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Molecules (Basel, Switzerland) Jun 2024ZnO nanorod nonwoven fabrics (ZNRN) were developed through hydrothermal synthesis to facilitate the prevention of the transmission of respiratory pathogens. The...
ZnO nanorod nonwoven fabrics (ZNRN) were developed through hydrothermal synthesis to facilitate the prevention of the transmission of respiratory pathogens. The superhydrophobicity and antibacterial properties of ZNRN were improved through the response surface methodology. The synthesized material exhibited significant water repellency, indicated by a water contact angle of 163.9°, and thus demonstrated antibacterial rates of 91.8% for Escherichia coli () and 79.75% for Staphylococcus aureus (). This indicated that with thinner peptidoglycan may be more easily killed than . This study identified significant effects of synthesis conditions on the antibacterial effectiveness, with comprehensive multivariate analyses elucidating the underlying correlations. In addition, the ZnO nanorod structure of ZNRN was characterized through SEM and XRD analyses. It endows the properties of superhydrophobicity (thus preventing bacteria from adhering to the ZNRN surface) and antibacterial capacity (thus damaging cells through the puncturing of these nanorods). Consequently, the alignment of two such features is desired to help support the development of personal protective equipment, which assists in avoiding the spread of respiratory infections.
Topics: Zinc Oxide; Anti-Bacterial Agents; Nanotubes; Hydrophobic and Hydrophilic Interactions; Escherichia coli; Staphylococcus aureus; Textiles; Microbial Sensitivity Tests; Surface Properties
PubMed: 38930981
DOI: 10.3390/molecules29122916 -
Antibiotics (Basel, Switzerland) Jun 2024The -independent oxacillin non-susceptible (MIONSA) strains represent a great clinical challenge, as they are not easily detected and can lead to treatment failure....
Genetic and Phenotypic Changes Related to the Development of -Independent Oxacillin Non-Susceptibility in ST8 Recovered after Antibiotic Therapy in a Patient with Bacteremia.
The -independent oxacillin non-susceptible (MIONSA) strains represent a great clinical challenge, as they are not easily detected and can lead to treatment failure. However, the responsible molecular mechanisms are still very little understood. Here, we studied four clinical ST8-MSSA- isolates recovered during the course of antibiotic treatment from a patient suffering successive episodes of bacteremia. The first isolates (SAMS1, SAMS2, and SAMS3) were susceptible to cefoxitin and oxacillin. The last one (SA2) was susceptible to cefoxitin, resistant to oxacillin, lacked genes, and had reduced susceptibility to teicoplanin. SA2 showed higher β-lactamase activity than SAMS1. However, β-lactamase hyperproduction could not be linked to oxacillin resistance as it was not inhibited by clavulanic acid, and no genetic changes that could account for its hyperproduction were found. Importantly, we hereby report the in vivo acquisition and coexistence of different adaptive mutations in genes associated with peptidoglycan synthesis (, , , , and /), which is possibly related with the development of oxacillin resistance and reduced susceptibility to teicoplanin in SA2. Using three-dimensional models and PBP binding assays, we demonstrated the high contribution of the SA2 PBP2 Ala450Asp mutation to the observed oxacillin resistance phenotype. Our results should be considered as a warning for physicians and microbiologists in the region, as MIONSA detection and treatment represent an important clinical challenge.
PubMed: 38927220
DOI: 10.3390/antibiotics13060554 -
Antibiotics (Basel, Switzerland) Jun 2024The rising incidence of extensively drug-resistant (XDR) , including carbapenem- and colistin-resistant strains, leads to the limitation of available effective...
The rising incidence of extensively drug-resistant (XDR) , including carbapenem- and colistin-resistant strains, leads to the limitation of available effective antibiotics. , known as chewing tea, is produced from var. or Assam tea leaves fermentation. Previous studies revealed that the extract of contains various phenolic and flavonoid compounds with numerous biological activities including antibacterial activity. However, the antibacterial activity of against XDR bacteria especially colistin-resistant strains had not been investigated. In this study, the compositions of phenolic and flavonoid compounds in fresh, steamed, and fermented Assam tea leaves were examined by HPLC, and their antibacterial activities were evaluated by the determination of the MIC and MBC. Pyrogallol was detected only in the extract from and showed the highest activities with an MIC of 0.25 mg/mL and an MBC of 0.25-0.5 mg/mL against methicillin-susceptible , methicillin-resistant , ATCC 25922, colistin-resistant , and colistin-resistant . The effects on morphology and proteomic changes in NH54 treated with extract were characterized by SEM and label-free quantitative shotgun proteomics analysis. The results revealed that extract caused the decrease in bacterial cell wall integrity and cell lysis. The up- and downregulated expression with approximately a 2 to >5-fold change in proteins involved in peptidoglycan synthesis and outer membrane, carbohydrate, and amino acid metabolism were identified. These findings suggested that containing pyrogallol and other secondary metabolites from fermentation has potential as an alternative candidate with an antibacterial agent or natural active pharmaceutical ingredient against XDR bacteria including colistin-resistant bacteria.
PubMed: 38927202
DOI: 10.3390/antibiotics13060536 -
Nature Communications Jun 2024Most rod-shaped bacteria elongate by inserting new cell wall material into the inner surface of the cell sidewall. This is performed by class A penicillin binding...
Most rod-shaped bacteria elongate by inserting new cell wall material into the inner surface of the cell sidewall. This is performed by class A penicillin binding proteins (PBPs) and a highly conserved protein complex, the elongasome, which moves processively around the cell circumference and inserts long glycan strands that act as barrel-hoop-like reinforcing structures, thereby giving rise to a rod-shaped cell. However, it remains unclear how elongasome synthesis dynamics and termination events are regulated to determine the length of these critical cell-reinforcing structures. To address this, we developed a method to track individual elongasome complexes around the entire circumference of Bacillus subtilis cells for minutes-long periods using single-molecule fluorescence microscopy. We found that the B. subtilis elongasome is highly processive and that processive synthesis events are frequently terminated by rapid reversal or extended pauses. We found that cellular levels of RodA regulate elongasome processivity, reversal and pausing. Our single-molecule data, together with stochastic simulations, show that elongasome dynamics and processivity are regulated by molecular motor tug-of-war competition between several, likely two, oppositely oriented peptidoglycan synthesis complexes associated with the MreB filament. Altogether these results demonstrate that molecular motor tug-of-war is a key regulator of elongasome dynamics in B. subtilis, which likely also regulates the cell shape via modulation of elongasome processivity.
Topics: Bacillus subtilis; Cell Wall; Bacterial Proteins; Penicillin-Binding Proteins; Peptidoglycan; Microscopy, Fluorescence; Single Molecule Imaging; Molecular Motor Proteins
PubMed: 38926336
DOI: 10.1038/s41467-024-49785-x -
Drug Discoveries & Therapeutics Jun 2024Staphylococcus aureus, a Gram-positive bacterium, causes inflammatory skin diseases, such as atopic dermatitis, and serious systemic diseases, such as sepsis. In the...
Staphylococcus aureus, a Gram-positive bacterium, causes inflammatory skin diseases, such as atopic dermatitis, and serious systemic diseases, such as sepsis. In the skin and nasal environment, peptidoglycan (PGN)-degrading enzymes, including lysozyme and lysostaphin, affects S. aureus PGN. However, the effects of PGN-degrading enzymes on the acute innate immune-inducing activity of S. aureus have not yet been investigated. In this study, we demonstrated that PGN-degrading enzymes induce acute silkworm hemolymph melanization by S. aureus. Insoluble fractions of S. aureus treated with lysozyme, lysostaphin, or both enzymes, were prepared. Melanization of the silkworm hemolymph caused by the injection of these insoluble fractions was higher than that of S. aureus without enzyme treatment. These results suggest that structural changes in S. aureus PGN caused by PGN-degrading enzymes affect the acute innate immune response in silkworms.
PubMed: 38925960
DOI: 10.5582/ddt.2024.01026 -
Toxics May 2024Acrylamide (AA) and 5-hydroxymethylfurfural (HMF), which are potentially carcinogenic to humans, are often produced during the hot processing of foods. This study first...
Acrylamide (AA) and 5-hydroxymethylfurfural (HMF), which are potentially carcinogenic to humans, are often produced during the hot processing of foods. This study first used a molecular docking model to simulate the binding behavior of four lactic acid bacteria peptidoglycans (PGNs) to AA/HMF, and the binding rate of LAB-based PGNs to AA/HMF was evaluated in vitro. In silico results show that interaction energy is the driving force responsible for the adsorption of LAB-derived PGNs to AA/HMF. In vitro results showed that the PGN of B1-04 bound the most AA (28.7%) and HMF (48.0%), followed by NCFM, CICC 6079, and CICC 22135. Moreover, an AA/HMF-bound layer on the cell surface of B1-04 was observed via AFM and SEM due to adsorption. XPS analysis indicated the removal rate of AA/HMF by selected strains was positively correlated with the proportion of C-O, C=O, and N-H groups of PGNs. The atoms O1, O2, O3, O4, N1, N2, N3, H1, and H2 are involved in the adsorption of LAB-based PGNs to AA/HMF. Thus, the PGNs derived from these four strains can be regarded as natural adsorbents for the binding of AA/HMF.
PubMed: 38922060
DOI: 10.3390/toxics12060380 -
Marine Drugs Jun 2024Sortase A (SrtA) is a cysteine transpeptidase that binds to the periplasmic membrane and plays a crucial role in attaching surface proteins, including staphylococcal...
Sortase A (SrtA) is a cysteine transpeptidase that binds to the periplasmic membrane and plays a crucial role in attaching surface proteins, including staphylococcal protein A (SpA), to the peptidoglycan cell wall. Six pentacyclic polyketides (-) were isolated from the marine sponge sp., and their structures were elucidated using spectroscopic techniques and by comparing them to previously reported data. Among them, halenaquinol () was found to be the most potent SrtA inhibitor, with an IC of 13.94 μM (4.66 μg/mL). Semi-quantitative reverse transcription PCR data suggest that halenaquinol does not inhibit the transcription of and , while Western blot analysis and immunofluorescence microscopy images suggest that it blocks the cell wall surface anchoring of SpA by inhibiting the activity of SrtA. The onset and magnitude of the inhibition of SpA anchoring on the cell wall surface in that has been treated with halenaquinol at a value 8× that of the IC of SrtA are comparable to those for an -deletion mutant. These findings contribute to the understanding of the mechanism by which marine-derived pentacyclic polyketides inhibit SrtA, highlighting their potential as anti-infective agents targeting virulence.
Topics: Aminoacyltransferases; Cysteine Endopeptidases; Staphylococcus aureus; Cell Wall; Bacterial Proteins; Animals; Porifera; Anti-Bacterial Agents; Polyketides
PubMed: 38921577
DOI: 10.3390/md22060266 -
Membranes Jun 2024Bacterial extracellular vesicles (bEVs) secreted by Gram-negative bacteria are referred to as outer membrane vesicles (OMVs) because they originate in the outer...
Bacterial extracellular vesicles (bEVs) secreted by Gram-negative bacteria are referred to as outer membrane vesicles (OMVs) because they originate in the outer membrane. OMVs are membrane-coated vesicles 20-250 nm in size. They contain lipopolysaccharide (LPS), peptidoglycan, proteins, lipids, nucleic acids, and other substances derived from their parent bacteria and participate in the transmission of information to host cells. OMVs have broad prospects in terms of potential application in the fields of adjuvants, vaccines, and drug delivery vehicles. Currently, there remains a lack of efficient and convenient methods to isolate OMVs, which greatly limits OMV-related research. In this study, we developed a fast, convenient, and low-cost gradient filtration method to separate OMVs that can achieve industrial-scale production while maintaining the biological activity of the isolated OMVs. We compared the gradient filtration method with traditional ultracentrifugation to isolate OMVs from probiotic Nissle 1917 (EcN) bacteria. Then, we used RAW264.7 macrophages as an in vitro model to study the influence on the immune function of EcN-derived OMVs obtained through the gradient filtration method. Our results indicated that EcN-derived OMVs were efficiently isolated using our gradient filtration method. The level of OMV enrichment obtained via our gradient filtration method was about twice as efficient as that achieved through traditional ultracentrifugation. The EcN-derived OMVs enriched through the gradient filtration method were successfully taken up by RAW264.7 macrophages and induced them to secrete pro-inflammatory cytokines such as tumor necrosis factor α (TNF-α) and interleukins (ILs) 6 and 1β, as well as anti-inflammatory cytokine IL-10. Furthermore, EcN-derived OMVs induced more anti-inflammatory response (i.e., IL-10) than pro-inflammatory response (i.e., TNF-α, IL-6, and IL-1β). These results were consistent with those reported in the literature. The related literature reported that EcN-derived OMVs obtained through ultracentrifugation could induce stronger anti-inflammatory responses than pro-inflammatory responses in RAW264.7 macrophages. Our simple and novel separation method may therefore have promising prospects in terms of applications involving the study of OMVs.
PubMed: 38921502
DOI: 10.3390/membranes14060135 -
MBio Jun 2024encodes the beta-lactamase AmpC, which promotes resistance to beta-lactam antibiotics. Expression of is induced by anhydro-muropeptides (AMPs) released from the...
UNLABELLED
encodes the beta-lactamase AmpC, which promotes resistance to beta-lactam antibiotics. Expression of is induced by anhydro-muropeptides (AMPs) released from the peptidoglycan (PG) cell wall upon beta-lactam treatment. AmpC can also be induced via genetic inactivation of PG biogenesis factors such as the endopeptidase DacB that cleaves PG crosslinks. Mutants in occur in beta-lactam-resistant clinical isolates of , but it has remained unclear why DacB inactivation promotes induction. Similarly, the inactivation of lytic transglycosylase (LT) enzymes such as SltB1 that cut PG glycans has also been associated with induction and beta-lactam resistance. Given that LT enzymes are capable of producing AMP products that serve as inducers, this latter observation has been especially difficult to explain. Here, we show that induction in or mutants requires another LT enzyme called MltG. In , MltG has been implicated in the degradation of nascent PG strands produced upon beta-lactam treatment. Accordingly, in and mutants, we detected the MltG-dependent production of pentapeptide-containing AMP products that are signatures of nascent PG degradation. Our results therefore support a model in which SltB1 and DacB use their PG-cleaving activity to open space in the PG matrix for the insertion of new material. Thus, their inactivation mimics low-level beta-lactam treatment by reducing the efficiency of new PG insertion into the wall, causing the degradation of some nascent PG material by MltG to produce the -inducing signal.
IMPORTANCE
Inducible beta-lactamases like the ampC system of are a common determinant of beta-lactam resistance among gram-negative bacteria. The regulation of is elegantly tuned to detect defects in cell wall synthesis caused by beta-lactam drugs. Studies of mutations causing induction in the absence of drug therefore promise to reveal new insights into the process of cell wall biogenesis in addition to aiding our understanding of how resistance to beta-lactam antibiotics arises in the clinic. In this study, the induction phenotype for mutants lacking a glycan-cleaving enzyme or an enzyme that cuts cell wall crosslinks was used to uncover a potential role for these enzymes in making space in the wall matrix for the insertion of new material during cell growth.
PubMed: 38920394
DOI: 10.1128/mbio.01419-24 -
Frontiers in Immunology 2024Therapeutic antibodies have become a major strategy to treat oncologic diseases. For chronic lymphocytic leukemia, antibodies against CD20 are used to target and elicit...
INTRODUCTION
Therapeutic antibodies have become a major strategy to treat oncologic diseases. For chronic lymphocytic leukemia, antibodies against CD20 are used to target and elicit cytotoxic responses against malignant B cells. However, efficacy is often compromised due to a suppressive microenvironment that interferes with cellular immune responses. To overcome this suppression, agonists of pattern recognition receptors have been studied which promote direct cytotoxicity or elicit anti-tumoral immune responses. NOD2 is an intracellular pattern recognition receptor that participates in the detection of peptidoglycan, a key component of bacterial cell walls. This detection then mediates the activation of multiple signaling pathways in myeloid cells. Although several NOD2 agonists are being used worldwide, the potential benefit of these agents in the context of antibody therapy has not been explored.
METHODS
Primary cells from healthy-donor volunteers (PBMCs, monocytes) or CLL patients (monocytes) were treated with versus without the NOD2 agonist L18-MDP, then antibody-mediated responses were assessed. In vivo, the Eµ-TCL1 mouse model of CLL was used to test the effects of L18-MDP treatment alone and in combination with anti-CD20 antibody.
RESULTS
Treatment of peripheral blood mononuclear cells with L18-MDP led to activation of monocytes from both healthy donors and CLL patients. In addition, there was an upregulation of activating FcγR in monocytes and a subsequent increase in antibody-mediated phagocytosis. This effect required the NF-κB and p38 signaling pathways. Treatment with L18-MDP plus anti-CD20 antibody in the Eµ-TCL model of CLL led to a significant reduction of CLL load, as well as to phenotypic changes in splenic monocytes and macrophages.
CONCLUSIONS
Taken together, these results suggest that NOD2 agonists help overturn the suppression of myeloid cells, and may improve the efficacy of antibody therapy for CLL.
Topics: Nod2 Signaling Adaptor Protein; Animals; Humans; Receptors, IgG; Mice; Macrophages; Leukemia, Lymphocytic, Chronic, B-Cell; Acetylmuramyl-Alanyl-Isoglutamine; Female; Mice, Inbred C57BL; Signal Transduction; Phagocytosis; Rituximab
PubMed: 38919608
DOI: 10.3389/fimmu.2024.1409333