scholarly journals Bridging the Gaps: Bole and Terra Sigillata as Artefacts, as Simples and as Antibacterial Clays

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 348 ◽  
Author(s):  
Danae Venieri ◽  
Iosifina Gounaki ◽  
George E. Christidis ◽  
Charles W. Knapp ◽  
Petros Bouras-Vallianatos ◽  
...  
Keyword(s):  
Yellow Powder ◽  
Antibacterial Action ◽  
Gram Negative Bacteria ◽  
Mineralogical Analysis ◽  
Mineralogical Characterization ◽  
Gram Negative ◽  
Microbiological Testing ◽  
Natural Clays ◽  
The University ◽  
Shed Light

Medicinal earths are an important and yet, so far, little scientifically explored archaeological resource. They are almost always identified by their source locality. Our work over the last few years has focused on their chemical and mineralogical characterization and their testing as anti-bacterials. This paper presents the results of the mineralogical analysis and antibacterial testing of six medicinal earths, bole or Terra Sigillata (stamped earth) of unknown date and provenance in the Pharmacy Museum of the University of Basel. Only one of them, a red (Armenian?) ‘bole’, was found to be antibacterial against both Gram-positive and Gram-negative bacteria. A yellow powder of Terra Tripolitania was mildly antibacterial and against one pathogen only. We argue that medicinal earths are in a pivotal place to bridge the gap between currently dispersed pieces of information. This information relates to: (a) their nature, attributes, and applications as described in the texts of different periods, (b) the source of their clays and how best to locate them in the field today, and (c) the methods employed for their beneficiation, if known. We propose that work should be focused primarily onto those medicinal earths whose clay sources can be re-discovered, sampled and assessed. From then on, a parallel investigation should be initiated involving both earths and their natural clays (mineralogy at bulk and nano-sized levels, bio-geochemistry, microbiological testing). We argue that the combined study can shed light into the parameters driving antibacterial action in clays and assist in the elucidation of the mechanisms involved.

scholarly journals Functional and structural characterization of Serratia marcescens ExbB: determinants of the interaction with HasB/TonB

2021 ◽  
Author(s):  
Valérie Biou ◽  
Ricardo Jorge D Adaixo ◽  
Mohamed Chami ◽  
Pierre-Damien Coureux ◽  
Benoist Laurent ◽  
...  
Keyword(s):  
Serratia Marcescens ◽  
Molecular Motor ◽  
Opportunistic Pathogen ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
E Coli ◽  
New Class ◽  
Heme Acquisition ◽  
Shed Light

ExbBD is part of a cytoplasmic membrane molecular motor driven by the proton-motive force. It belongs to the larger family of motors involved in nutriment import across the outer membrane of Gram-negative bacteria (ExbBD), flagellar rotation (MotAB) or late steps of cell division in Gram-negative bacteria (TolQR). ExbB and ExbD are integral membrane proteins with three (ExbB) or one (ExbD) transmembrane segment. Here we have solved by single-particle cryo-EM the structures of ExbB alone and of the ExbB-ExbD complex of the opportunistic pathogen Serratia marcescens. ExbBSm alone behaves as a stable pentamer, and the complex displays the ExbB5-ExbD2 stoichiometry. This is similar to what has been observed for ExbB-ExbD complexes from Escherichia coli and Pseudomonas savastanoi as well as MotAB complexes from various species. We identified residues located in the first TM of ExbBSm and ExbBEc that are likely involved in the interaction with TonB/HasB and that are essential for function. ExbBSm has a ca. 40 residues long periplasmic extension absent in E. coli. Such long ExbBs are found in some Gammaproteobacteria, and several genera of Alphaproteobacteria. We show that this extension interacts with HasB, a dedicated TonB paralog from the heme acquisition system (Has) from S. marcescens. We also show that it is involved in heme acquisition via the Has system from S. marcescens. ExbBSm represents thus a new class of ExbB protein and our results shed light on the specificity determinants between the ExbB-ExbD complex and their associated TonB partners.

PHLORETIN: AN ANTIBACTERIAL SUBSTANCE OBTAINED FROM APPLE LEAVES

1952 ◽  
Vol 30 (4) ◽  
pp. 486-489 ◽  
Author(s):  
Russell E. MacDonald ◽  
Charles J. Bishop
Keyword(s):  
Bacterial Cell ◽  
Antibacterial Action ◽  
Gram Negative Bacteria ◽  
Antibacterial Substance ◽  
Gram Positive ◽  
Gram Negative ◽  
Apple Leaves

A crystalline antibacterial substance isolated from apple leaves has been identified as phloretin. It has been shown to inhibit the growth of a number of Gram-positive and Gram-negative bacteria. The activity of the compound is bacteriostatic in nature and is shown in concentrations as low as 30 p.p.m. Its antibacterial action may be related to inhibition of the uptake of phosphorus by the bacterial cell.

scholarly journals Characteristics of Microbial Factors of Healthcare-Associated Infections Including Multidrug-Resistant Pathogens and Antibiotic Consumption at the University Intensive Care Unit in Poland in the Years 2011–2018

2020 ◽  
Vol 17 (19) ◽  
pp. 6943
Author(s):  
Agnieszka Litwin ◽  
Olga Fedorowicz ◽  
Wieslawa Duszynska
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Multidrug Resistant ◽  
Defined Daily Dose ◽  
Gram Negative Bacteria ◽  
Healthcare Associated Infections ◽  
Gram Negative ◽  
Enterococcus Spp ◽  
Healthcare Associated ◽  
The University

Introduction: In recent years, an increase in healthcare-associated infections (HAIs) caused by resistant pathogens, which is a clinically troublesome trend, has been observed. The aim of the study was to analyze the microbial factors of HAIs and the drug resistance of microorganisms to selected antibiotics and their consumption. Material and Methods: The retrospective study included 3708 patients hospitalized in the intensive care unit (ICU) of the University Teaching Hospital in Wroclaw, who were diagnosed with 742 HAIs in the period from 1 January 2011 to 31 December 2018. The aim of the study was the analysis of microorganisms isolated in the respective clinical forms of HAIs, including the occurrence of “alert pathogens”, presence of multidrug-resistant (MDR) strains, and consumption of selected antibiotics. Findings: During the study period, 846 microorganisms were cultured in patients with HAIs, and among them, Acinetobacter baumannii MDR represented 31.8%; Klebsiella pneumoniae ESBLs, 11.3%; Pseudomonas aeruginosa MDR, 4.1% and MRSA, 2.2%; and Enterococcus spp. vancomycin-resistant enterococci (VRE), 1.3%. Among all the pathogens, Gram-negative bacteria (GNB) were dominant (71.6%). Gram-positive bacteria and fungi accounted for 21.6% and 7%, respectively. The total number of strains responsible for ventilator-associated pneumonia (VAP), urinary tract infection (UTI), and central line-associated blood stream infection (CLA-BSI) was as follows: 458 (54.1%), 274 (32.4%), and 114 (13.5%), respectively. Among the etiological factors of VAP, there was a prevalence of A. baumannii MDR (41.9%), as well as in the case of UTI (21.9%). With regards to CLA-BSI, MRCNS (29.8%) was the dominant pathogen. The “alert pathogens” accounted for 54.7% of all the analyzed strains. The MDR strains represented 72.6% and 9.7% among A. baumannii and P. aeruginosa, respectively. In the years 2011 vs. 2018, an increase in infections with MDR bacilli was observed, 34.6% vs. 61.0% (p = 0.0008), respectively, including A. baumannii MDR 16.54% vs. 34.56 % (p = 0.0009) and Enterobacterales ESBL+/AMPC 11.8% vs. 15.44 % (p = 0.3921). Resistance to methicillin was confirmed in 35.2% of S. aureus strains. Resistance to vancomycin was found among 30.9% of Enterococcus spp. The observed period was marked by an increase in the consumption of carbapenems: 197.7 vs. 235.9 defined daily dose (DDD)/1000 patients-days. Conclusions: Gram-negative bacteria were found to be dominant pathogens in healthcare-associated infections. The most frequently cultured pathogens were multidrug-resistant A. baumannii, K. pneumoniae ESBL(+), and P. aeruginosa. The study showed an increase in the incidence of “alert pathogens” and MDR bacilli, as well as the tendency of a growing resistance to antibiotics during the observed period. Microbiological analysis of HAIs and the consumption of antibiotics is the necessary element of the proper antibiotic policy in hospitals.

scholarly journals Menaquinone biosynthesis inhibition: a review of advancements toward a new antibiotic mechanism

RSC Advances ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 5099-5105 ◽  
Author(s):  
M. Boersch ◽  
S. Rudrawar ◽  
G. Grant ◽  
M. Zunk
Keyword(s):  
Electron Transport ◽  
Antibacterial Action ◽  
Gram Negative Bacteria ◽  
Biosynthesis Pathway ◽  
Gram Positive ◽  
Gram Negative ◽  
Atp Generation ◽  
Bacteria Inhibition

Menaquinone is essential in electron transport and ATP generation in all Gram-positive, and anaerobically respiring Gram-negative bacteria. Inhibition of menaquinone production at different steps of the biosynthesis pathway has shown promising novel antibacterial action.

scholarly journals Antibacterial action of a novel functionalized chitosan-arginine against Gram-negative bacteria

2010 ◽  
Vol 6 (7) ◽  
pp. 2562-2571 ◽  
Author(s):  
Hong Tang ◽  
Peng Zhang ◽  
Thomas L. Kieft ◽  
Shannon J. Ryan ◽  
Shenda M. Baker ◽  
...  
Keyword(s):  
Antibacterial Action ◽  
Gram Negative Bacteria ◽  
Gram Negative

scholarly journals On Gram-Positive- and Gram-Negative-Bacteria-Associated Canine and Feline Skin Infections: A 4-Year Retrospective Study of the University Veterinary Microbiology Diagnostic Laboratory of Naples, Italy

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1603
Author(s):  
Francesca Paola Nocera ◽  
Monica Ambrosio ◽  
Filomena Fiorito ◽  
Laura Cortese ◽  
Luisa De Martino
Keyword(s):  
Antibiotic Resistance ◽  
Retrospective Study ◽  
P Value ◽  
Gram Negative Bacteria ◽  
Skin Infections ◽  
Coagulase Negative Staphylococci ◽  
Gram Positive ◽  
Diagnostic Laboratory ◽  
Gram Negative ◽  
The University

A 4-year retrospective study (2016–2019) of selected routine bacteriological examinations of the veterinary microbiology laboratory of the University Veterinary Teaching Hospital of Naples (Italy) was carried out. A total of 189 bacteriological samples were collected from 171 dogs and 18 cats suffering from skin infections. In dogs, the most common cutaneous infection was otitis externa, while pyoderma was found to be prevalent in cats. The number of recorded Gram-positive strains over the study period did not vary considerably from year to year and was always significantly higher (p-value = 0.0007) in comparison with Gram-negative bacterial isolations. In dogs, Staphylococcus pseudintermedius was the most common identified Gram-positive bacterium (65%), while Pseudomonas aeruginosa (36%) was the one among the isolated Gram-negative bacteria. In cats, coagulase-negative staphylococci were the most predominant isolated bacteria (47%). The phenotypic profiles of antibiotic resistance showed that most of the strains were resistant to amoxicillin–clavulanate, penicillin, clindamycin, and trimethoprim–sulfamethoxazole. Several multi-drug-resistant strains (35%) were detected in canine isolates. An updating of antibiotic resistance profiles of the main Gram-positive and Gram-negative bacteria principally associated with skin infections of pet animals is necessary to improve stewardship programs of veterinary hospitals and clinics.

scholarly journals Cryo-EM structures of lipopolysaccharide transporter LptB2FGC in lipopolysaccharide or AMP-PNP-bound states reveal its transport mechanism

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Xiaodi Tang ◽  
Shenghai Chang ◽  
Qinghua Luo ◽  
Zhengyu Zhang ◽  
Wen Qiao ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Transport Mechanism ◽  
Bound States ◽  
Bound State ◽  
Gram Negative Bacteria ◽  
Transmembrane Helices ◽  
Gram Negative ◽  
Functional Assays ◽  
Shed Light ◽  
Bridge Functional

Abstract Lipopolysaccharides (LPS) of Gram-negative bacteria are critical for the defence against cytotoxic substances and must be transported from the inner membrane (IM) to the outer membrane (OM) through a bridge formed by seven membrane proteins (LptBFGCADE). The IM component LptB2FG powers the process through a yet unclarified mechanism. Here we report three high-resolution cryo-EM structures of LptB2FG alone and complexed with LptC (LptB2FGC), trapped in either the LPS- or AMP-PNP-bound state. The structures reveal conformational changes between these states and substrate binding with or without LptC. We identify two functional transmembrane arginine-containing loops interacting with the bound AMP-PNP and elucidate allosteric communications between the domains. AMP-PNP binding induces an inward rotation and shift of the transmembrane helices of LptFG and LptC to tighten the cavity, with the closure of two lateral gates, to eventually expel LPS into the bridge. Functional assays reveal the functionality of the LptF and LptG periplasmic domains. Our findings shed light on the LPS transport mechanism.

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