scholarly journals MCR Expression Conferring Varied Fitness Costs on Host Bacteria and Affecting Bacteria Virulence

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 872
Author(s):  
Wan Li ◽  
Zhihai Liu ◽  
Wenjuan Yin ◽  
Lu Yang ◽  
Lu Qiao ◽  
...  
Keyword(s):  
Galleria Mellonella ◽  
Membrane Damage ◽  
Bacterial Virulence ◽  
Bacterial Membrane ◽  
Fitness Costs ◽  
Worldwide Distribution ◽  
Well Model ◽  
Penetration Ability ◽  
Different Levels ◽  
Physiological Background

Since the first report of the plasmid-mediated, colistin-resistant gene, mcr-1, nine mcr genes and their subvariants have been identified. The spreading scope of mcr-1~10 varies greatly, suggesting that mcr-1~10 may have different evolutionary advantages. Depending on MCR family phylogeny, mcr-6 is highly similar to mcr-1 and -2, and mcr-7~10 are highly similar to mcr-3 and -4. We compared the expression effects of MCR-1~5 on bacteria of common physiological background. The MCR-1-expressing strain showed better growth than did MCR-2~5-expressing strains in the presence of colistin. LIVE/DEAD staining analysis revealed that MCR-3~5 expression exerted more severe fitness burdens on bacteria than did MCR-1 and -2. Bacteria expressing MCRs except MCR-2 showed enhanced virulence with increased epithelial penetration ability determined by trans-well model (p < 0.05). Enhanced virulence was also observed in the Galleria mellonella model, which may have resulted from bacterial membrane damage and different levels of lipopolysaccharide (LPS) release due to MCR expression. Collectively, MCR-1-expressing strain showed the best survival advantage of MCR-1~5-expressing strains, which may partly explain the worldwide distribution of mcr-1. Our results suggested that MCR expression may cause increased bacterial virulence, which is alarming, and further attention will be needed to focus on the control of infectious diseases caused by mcr-carrying pathogens.

scholarly journals Oxidative stress generated at nickel oxide nanoparticle interface results in bacterial membrane damage leading to cell death

RSC Advances ◽  
2019 ◽  
Vol 9 (43) ◽  
pp. 24888-24894 ◽  
Author(s):  
Nibedita Behera ◽  
Manoranjan Arakha ◽  
Mamali Priyadarshinee ◽  
Biraja S. Pattanayak ◽  
Siba Soren ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Nickel Oxide ◽  
Metal Oxide Nanoparticles ◽  
Membrane Damage ◽  
Oxide Nanoparticles ◽  
Bacterial Membrane ◽  
Antibacterial Effects ◽  
Nickel Oxide Nanoparticle ◽  
Oxide Nanoparticle

Metal oxide nanoparticles (NPs) have shown enhanced antibacterial effects against many bacteria.

scholarly journals Pathogenicity Levels of Colombian Strains of Candida auris and Brazilian Strains of Candida haemulonii Species Complex in Both Murine and Galleria mellonella Experimental Models

2020 ◽  
Vol 6 (3) ◽  
pp. 104
Author(s):  
Julián E. Muñoz ◽  
Laura M. Ramirez ◽  
Lucas dos Santos Dias ◽  
Laura A. Rivas ◽  
Lívia S. Ramos ◽  
...  
Keyword(s):  
Survival Rate ◽  
Species Complex ◽  
Galleria Mellonella ◽  
Experimental Models ◽  
Candida Auris ◽  
Candida Haemulonii ◽  
Virulent Strains ◽  
Inert Surface ◽  
Phagocytosis Index ◽  
Different Levels

Candida auris and Candida haemulonii complex (C. haemulonii, C. haemulonii var. vulnera and C. duobushaemulonii) are phylogenetically related species that share some physiological features and habits. In the present study, we compared the virulence of these yeast species using two different experimental models: (i) Galleria mellonella larvae to evaluate the survival rate, fungal burden, histopathology and phagocytosis index and (ii) BALB/c mice to evaluate the survival. In addition, the fungal capacity to form biofilm over an inert surface was analyzed. Our results showed that in both experimental models, the animal survival rate was lower when infected with C. auris strains than the C. haemulonii species complex. The hemocytes of G. mellonella showed a significantly reduced ability to phagocytize the most virulent strains forming the C. haemulonii species complex. Interestingly, for C. auris, it was impossible to measure the phagocytosis index due to a general lysis of the hemocytes. Moreover, it was observed a greater capability of biofilm formation by C. auris compared to C. haemulonii species complex. In conclusion, we observed that C. auris and C. haemulonii complex have different levels of pathogenicity in the experimental models employed in the present study.

scholarly journals SlyA Is a Transcriptional Regulator Involved in the Virulence of Enterococcus faecalis

2011 ◽  
Vol 79 (7) ◽  
pp. 2638-2645 ◽  
Author(s):  
Charlotte Michaux ◽  
Maurizio Sanguinetti ◽  
Fany Reffuveille ◽  
Yanick Auffray ◽  
Brunella Posteraro ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Galleria Mellonella ◽  
Peritoneal Macrophages ◽  
Bacterial Virulence ◽  
Transcriptional Analysis ◽  
Infection Model ◽  
Wild Type ◽  
Content Type ◽  
Wild Type Parent

ABSTRACTPhylogenetic analysis of the crystal structure of theEnterococcus faecalisSlyA (EF_3002) transcriptional factor places it between the SlyA and MarR regulator subfamilies. Proteins of these families are often involved in the regulation of genes important for bacterial virulence and stress response. To gather evidence for the role of this putative regulator inE. faecalisbiology, we dissected the genetic organization of theslyA-EF_3001 locus and constructed aslyAdeletion mutant as well as complemented strains. Interestingly, compared to the wild-type parent, the ΔslyAmutant is more virulent in an insect infection model (Galleria mellonella), exhibits increased persistence in mouse kidneys and liver, and survives better inside peritoneal macrophages. In order to identify a possible SlyA regulon, global microarray transcriptional analysis was performed. This study revealed that theslyA-EF_3001 locus appears to be autoregulated and that 117 genes were differentially regulated in the ΔslyAmutant. In the mutant strain, 111 were underexpressed and 6 overexpressed, indicating that SlyA functions mainly as an activator of transcription.

scholarly journals Microampere electric currents caused bacterial membrane damage and two-way leakage in short time

2020 ◽  
Author(s):  
V R Krishnamurthi ◽  
A Rogers ◽  
J Peifer ◽  
I Niyonshuti ◽  
J Chen ◽  
...  
Keyword(s):  
Small Molecules ◽  
Single Molecule ◽  
Propidium Iodide ◽  
Membrane Damage ◽  
Bacterial Membrane ◽  
Electric Currents ◽  
Localization Microscopy ◽  
Propidium Iodide Staining ◽  
Short Time ◽  
Single Molecule Localization Microscopy

AbstractPhysical agents such as low electric voltages and currents have recently gained attention for antimicrobial treatment due to their bactericidal capability. Although microampere electric currents were shown to suppress the growth of bacteria, it remains unclear to what extent the microampere currents damage bacterial membrane. Here, we investigated the membrane damage and two-way leakage caused by microampere electric currents (≤ 100 μA) in a short time (30 min). Based on MitoTracker staining, propidium iodide staining, filtration assays, and quantitative single-molecule localization microscopy, we found that microampere electric currents caused significant membrane damages and allowed two-way leakages of ions, small molecules and proteins. This study paves the way to new development and antibiotic applications of ultra-low electric voltages and currents.Statement of SignificancePrevious studies showed that treating bacteria with milliampere electric currents for 72 hours led to significant damages of the bacterial membrane. However, it remains unclear to what extent membrane damages and two-way (i.e. inward and outward) leakages are caused by lower electric currents in a shorter time. In this work, we set out to answer this question. We carried out several assays on the bacteria treated by microampere electric currents of ≤ 100 μA for 30 min, including MitoTracker staining, propidium iodide staining, filtration assays, and quantitative single-molecule localization microscopy. We found and quantified that the membrane damages were caused by microampere electric currents in half an hour and allowed two-way leakages of ions, small molecules, and proteins.

scholarly journals Combinatorial Antimicrobial Efficacy and Mechanism of Linalool Against Clinically Relevant Klebsiella pneumoniae

2021 ◽  
Vol 12 ◽  
Author(s):  
Shun-Kai Yang ◽  
Khatijah Yusoff ◽  
Mokrish Ajat ◽  
Chien-Yeong Wee ◽  
Polly-Soo-Xi Yap ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Klebsiella Pneumoniae ◽  
Membrane Permeability ◽  
Membrane Damage ◽  
Bacterial Membrane ◽  
Bacterial Cells ◽  
Bacterial Killing ◽  
Potential Measurement ◽  
Bacterial Surface ◽  
Electron Microscopies

Antibiotic–adjuvant combinatory therapy serves as a viable treatment option in addressing antibiotic resistance in the clinical setting. This study was carried out to assess and characterize the adjuvant potential and mode of action of linalool against carbapenemase-producing Klebsiella pneumoniae (KPC-KP). Linalool exhibited bactericidal activity alone (11,250 μg/ml) and in combination with meropenem (5,625 μg/ml). Comparative proteomic analysis showed significant reduction in the number of cytoplasmic and membrane proteins, indicating membrane damage in linalool-treated KPC-KP cells. Upregulation of oxidative stress regulator proteins and downregulation of oxidative stress-sensitive proteins indicated oxidative stress. Zeta potential measurement and outer membrane permeability assay revealed that linalool increases the bacterial surface charge as well as the membrane permeability. Intracellular leakage of nucleic acid and proteins was detected upon linalool treatment. Scanning and transmission electron microscopies further revealed the breakage of bacterial membrane and loss of intracellular materials. Linalool induced oxidative stress by generating reactive oxygen species (ROS) which initiates lipid peroxidation, leading to damage of the bacterial membrane. This leads to intracellular leakage, eventually killing the KPC-KP cells. Our study demonstrated that linalool possesses great potential in future clinical applications as an adjuvant along with existing antibiotics attributed to their ability in disrupting the bacterial membrane by inducing oxidative stress. This facilitates the uptake of antibiotics into the bacterial cells, enhancing bacterial killing.

scholarly journals Regulation of Secondary Metabolism in the Penicillium Genus

2020 ◽  
Vol 21 (24) ◽  
pp. 9462
Author(s):  
Christelle El Hajj Assaf ◽  
Chrystian Zetina-Serrano ◽  
Nadia Tahtah ◽  
André El Khoury ◽  
Ali Atoui ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Human Health ◽  
Secondary Metabolism ◽  
Ochratoxin A ◽  
Food Crops ◽  
Penicillium Species ◽  
Diverse Range ◽  
Worldwide Distribution ◽  
Varied Range ◽  
Different Levels

Penicillium, one of the most common fungi occurring in a diverse range of habitats, has a worldwide distribution and a large economic impact on human health. Hundreds of the species belonging to this genus cause disastrous decay in food crops and are able to produce a varied range of secondary metabolites, from which we can distinguish harmful mycotoxins. Some Penicillium species are considered to be important producers of patulin and ochratoxin A, two well-known mycotoxins. The production of these mycotoxins and other secondary metabolites is controlled and regulated by different mechanisms. The aim of this review is to highlight the different levels of regulation of secondary metabolites in the Penicillium genus.

Effect of Background Case Characteristics on Decisions in the Delivery Room

2010 ◽  
Vol 30 (4) ◽  
pp. 518-522 ◽  
Author(s):  
Ori Shen ◽  
Ron Rabinowitz ◽  
Ruth R. Geist ◽  
Eldar Shafir
Keyword(s):  
Decision Making ◽  
Prior Experience ◽  
Test Case ◽  
Invasive Treatment ◽  
Medical Test ◽  
Case Methods ◽  
First Results ◽  
Case Characteristics ◽  
Different Levels ◽  
Physiological Background

Background. The authors investigated whether obstetricians make different decisions about a medical test case depending on the characteristics of background cases that preceded the test case. Methods. Five hypothetical cases were sent to 1247 obstetricians. The outcome of interest was the proportion of physicians who elect to perform a cesarean on a borderline test case, presented with 4 background cases. Participants were randomly assigned to 1 of 3 conditions: 1) pathological background, in which the test case was preceded by abnormal cases, typically requiring cesarean; 2) physiological background, where the test case was preceded by relatively uncomplicated cases, often suggesting a less invasive treatment; and 3) control, where the test case appeared first. Results. A significantly higher proportion of respondents chose a cesarean when the test case was preceded by physiological cases (75.4%) than when it was preceded by pathological cases (52.2%). This tendency was observed among those actively and not actively involved in obstetrics and in physicians with different levels of training. Conclusions. A patient’s chances of undergoing cesarean section can be influenced by the immediately prior experience of the physician. This study with hypothetical vignettes found that background cases can influence physicians’ decisions. The test case was apparently perceived as more grave when it followed uncomplicated cases as compared to when it was preceded by abnormal cases. Such inconsistencies in decision making are unlikely to be fully resolved by expertise, as suggested by the lack of differences between physicians with different training levels. An understanding of such effects may contribute to more informed consideration of unappreciated influences in making decisions.

scholarly journals Insertion sequences drive the emergence of a highly adapted human pathogen

2020 ◽  
Vol 6 (9) ◽  
Author(s):  
Erwin Sentausa ◽  
Pauline Basso ◽  
Alice Berry ◽  
Annie Adrait ◽  
Gwendoline Bellement ◽  
...  
Keyword(s):  
Galleria Mellonella ◽  
Opportunistic Pathogen ◽  
Insertion Sequences ◽  
Pathogenic Potential ◽  
Highly Pathogenic ◽  
Type Iv ◽  
Genome Wide ◽  
Outer Membrane Porin ◽  
Specific Antigens ◽  
Different Levels

Pseudomonas aeruginosa is a highly adaptive opportunistic pathogen that can have serious health consequences in patients with lung disorders. Taxonomic outliers of P. aeruginosa of environmental origin have recently emerged as infectious for humans. Here, we present the first genome-wide analysis of an isolate that caused fatal haemorrhagic pneumonia. In two clones, CLJ1 and CLJ3, sequentially recovered from a patient with chronic pulmonary disease, insertion of a mobile genetic element into the P. aeruginosa chromosome affected major virulence-associated phenotypes and led to increased resistance to the antibiotics used to combat the infection. Comparative genome, proteome and transcriptome analyses revealed that this ISL3-family insertion sequence disrupted the genes for flagellar components, type IV pili, O-specific antigens, translesion polymerase and enzymes producing hydrogen cyanide. Seven-fold more insertions were detected in the later isolate, CLJ3, than in CLJ1, some of which modified strain susceptibility to antibiotics by disrupting the genes for the outer-membrane porin OprD and the regulator of β-lactamase expression AmpD. In the Galleria mellonella larvae model, the two strains displayed different levels of virulence, with CLJ1 being highly pathogenic. This study revealed insertion sequences to be major players in enhancing the pathogenic potential of a P. aeruginosa taxonomic outlier by modulating both its virulence and its resistance to antimicrobials, and explains how this bacterium adapts from the environment to a human host.

scholarly journals Microampere Electric Current Causes Bacterial Membrane Damage and Two-Way Leakage in a Short Period of Time

2020 ◽  
Vol 86 (16) ◽  
Author(s):  
Venkata Rao Krishnamurthi ◽  
Ariel Rogers ◽  
Janet Peifer ◽  
Isabelle I. Niyonshuti ◽  
Jingyi Chen ◽  
...  
Keyword(s):  
Small Molecules ◽  
Electric Current ◽  
Single Molecule ◽  
Membrane Damage ◽  
Short Exposure ◽  
Bacterial Membrane ◽  
Electric Voltage ◽  
Short Exposure Time ◽  
Short Period ◽  
Growth Of Bacteria

ABSTRACT Physical agents, such as low electric voltage and current, have recently gained attention for antimicrobial treatment due to their bactericidal capability. Although microampere electric current was shown to suppress the growth of bacteria, it remains unclear to what extent the microampere current damaged the bacterial membrane. Here, we investigated the membrane damage and two-way leakage caused by microampere electric current (≤100 μA) with a short exposure time (30 min). Based on MitoTracker staining, propidium iodide staining, filtration assays, and quantitative single-molecule localization microscopy, we observed significant membrane damage, which allowed two-way leakage of ions, small molecules, and proteins. This study paves the way to new development of antimicrobial applications for ultralow electric voltage and current. IMPORTANCE Although electric voltage and current have been studied for a long time in terms of their ability to suppress the growth of bacteria and to kill bacteria, increasing interest has been aroused more recently due to the prevalence of antibiotic resistance of microbes in past decades. Toward understanding the antimicrobial mechanism of low electric voltage and current, previous studies showed that treating bacteria with milliampere electric currents (≥5 mA) for ≥72 h led to significant damage of the bacterial membrane, which likely resulted in leakage of cellular contents and influx of toxic substances through the damaged membrane. However, it remains unclear to what extent membrane damage and two-way (i.e., inward and outward) leakage are caused by lower (i.e., microampere) electric current in a shorter time frame. In this work, we set out to answer this question. We observed that the membrane damage was caused by microampere electric current in half an hour, which allowed two-way leakage of ions, small molecules, and proteins.

scholarly journals Detrimental Effect of Ozone on Pathogenic Bacteria

2021 ◽  
Author(s):  
Karyne Rangel ◽  
Felipe O Cabral ◽  
Guilherme Curty Lechuga ◽  
João P.R.S. Carvalho ◽  
Maria H.S. Villas-Bôas ◽  
...  
Keyword(s):  
Cell Viability ◽  
Pathogenic Bacteria ◽  
Detrimental Effect ◽  
Membrane Damage ◽  
Control Group ◽  
Bacterial Membrane ◽  
Low Doses ◽  
Bacterial Inactivation ◽  
E Coli ◽  
Minimal Concentration

(1) Background: Disinfection of medical devices designed for clinical use associated or not with the growing area of tissue engineering is an urgent need. However, traditional disinfection methods are not always suitable for some biomaterials, especially those sensitive to chemical, thermal, or radiation. Therefore, the objective of this study was to evaluate the minimal concentration of ozone gas (O3) necessary to control and kill a set of sensitive or multi-resistant Gram-positive and Gram-negative bacteria. The cell viability, membrane permeability, and the levels of reactive intracellular oxygen (ROS) species were also investigated; (2) Material and Methods: Four standard strains and a clinical MDR strain were exposed to low doses of ozone at different concentrations and times. Bacterial inactivation (cultivability, membrane damage) was investigated using colony counts, resazurin as a metabolic indicator, and propidium iodide (PI). A fluorescent probe (H2DCFDA) was used for the ROS analyses; (3) Results: No reduction in the count colony was detected after O3 exposure, compared to the control group. However, the cell viability of E. coli (30%), P. aeruginosa (25%), and A. baumannii (15%) was reduced considerably. The bacterial membrane of all strains was not affected by O3 but presented a significant increase of ROS in E. coli (90 ± 14%), P. aeruginosa (62.5 ± 19%), and A. baumanni (52.6 ± 5%); (4) Conclusion: Low doses of ozone were able to interfere in the cell viability of most strains studied, and although it does not cause damage to the bacterial membrane, increased levels of reactive ROS are responsible for causing a detrimental effect in the lipids, proteins, and DNA metabolism.

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