-
Marine Drugs Jun 2024This study aimed to improve the conventional procedure of alginate isolation from the brown seaweed ( L.) biomass and investigate the possibility of further valorization...
This study aimed to improve the conventional procedure of alginate isolation from the brown seaweed ( L.) biomass and investigate the possibility of further valorization of the ethanolic fraction representing the byproduct after the degreasing and depigmentation of biomass. The acid treatment of biomass supported by ultrasound was modeled and optimized regarding the alginate yield using a response surface methodology based on the Box-Behnken design. A treatment time of 30 min, a liquid-to-solid ratio of 30 mL/g, and a treatment temperature of 47 °C were proposed as optimal conditions under which the alginate yield related to the mass of dry biomass was 30.9%. The use of ultrasonic radiation significantly reduced the time required for the acid treatment of biomass by about 4 to 24 times compared to other available conventional procedures. The isolated alginate had an M/G ratio of 1.08, which indicates a greater presence of M-blocks in its structure and the possibility of forming a soft and elastic hydrogel with its use. The chemical composition of the ethanolic fraction including total antioxidant content (293 mg gallic acid equivalent/g dry weight), total flavonoid content (14.9 mg rutin equivalent/g dry weight), contents of macroelements (the highest content of sodium, 106.59 mg/g dry weight), and microelement content (the highest content of boron, 198.84 mg/g dry weight) was determined, and the identification of bioactive compounds was carried out. The results of ultra high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry analysis confirmed the presence of 48 compounds, of which 41 compounds were identified as sugar alcohol, phenolic compounds, and lipids. According to the 2,2-diphenyl-1-picrylhydrazyl assay, the radical scavenging activity of the ethanolic fraction (the half-maximal inhibitory concentration of 42.84 ± 0.81 μg/mL) indicated its strong activity, which was almost the same as in the case of the positive control, synthetic antioxidant butylhydroxytoluene (the half-maximal inhibitory concentration of 36.61 ± 0.79 μg/mL). Gram-positive bacteria (, , and ) were more sensitive to the ethanolic fraction compared to Gram-negative bacteria (, , and ). The obtained results indicated the possibility of the further use of the ethanolic fraction as a fertilizer for plant growth in different species and antifouling agents, applicable in aquaculture.
Topics: Alginates; Laminaria; Antioxidants; Ethanol; Seaweed; Biomass; Flavonoids; Edible Seaweeds
PubMed: 38921591
DOI: 10.3390/md22060280 -
Marine Drugs May 2024Five new naphthalene derivatives dalesconosides A-D, F (-, ), a known synthetic analogue named dalesconoside E (), and eighteen known compounds (-) were isolated from...
Five new naphthalene derivatives dalesconosides A-D, F (-, ), a known synthetic analogue named dalesconoside E (), and eighteen known compounds (-) were isolated from MCZ-18, which is an endophytic fungus obtained from the Chinese mangrove plant . Differing from previously reported naphthalenes, compounds and were bearing a rare ribofuranoside substituted at C-1 and the 5-methyltetrahydrofuran-2,3-diol moiety, respectively. Their structures were determined by detailed nuclear magnetic resonance (NMR) and mass spectroscopic (MS) analyses, while the absolute configurations were established by theoretical electronic circular dichroism (ECD) calculation. Compounds , , - and showed broad ranges of antimicrobial spectrum against five indicator test microorganisms (, Methicillin-resistant , , and ); especially, , and were most potent. The variations in structure and attendant biological activities provided fresh insights concerning structure-activity relationships for the naphthalene derivatives.
Topics: Naphthalenes; Microbial Sensitivity Tests; Structure-Activity Relationship; Magnetic Resonance Spectroscopy; Anti-Bacterial Agents; Candida albicans; Molecular Structure; Rhizophoraceae; Endophytes; Anti-Infective Agents
PubMed: 38921554
DOI: 10.3390/md22060242 -
Journal of Fungi (Basel, Switzerland) May 2024In this study, bacteria residing in the gut of the rice weevils ( L.) (Coleoptera: Curculionidae) feeding on aflatoxin-contaminated corn kernels were isolated and...
In this study, bacteria residing in the gut of the rice weevils ( L.) (Coleoptera: Curculionidae) feeding on aflatoxin-contaminated corn kernels were isolated and evaluated for their ability to suppress and to remove/degrade aflatoxin B1 (AFB1). Four morphologically distinct gut-associated bacterial isolates were isolated and identified as (RWGB1), (RWGB2), (RWGB3), and (RWGB4) based on 16S rRNA gene sequence analysis. These bacterial isolates inhibited growth in the dual culture assay and induced morphological deformities in the fungal hyphae, as confirmed by scanning electron microscopy. All four bacterial isolates were capable of removing AFB1 from the nutrient broth medium. In addition, culture supernatants of these bacterial isolates degraded AFB1, and the degradation of toxin molecules was confirmed by liquid chromatography-mass spectrometry. The bacterial isolates, RWGB1, RWGB2, and RWGB4, were capable of producing antifungal volatile organic compounds that inhibited growth. These results suggest that the bacterial isolates from gut have the potential to bind and/or degrade AFB1. Further research on their application in the food and feed industries could enhance the safety of food and feed production.
PubMed: 38921363
DOI: 10.3390/jof10060377 -
Gels (Basel, Switzerland) Jun 2024A combination of Poloxamer 407 (P407) and hydroxypropyl methylcellulose (HPMC) hydrosols is proposed as an in situ thermo-gelling vehicle for the nasal drug delivery of...
A combination of Poloxamer 407 (P407) and hydroxypropyl methylcellulose (HPMC) hydrosols is proposed as an in situ thermo-gelling vehicle for the nasal drug delivery of chlorhexidine-silver nanoparticles conjugates (SN-CX). Optimization of the formulation was carried out by applying varying ratios of P407 and HPMC in the presence and absence of SN-CX so that gelation would occur in the temperature range of the nasal cavity (30-34 °C). Mechanisms for the observed gelation phenomena were suggested based on viscosimetry, texture analysis, and dynamic light scattering. Tests were carried out for sprayability, washout time, in vitro drug release, ex vivo permeation, and antimicrobial activity. When applied separately, HPMC was found to lower the P407 gelation temperature (T), whereas SN-CX increased it. However, in the presence of HPMC, SN-CX interfered with the P407 micellar organization in a principally contrasting way while leading to an even further decrease in T. SN-CX-loaded nasal formulations composed of P407 16% and HPMC 0.1% demonstrated a desired gelation at 31.9 °C, good sprayability (52.95% coverage of the anterior nasal cavity), mucoadhesion for 70 min under simulated nasal clearance, expedient release and permeation, and preserved anti-infective activity against seasonal Influenza virus and beta-coronavirus, and other pathogens. Our findings suggest that the current development could be considered a potential formulation of a protective nasal spray against respiratory infections.
PubMed: 38920931
DOI: 10.3390/gels10060385 -
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 -
Journal of Inflammation Research 2024Sepsis-associated acute kidney injury (S-AKI) contributes to high mortality, but it is lack of specific treatments. We aimed to investigate the underlying mechanism of...
PURPOSE
Sepsis-associated acute kidney injury (S-AKI) contributes to high mortality, but it is lack of specific treatments. We aimed to investigate the underlying mechanism of S-AKI and to identify target drugs to alleviate AKI.
METHODS
We establish a stable mouse model of S-AKI by Pseudomonas aeruginosa incision infection. Based on high-throughput sequencing and bioinformatics analysis, we investigated the underlying mechanism and selected the target drug (VX-702) for S-AKI. An in vitro model established by co-cultured of kidney tubular epithelial cell line (TCMK-1) cells with lipopolysaccharide (LPS)-induced leukemic monocyte/macrophage cells (RAW264.7), we explored the effect of VX-702 on S-AKI.
RESULTS
The data showed interleukin (IL)-6 and IL-1β were the hub genes, and the mitogen-activated protein kinase (MAPK) signaling pathway was the main pathway involved in S-AKI. Administration of VX-702 by oral gavage decreased the elevated concentrations of IL-6, IL-1β, serum creatinine, and blood urea nitrogen in mice with S-AKI. Moreover, VX-702 reduced the number of apoptotic cells in damaged kidney tissues. Cell viability was decreased, and the number of apoptotic cells was increased in TCMK-1 cells co-cultured with LPS-induced RAW264.7 cells compared to LPS-induced TCMK-1 cells. VX-702 treatment reversed this effect. VX-702 treatment reduced the levels of phosphorylated p38 MAPK and proinflammatory cytokines in RAW264.7 cells and the supernatant. VX-702 could bind IL-6, IL-1β and MAPK, and affect the binding of IL-1β and its receptor, as demonstrated by molecular docking.
CONCLUSION
VX-702 ameliorated S-AKI by inhibiting the release of proinflammatory cytokines from macrophages, indicating its potential as a novel therapeutic for S-AKI treatment.
PubMed: 38919509
DOI: 10.2147/JIR.S464018 -
Journal of Anaesthesiology, Clinical... 2024Ventilator-associated pneumonia (VAP) is a nosocomial infection associated with high morbidity and mortality. This study was undertaken to monitor the trend of the...
Antimicrobial resistance pattern in aerobic bacteria isolated from endotracheal aspirate in ventilator-associated pneumonia: Ten years observation from a tertiary care hospital.
BACKGROUND AND AIMS
Ventilator-associated pneumonia (VAP) is a nosocomial infection associated with high morbidity and mortality. This study was undertaken to monitor the trend of the demographical details, comorbid conditions, bacterial etiological agents, and their antibiogram causing VAP in adults in the year 2008, 2013 and 2018.
MATERIAL AND METHODS
A retrospective study conducted at the Department of Microbiology, Hospital Infection control and Quality Control at a tertiary care teaching hospital. All the adult patients with more than 48 h of the mechanical ventilator with endotracheal intubation with Clinical Pulmonary infection Score >6 with suspicion of VAP were included in the study at a difference of 5 years, i.e., 2008, 2013, and 2018.
RESULTS
A total of 338 patients were included in the study, of which males accounted for more than two-third of the patients studied. Nearly 45% of the patients belonged to geriatric (>60 years) age group. The most common comorbid conditions were chronic obstructive pulmonary disease, hypertension and diabetes mellitus. Among the gram-negative isolates, , species, and were the most common. There is an emergence of resistance to most commonly administered antimicrobial agents like aminoglycosides, levofloxacin, piperacillin/tazobactum, and carbapenems during the study period.
CONCLUSION
This is a ten-year study on the antibiotic resistance pattern of organisms causing VAP. As far as the authors are aware, this is the first study addressing the pattern of change in drug resistance in the organisms causing VAP over a decade. The emergence of multi-drug resistant (MDR) MDR pathogens, especially in intensive care unit (ICU), is a great concern for the intensivist and infection control physicians. Preventive measures need to be undertaken to control the spread of these pathogens to the patients in the ICU.
PubMed: 38919443
DOI: 10.4103/joacp.joacp_410_22 -
NPJ Biofilms and Microbiomes Jun 2024It is becoming increasingly apparent that commensal skin bacteria have an important role in wound healing and infection progression. However, the precise mechanisms...
It is becoming increasingly apparent that commensal skin bacteria have an important role in wound healing and infection progression. However, the precise mechanisms underpinning many of these probiotic interactions remain to be fully uncovered. In this work, we demonstrate that the common skin commensal Cutibacterium acnes can limit the pathogenicity of the prevalent wound pathogen Pseudomonas aeruginosa in vivo. We show that this impact on pathogenicity is independent of any effect on growth, but occurs through a significant downregulation of the Type Three Secretion System (T3SS), the primary toxin secretion system utilised by P. aeruginosa in eukaryotic infection. We also show a downregulation in glucose acquisition systems, a known regulator of the T3SS, suggesting that glucose availability in a wound can influence infection progression. C. acnes is well known as a glucose fermenting organism, and we demonstrate that topically supplementing a wound with glucose reverses the probiotic effects of C. acnes. This suggests that introducing carbon source competition within the wound microenvironment may be an effective way to prevent or limit wound infection.
Topics: Pseudomonas aeruginosa; Glucose; Animals; Type III Secretion Systems; Propionibacterium acnes; Wound Infection; Mice; Pseudomonas Infections; Skin; Carbon; Wound Healing; Antibiosis; Disease Progression; Humans
PubMed: 38918415
DOI: 10.1038/s41522-024-00518-4 -
Med (New York, N.Y.) Jun 2024Cystic fibrosis (CF) patients are prone to recurrent multi-drug-resistant (MDR) bacterial lung infections. Under this scenario, phage therapy has been proposed as a...
BACKGROUND
Cystic fibrosis (CF) patients are prone to recurrent multi-drug-resistant (MDR) bacterial lung infections. Under this scenario, phage therapy has been proposed as a promising tool. However, the limited number of reported cases hampers the understanding of clinical outcomes. Anti-phage immune responses have often been overlooked and only described following invasive routes of administration.
METHODS
Three monophage treatments against Staphylococcus aureus and/or Pseudomonas aeruginosa lung infections were conducted in cystic fibrosis patients. In-house phage preparations were nebulized over 10 days with standard-of-care antibiotics. Clinical indicators, bacterial counts, phage and antibiotic susceptibility, phage detection, and immune responses were monitored.
FINDINGS
Bacterial load was reduced by 3-6 log in two of the treatments. No adverse events were described. Phages remained in sputum up to 33 days after completion of the treatment. In all cases, phage-neutralizing antibodies were detected in serum from 10 to 42 days post treatment, with this being the first report of anti-phage antibodies after nebulized therapy.
CONCLUSIONS
Nebulized phage therapy reduced bacterial load, improving quality of life even without bacterial eradication. The emergence of antibodies emphasizes the importance of long-term monitoring to better understand clinical outcomes. These findings encourage the use of personalized monophage therapies in contrast to ready-to-use cocktails, which might induce undesirable antibody generation.
FUNDING
This study was supported by the Spanish Ministry of Science, Innovation and Universities; Generalitat Valenciana; and a crowdfunding in collaboration with the Spanish Cystic Fibrosis Foundation.
PubMed: 38917792
DOI: 10.1016/j.medj.2024.05.017 -
International Journal of Surgery Case... Jun 2024Fournier's gangrene (FG) in neonates is less common than in adults, but this case can lead to a poor prognosis. FG is a disease of the genital, perianal, and perineal...
INTRODUCTION
Fournier's gangrene (FG) in neonates is less common than in adults, but this case can lead to a poor prognosis. FG is a disease of the genital, perianal, and perineal areas characterized by necrotizing infections. Here, we report a case of a 24-day-old male infant diagnosed with Fournier's gangrene involving the scrotum.
CASE PRESENTATION
The patient presented with scrotal swelling, fever, erythema, and insect bites on the penile tip that had gradually extended to the proximal area and bilateral scrotum. On physical examination, indurated grayish and blackish-brown scrotal skin with sharp distinction from the surrounding normal skin, erythema, purulence, ulceration, and necrotic tissue were observed. Abdominal X-ray and scrotal ultrasonography revealed gaseous distension of the scrotal region, free fluid on bilateral testes, and enlargement of bilateral testicles. Immediate surgical debridement, along with broad-spectrum antibiotics, was initiated, and a microbiological culture identified the presence of Pseudomonas aeruginosa. The patient demonstrated the completed healing of the surgical wound after thirty days of surgical intervention.
DISCUSSION
Fournier's gangrene in neonates is a sporadic case. Our patient presented with multiple predisposing factors, including insect bites and poor hygiene, underscoring the need for heightened clinical suspicion in vulnerable populations. Prompt recognition and intervention are critical, given the rapid progression of FG.
CONCLUSION
This case underscores the importance of timely diagnosis and early initiation of surgical and medical interventions in neonatal Fournier's gangrene, particularly in cases involving the scrotum.
PubMed: 38917701
DOI: 10.1016/j.ijscr.2024.109861