The emergence and worldwide dissemination of carbapenemase-producing Gram-negative bacteria are a major public health threat. Metallo-β-lactamases (MBLs) represent the largest family of ...carbapenemases. Regrettably, these resistance determinants are spreading worldwide. Among them, the New Delhi metallo-β-lactamase (NDM-1) is experiencing the fastest and largest geographical spread. NDM-1 β-lactamase is anchored to the bacterial outer membrane, while most MBLs are soluble, periplasmic enzymes. This unique cellular localization favors the selective secretion of active NDM-1 into outer membrane vesicles (OMVs). Here, we advance the idea that NDM-containing vesicles serve as vehicles for the local dissemination of NDM-1. We show that OMVs with NDM-1 can protect a carbapenem-susceptible strain of Escherichia coli upon treatment with meropenem in a Galleria mellonella infection model. Survival curves of G. mellonella revealed that vesicle encapsulation enhances the action of NDM-1, prolonging and favoring bacterial protection against meropenem inside the larva hemolymph. We also demonstrate that E. coli cells expressing NDM-1 protect a susceptible Pseudomonas aeruginosa strain within the larvae in the presence of meropenem. By using E. coli variants engineered to secrete variable amounts of NDM-1, we demonstrate that the protective effect correlates with the amount of NDM-1 secreted into vesicles. We conclude that secretion of NDM-1 into OMVs contributes to the survival of otherwise susceptible nearby bacteria at infection sites. These results disclose that OMVs play a role in the establishment of bacterial communities, in addition to traditional horizontal gene transfer mechanisms.
Resistance to carbapenems, last-resort antibiotics, is spreading worldwide, raising great concern. NDM-1 is one of the most potent and widely disseminated carbapenem-hydrolyzing enzymes spread among many bacteria and is secreted to the extracellular medium within outer membrane vesicles. We show that vesicles carrying NDM-1 can protect carbapenem-susceptible strains of E. coli and P. aeruginosa upon treatment with meropenem in a live infection model. These vesicles act as nanoparticles that encapsulate and transport NDM-1, prolonging and favoring its action against meropenem inside a living organism. Secretion of NDM-1 into vesicles contributes to the survival of otherwise susceptible nearby bacteria at infection sites. We propose that vesicles play a role in the establishment of bacterial communities and the dissemination of antibiotic resistance, in addition to traditional horizontal gene transfer mechanisms.
Azithromycin (AZ) is a broad-spectrum antibiotic with anti-inflammatory and antiquorum sensing activity against biofilm forming bacteria such as Pseudomonas aeruginosa. AZ administered by oral or ...parenteral routes, however, neither efficiently accesses nor remains in therapeutic doses inside pulmonary biofilm depths. Instead, inhaled nanocarriers loaded with AZ may revert the problem of low accessibility and permanence of AZ into biofilms, enhancing its antimicrobial activity. The first inhalable nanovesicle formulation of AZ, nanoarchaeosome-AZ (nanoARC-AZ), is here presented. NanoARC prepared with total polar archaeolipids (TPAs), rich in 2,3-di-O-phytanyl-sn-glycero-1-phospho-(3′-sn-glycerol-1′-methylphosphate) (PGP-Me) from Halorubrum tebenquichense archaebacteria, consisted of ∼180 nm-diameter nanovesicles, loaded with 0.28 w/w AZ/TPA. NanoARC-AZ displayed lower minimal inhibitory concentration and minimal bactericidal concentration, higher preformed biofilm disruptive, and anti-PAO1 activity in biofilms than AZ. NanoARC penetrated and disrupted the structure of the PAO1 biofilm within only 1 h. Two milliliters of 15 μg/mL AZ nanoARC-AZ nebulized for 5 min rendered AZ doses compatible with in vitro antibacterial activity. The strong association between AZ and the nanoARC bilayer, combined with electrostatic attraction and trapping into perpendicular methyl groups of archaeolipids, as determined by Laurdan fluorescence anisotropy, generalized polarization, and small-angle X-ray scattering, was critical to stabilize during storage and endure shear forces of nebulization. NanoARC-AZ was noncytotoxic on A549 cells and human THP-1-derived macrophages, deserving further preclinical exploration as enhancers of AZ anti-PAO1 activity.
In the last years, the decreasing effectiveness of conventional antimicrobial-drugs has caused serious problems due to the rapid emergence of multidrug-resistant pathogens. This situation has brought ...attention to other antimicrobial agents like antimicrobial peptides (AMPs), for being considered an alternative to conventional drugs. These compounds target bacterial membranes for their activity, which gives them a broad spectrum of action and less probable resistance development. That is why the peptide-membrane interaction is a crucial aspect to consider in the study of AMPs. The aim of this work was the characterization of the “de novo” designed peptide P1, studying its interactions with model membranes (i.e. liposomes of DMPC:DMPG 5:1) in order to evaluate the final position of the peptide upon interacting with the membrane. Also, we tested the effects of the peptide in gram-positive and gram-negative bacteria. Later, by spectroscopic methods, the ability of the peptide to permeabilize the inner and outer membrane of E. coli and plasmatic membrane of S. aureus was assessed. The results obtained confirmed that P1 can disrupt both membranes, showing some difference in its activity as a function of the nature of each bacterial cell wall, confirming higher effects on gram-positive S. aureus. Finally, we also showed the ability of P1 to inhibit biofilms of that gram-positive bacterium.
All data obtained in this work allowed us to propose a model, where the first interactions of the peptide with the bacterial envelope, seem to depend on the gram-negative and gram-positive cell wall structure. After that first interaction, the peptide is stabilized by Trp residues depth inserted into the hydrocarbon region, promoting several changes in the organization of the lipid bilayer, following a carpet-like mechanism, which results in permeabilization of the membrane, triggering the antimicrobial activity.
•The difference in gram-negative and gram-positive envelop play a key role in the interaction of P1.•P1 acts through the carpet-like model, covering the surface in parallel alignments to the membrane.•Cooperativity and kinetics of membrane permeabilization are key factors in antimicrobial activity.•P1 was able to inhibit the biofilm formation of S. aureus at sub-MIC concentrations.
Cationic antimicrobial peptides (AMPs) are short linear amino acid sequences, which display antimicrobial activity against a wide range of bacterial species. They are promising novel antimicrobials ...since they have shown bactericidal effects against multiresistant bacteria. Their amphiphilic structure with hydrophobic and cationic regions drives their interaction with anionic bacterial cytoplasmic membranes, which leads to their disruption. In this work two synthetic designed AMPs, P5 and P6.2, which have been previously analyzed in their ability to interact with bacterial or eukaryotic membranes, were evaluated in their anti-biofilm and in vivo antibacterial activity. In a first step, a time-kill kinetic assay against P. aeruginosa and S. aureus and a curve for hemolytic activity were performed in order to determine the killing rate and the possible undesirable toxic effect, respectively, for both peptides. The biofilm inhibitory activity was quantified at sub MIC concentrations of the peptides and the results showed that P5 displayed antibiofilm activity on both strains while P6.2 only on S. aureus. Scanning electron microscopy (SEM) of bacteria treated with peptides at their MIC revealed protruding blisters on Gam-negative P. aeruginosa strain, but almost no visible surface alteration on Gram-positive S. aureus. These micrographs highlighted different manifestations of the membrane-disrupting activity that these kinds of peptides possess. Finally, both peptides were analyzed in vivo, in the lungs of neutropenic mice previously instilled with P. aeruginosa. Mice lungs were surgically extracted and bacteria and pro-inflammatory cytokines (IL-β, IL-6 and TNF-α) were quantified by colony forming units and ELISA, respectively. Results showed that instillation of the peptides produced a significant decrease in the number of living bacteria in the lungs, concomitant with a decrease in pro-inflammatory cytokines. Overall, the results presented here suggest that these two new peptides could be good candidates for future drug development for anti-biofilm and anti-infective therapy.
•Two novel AMPs P5 and P6.2 were analyzed in P.aeruginosa and S. aureus.•Scanning electron microscopy revealed distinct membranolytic activity.•Both peptides display in vitro antibiofilm activity.•Peptides diminished P.aeruginosa burden in the lungs of neutropenic mice.•P5 and P6.2 diminished lung pro-inflammatory cytokines.
Este artículo presenta los resultados de una investigación realizada con el objetivo de comprender la relación entre esta pandemia y el medioambiente, tema crucial en la coyuntura porque la ...propagación global de la COVID-19 se convirtió en un momento para repensar nuestra relación con el planeta, asunto que los medios contribuyen a debatir. Se hizo un análisis de la cobertura periodística en El Tiempo y El Espectador durante los tres meses de confinamiento estricto. La metodología utilizada fue el análisis del tratamiento informativo a partir de las categorías de cubrimiento y despliegue en el marco de una convergencia mediática. Entre los principales hallazgos encontramos una alta procedencia de información de agencias; predominio de la noticia como género y un promedio de fuentes consultadas cuya calidad favorece la diversidad de voces e intereses. Además, el tema predominante en El Espectador es la reducción de la contaminación por el confinamiento, mientras que en El Tiempo son las acciones desfavorables para el medioambiente. El enfoque ambiental general en las publicaciones es antropocentrista y la narrativa periodística sigue las lógicas análogas, desaprovechando las potencialidades del ecosistema digital.
, the etiologic agent of tuberculosis (TB), has killed nearly one billion people during the last two centuries. Nowadays, TB remains a major global health problem ranked among the top 10 causes of ...death worldwide. One of the main challenges in developing new strategies to fight TB is focused on reducing the duration and complexity of drug regimens. Cannabidiol (CBD) is the main nonpsychoactive ingredient extracted from the
. plant, which has been shown to be biologically active against bacteria. The purpose of this work was to investigate the antimicrobial effect of CBD on
intracellular infection.
To assess the minimum inhibitory concentration (MIC) of CBD on mycobacterial strains, the MTT assay was performed on
, and the Colony-Forming Unit (CFU) assay was conducted on
H37Rv. Additionally, the cytotoxic effect of CBD on THP-1 cells was assessed by MTT assay. Moreover, macrophages derived from the THP-1 cell were infected with
H37Rv (multiplicity of infection 1:10) to evaluate the intracellular activity of CBD by determining the CFU/mL.
Antimicrobial activity against
(MIC=100 μM) and
H37Rv (MIC=25 μM) cultures was exhibited by CBD. Furthermore, the effect of CBD was also evaluated on
H37Rv infected macrophage cells. Interestingly, a reduction in viable intracellular
H37Rv bacteria was observed after 24 h of treatment. Moreover, CBD exhibited a safe profile toward human THP-1 cells, since it showed no toxicity (CC
=1075 μM) at a concentration of antibacterial effect (selectivity index 43).
These results extend the knowledge regarding the antimicrobial activity of CBD and demonstrate its ability to kill the human intracellular pathogen
Antimicrobial peptides (AMPs) are promising novel antibiotics since they have shown antimicrobial activity against a wide range of bacterial species, including multiresistant bacteria; however, ...toxicity is the major barrier to convert antimicrobial peptides into active drugs. A profound and proper understanding of the complex interactions between these peptides and biological membranes using biophysical tools and model membranes seems to be a key factor in the race to develop a suitable antimicrobial peptide therapy for clinical use. In the search for such therapy, different combined approaches with conventional antibiotics have been evaluated in recent years and demonstrated to improve the therapeutic potential of AMPs. Some of these approaches have revealed promising additive or synergistic activity between AMPs and chemical antibiotics. This review will give an insight into the possibilities that physicochemical tools can give in the AMPs research and also address the state of the art on the current promising combined therapies between AMPs and conventional antibiotics, which appear to be a plausible future opportunity for AMPs treatment.
•The biophysical and microbiological characteristics of 3 new designed cationic antimicrobial peptides (CAMPs) were studied.•A CAMP sequence was modified in order to increase or diminish the ...hydrophobic face when structured as alpha helix.•Importance of the hydrophobic moment in the peptide-membrane interaction was analyzed through extensive biophysical studies.•A mode of action of these amphipathic alpha helical peptides is also proposed.
Cationic antimicrobial peptides (CAMPs) represent important self defense molecules in many organisms, including humans. These peptides have a broad spectrum of activities, killing or neutralizing many Gram-negative and Gram-positive bacteria. The emergence of multidrug resistant microbes has stimulated research on the development of alternative antibiotics. In the search for new antibiotics, cationic antimicrobial peptides (CAMPs) offer a viable alternative to conventional antibiotics, as they physically disrupt the bacterial membranes, leading to lysis of microbial membranes and eventually cell death. In particular, the group of linear α-helical cationic peptides has attracted increasing interest from clinical as well as basic research during the last decade.
In this work, we studied the biophysical and microbiological characteristics of three new designed CAMPs. We modified a previously studied CAMP sequence, in order to increase or diminish the hydrophobic face, changing the position of two lysines or replacing three leucines, respectively. These mutations modified the hydrophobic moment of the resulting peptides and allowed us to study the importance of this parameter in the membrane interactions of the peptides. The structural properties of the peptides were also correlated with their membrane-disruptive abilities, antimicrobial activities and hemolysis of human red blood cells.
Antibiotic resistance is one of the main problems concerning public health or clinical practice. Antimicrobial peptides appear as good candidates for the development of new therapeutic drugs. In this ...study we de novo designed a group of cationic antimicrobial peptides, analyzed its physicochemical properties, including its structure by circular dichroism and studied its antimicrobial properties against a panel of clinical isolates expressing different mechanisms of resistance. Three cationic alpha helical peptides exhibited antimicrobial activity comparable to, or even better than the comparator omiganan (MBI-226).
De novo designed alpha helical cationic peptides with antimicrobial activity against multi-resistant clinical isolates. Display omitted
•De novo designed cationic peptides.•Physicochemical properties of peptides.•Antimicrobial resistant bacteria.
High spatial and temporal resolution hydrographic data collected by Southern Elephant Seals (Mirounga leonina, SESs) and satellite remote sensing data allow a detailed oceanographic description of ...the Argentine Continental Shelf (ACS). In-situ data were obtained from the CTD (Conductivity, Temperature, and Depth), accelerometer, and hydrophone sensors attached to five SESs that crossed the ACS between the 17th and 31st of October 2019. The analysis of the temperature (T) and salinity (S) along the trajectories allowed us to identify two different regions: north and south of 42°S. Satellite Sea Surface Temperature (SST) data suggests that north of 42°S, warm waters are coming from the San Matias Gulf (SMG). The high spatio-temporal resolution of the in-situ data shows regions with intense gradients along the T and S sections that were associated with a seasonal front that develops north of Península Valdés in winter due to the entrance of cold and fresh water to the SMG. The speed of the SESs is correlated with tidal currents in the coastal portion of the northern region, which is in good agreement with the macrotidal regime observed. A large number of Prey Catch Attempts (PCA), a measure obtained from the accelerometer sensor, indicates that SESs also feed in this region, contradicting suggestions from previous works. The analysis of wind intensity estimated from acoustic sensors allowed us to rule out the local wind as the cause of fast thermocline breakups observed along the SESs trajectories. Finally, we show that the maximum depth reached by the elephant seals can be used to detect errors in the bathymetry charts.
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