Targeting intracellular bacteria with an extended cationic amphiphilic polyproline helix

2015 ◽  
Vol 13 (21) ◽  
pp. 5930-5936 ◽  
Author(s):  
Manish Nepal ◽  
Shankar Thangamani ◽  
Mohamed N. Seleem ◽  
Jean Chmielewski
Keyword(s):  
Antibacterial Activity ◽  
Mammalian Cell ◽  
Mammalian Cells ◽  
Pathogenic Bacteria ◽  
Intracellular Bacteria ◽  
Cell Penetration

Eradicating pathogenic bacteria that reside within mammalian cells is currently quite difficult. Herein we describe an agent with the dual properties of efficient mammalian cell penetration and potent antibacterial activity. Significantly, these activities can be combined to target pathogenic bacteria within macrophages.

Bismuth(III) Thiophosphinates: Understanding How a Small Atomic Change Influences Antibacterial Activity and Mammalian Cell Viability

2020 ◽  
Vol 73 (12) ◽  
pp. 1226
Author(s):  
Dimuthu C. Senevirathna ◽  
Rebekah N. Duffin ◽  
Liam J. Stephens ◽  
Megan E. Herdman ◽  
Melissa V. Werrett ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Cell Viability ◽  
Mammalian Cell ◽  
Mammalian Cells ◽  
Bacterial Strains ◽  
X Ray Diffraction ◽  
Gram Negative ◽  
X Ray ◽  
X Ray Crystallography ◽  
Biological Studies

Diphenylphosphinothioic acid (HSP(=O)Ph2) and diphenylphosphinodithioic acid (HSP(=S)Ph2) have been used to synthesise four BiIII complexes: 1 [Bi(SP(=O)Ph2)3], 2 [BiPh(SP(=O)Ph2)2], 3 [BiPh2(SP(=O)Ph2)], and 4 [Bi(SP(=S)Ph2)3], using BiPh3 and [Bi(OtBu)3] as bismuth sources. The complexes have been characterised by NMR spectroscopy, mass spectrometry, infrared spectroscopy, powder X-ray diffraction, and singe crystal X-ray crystallography (2–4). Biological studies indicated that despite complexes 2 and 3 reducing mammalian cell viability, their antibacterial activity provides a good degree of selectivity towards both Gram positive and Gram negative bacterial strains. The minimum inhibitory concentrations for complexes 2 and 3 are in the range of 0.52–5.5µM towards the bacteria tested. Homoleptic complexes 1 and 4 were generally less active towards both bacterial and mammalian cells.

A double-label confocal imaging method for detecting the internalization of bacteria by non-phagocytic mammalian cells

1994 ◽  
Vol 52 ◽  
pp. 216-217
Author(s):  
M. H. Chestnut ◽  
L. L. Odioso ◽  
T. E. Otte ◽  
B.C. Hulette
Keyword(s):  
Plasma Membrane ◽  
Mammalian Cell ◽  
Mammalian Cells ◽  
Pathogenic Bacteria ◽  
Confocal Imaging ◽  
Imaging Method ◽  
Thin Sections ◽  
Double Label ◽  
Human Gingival Epithelial Cells ◽  
Immunofluorescence Labeling

Internalization by non-phagocytic mammalian cells is a key part of the life cycle of several important pathogenic bacteria. Mechanistic studies of this event often include transmission electron micrographs intended to demonstrate the presence of bacteria within the mammalian cell, but these data are often uncompelling. It is very difficult to be certain, based on the appearance and number of phospholipid membranes surrounding the bacterial cell, if it is enclosed in a vesicle, is surrounded directly by mammalian cell cytoplasm, or is merely contained within an invagination of the plasma membrane. Serial thin sections could provide the needed clarification, but are almost never presented, presumably because of the effort involved. Here we offer an alternative method, combining immunofluorescence labeling of the bacterium and fluorescence staining of the mammalian cell plasma membrane with a lipophilic dye, to visualize the internalization of bacteria by mammalian cells.Freshly isolated human gingival epithelial cells were cultured in keratinocyle serum-free medium (KSFM). Second passage cells were seeded on coverslips and placed in 24-well plates.

scholarly journals CodY-Mediated c-di-GMP-Dependent Inhibition of Mammalian Cell Invasion in Listeria monocytogenes

2017 ◽  
Vol 200 (5) ◽  
Author(s):  
Ahmed M. Elbakush ◽  
Kurt W. Miller ◽  
Mark Gomelsky
Keyword(s):  
Transcription Factor ◽  
Listeria Monocytogenes ◽  
Mammalian Cell ◽  
Cell Invasion ◽  
Mammalian Cells ◽  
Pathogenic Bacteria ◽  
Second Messenger ◽  
Content Type ◽  
Branched Chain

ABSTRACT Elevated levels of the second messenger c-di-GMP suppress virulence in diverse pathogenic bacteria, yet mechanisms are poorly characterized. In the foodborne pathogen Listeria monocytogenes , high c-di-GMP levels inhibit mammalian cell invasion. Here, we show that invasion is impaired because of the decreased expression levels of internalin genes whose products are involved in invasion. We further show that at high c-di-GMP levels, the expression of the entire virulence regulon is suppressed, and so is the expression of the prfA gene encoding the master activator of the virulence regulon. Analysis of mechanisms controlling prfA expression pointed to the transcription factor CodY as a c-di-GMP-sensitive component. In high-c-di-GMP strains, codY gene expression is decreased, apparently due to the lower activity of CodY, which functions as an activator of codY transcription. We found that listerial CodY does not bind c-di-GMP in vitro and therefore investigated whether c-di-GMP levels affect two known cofactors of listerial CodY, branched-chain amino acids and GTP. Our manipulation of branched-chain amino acid levels did not perturb the c-di-GMP effect; however, our replacement of listerial CodY with the streptococcal CodY homolog, whose activity is GTP independent, abolished the c-di-GMP effect. The results of this study suggest that elevated c-di-GMP levels decrease the activity of the coordinator of metabolism and virulence, CodY, possibly via lower GTP levels, and that decreased CodY activity suppresses L. monocytogenes virulence by the decreased expression of the PrfA virulence regulon. IMPORTANCE Listeria monocytogenes is a pathogen causing listeriosis, a disease responsible for the highest mortality rate among foodborne diseases. Understanding how the virulence of this pathogen is regulated is important for developing treatments to decrease the frequency of listerial infections in susceptible populations. In this study, we describe the mechanism through which elevated levels of the second messenger c-di-GMP inhibit listerial invasion in mammalian cells. Inhibition is caused by the decreased activity of the transcription factor CodY that coordinates metabolism and virulence.

scholarly journals Mammalian Cell Entry domains are required for bile resistance and virulence inSalmonella

2018 ◽  
Author(s):  
Georgia L. Isom ◽  
Jessica L. Rooke ◽  
Camila A. Antunes ◽  
Emma Sheehan ◽  
Timothy J. Wells ◽  
...  
Keyword(s):  
Mammalian Cell ◽  
Mammalian Cells ◽  
Bile Salts ◽  
Pathogenic Bacteria ◽  
Cell Entry ◽  
Direct Role ◽  
Bile Resistance ◽  
Mammalian Infection ◽  
Membrane Physiology

AbstractMCE domains were first reported inMycobacteriaas having a role inMammalianCellEntry, with subsequent studies showing their importance during infection. Here, we have examined the function of MCE proteins inSalmonellaTyphimurium during mammalian infection. We report that MCE proteins are required forSalmonellavirulence, but that this is not related to decreased adherence, entry or survival in mammalian cells. Instead, we reveal that MCE proteins are required forSalmonellabile resistance, in particular to withstand bile salts such as cholate and deoxycholate. Based on our previous work inEscherichia coli, and other studies that have reported roles for MCE proteins in membrane biogenesis, we propose thatSalmonellalacking MCE domains have a defective outer membrane that results in bile sensitivity and decreased virulencein vivo. These results suggest that MCE domains mediate fundamental aspects of bacterial membrane physiology as opposed to a proposed direct role in mammalian cell entry, explaining their conservation across both pathogenic and non-pathogenic bacteria.

scholarly journals Early Stage Efficacy and Toxicology Screening for Antibiotics and Enzyme Inhibitors

2018 ◽  
Author(s):  
Amarjit Luniwal
Keyword(s):  
Mammalian Cell ◽  
Mammalian Cells ◽  
Pathogenic Bacteria ◽  
Antimicrobial Agents ◽  
Early Stage ◽  
Antibiotic Activity ◽  
Cell Toxicity ◽  
Semialdehyde Dehydrogenase ◽  
Mammalian Cell Lines ◽  
Mammalian Cell Toxicity

The rise in organisms resistant to existing drugs has added urgency to the search for new antimicrobial agents. Aspartate β-semialdehyde dehydrogenase (ASADH) catalyzes a critical step in an essential microbial pathway that is absent in mammals. Our laboratory is using fragment library screening to identify efficient and selective ASADH inhibitors. These preliminary agents are then tested to identify compounds with desired antimicrobial properties for further refinement. Towards this end, we have established a microplate-based, dual assay approach using a single reagent to evaluate antibiotic activity and mammalian cell toxicity during early stage screening. The bacterial assay utilizes non-pathogenic bacteria to allow efficacy testing without a dedicated microbial laboratory. Toxicity assays are performed with a panel of mammalian cells derived from representative susceptible tissues. These assays can be adapted to target other microbial systems, such as fungi and biofilms, and additional mammalian cell lines can be added as needed. Application of this screening approach to antibiotic standards demonstrates the ability of these assays to identify bacterial selectivity and potential toxicity issues. Tests with ASADH inhibitors show some compounds with antibiotic activity, but as expected most of these early agents display higher than desired mammalian cell toxicity.

Bioenhancing Effect of Cow Urine Distillate and Pepper Extract on Antibacterial Activity of Azadirachta Indica Leaves

1970 ◽  
Vol 9 (2) ◽  
pp. 3212-3214
Author(s):  
Pramod Dhakal ◽  
Ankit a Achary ◽  
Vedamurthy Joshi
Keyword(s):  
Antibacterial Activity ◽  
Azadirachta Indica ◽  
Pathogenic Bacteria ◽  
Ethanol Extract ◽  
Watery Diarrhea ◽  
Diffusion Method ◽  
E Coli ◽  
Drug Molecules ◽  
Cow Urine

Bioenhancers are drug facilitator which do not show the typical drug activity but in combination to enhance the activity of other molecule in several way including increase the bioavailability of drug across the membrane, potentiating the drug molecules by conformational interaction, acting as receptor for drug molecules and making target cell more receptive to drugs and promote and increase the bioactivity or bioavailability or the uptake of drugs in combination therapy. The objective of the present study was to evaluate the antibacterial and activity of combination in Azadirachta indica extract with cow urine distillate and pepper extract against common pathogenic bacteria, a causative agent of watery diarrhea. It has been found that Indian indigenous cow urine and its distillate also possess bioenhancing ability. Bioenhancing role of cow urine distillate (CUD) and pepper extract was investigated on antibacterial activity of ethanol extract of Azadirachta indica. Antibacterial activity of ethanol extract neem alone and in combination with CUD and pepper extract were determined the ATCC strains against Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa and E-coli by cup plate diffusion method. Ethanol extract of neem has showed more effect on P. aeruginosa, E-coli than S. aureus and K. pneumonia with combination of CUD and pepper extract. CUD and pepper did not show any inhibition of test bacteria in low concentration. The antibacterial effect of combination of extract and CUD was higher than the inhibition caused by extract alone and is suggestive of the bioenhancing role of cow urine distillate and pepper. Moreover, inhibition of test bacteria was observed with less concentration of extract on combining with CUD

Biochemical Composition, Antibacterial and Anti-Biofilm Activities of Indian Medicinal Plants

2020 ◽  
Vol 18 ◽  
Author(s):  
Mulugeta Mulat ◽  
Fazlurrahman Khan ◽  
Archana Pandita
Keyword(s):  
Antibacterial Activity ◽  
Medicinal Plants ◽  
Pathogenic Bacteria ◽  
Chemical Constituents ◽  
Multidrug Resistant ◽  
Chloroform Extract ◽  
Acetone Extract ◽  
Biologically Active ◽  
Ocimum Sanctum ◽  
Agar Disc

Background: Medicinal plants have been used for treatments of various health ailments and the practices as a remedial back to thousands of years. Currently, plant-derived compounds used as alternative ways of treatment for multidrug-resistant pathogens. Objective: In the present study, various parts of six medical plants such as Solanum nigrum, Azadirachta indica, Vitex negundo, Mentha arvensis, Gloriosa superba, and Ocimum sanctum were extracted for obtaining biological active constituents. Methods: Soxhlet method of extraction was used for obtaining crude extracts. Agar disc diffusion and 96-well plate spectroscopic reading were used to detect the extract’s antibacterial and antibiofilm properties. Results: The obtained extracts were tested for antimicrobial and antibiofilm properties at 25 mg/mL concentrations. Maximum antibacterial activity was observed in O. sanctum chloroform extract (TUCE) against Staphylococcus aureus (24.33±1.52 mm), S. nigrum acetone extract (MAAC) against Salmonella Typhimurium (12.6 ± 1.5 mm) and Pseudomonas aeruginosa (15.0 ±2.0 mm). Only TUCE exhibited antibacterial activity at least a minimum inhibitory concentration of 0.781 mg/mL. Better antibiofilm activities were also exhibited by petroleum extracts of G. superba (KAPE) and S. nigrum (MAPE) against Escherichia coli, S. Typhimurium, P. aeruginosa and S. aureus. Moreover, S. nigrum acetone extract (MAAC) and O. sanctum chloroform extract (TUCE) were showed anti-swarming activity with a reduction of motility 56.3% against P. aeruginosa and 37.2% against S. aureus. MAAC also inhibits Las A activity (63.3% reduction) in P. aeruginosa. Conclusion: Extracts of TUCE, MAAC, MAPE, and KAPE were exhibited antibacterial and antibiofilm properties against the Gram-positive and Gram-negative pathogenic bacteria. GCMS identified chemical constituents are responsible for being biologically active.

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