Flow microcalorimetric assay of antibiotics —IV. Polymyxin B sulphate, neomycin sulphate, zinc bacitracin and their combinations with Escherichia coli suspended in buffer plus glucose medium

1989 ◽  
Vol 7 (7) ◽  
pp. 871-875 ◽  
Author(s):  
N.Joslin Kjeldsen ◽  
A.E. Beezer ◽  
R.J. Miles ◽  
H. Sodha
Keyword(s):  
Escherichia Coli ◽  
Polymyxin B ◽  
Glucose Medium ◽  
Zinc Bacitracin

Two Novel Mutations Associated with Polymyxin-B Resistance in a Pandemic Lineage of Uropathogenic Escherichia coli of the Sequence Type 69

Chemotherapy ◽  
2021 ◽  
pp. 1-7
Author(s):  
Carla Adriana dos Santos ◽  
Rodrigo Tavanelli Hernandes ◽  
Marcos Paulo Vieira Cunha ◽  
Filipe Onishi Nagamori ◽  
Claudia Regina Gonçalves ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Susceptibility Testing ◽  
Polymyxin B ◽  
Antimicrobial Treatment ◽  
Sequence Type ◽  
Broth Microdilution ◽  
Economic Costs ◽  
Novel Mutations ◽  
E Coli ◽  
Total Inhibition

<b><i>Background:</i></b> Uropathogenic <i>Escherichia coli</i> (UPEC) are frequent pathogens worldwide, impacting on the morbidity and economic costs associated with antimicrobial treatment. <b><i>Objectives:</i></b> We report two novel mutations associated with polymyxin-B resistance in an UPEC isolate collected in 2019. <b><i>Methods:</i></b> Isolate was submitted to antimicrobial susceptibility testing including broth microdilution for polymyxin B. Whole genome was sequenced and analyzed. <b><i>Results:</i></b> Polymyxin-B total inhibition occurred at 16 mg/L (resistant). UPEC isolate was assigned to the phylogroup D, serotype O117:H4, and Sequence Type 69. <i>mcr</i> genes were not detected, but two novel mutations in the <i>pmrA/basS</i> (A80S) and <i>pmrB/</i>basR (D149N) genes were identified. <b><i>Conclusions:</i></b> The occurrence of non-<i>mcr</i> polymyxin resistance in <i>E. coli</i> from extraintestinal infections underscores the need of a continuous surveillance of this evolving pathogen.

scholarly journals An Unusual Cause of Keratitis

1970 ◽  
Vol 12 (3) ◽  
pp. 177-178
Author(s):  
Saroj Gupta ◽  
Atul Aher
Keyword(s):  
Escherichia Coli ◽  
Normal Saline ◽  
Unusual Case ◽  
Polymyxin B ◽  
Nutrient Agar ◽  
Eye Drops ◽  
Minor Trauma ◽  
Parasite Culture ◽  
Wet Mount ◽  
Corneal Scraping

This report is of an unusual case of keratitis in a young healthy man who presented with minor trauma to his left eye. At examination, a characteristic ring infiltrate was seen in the centre of the cornea. Normal saline wet mount preparation of the corneal scraping showed unusual motile trophozoites of a parasite. Culture on non-nutrient agar with Escherichia coli overlay was negative. The patient was treated with topical neomycin, polymyxin B, and bacitracin eye drops and responded well to treatment.

scholarly journals Antibiotic-Mediated Modulations of Outer Membrane Vesicles in Enterohemorrhagic Escherichia coli O104:H4 and O157:H7

2017 ◽  
Vol 61 (9) ◽  
Author(s):  
Andreas Bauwens ◽  
Lisa Kunsmann ◽  
Helge Karch ◽  
Alexander Mellmann ◽  
Martina Bielaszewska
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Shiga Toxin ◽  
Membrane Vesicles ◽  
Polymyxin B ◽  
Outer Membrane Vesicles ◽  
Enterohemorrhagic Escherichia Coli ◽  
Content Type ◽  
E Coli ◽  
Major Virulence Factor

ABSTRACT Ciprofloxacin, meropenem, fosfomycin, and polymyxin B strongly increase production of outer membrane vesicles (OMVs) in Escherichia coli O104:H4 and O157:H7. Ciprofloxacin also upregulates OMV-associated Shiga toxin 2a, the major virulence factor of these pathogens, whereas the other antibiotics increase OMV production without the toxin. These two effects might worsen the clinical outcome of infections caused by Shiga toxin-producing E. coli. Our data support the existing recommendations to avoid antibiotics for treatment of these infections.

scholarly journals Structure and Association of Human Lactoferrin Peptides with Escherichia coli Lipopolysaccharide

2004 ◽  
Vol 48 (6) ◽  
pp. 2190-2198 ◽  
Author(s):  
Daniel S. Chapple ◽  
Rohanah Hussain ◽  
Christopher L. Joannou ◽  
Robert E. W. Hancock ◽  
Edward Odell ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Bactericidal Activity ◽  
Membrane Surface ◽  
Polymyxin B ◽  
Cd Spectroscopy ◽  
Time Dependent ◽  
Human Lactoferrin ◽  
Lag Phase ◽  
Ligand Interaction

ABSTRACT An 11-amino-acid amphipathic synthetic peptide homologous to a helical region on helix 1 of human lactoferrin HLP-2 exhibited bactericidal activity against Escherichia coli serotype O111, whereas an analogue synthesized with Pro substituted for Met, HLP-6, had greatly reduced antimicrobial activity. The bactericidal activity of HLP-2 was 10-fold greater than that of HLP-6 in both buffer and growth medium by time-kill assays. These assays also showed a pronounced lag phase that was both concentration and time dependent and that was far greater for HLP-2 than for HLP-6. Both peptides, however, were shown to be equally efficient in destabilizing the outer membrane when the hydrophobic probe 1-N-phenylnaphthylamine was used and to have the same lipopolysaccharide (LPS) binding affinity, as shown by polymyxin B displacement. Circular dichroism (CD) spectroscopy was used to study the structure and the organization of the peptides in solution and upon interaction with E. coli LPS. In the presence of LPS, HLP-2 and HLP-6 were found to bind and adopt a β-strand conformation rather than an α-helix, as shown by nonimmobilized ligand interaction assay-CD spectroscopy. Furthermore, this assay was used to show that there is a time-dependent association of peptide that results in an ordered formation of peptide aggregates. The rate of interpeptide association was far greater in HLP-2 LPS than in HLP-6 LPS, which was consistent with the lag phase observed on the killing curves. These results allow us to propose a mechanism by which HLP-2 folds and self-assembles at the outer membrane surface before exerting its activity.

Quantitative proteomic analysis reveals the mechanisms of polymyxin B toxicity to Escherichia coli

Chemosphere ◽  
2020 ◽  
Vol 259 ◽  
pp. 127449 ◽  
Author(s):  
Juan Liu ◽  
Zhiyan Huang ◽  
Bo Ruan ◽  
Huimin Wang ◽  
Meiqing Chen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Proteomic Analysis ◽  
Polymyxin B ◽  
Quantitative Proteomic Analysis

scholarly journals Polymyxin B–modified upconversion nanoparticles for selective detection of Gram-negative bacteria such as Escherichia coli

2020 ◽  
Vol 44 (11-12) ◽  
pp. 756-761
Author(s):  
Yan Qiao ◽  
Hongchao Geng ◽  
Ning Jiang ◽  
Xingqi Zhu ◽  
Chenyi Li ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Limit Of Detection ◽  
Polymyxin B ◽  
Upconversion Nanoparticles ◽  
Selective Detection ◽  
Gram Negative Bacteria ◽  
Cationic Antimicrobial Peptide ◽  
Gram Negative ◽  
In Vivo Fluorescence Imaging

Upconversion nanoparticles, Yb,Tm,Fe-doped NaYF4 nanoparticles, are synthesized and modified with polymyxin B for the selective detection of Gram-negative bacteria. Polymyxin B, a cyclic cationic antimicrobial peptide which can specifically bind to the lipopolysaccharides of cell wall of Gram-negative bacteria, such as Escherichia coli, is used to target and bind Gram-negative bacteria. The bacteria are then quantified by measuring the fluorescence intensity of the upconversion nanoparticle–bacteria complexes at 801 nm under 980 nm excitation. A limit of detection of 36 CFU/mL is achieved in the detection of Escherichia coli, and Escherichia coli in soybean milk is successfully detected. The limited autofluorescence and photobleaching properties of the upconversion nanoparticles make the proposed method useful for in vivo fluorescence imaging of Gram-negative bacteria.

scholarly journals Biological Characterization of Endotoxins Released from Antibiotic-Treated Pseudomonas aeruginosa and Escherichia coli

1998 ◽  
Vol 42 (5) ◽  
pp. 1015-1021 ◽  
Author(s):  
Teruo Kirikae ◽  
Fumiko Kirikae ◽  
Shinji Saito ◽  
Kaoru Tominaga ◽  
Hirohi Tamura ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Lipid A ◽  
Biological Activities ◽  
Polymyxin B ◽  
Mitogen Activated Protein Kinase ◽  
No Production ◽  
Endotoxic Activity

ABSTRACT The supernatants taken from Pseudomonas aeruginosa andEscherichia coli cultures in human sera or chemically defined M9 medium in the presence of ceftazidime (CAZ) contained high levels of endotoxin, while those taken from the same cultures in the presence of imipenem (IPM) yielded a very low level of endotoxin. The biological activities of endotoxin in the supernatants were compared with those of phenol water-extracted lipopolysaccharide (LPS). The endotoxin released from the organisms as a result of CAZ treatment (CAZ-released endotoxin) contained a large amount of protein. The protein, however, lacked endotoxic activity, since the endotoxin did not show any in vivo toxic effects in LPS-hyporesponsive C3H/HeJ mice sensitized with d-(+)-galactosamine (GalN) or any activation of C3H/HeJ mouse macrophages in vitro. The activities of CAZ- and IPM-released endotoxin (as assessed by a chromogenicLimulus test) were fundamentally the same as those ofP. aeruginosa LPS, since their regression lines were parallel. The CAZ-released endotoxin was similar to purified LPS with respect to the following biological activities in LPS-responsive C3H/HeN mice and LPS-hyporesponsive C3H/HeJ mice: lethal toxicity in GalN-sensitized mice, in vitro induction of tumor necrosis factor- and NO production by macrophages, and mitogen-activated protein kinase activation in macrophages. The macrophage activation by CAZ-released endotoxin as well as LPS was mainly dependent on the presence of serum factor and CD14 antigen. Polymyxin B blocked the activity. These findings indicate that the endotoxic activity of CAZ-released endotoxin is due primarily to LPS (lipid A).

scholarly journals Phenotypic and Genotypic Characterization of Escherichia coli Isolated from Untreated Surface Waters

2013 ◽  
Vol 7 (1) ◽  
pp. 9-19 ◽  
Author(s):  
Kristopher J Janezic ◽  
Blake Ferry ◽  
Eric W Hendricks ◽  
Brian A Janiga ◽  
Tiffany Johnson ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Surface Waters ◽  
Antimicrobial Agents ◽  
Genotypic Variation ◽  
Virulence Gene ◽  
Genotypic Diversity ◽  
Housekeeping Gene ◽  
Polymyxin B ◽  
Fecal Coliforms ◽  
E Coli

A common member of the intestinal microbiota in humans and animals isEscherichia coli. Based on the presence of virulence factors,E. colican be potentially pathogenic. The focus of this study was to isolateE. colifrom untreated surface waters (37 sites) in Illinois and Missouri and determine phenotypic and genotypic diversity among isolates. Water samples positive for fecal coliforms based on the Colisure®test were streaked directly onto Eosin Methylene Blue (EMB) agar (37°C) or transferred to EC broth (44.5°C). EC broth cultures producing gas were then streaked onto EMB agar. Forty-five isolates were identified asE. coliusing API 20E and Enterotube II identification systems, and some phenotypic variation was observed in metabolism and fermentation. Antibiotic susceptibility of each isolate was also determined using the Kirby-Bauer Method. Differential responses to 10 antimicrobial agents were seen with 7, 16, 2, and 9 of the isolates resistant to ampicillin, cephalothin, tetracycline, and triple sulfonamide, respectively. All of the isolates were susceptible or intermediate to amoxicillin, ciprofloxacin, polymyxin B, gentamicin, imipenem, and nalidixic acid. Genotypic variation was assessed through multiplex Polymerase Chain Reaction for four virulence genes (stx1andstx2[shiga toxin],eaeA[intimin]; andhlyA[enterohemolysin]) and one housekeeping gene (uidA[β-D-glucuronidase]). Genotypic variation was observed with two of the isolates possessing the virulence gene (eaeA) for intimin. These findings increase our understanding of the diversity ofE. coliin the environment which will ultimately help in the assessment of this organism and its role in public health.

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