Growth Of MRSA Research Articles

GC-MS Analysis and Evaluation of Combination effect of Syzygium cumini L. Skeels Ethanolic Seed Extract and Vancomycin against Clinical Methicillin-Resistant Staphylococcus aureus

Syzygium cumini (L.) has been traditionally used as an antimicrobial agent and is potential to be developed. The ethanol extract of S. cumini seed was obtained through maceration and assessed for its antibacterial activity using a dilution method, with extract concentrations of 1.625; 3.125; 6.25; 12.5, and 25mg/ml. The minimum inhibitory concentration (MIC) and fractional inhibitory concentration index (FICI) of the extract-antibiotic combination against Methicillin-Resistant Staphylococcus aureus were determined. Phytochemical screening was performed using Gas Chromatography-Mass Spectrometry (GC-MS) and the result revealed the presence of 22 compounds in S. cumini ethanolic seed extract, including fatty acids (69.63%), sesquiterpenes (11.29%), monoterpenes (2.94%), steroids (6.06%), and others (8.59%). The MIC of the single extract and vancomycin against the tested bacteria was 0.78mg/ml and 2µg/ml, respectively. The lowest concentration (MIC) of the extract-vancomycin combination inhibiting the growth of MRSA was 0.39mg/ml. The FICI value was 1.5, suggesting indifferent interaction between the extract and antibiotic.

A challenging coexistence: community-acquired methicillin-resistant Staphylococcus aureus and Mycobacterium tuberculosis

BackgroundCommunity-acquired Methicillin-resistant Staphylococcus aureus (CA-MRSA) usually emerges after a viral infection and causes severe disease in immunocompetent individuals. Concurrent infection with tuberculosis (TB) is generally very rare in immunocompetent patients. Our case is the first report of the coexistence of CA-MRSA and TB in an immunocompetent patient.Case presentationA 24-year-old male patient of African origin, who has been living in Turkey for a year, was admitted to our hospital 3 months ago with fever, cough, and sputum complaints, which developed following symptoms of influenza infection. More intense bilateral infiltration and cavitary appearance were observed on the left in the chest radiography of the patient who did not respond to amoxicillin and gemifloxacin treatments. The patient’s sputum culture showed MRSA growth, and his sputum acid-resistant bacteria (ARB) was reported as three positive. Vancomycin, isoniazid, rifampicin, pyrazinamide, and ethambutol treatments were started. Subsequently, Mycobacterium Tuberculosis growth was also detected in the mycobacteria culture. Vancomycin treatment was completed in 14 days. There was no growth in the control sputum culture. When the patient, who gave clinical and laboratory response, was admitted with increased shortness of breath complaint two months after discharge, it was observed that minimal spontaneous pneumothorax developed in the left lung, and it was decided to follow up without intervention. In the second month of tuberculosis treatment, sputum ARB and mycobacteria culture became negative, and the patient was switched to dual antituberculosis treatment (isoniazid, rifampicin), and his treatment is still ongoing.ConclusionsMixed infections should be considered in case of non-response to treatment in patients with pneumonia. Mixed infections should also be followed closely as they may be more complicated.

Antimicrobial impact of a propolis/PVA/chitosan composite and its prospective application against methicillin resistance bacterial infection

Seriously damaged skin could be infected by methicillin-resistant bacteria, which delays restoration. Propolis has bioactivity linked with its minor components, such as antimicrobials and antioxidants. Active sites in polyvinyl alcohol (PVA) and chitosan (CS) can enhance the nano-loading of natural extracts with activity amelioration. Korean propolis extract (KPE) loading to a nanocomposite possibly enhances its antimicrobial and anti-inflammatory potency. Composites were formed using two PVA/CS structures (1:1; 2:1), and their skin-application appropriateness was determined by mechanical properties, moisture content, water activity, and color. The composite of PVA/CS (1:1) was more practicable for KPE-loading. Increasing KPE concentrations (50, 100, 150, and 200 ng/mL) alters composite bioactivity measured by Fourier transmission infrared (FT-IR). Antibacterial potency of 200 ng KPE/mL was the most effective concentration, followed by 150 ng KPE/mL, against Staphylococcus aureus (MRSA) and Clostridium perfringens. The composite activity was measured as minimum inhibition (MIC) and minimum bacterial concentrations (MBC). At 200 ng KPE/mL, MIC and MBC against MRSA were 14.93 ± 1.21 and 20.21 ± 1.97 mg composite/mL, respectively. Significant inhibition was also recorded for antibiofilm formation, where MRSA growth was not detected after 4 hours of time intervals to the stainless-steel coupon. Compared to planktonic bacteria, the formed barrier of PVA/CS restrained the biofilm matrix formation and supported KPE antimicrobial. The impact of inhibition against biofilm formation depends on two parallel mechanisms (PVA barrier with hydrogen bonds, besides nano-KPE particle penetration into bacterial cells). The KPE-composite application to rats’ wounds shows significantly reduced MRSA infection. The results demonstrate the capability of KPE composite in reducing infection, healing correctly, and restoring hair. The wound swabbed test emphasizes this capacity, in which bacterial growth rate restriction was evaluated using a plate count assay. The results recommended 150 ng KPE/mL loading into CS/PVA (1:1) as an effective anti-pathogenic treatment, particularly against the MRSA infection of wounds.

Antibacterial and Antioxidant Activity of Synthetic Polyoxygenated Flavonoids.

Flavonoids are an abundant class of naturally occurring compounds with broad biological activities, but their limited abundance in nature restricts their use in medicines and food additives. Here we present the synthesis and determination of the antibacterial and antioxidant activities of twenty-two structurally related flavonoids (five of which are new) by scientifically validated methods. Flavanones (FV1-FV11) had low inhibitory activity against the bacterial growth of MRSA 97-7. However, FV2 (C5,7,3',4' = OH) and FV6 (C5,7 = OH; C4' = SCH3) had excellent bacterial growth inhibitory activity against Gram-negative E. coli (MIC = 25 µg/mL for both), while Chloramphenicol (MIC = 25 µg/mL) and FV1 (C5,7,3' = OCH3; 4' = OH) showed inhibitory activity against Gram-positive L. monocytogenes (MIC = 25 µg/mL). From the flavone series (FO1-FO11), FO2 (C5,7,3',4' = OH), FO3 (C5,7,4' = OH; 3' = OCH3), and FO5 (C5,7,4' = OH) showed good inhibitory activity against Gram-positive MRSA 97-7 (MIC = 50, 12, and 50 µg/mL, respectively), with FO3 being more active than the positive control Vancomycin (MIC = 25 µg/mL). FO10 (C5,7= OH; 4' = OCH3) showed high inhibitory activity against E. coli and L. monocytogenes (MIC = 25 and 15 µg/mL, respectively). These data add significantly to our knowledge of the structural requirements to combat these human pathogens. The positions and number of hydroxyl groups were key to the antibacterial and antioxidant activities.

Investigation of Osteomyelitis Inducing Methicillin-Resistant Staphylococcus aureus Inhibition Effect by Strontium-Substituted Borate Bioactive Glasses.

Borate glass transforms into hydroxycarbonate apatite more rapidly than silicate glass. This research aims to evaluate strontium's structural and biological effects on borate bioactive glass (BBG) and the influence of strontium concentrations (0%, 5%, 10%, and 15% Sr) prepared via the sol-gel method. The study reveals significant findings related to the physicochemical properties of the glass. Immersion of the glass powders in a simulated body fluid (SBF) led to the development of a hydroxyapatite (HAP) layer on the glass surfaces. This transformation was verified through X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) analyses. In particular, 5% strontium exhibited gradual degradation, resulting in particle sizes below 100 nm. The BBG-15%Sr demonstrates heightened pathogenic activity as it shows a significant inhibition zone of 14 mm at 250 μg/mL, surpassing other substituted BBGs. It effectively combats Gram-positive bacteria, completely inhibiting MRSA growth at 50 μg/mL. This underscores its robust biofilm disruption capabilities, eradicating biofilms, even at minimal concentrations after prolonged exposure. C. elegans when subjected to BBG-15%Sr shows less ROS production when compared with the others. Moreover, the results suggest that the modified glass could be a potential material for the treatment of osteomyelitis-affected bone repair.

Design, Synthesis, Biological Evaluation, and Molecular Docking Studies of Pleuromutilin Derivatives Containing Thiazole.

In this study, we designed and synthesized a series of pleuromutilin derivatives containing thiazole. The in vitro antimicrobial efficacy of these synthesized compounds was examined by using four strains. Compared with tiamulin (MIC = 0.25 μg/mL), compound 14 exhibited potency in inhibiting MRSA growth (MIC = 0.0625 μg/mL) in these derivatives. Meanwhile, the time-killing kinetics further demonstrated that compound 14 could efficiently inhibit the MRSA growth. After exposure at 4 × MIC, the postantibiotic effect (PAE) of compound 14 was 1.29 h. Additionally, in thigh-infected mice, compound 14 exhibited a more potent antibacterial efficacy (-1.78 ± 0.28 log10 CFU/g) in reducing MRSA load compared to tiamulin (-1.21 ± 0.23 log10 CFU/g). Moreover, the MTT assay on RAW 264.7 cells demonstrated that compound 14 (8 μg/mL) had no significant cytotoxicity. Docking studies indicated the strong affinity of compound 14 toward the 50S ribosomal subunit, with a binding free energy of -9.63 kcal/mol. Taken together, it could be deduced that compound 14 was a promising candidate for treating MRSA infections.

A QuEChERS Cyanin based Chromogenic Method for the Sensitive Identification of MRSA from Various Food Sources and its Molecular Characterization

Methicillin resistant Staphylococcus aureus harbouring other virulence factors in food is a serious threat to food safety. Delayed detection of MRSA may lead to fatal consequences due to the challenging treatment methods. To address the issue, early prognosis is prerequisite. We report one step QuEChERS detection method wherein, a media with selective agents such as cefoxitin, cyanidin, lithium chloride and methicillin (CCLM) was formulated for the specific cultivation and detection of MRSA within 5 hours. Direct application of the newly developed method was tested by screening food for MRSA and its comparison with conventional biochemical and molecular characterization. Growth of MRSA in the CCLM media was observed within 4 hours. This highly specific method is sensitive to detect 104 CFU/mL visually and 101 CFU/mL spectrophotometrically. 25% of food samples harboured MRSA which points to an immediate need of consideration by the authorities. The newly designed QuEChERS cyanin based chromogenic detection system is unequivocal with the conventional and molecular method of MRSA detection and can be of great use in diagnostic and in food safety laboratories.

Penurunan Aktivitas Biofilm Strain MRSA 22156 oleh Tanaman Saga (Abrus precatorius L.)

The aim of this research is to determine the effect of using saga extract on bacterial biofilm growth, and to determine the most appropriate dose of saga extract in reducing MRSA 22156 biofilm activity. This research uses the Dowd method to determine the total flavonoid content of A. precatorius L leaves. Treatment reduction in MRSA 22156 biofilm growth using the Plate Biofilm Assay method with three repetitions. The results of the research show that total flavonoids can reduce the growth of MRSA 22156 biofilms. The use of total flavonoids from A. precatorius L. leaves in concentrations of 800 mgL-1 to 25 mgL-1 has been proven to have an effect on biofilm growth activity as indicated by the reduction in MRSA 22156 biofilm growth by 67.9% and 25%. The ethanol extract of A. precatorius L. has anti-biofilm activity in reducing the growth of Staphylococcus aureus bacteria that are resistant to Methicillin.

In vitro evaluation of nanocomposites of linseed mucilage and k-carrageenan loaded with Achyrocline satureioides nanoemulsion: a gradual-release candidate of antimicrobials for the treatment of bovine mastitis.

This research paper presents the development and evaluation of pioneering nanocomposites (NCs) based on the combination of k-carrageenan and linseed mucilage. When loaded with macela extract nanoemulsion they present an innovative approach for the sustained release of antimicrobial herbal constituents, specifically tailored for bovine mastitis treatment. The NCs, encompassing various ratios of k-carrageenan and linseed mucilage polymers (8:2, 7:3, and 5:5 w/w) with 1.25 mg of macela extract/g of gel, underwent in vitro assessment, emphasizing viscosity, degradation speed, release of herbal actives from macela nanoemulsion and antimicrobial activity. The NCs exhibited thermoreversible characteristics, transitioning from liquid at 60°C to a gel at 25°C. NCs allowed a gradual release of phenolic compounds, reaching approximately 80% of total phenolics release (w/v) within 72 h. NCs inhibited the growth of MRSA (ATCC 33592) until 8 h of incubation. No toxic effect in vitro of NCs was found on MAC-T cells. Thus, the developed materials are relevant for the treatment of bovine mastitis, especially in the dry period, and the data support future evaluations in vivo.

Three‐Step Regenerative Strategy: Multifunctional Bilayer Hydrogel for Combined Photothermal/Photodynamic Therapy to Promote Drug‐Resistant Bacteria‐Infected Wound Healing

AbstractThe drug‐resistant bacterial‐infected skin wound is still a severe healthcare problem. Uncontrolled bacterial infection, abundant reactive oxygen species (ROS) content, and prolonged inflammatory response are detrimental to wound healing. Moreover, excessive vessel growth can result in unsatisfactory scar formation. Herein, a three‐step regenerative strategy based on a bilayered gelatin/acryloyl β‐cyclodextrin (BGACD) hydrogel containing physical host–guest complexations and chemical crosslinks is proposed. The hydrogel is loaded with humic acids (HAs) and astragaloside IV (AS) in the lower layer and verteporfin (Vt) in the upper layer. Different gelatin/acryloyl β‐cyclodextrin ratios endow the lower and upper layers of the hydrogel with different degradation rates. Under light irradiation, the combination of HAs‐induced photothermal therapy (PTT) and verteporfin‐induced photodynamic therapy effectively inhibits MRSA growth. The HAs and astragaloside IV are released from the lower layer to scavenge ROS and promote M2 macrophage polarization and angiogenesis during the inflammation and early proliferation phases, while verteporfin releases from the upper layer suppress excessive vessel growth during the late proliferation and remodeling phases. The HAs‐AS@Vt@BGACD hydrogel successfully achieves rapid and scarless wound healing in an MRSA‐infected wound model in rats. Therefore, the HAs‐AS@Vt@BGACD hydrogel shows promising potential for the treatment of drug‐resistant bacteria‐infected skin wound healing.

Design, synthesis, and biological evaluation of pleuromutilin derivatives containing 1,2,4-triazole linker.

A series of thioether pleuromutilin derivatives containing 1,2,4-triazole on the side chain of C14 were designed and synthesized. The in vitro antibacterial activities experiments of the synthesized derivatives showed that compounds 72 and 73 displayed superior in vitro antibacterial effect against MRSAminimal inhibitory concentration (MIC = 0.0625 μg/mL) than tiamulin (MIC = 0.5 μg/mL). The results of time-kill study and postantibiotic effect study indicated that compound 72 could inhibit the growth of MRSA quickly (-2.16 log10 CFU/mL) and showed certain postantibiotic effect(PAE) time (exposure to 2 × MIC and 4 × MIC for 2 h, the PAE was 1.30 and 1.35 h) against MRSA. Furthermore, the binding mode between compound 72 and 50S ribosome of MRSA was explored by molecular docking and five hydrogen bonds were formed between compound 72 and 50S ribosome.

Methicillin-Resistant Staphylococcus aureus Nasal Swab Is Insufficient to Withhold Empiric Methicillin-Resistant Staphylococcus aureus Pneumonia Coverage in a Trauma Population

IntroductionMethicillin-resistant staphylococcus aureus (MRSA) nasal colonization is a predictor of MRSA pneumonia in intensive care unit (ICU) patients. Negative nasal swabs have shown up to a 97% negative predictive value for MRSA pneumonia in nontrauma populations, though little investigation has been pursued in trauma patients. Materials and methodsAll trauma patients admitted to the ICU from April 2018 to February 2019 were screened for MRSA colonization by nasal swab. Patients with suspicion for pneumonia underwent bronchoalveolar lavage or quantitative sputum culture and were started on empiric antibiotic therapy based on the swab result. Swab-positive patients were started on empiric MRSA coverage and swab-negative patients were not. ResultsMRSA nasal swab screening was performed in 601 trauma ICU patients. Ninety-six patients subsequently underwent pneumonia workup and were started on an empiric antibiotic regimen based on nasal swab results. Seventeen (17.7%) patients were MRSA nasal swab positive on screening, and 22 (22.9%) patients subsequently had significant growth of MRSA on quantitative respiratory culture. The sensitivity of nasal swab was 50.0% and the specificity was 91.9%. Eleven patients had a negative MRSA nasal swab but a positive MRSA pneumonia (11.5%). Patients with inadequate antibiotic coverage had statistically longer hospital length of stay, ICU length of stay, ventilator days, and rates of unplanned intubation compared to patients with adequate antibiotic coverage. ConclusionsNasal swab screening was not sensitive enough in a trauma population with a high endemic incidence of MRSA colonization to warrant withholding empiric antibiotic MRSA coverage in patients with suspected pneumonia.

Bacterial Pyruvate Kinase: A New Potential Target to Combat Drug‐Resistant Staphylococcus aureus Infections

AbstractSeverity of Infections caused by Staphylococcus aureus ranges from trivial to spine chilling. Irrespective of multiple drugs availability to treat S. aureus infections, increase in drug‐resistance has led to the continuous emergence of resistant strains of all S. aureus including MRSA. Hence, there is an urgent unmet need for novel antibacterial agents to combat multi drug resistant infections which act through unexploited targets/mechanism. Bacterial pyruvate kinase (PK) is one such unique cytoplasmic enzyme crucial in carbohydrate metabolism. It exists in several microorganisms including Mycobacterium sp, P. falciparaum, T. gondii, L. mexicana, V. cholera, etc. In MRSA, PK is an important hub in protein‐protein network with more than 200 interacting partners in a large‐scale protein interaction analysis and might be less susceptible to genetic mutation and resistance due to the network centrality‐lethality criteria. Methicillin resistant S. aureus pyruvate kinase (SAPK) antisense and knockout tests revealed that it is required for growth of MRSA. In recent times, PKs gained attention as potential new targets to combat trypanosomal, leishmanial, malarial and viral infections. This review provides valuable insights about indole alkaloids from natural products and synthetic SAPK inhibitors along with their inhibitory properties against S. aureus and MRSA strains. This review also describes essential structural features and Structure‐Activity Relationship (SAR) for SAPK inhibition.

Study of the Antimicrobial Activity of the Chinese Dong Ethnic Minority Medicine, Madeng'ai.

The overuse of antibiotics has contributed to the emergence of multidrug-resistant bacteria, which poses a challenging task for clinical therapy. Thus, new agents with antibiotic efficacy against multidrug-resistant infections are needed. The traditional Dong ethnic minority medicines have emerged as a new source for prodrug selection. Among them, Madeng'ai (PotentillafreynianaBornm) is widely used by the folk for anti-infection and wound healing, although the mechanisms remain unclear. In this study, the antimicrobial activities of Dong medicine Madeng'ai were evaluated both in vitro and in vivo. S. aureus, E. coli, E. faecalis, P. aeruginosa, K. pneumoniae, and A. baumannii were cultured in LB media, different concentrations of Madeng'ai powder solution were added to the LB agar plates to evaluate minimal inhibitory concentration. An animal study was performed on a mouse excisional wound model combined with bacterial solution injection in the wound area. After Madeng'ai or PBS treatment, hematoxylin and eosin analysis were used for pathological analysis of skin tissues from the infected area. Madeng'ai powder solution over 2 mg/mL concentration completely inhibited E. coli growth. At 4.0 mg/mL, Madeng'ai significantly inhibited the growth of E. faecalis, Pseudomonas aeruginosa (PAE), Klebsiella pneumoniae, and Acinetobacter baumannii. The mouse model revealed that Madeng'ai could suppress the growth of MRSA and PAE and accelerate healing of cutaneous wounds. Madeng'ai, a newly discovered Dong ethnic minority medicine possesses considerable antimicrobial activity against both human normal pathogenic bacteria and multiresistance bacteria such as Pseudomonas aeruginosa, S. aureus, and Acinetobacter baumannii. Therefore, Madeng'ai has great potential for further study and clinical application.

Platelets Inhibit Methicillin-Resistant Staphylococcus aureus by Inducing Hydroxyl Radical-Mediated Apoptosis-Like Cell Death.

ABSTRACTMethicillin-resistant Staphylococcus aureus (MRSA) is one of the most common drug-resistant bacteria and poses a significant threat to human health. Due to the emergence of multidrug resistance, limited drugs are available for the treatment of MRSA infections. In recent years, platelets have been reported to play important roles in inflammation and immune responses, in addition to their functions in blood hemostasis and clotting. We and other researchers have previously reported that platelets can inhibit Staphylococcus aureus growth. However, it remained unclear whether platelets have the same antibacterial effect on drug-resistant strains. In this study, we hypothesized that platelets may also inhibit the growth of MRSA; the results confirmed that platelets significantly inhibited the growth of MRSA in vitro. In a murine model of MRSA infection, we found that a platelet transfusion alleviated the symptoms of MRSA infection; in contrast, depletion of platelets aggravated infective symptoms. Moreover, we observed an overproduction of hydroxyl radicals in MRSA following platelet treatment, which induced apoptosis-like death of MRSA. Our findings demonstrate that platelets can inhibit MRSA growth by promoting the overproduction of hydroxyl radicals and inducing apoptosis-like death.IMPORTANCE The widespread use of antibiotics has led to the emergence of drug-resistant bacteria, particularly multidrug-resistant bacteria. MRSA is the most common drug-resistant bacterium that causes suppurative infections in humans. As only a limited number of drugs are available to treat the infections caused by drug-resistant pathogens, it is imperative to develop novel and effective biological agents for treating MRSA infections. This is the first study to show that platelets can inhibit MRSA growth in vitro and in vivo. Our results revealed that platelets enhanced the production of hydroxyl radicals in MRSA, which induced a series of apoptosis hallmarks in MRSA, including DNA fragmentation, chromosome condensation, phosphatidylserine exposure, membrane potential depolarization, and increased intracellular caspase activity. These findings may further our understanding of platelet function.

Antibacterial Properties of PMMA Functionalized with CuFe2O4/Cu2O/CuO Nanoparticles

We have prepared a composite thin coating by incorporation of CuFe2O4/Cu2O/CuO nanoparticles in polymethyl methacrylate (PMMA) matrix by using the solution casting method. The electrical explosion of two twisted wires (EETW) was used to obtain multicomponent CuFe2O4/Cu2O/CuO nanoparticles with an average particle size of 20–70 nm. The microscopic studies showed that the nanoparticles in the composite coatings are evenly distributed. However, nanoparticles are strongly agglomerated as the powder concentration in the coating increases to 5 wt.% and 10 wt.%, as the size of particle agglomerates increases to 50 and 100 μm, respectively. Therefore, nanoparticles were pre-treated with ultrasound when introduced into the PMMA matrix. The thermal stability of the composite coating does not change with the introduction of CuFe2O4/Cu2O/CuO nanoparticles in the amount of 5 wt.%. The inclusion of nanoparticles in the PMMA matrix significantly enhances its antibacterial activity. The addition of 5 wt.% nanoparticles inhibited the growth of E. coli by 100% and the growth of MRSA by 99.94% compared to pure PMMA already after 3 h of exposure of bacteria on the surface of the composites. This research provides an easy-to-manufacture and cost-efficient method for producing a CuFe2O4/Cu2O/CuO/PMMA composite coating with a broad application as an antibacterial material.

The synergistic inhibition and mechanism of epicatechin gallate and Chitosan against Methicillin-resistant Staphylococcus aureus and the application in pork preservation

Livestock-associated -Methicillin-resistant S. aureus (LA-MRSA) contamination on pork has emerged as one of the major concerns worldwide. Combinations of natural plant extracts (NPEs) and food preservatives were tested for their anti-MRSA activities. The most effective combination was evaluated using texture profile, physicochemical analysis and sensory quality. The synergistic antibacterial mechanisms were examined using transcriptomic sequencing and electron microscope. Results showed that 1/8 minimal inhibitory concentration (MIC) (−)-epicatechin gallate (ECG) + 1/16 MIC chitosan had the optimum inhibition on the growth of MRSA with FIC of 0.19. The combination extended the shelf life of pork from 5 to 7 d at 4 °C and from 36 h to 48 h at 25 °C based on MRSA challenge test. The combination effectively maintained the hardness, elasticity, cohesion, recovery, and chewiness of pork and delayed the process of spoilage, lipid oxidation, accumulation of free amino acid, and Met Mb of pork contaminated by MRSA. Synergistic antibacterial mechanisms may be associated with improved cell deformation (stickiness and slight shrinkage). Six differentially expressed genes, lrgB and LytM, clfA, icaB, and icaA and blaI were confirmed to be responsible for the synergistic antibacterial mechanisms. Combining ECG with chitosan may be useful food preservatives in the pork industry.

Exploring rheological properties of chitosan gel and antimicrobial activities of 5-FU against diabetic wound pathogens

Diabetic skin wound is a common complication that occurs in about 15% of diabetic patients and often requires prolonged hospitalization. Diabetic wounds are slow to heal and last for weeks, making it difficult to be manage in clinical settings. Chitosan (CS) gel has become a focus of attention in delivering therapeutics such as antimicrobial agents to site of action in diabetic wounds without negative side effects. The objective of this study was to explore rheological properties of CS gel and determine the therapeutic effects of 5-FU against common diabetic wound pathogens.
 Chitosan gel (2% w/w) was prepared in serial dilutions of 5-FU. Stability, antimicrobial activities, and rheological properties (flow behavior and oscillatory sweep tests) of 5-FU-CS gels were analyzed.
 2% CS gel demonstrated a shear thinning behavior with a flow index < 1. The gel displayed weak gel-like properties with storage modulus values (G') less than loss modulus values (G''). Stability (pH) was maintained after three weeks of storage at 4-8oC and 20-25oC. Unlike E. coli, 5-FU and 5-FU-CS gel significantly inhibited MRSA and RN1 growth. Drug-free CS gel had no growth inhibition against MRSA, RN1 or E. coli. The MIC for 5- FU against MRSA, RN1, and E. coli were 0.5μg/mL, 0.5μg/mL, and 8.0μg/mL, respectively.
 CS was successfully formulated into non-Newtonian gel with shear thinning properties. The gel was viscous and less elastic. 5-FU-CS gel was stable at both room and cold temperatures after three weeks of storage, with antimicrobial activities against MRSA and RN1 at low concentrations, and against E. coli at higher concentrations.
 Understanding rheological properties of CS would enhance its utilization as a drug delivery vehicle for diabetic wounds given its biodegradable, biocompatible, and biological properties.

Unique Carbazole-Oxadiazole Derivatives as New Potential Antibiotics for Combating Gram-Positive and -Negative Bacteria.

Novel carbazole-oxadiazoles were developed as new potential antibacterial agents to combat dreadful resistance. Some target compounds displayed predominant inhibitory effects on the tested Gram-positive and -negative bacteria, and carbazole-oxadiazoles 5g, 5i-k, 16a-c, and tetrazole analogues 23b-c were found to be efficient in impeding the growth of MRSA and Pseudomonas aeruginosa ATCC 27853 (MICs = 0.25-4 μg/mL). Furthermore, compounds 5g and 23b-c not only possessed rapid bactericidal ability and low tendency to develop resistance but also exhibited low cytotoxic effects toward Hek 293T, HeLa, and red blood cells (RBCs), especially molecule 5g also showed low toxicity in vivo, which showed the therapeutic potential of these compounds. Further exploration indicated that compounds 5g, 5i, and 23b-c could disintegrate the integrity of bacterial cell membranes to leak the cytoplasmic contents, thus exerting excellent antibacterial effects. These facts mean that carbazole-based antibacterial agents might have bright prospects in confronting bacterial infections.

Pyrogallol Induces Antimicrobial Effect and Cell Membrane Disruption on Methicillin-Resistant Staphylococcus aureus (MRSA)

Background: Pyrogallol is present naturally in numerous plants. It is also an important functional group in many polyphenol compounds. Objectives: The antibacterial activity, efficacy, and mechanism of pyrogallol towards MRSA strains were evaluated. Methods: Microbroth dilution method was used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Time-kill kinetic assay was adopted to determine the killing pattern of pyrogallol towards MRSA. The antibacterial mechanism was determined using scanning electron microscopy (SEM), Fourier Transform-Infrared (FT-IR) spectroscopy and crystal violet assay. Results: Pyrogallol exhibited strong antibacterial activity against MRSA with MIC and MBC 15.6 μg/mL. Pyrogallol could inhibit the exponential growth of MRSA and kill the bacterial cells at higher concentrations. Pyrogallol was found targeting the cell membrane fatty acids, proteins/peptides, polysaccharides/carbohydrates and peptidoglycan of cell walls in the antibacterial mechanism. This has been confirmed through SEM, FT-IR spectroscopy and crystal violet assay. Conclusion : Overall, the findings suggest that pyrogallol has the potential to be used as antibiotics which are used to treat multidrug-resistant bacteria.