicrobial agents and their reversion by NMP were analyzed by Principal Component Analysis (PCA). PCA revealed a group of 17/34 MDR-E. coli exhibiting increased susceptibility to treatment with NMP suggesting an enhanced contribution of efflux pumps to antimicrobial resistance in these strains (termed “enhanced efflux phenotype” [EEP]). Only 1/17 EEP strains versus 12/17 non-EEP MDR strains belonged to the ST131 clonal group. Whole-genome sequencing revealed marked differences in efflux-related genes between EEP and control strains, with the majority of notable amino-acid substitutions occurring in AcrR, MarR and SoxR. qRT-PCR of multiple efflux-related genes showed significant overexpression of the AcrAB-TolC-system in EEP strains, whereas in the remaining strains we found enhanced expression of alternative efflux proteins. We conclude that a proportion of MDR E. coli exhibit an EEP, which is linked to an overexpression of the AcrAB-TolC-efflux-pump and a distinct array of genomic variations. Members of ST131, although highly successful, are less likely to exhibit the EEP.

scholarly journals ANTIMICROBIAL RESISTANCE OF ESCHERIСHIA COLI STRAINS ISOLATED FROM PATIENTS WITH PURULENT PERITONITIS

2021 ◽  
pp. 53-57
Author(s):  
O. V. Kotsar ◽  
O. V. Kochnieva
Keyword(s):  
Bacterial Infections ◽  
Current Knowledge ◽  
Abdominal Cavity ◽  
Multidrug Resistant ◽  
Therapeutic Interventions ◽  
Health Concern ◽  
Promising Alternative ◽  
E Coli ◽  
Purulent Peritonitis ◽  
And Control

Escherichia coli remains one of the most frequent causes of several common bacterial infections in humans. Surgery on the abdominal cavity is usually complicated by peritonitis caused by E. coli strains. Recently, there are data confirming the high degree of resistance of this strain. The prevalence of multidrug-resistant E. coli strains is increasing worldwide principally due to the spread of mobile genetic elements, such as plasmids. The rise of multidrug-resistant strains of E. coli also occurs in Ukraine. Therefore, the spread of resistance E. coli is an increasing public health concern in our country. This paper summarizes the antibiotic resistance of clinical E. coli strains, isolated from patients with peritonitis. Furthermore, therapeutic interventions and strategies to prevent and control infections are presented and discussed. The article also provides an overview of the current knowledge concerning promising alternative therapies against E. coli diseases.

scholarly journals Antibacterial Activity of Medicinal Flowers against Multi Drug Resistant E. coli

2021 ◽  
Vol 41 (01) ◽  
pp. 166-168
Author(s):  
Iqra Nazir
Keyword(s):  
Antibacterial Activity ◽  
Taraxacum Officinale ◽  
Multidrug Resistant ◽  
Achillea Millefolium ◽  
Rosa Damascena ◽  
Drug Resistant ◽  
E Coli ◽  
And Control ◽  
Woodfordia Fruticosa ◽  
Hyssopus Officinalis

The antibiotic resistance is creating a serious challenge to treat diseases especially against multidrug resistant (MDR) E. coli. The present study was conducted to evaluate the antibacterial activity of seven different flowers ethanolic extracts named as Achillea millefolium, Bombax ceiba, Chrysanthemum cinerarifolium, Hyssopus officinalis, Rosa damascena Miller, Taraxacum officinale Weber and Woodfordia fruticosa against MDR E. coli through spot test and minimum inhibitory concentrations (MIC) test. The results showed all the seven extracts have significant antibacterial activity against MDR E. coli and control. The MIC of Rosa damascena Miller, Bombax ceiba was 3.125 mg/ml and Taraxacum officinale Weber was 12.5 mg/ml for MDR E. coli. Similarly, Achillea millefolium, Hyssopus officinalis, Chrysanthemum cinerarifolium MIC value was 25 mg/ml and 12.5 mg/ml for Woodfordia fruticosa Kurtz. The current study reveals that these flowers possess strong antibacterial activity and thus can be used as potential antimicrobial agent against various resistant bacterial pathogens

Time-resolved high-resolution electron microscopy of structural stability in mgo clusters

1996 ◽  
Vol 54 ◽  
pp. 672-673
Author(s):  
T. Kizuka ◽  
N. Tanaka
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Magnesium Oxide ◽  
Structural Stability ◽  
High Resolution Electron Microscopy ◽  
Video Tape ◽  
Solid State Physics ◽  
Time Resolved ◽  
Resolution Electron ◽  
Structural And Functional Properties

Structure and stability of atomic clusters have been studied by time-resolved high-resolution electron microscopy (TRHREM). Typical examples are observations of structural fluctuation in gold (Au) clusters supported on silicon oxide films, graphtized carbon films and magnesium oxide (MgO) films. All the observations have been performed on the clusters consisted of single metal element. Structural stability of ceramics clusters, such as metal-oxide, metal-nitride and metal-carbide clusters, has not been observed by TRHREM although the clusters show anomalous structural and functional properties concerning to solid state physics and materials science.In the present study, the behavior of ceramic, magnesium oxide (MgO) clusters is for the first time observed by TRHREM at 1/60 s time resolution and at atomic resolution down to 0.2 nm.MgO and gold were subsequently deposited on sodium chloride (001) substrates. The specimens, single crystalline MgO films on which Au particles were dispersed were separated in distilled water and observed by using a 200-kV high-resolution electron microscope (JEOL, JEM2010) equipped with a high sensitive TV camera and a video tape recorder system.

The effect of type of water supply on water quality in a developing community in South Africa

1997 ◽  
Vol 35 (11-12) ◽  
pp. 35-40 ◽  
Author(s):  
B. Genthe ◽  
N. Strauss ◽  
J. Seager ◽  
C. Vundule ◽  
F. Maforah ◽  
...  
Keyword(s):  
Water Quality ◽  
Water Supply ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
E Coli ◽  
Guideline Values ◽  
Developing Communities ◽  
Quality Guideline ◽  
And Control ◽  
The Relationship

Efforts to provide water to developing communities in South Africa have resulted in various types of water supplies being used. This study examined the relationship between the type of water supply and the quality of water used. Source (communal taps, private outdoor and indoor taps) and point-of-use water samples were examined for heterotrophic plate counts (HPC), total and faecal coliforms, E. coli, and coliphages. Ten percent of samples were also analysed for enteric viruses, Giardia and Cryptosporidium. Approximately 320 households were included in a case-control study. In addition, a cross-sectional study was conducted. Both studies examined the relationship between different types of water facilities and diarrhoea among pre-school children. The source water was of good microbial quality, but water quality was found to have deteriorated significantly after handling and storage in both case and control households, exceeding drinking water quality guideline values by 1-6 orders of magnitude. Coliphage counts were low for all water samples tested. Enteric viruses and Cryptosporidium oocysts were not detected. Giardia cysts were detected on one occasion in case and control in-house samples. Comparisons of whether in-house water, after handling and storage, complied with water quality guideline values demonstrated households using communal taps to have significantly poorer quality than households using private outdoor or indoor taps for HPC and E. coli (χ2 = 14.9, P = 0.001; χ2 = 6.6, P = 0.04 respectively). A similar trend (although not statistically significant) was observed for the other microbial indicators. The cross-sectional study demonstrated an apparent decrease in health risk associated with private outdoor taps in comparison to communal taps. This study suggests that a private outdoor tap is the minimum level of water supply in order to ensure the supply of safe water to developing communities.

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