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Fulltext Antimicrobial activities of Bacillus velezensis strains isolated from stingless bee products against methicillin-resistant Staphylococcus aureus

Baharudin MMA, Ngalimat MS, Mohd Shariff F, Balia Yusof ZN, Karim M, Baharum SN, et al.

PLoS One, 2021;16(5):e0251514.
PMID: 33974665 DOI: 10.1371/journal.pone.0251514

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) have reached epidemic proportions globally. Therefore, there is an urgent need for a continuous supply of antibiotics to combat the problem. In this study, bacteria initially identified as species belonging to the Bacillus amyloliquefaciens operational group were re-identified based on the housekeeping gene, gyrB. Cell-free supernatants (CFS) from the strains were used for antimicrobial tests using the agar well diffusion assay against MRSA and various types of pathogenic bacteria. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and physicochemical characteristics of the CFS were determined. Based on gyrB sequence analysis, five strains (PD9, B7, PU1, BP1 and L9) were identified as Bacillus velezensis. The CFS of all B. velezensis strains showed broad inhibitory activities against Gram-negative and -positive as well as MRSA strains. Strain PD9 against MRSA ATCC 33742 was chosen for further analysis as it showed the biggest zone of inhibition (21.0 ± 0.4 mm). The MIC and MBC values obtained were 125 μl/ml. The crude antimicrobial extract showed bactericidal activity and was stable at various temperatures (40-80°C), pH (4-12), surfactants (Tween 20, Tween 80, SDS and Triton X-100) and metal ions (MgCI2, NaCI2, ZnNO3 and CuSO4) when tested. However, the crude extract was not stable when treated with proteinase K. All these properties resembled the characteristics of peptides. The antimicrobial compound from the selected strain was purified by using solvent extraction method and silica gel column chromatography. The purified compound was subjected to High Performance Liquid Chromatography which resulted in a single peak of the anti-MRSA compound being detected. The molecular weight of the anti-MRSA compound was determined by using SDS-PAGE and zymogram. The size of the purified antimicrobial peptide was approximately ~ 5 kDa. The antimicrobial peptide produced from B. velezensis strain PD9 is a promising alternative to combat the spread of MRSA infections in the future.

Matched MeSH terms: Gram-Positive Bacteria/drug effects; Gram-Positive Bacteria/growth & development
Effect of annealing temperature on antimicrobial and structural properties of bio-synthesized zinc oxide nanoparticles using flower extract of Anchusa italica

Azizi S, Mohamad R, Bahadoran A, Bayat S, Rahim RA, Ariff A, et al.

J. Photochem. Photobiol. B, Biol., 2016 Aug;161:441-9.
PMID: 27318600 DOI: 10.1016/j.jphotobiol.2016.06.007

The use of nontoxic biological compounds in the synthesis of nanomaterials is an economic and eco-friendly approach. The present work was undertaken to develop zinc oxide nanoparticles (ZnO-NPs) by a green method using simple precursor from the solution consisting of zinc acetate and the flower extract of Anchusa italica (A. italica). Effect of annealing temperature on structural and antimicrobial properties was investigated. The crystalline structure of ZnO-NPs was shown using X-ray diffraction (XRD) analysis. Transmission electron microscopy (TEM) results showed that ZnO-NPs are hexagonal in shapes with mean particle size of ~8 and ~14nm at 100°C and 200°C annealing temperatures respectively. The optical band gap was increased from 3.27eV to 3.30eV with the decreasing of the particle size. The antimicrobial activity of ZnO-NPs towards Gram positive (Bacillus megaterium and Stapphylococcus aureus) and Gram negative (Escherichia coli and Salmonella typhimurium) pathogens decreased with the increasing of the heat treating temperature. In vitro cytotoxicity studies on Vero cells, a dose dependent toxicity with non-toxic effect of concentration below 142μg/mL was shown. The results indicated that A. italica is an appropriate reaction media to prepare ZnO-NPs for cosmetic and bio-medical productions.

Matched MeSH terms: Gram-Positive Bacteria/drug effects
Fulltext Impact of COVID-19 pandemic on multidrug resistant gram positive and gram negative pathogens: A systematic review

Abubakar U, Al-Anazi M, Alanazi Z, Rodríguez-Baño J

J Infect Public Health, 2023 Mar;16(3):320-331.
PMID: 36657243 DOI: 10.1016/j.jiph.2022.12.022

BACKGROUND: There is paucity of data describing the impact of COVID-19 pandemic on antimicrobial resistance. This review evaluated the changes in the rate of multidrug resistant gram negative and gram positive bacteria during the COVID-19 pandemic.
METHODS: A search was conducted in PubMed, Science Direct, and Google Scholar databases to identify eligible studies. Studies that reported the impact of COVID-19 pandemic on carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Enterobacteriaceae (CRE), extended-spectrum beta-lactamase inhibitor (ESBL)-producing Enterobacteriaceae, vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA) and carbapenem-resistant Pseudomonas aeruginosa (CPE) were selected. Studies published in English language from the start of COVID-19 pandemic to July 2022 were considered for inclusion.
RESULTS: Thirty eligible studies were selected and most of them were from Italy (n = 8), Turkey (n = 3) and Brazil (n = 3). The results indicated changes in the rate of multidrug resistant bacteria, and the changes varied between the studies. Most studies (54.5%) reported increase in MRSA infection/colonization during the pandemic, and the increase ranged from 4.6 to 170.6%. Five studies (55.6%) reported a 6.8-65.1% increase in VRE infection/colonization during the pandemic. A 2.4-58.2% decrease in ESBL E. coli and a 1.8-13.3% reduction in ESBL Klebsiella pneumoniae was observed during the pandemic. For CRAB, most studies (58.3%) reported 1.5-621.6% increase in infection/colonization during the pandemic. Overall, studies showed increase in the rate of CRE infection/colonization during the pandemic. There was a reduction in carbapenem-resistant E. coli during COVID-19 pandemic, and an increase in carbapenem-resistant K. pneumoniae. Most studies (55.6%) showed 10.4 - 40.9% reduction in the rate of CRPA infection during the pandemic.
CONCLUSION: There is an increase in the rate of multidrug resistant gram positive and gram negative bacteria during the COVID-19 pandemic. However, the rate of ESBL-producing Enterobacteriaceae and CRPA has decrease during the pandemic. Both infection prevention and control strategies and antimicrobial stewardship should be strengthen to address the increasing rate of multidrug resistant gram positive and gram negative bacteria.

Matched MeSH terms: Gram-Positive Bacteria
Polyvinylpyrrolidone oral films of enrofloxacin: film characterization and drug release

Kumar GP, Phani AR, Prasad RG, Sanganal JS, Manali N, Gupta R, et al.

Int J Pharm, 2014 Aug 25;471(1-2):146-52.
PMID: 24858388 DOI: 10.1016/j.ijpharm.2014.05.033

Enrofloxacin is a fluoroquinolone derivative used for treating urinary tract, respiratory and skin infections in animals. However, low solubility and low bioavailability prevented it from using on humans. Polyvinylpyrrolidone (PVP) is an inert, non toxic polymer with excellent hydrophilic properties, besides it can enhance bioavailability by forming drug polymer conjugates. With the aim of increasing solubility and bioavailability, enrofloxacin thin films were prepared using PVP as a polymer matrix. The obtained oral thin films exhibited excellent uniformity and mechanical properties. Swelling properties of the oral thin films revealed that the water uptake was enhanced by 21%. The surface pH has been found to be 6.8±0.1 indicating that these films will not cause any irritation to oral mucosa. FTIR data of the oral thin films indicated physical interaction between drug and polymer. SEM analysis revealed uniform distribution of drug in polymer matrix. In vitro drug release profiles showed enhanced release profiles (which are also pH dependant) for thin films compared to pure drug. Antibacterial activity was found to be dose dependent and maximum susceptibility was found on Klebsiella pneumonia making this preparation more suitable for respiratory infections.

Matched MeSH terms: Gram-Positive Bacteria/drug effects; Gram-Positive Bacteria/growth & development
Fulltext Microbiology of diabetic foot infections in a teaching hospital in Malaysia: a retrospective study of 194 cases

Raja NS

J Microbiol Immunol Infect, 2007 Feb;40(1):39-44.
PMID: 17332905

Diabetes mellitus is a progressive disease with chronic complications. Foot infections are a major complication of diabetes and eventually lead to development of gangrene and lower extremity amputation. The microbiological characteristics of diabetic foot infections have not been extensively studied in Malaysia. This study investigated the microbiology of diabetic foot infections and their resistance to antibiotics in patients with diabetic foot infections treated at University of Malaya Medical Centre in Kuala Lumpur, Malaysia.

Matched MeSH terms: Gram-Positive Bacteria/classification; Gram-Positive Bacteria/drug effects; Gram-Positive Bacteria/isolation & purification*
Synthesis, in vitro antimycobacterial evaluation and docking studies of some new 5,6,7,8-tetrahydropyrido[4',3':4,5]thieno[2,3-d]pyrimidin-4(3H)-one schiff bases

Narender M, Jaswanth S B, Umasankar K, Malathi J, Raghuram Reddy A, Umadevi KR, et al.

Bioorg Med Chem Lett, 2016 Feb 01;26(3):836-840.
PMID: 26755393 DOI: 10.1016/j.bmcl.2015.12.083

Development of multidrug resistant (MDR) and extensively drug resistant (XDR) tuberculosis (TB) has been considered as major health burden, globally. In order to develop novel, potential molecules against drug resistant TB, twenty two (22) new 3-substituted-7-benzyl-5,6,7,8-tetrahydropyrido[4',3':4,5]thieno[2,3-d]pyrimidin-4(3H)-one (6a-k) and 3-substituted-7-benzyl-2-methyl-5,6,7,8-tetrahydropyrido[4',3':4,5]thieno[2,3-d]pyrimidin-4(3H)-one (7a-k) derivatives were designed and synthesized by using appropriate synthetic protocols. Pantothenate synthetase (PS) was considered as the target for the molecular docking studies and evaluated the binding pattern at active site, as PS plays a significant role in the biosynthesis of pantothenate in Mycobacterium tuberculosis (MTB). The preliminary in vitro antibacterial screening of test compounds was carried out against two strains of Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Klebsiella pneumoniae) bacteria. The antimycobacterial screening was performed against MTB H37Rv and an isoniazid-resistant clinical isolate of MTB. The compounds 6b, 6c, 6d, 6k, 7b, 7c, 7d and 7k exhibited promising antibacterial activity MIC in the range of 15-73 μM against all bacterial strains used and compounds 6d and 7b showed antimycobacterial activity (IC50 <340 μM in LRP assay) and (MIC <9 μM in broth microdilution method).

Matched MeSH terms: Gram-Positive Bacteria/drug effects; Gram-Positive Bacteria/metabolism
Fulltext Bio-Mediated Synthesis of Reduced Graphene Oxide Nanoparticles from Chenopodium album: Their Antimicrobial and Anticancer Activities

Umar MF, Ahmad F, Saeed H, Usmani SA, Owais M, Rafatullah M

Nanomaterials (Basel), 2020 Jun 01;10(6).
PMID: 32492878 DOI: 10.3390/nano10061096

A novel method of preparing reduced graphene oxide (RGOX) from graphene oxide (GOX) was developed employing vegetable extract, Chenopodium album, as a reducing and stabilizing agent. Chenopodium album is a green leafy vegetable with a low shelf life, fresh leaves of this vegetable are encouraged to be used due to high water content. The previously modified 'Hummers method' has been in practice for the preparation of GOX by using precursor graphite powder. In this study, green synthesis of RGOX was functionally verified by employing FTIR and UV-visible spectroscopy, along with SEM and TEM. Our results demonstrated typical morphology of RGOX stacked in layers that appeared as silky, transparent, and rippled. The antibacterial activity was shown by analyzing minimal inhibitory concentration values, agar diffusion assay, fluorescence techniques. It showed enhanced antibacterial activity against Gram-positive and Gram-negative bacteria in comparison to GOX. It has also been shown that the synthesized compound exhibited enhanced antibiofilm activity as compared to its parent compound. The efficacy of RGOX and GOX has been demonstrated on a human breast cancer cell line, which suggested RGOX as a potential anticancer agent.

Matched MeSH terms: Gram-Positive Bacteria
Fulltext Behavior of schmutzdecke with varied filtration rates of slow sand filter to remove total coliforms

Matuzahroh N, Fitriani N, Ardiyanti PE, Kuncoro EP, Budiyanto WD, Isnadina DRM, et al.

Heliyon, 2020 Apr;6(4):e03736.
PMID: 32280804 DOI: 10.1016/j.heliyon.2020.e03736

The previous research showed that slow sand filtration (SSF) can remove the total coli by approximately 99% because of the schmutzecke layer in the filter. The presented study aimed to complete the previous research on SSF, especially on the schmuztdecke layer mechanism, to remove total coli. Total coli is a parameter of water quality standard in Indonesia, and the behavior of schmutzdecke affects the total coli removal. In the present study, the raw water from Amprong River was treated using horizontal roughing filter (HRF) and SSF. The variations in SSF rate used were 0.2 and 0.4 m/h. Total coliforms were analyzed using the most probable number test, and schmutzdecke visualization was conducted through scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX). The best coliform concentration in water treated by the combination of HRF and SSF was 4,386 colonies per 100 mL of sample using the filtration rate of 0.2 m/h, and its removal efficiency was 99.60%. However, the quality of water treated by the combination of HRF and SSF did not meet the drinking water quality standard because the removal of total coli must be 100%. The SEM-EDX visualization results in schmutzdecke showed that the average bacteria in the schmutzdecke layer were small, white, opaque, and circular, with entire edge and flat elevation. The Gram test results showed that the schmutzdecke bacteria consisted of Gram-positive and Gram-negative bacteria with basil as the common cell form.

Matched MeSH terms: Gram-Positive Bacteria
Fulltext New insights into the mode of action of the lantibiotic salivaricin B

Barbour A, Tagg J, Abou-Zied OK, Philip K

Sci Rep, 2016 08 16;6:31749.
PMID: 27526944 DOI: 10.1038/srep31749

Salivaricin B is a 25 amino acid polycyclic peptide belonging to the type AII lantibiotics and first shown to be produced by Streptococcus salivarius. In this study we describe the bactericidal mode of action of salivaricin B against susceptible Gram-positive bacteria. The killing action of salivaricin B required micro-molar concentrations of lantibiotic whereas the prototype lantibiotic nisin A was shown to be potent at nano-molar levels. Unlike nisin A, salivaricin B did not induce pore formation or dissipate the membrane potential in susceptible cells. This was established by measuring the fluorescence of the tryptophan residue at position 17 when salivaricin B interacted with bacterial membrane vesicles. The absence of a fluorescence blue shift indicates a failure of salivaricin B to penetrate the membranes. On the other hand, salivaricin B interfered with cell wall biosynthesis, as shown by the accumulation of the final soluble cell wall precursor UDP-MurNAc-pentapeptide which is the backbone of the bacterial peptidoglycan. Transmission electron microscopy of salivaricin B-treated cells showed a reduction in cell wall thickness together with signs of aberrant septum formation in the absence of visible changes to cytoplasmic membrane integrity.

Matched MeSH terms: Gram-Positive Bacteria/drug effects*; Gram-Positive Bacteria/ultrastructure
Fulltext Pentocin MQ1: A Novel, Broad-Spectrum, Pore-Forming Bacteriocin From Lactobacillus pentosus CS2 With Quorum Sensing Regulatory Mechanism and Biopreservative Potential

Wayah SB, Philip K

Front Microbiol, 2018;9:564.
PMID: 29636737 DOI: 10.3389/fmicb.2018.00564

Micrococcus luteus, Listeria monocytogenes, and Bacillus cereus are major food-borne pathogenic and spoilage bacteria. Emergence of antibiotic resistance and consumer demand for foods containing less of chemical preservatives led to a search for natural antimicrobials. A study aimed at characterizing, investigating the mechanism of action and regulation of biosynthesis and evaluating the biopreservative potential of pentocin from Lactobacillus pentosus CS2 was conducted. Pentocin MQ1 is a novel bacteriocin isolated from L. pentosus CS2 of coconut shake origin. The purification strategy involved adsorption-desorption of bacteriocin followed by RP-HPLC. It has a molecular weight of 2110.672 Da as determined by MALDI-TOF mass spectrometry and a molar extinction value of 298.82 M-1 cm-1. Pentocin MQ1 is not plasmid-borne and its biosynthesis is regulated by a quorum sensing mechanism. It has a broad spectrum of antibacterial activity, exhibited high chemical, thermal and pH stability but proved sensitive to proteolytic enzymes. It is potent against M. luteus, B. cereus, and L. monocytogenes at micromolar concentrations. It is quick-acting and exhibited a bactericidal mode of action against its targets. Target killing was mediated by pore formation. We report for the first time membrane permeabilization as a mechanism of action of the pentocin from the study against Gram-positive bacteria. Pentocin MQ1 is a cell wall-associated bacteriocin. Application of pentocin MQ1 improved the microbiological quality and extended the shelf life of fresh banana. This is the first report on the biopreservation of banana using bacteriocin. These findings place pentocin MQ1 as a potential biopreservative for further evaluation in food and medical applications.

Matched MeSH terms: Gram-Positive Bacteria
Synthesis of ZnO nanoparticles with chitosan as stabilizing agent and their antibacterial properties against Gram-positive and Gram-negative bacteria

Yusof NAA, Zain NM, Pauzi N

Int J Biol Macromol, 2019 Mar 01;124:1132-1136.
PMID: 30496864 DOI: 10.1016/j.ijbiomac.2018.11.228

Antibacterial activity of zinc oxide (ZnO) nanoparticles have received significant interest, particularly by the implementation of nanotechnology to synthesize particles in nanometer region. ZnO nanoparticles were successfully synthesized through microwave heating by using chitosan as a stabilizing agent and characterized by UV-vis, FTIR, XRD and FESEM-EDX. The aim of the present study is to determine the antibacterial activity of ZnO nanoparticles against Gram-positive bacterium Staphylococcus aureus (S. aureus) and Gram-negative bacterium Escherichia coli (E. coli). The antibacterial effect of ZnO nanoparticles was investigated for the inhibition zone and inactivation of cell growth. The absorption of ZnO nanoparticles was found to be around 360 nm. FTIR results showed the stretching mode of ZnO nanoparticles at 475 cm-1 of the absorption band. EDX results indicated that ZnO nanoparticles have been successfully formed with an atomic percentage of zinc and oxygen at 23.61 and 46.57% respectively. X-ray diffraction result was confirmed the single-phase formation of ZnO nanoparticles and the particle sizes were observed to be around 50 to 130 nm. The results showed that ZnO nanoparticles have displayed inhibition zone of 16 and 13 mm against S. aureus and E. coli respectively. Gram-negative bacteria seemed to be more resistant to ZnO nanoparticles than Gram-positive bacteria.

Matched MeSH terms: Gram-Positive Bacteria
Review: dalbavancin--a novel lipoglycopeptide antimicrobial for gram positive pathogens

Das B, Sarkar C, Biswas R, Pandey S

Pak J Pharm Sci, 2008 Jan;21(1):78-87.
PMID: 18166524

Glycopeptide antibiotics represent an important class of microbial compounds produced by several genera of actinomycetes. The emergence of resistance to glycopeptides among enterococci and staphylococci has prompted the search for second-generation drugs of this class and semi-synthetic derivatives are currently under clinical trials. Antimicrobial resistance among gram-positive organisms has been increasing steadily during the past several decades. Dalbavancin, a novel lipoglycopeptide, has a mechanism of action similar to that of other glycopeptides. It has in vitro activity against a variety of Gram-positive organisms specially multidrug resistant Staphylococcus aureus, but no activity against Gram-negative or vancomycin-resistant enterococci that possess vanA gene. Due to its prolonged half-life (6-10 days), dalbavancin can be administered intravenously once weekly. In Phase II and III clinical trials, dalbavancin was effective and well-tolerated for the treatment of skin and soft-tissue infections, catheter-related bloodstream infections, and skin and skin-structure infections. To date, adverse events have been mild and limited; the most common being pyrexia, headache, diarrhea. Dalbavancin appears to be a promising antimicrobial agent for the treatment of Gram-positive infections. Additional clinical data are required to fully assess its use. Despite the remarkable and favorable pharmacokinetic and pharmacodynamic properties, the use of this potent agent should be restricted to severe infections due to multidrug resistant organisms to limit the risk of selection of resistance. It is active against Gram-positive aerobes and anerobes, including resistant pathogens, with the exception of strains producing vanA-mediated resistance. Its approval by the FDA is expected soon. The extent to which dalbavancin will supplant vancomycin and whether it will be preferred over other newer agents such as linezolid in the next decade remains to be seen.

Matched MeSH terms: Gram-Positive Bacteria/drug effects; Gram-Positive Bacterial Infections/drug therapy*
Fulltext Flavonoid analyses and antimicrobial activity of various parts of Phaleria macrocarpa (Scheff.) Boerl fruit

Hendra R, Ahmad S, Sukari A, Shukor MY, Oskoueian E

Int J Mol Sci, 2011;12(6):3422-31.
PMID: 21747685 DOI: 10.3390/ijms12063422

Phaleria macrocarpa (Scheff.) Boerl (Thymelaceae) is commonly known as 'Crown of God', 'Mahkota Dewa', and 'Pau'. It originates from Papua Island, Indonesia and it grows in tropical areas. Empirically, it is potent in treating the hypertensive, diabetic, cancer and diuretic patients. It has a long history of ethnopharmacological usage, and the lack of information about its biological activities led us to investigate the possible biological activities by characterisation of flavonoids and antimicrobial activity of various part of P. macrocarpa against pathogenic bacteria and fungi. The results showed that kaempferol, myricetin, naringin, and rutin were the major flavonoids present in the pericarp while naringin and quercetin were found in the mesocarp and seed. Furthermore, the antibacterial activity of different parts of P. macrocarpa fruit showed a weak ability to moderate antibacterial activity against pathogenic tested bacteria (inhibition range: 0.93-2.17 cm) at concentration of 0.3 mg/disc. The anti fungi activity was only found in seed extract against Aspergillus niger (1.87 cm) at concentration of 0.3 mg/well. From the results obtained, P. macrocarpa fruit could be considered as a natural antimicrobial source due to the presence of flavonoid compounds.

Matched MeSH terms: Gram-Positive Bacteria/drug effects
Design, synthesis and antimicrobial evaluation of novel glycosylated-fluoroquinolones derivatives

Mohammed AAM, Suaifan GARY, Shehadeh MB, Okechukwu PN

Eur J Med Chem, 2020 Sep 15;202:112513.
PMID: 32623216 DOI: 10.1016/j.ejmech.2020.112513

Herein we report the design, synthesis and biological evaluation of structurally modified ciprofloxacin, norfloxacin and moxifloxacin standard drugs, featuring amide functional groups at C-3 of the fluoroquinolone scaffold. In vitro antimicrobial testing against various Gram-positive bacteria, Gram-negative bacteria and fungi revealed potential antibacterial and antifungal activity. Hybrid compounds 9 (MIC 0.2668 ± 0.0001 mM), 10 (MIC 0.1358 ± 00025 mM) and 13 (MIC 0.0898 ± 0.0014 mM) had potential antimicrobial activity against a fluoroquinolone-resistant Escherichia coli clinical isolate, compared to ciprofloxacin (MIC 0.5098 ± 0.0024 mM) and norfloxacin (MIC 0.2937 ± 0.0021 mM) standard drugs. Interestingly, compound 10 also exerted potential antifungal activity against Candida albicans (MIC 0.0056 ± 0.0014 mM) and Penicillium chrysogenum (MIC 0.0453 ± 0.0156 mM). Novel derivatives and standard fluoroquinolone drugs exhibited near-identical cytotoxicity levels against L6 muscle cell-line, when measured using the MTT assay.

Matched MeSH terms: Gram-Positive Bacteria/drug effects
Fulltext The evaluation of Streptococcus mutans content of saliva in patients with recurrent oral ulceration

Al-Ahmad, Basma Ezzat Mustafa, Muhannad Ali Kashmoola, Nur Aini Zakaria

International Medical Journal Malaysia, 2017;16(21):14-14.
MyJurnal

Recurrent oral ulcer is a chronic inflammatory condition characterized by mucosa
ulceration, which was believed to have bacterial etiology. Streptococcus mutans is one of the
bacteria which have been implicated in this case; it is gram-positive bacteria that reside in the
biofilms on the tooth surfaces. The aim of this study was to evaluate Streptococcus mutans content
in saliva of recurrent oral ulcer patients and its role as a prognostic factor. (Copied from article).

Matched MeSH terms: Gram-Positive Bacteria
Effects of Methanol Extract of Wedelia chinensis Osbeck (Asteraceae) Leaves against Pathogenic Bacteria with Emphasise on Bacillus cereus

Darah I, Lim SH, Nithianantham K

Indian J Pharm Sci, 2013 Sep;75(5):533-9.
PMID: 24403653

The antibacterial activity of the methanol extract of Wedelia chinensis leave was studied and tested against three pathogenic Gram positive bacteria (Bacillus cereus, B. subtilis and Stapylococcus aureus) and three pathogenic Gram negative bacteria (Escherichia coli, Proteus rettgeri and Pseudomonas aeruginosa) by the disk diffusion assay and broth dilution methods. The extract exhibited favourable antibacterial activity against the bacterial cells but was more potent against Gram positive bacteria with the minimum inhibition concentration of 3.12 to 6.25 mg/ml compared to the Gram negative bacteria which had minimum inhibition concentration values of 25 mg/ml. The time-kill study suggested that the extract possessed bactericidal properties at higher concentrations and eradicated the growth of bacterial cells. The major abnormalities occurred to the bacterial cells after exposed to the extract were complete alterations in their morphology and collapsed of the cells beyond repair. The methanol extract of W. chinensis may be an effective antibacterial agent to treat bacterial infections.

Matched MeSH terms: Gram-Positive Bacteria
Antimicrobial properties of starch films incorporated with chitosan nanoparticles: In vitro and in vivo evaluation

Shapi'i RA, Othman SH, Nordin N, Kadir Basha R, Nazli Naim M

Carbohydr Polym, 2020 Feb 15;230:115602.
PMID: 31887886 DOI: 10.1016/j.carbpol.2019.115602

Chitosan nanoparticles (CNP) were synthesized via ionic gelation and used for the preparation of starch-based nanocomposite films containing different concentration of CNP (0, 5, 10, 15, 20% w/w). Antimicrobial properties of starch/CNP films was evaluated via in vitro (disc diffusion analysis) and in vivo (microbial count in wrapped cherry tomatoes) study. It was found that inhibitory zone of the 15 and 20% of starch/CNP films were clearly observed for all the tested bacteria including Bacillus cereus, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium. In vivo study revealed that the starch/CNP film (15% w/w) was more efficient to inhibit the microbial growth in cherry tomatoes (7 × 102 CFU/g) compared to neat starch film (2.15 × 103 CFU/g) thus confirmed the potential application of the films as antimicrobial food packaging.

Matched MeSH terms: Gram-Positive Bacteria/drug effects
Screening antimicrobial activity of various extracts of Urtica dioica

Modarresi-Chahardehi A, Ibrahim D, Fariza-Sulaiman S, Mousavi L

Rev. Biol. Trop., 2012 Dec;60(4):1567-76.
PMID: 23342511

Urtica dioica or stinging nettle is traditionally used as an herbal medicine in Western Asia. The current study represents the investigation of antimicrobial activity of U. dioica from nine crude extracts that were prepared using different organic solvents, obtained from two extraction methods: the Soxhlet extractor (Method I), which included the use of four solvents with ethyl acetate and hexane, or the sequential partitions (Method II) with a five solvent system (butanol). The antibacterial and antifungal activities of crude extracts were tested against 28 bacteria, three yeast strains and seven fungal isolates by the disc diffusion and broth dilution methods. Amoxicillin was used as positive control for bacteria strains, vancomycin for Streptococcus sp., miconazole nitrate (30 microg/mL) as positive control for fungi and yeast, and pure methanol (v/v) as negative control. The disc diffusion assay was used to determine the sensitivity of the samples, whilst the broth dilution method was used for the determination of the minimal inhibition concentration (MIC). The ethyl acetate and hexane extract from extraction method I (EA I and HE I) exhibited highest inhibition against some pathogenic bacteria such as Bacillus cereus, MRSA and Vibrio parahaemolyticus. A selection of extracts that showed some activity was further tested for the MIC and minimal bactericidal concentrations (MBC). MIC values of Bacillus subtilis and Methicillin-resistant Staphylococcus aureus (MRSA) using butanol extract of extraction method II (BE II) were 8.33 and 16.33mg/mL, respectively; while the MIC value using ethyl acetate extract of extraction method II (EAE II) for Vibrio parahaemolyticus was 0.13mg/mL. Our study showed that 47.06% of extracts inhibited Gram-negative (8 out of 17), and 63.63% of extracts also inhibited Gram-positive bacteria (7 out of 11); besides, statistically the frequency of antimicrobial activity was 13.45% (35 out of 342) which in this among 21.71% belongs to antimicrobial activity extracts from extraction method I (33 out of 152 of crude extracts) and 6.82% from extraction method II (13 out of 190 of crude extracts). However, crude extracts from method I exhibited better antimicrobial activity against the Gram-positive bacteria than the Gram-negative bacteria. The positive results on medicinal plants screening for antibacterial activity constitutes primary information for further phytochemical and pharmacological studies. Therefore, the extracts could be suitable as antimicrobial agents in pharmaceutical and food industry.

Matched MeSH terms: Gram-Positive Bacteria/classification; Gram-Positive Bacteria/drug effects*
In vitro antibacterial effects of Cinnamomum extracts on common bacteria found in wound infections with emphasis on methicillin-resistant Staphylococcus aureus

Buru AS, Pichika MR, Neela V, Mohandas K

J Ethnopharmacol, 2014 May 14;153(3):587-95.
PMID: 24613273 DOI: 10.1016/j.jep.2014.02.044

Cinnamomum species have been widely used in many traditional systems of medicine around the world. In the Malaysian traditional system of medicine, the leaves, stem bark and stem wood of Cinnamomum iners, Cinnamomum porrectum, Cinnamomum altissimum and Cinnamomum impressicostatum have been used to treat wound infections. To study the antibacterial effects of Cinnamomum iners, Cinnamomum porrectum, Cinnamomum altissimum and Cinnamomum impressicostatum against common bacteria found in wound infections with primary focus on methicillin-resistant Staphylococcus aureus (MRSA).

Matched MeSH terms: Gram-Positive Bacteria/drug effects*; Gram-Positive Bacteria/growth & development
Fulltext Sustainable drug release from polycaprolactone coated chitin-lignin gel fibrous scaffolds

Abudula T, Gauthaman K, Mostafavi A, Alshahrie A, Salah N, Morganti P, et al.

Sci Rep, 2020 11 24;10(1):20428.
PMID: 33235239 DOI: 10.1038/s41598-020-76971-w

Non-healing wounds have placed an enormous stress on both patients and healthcare systems worldwide. Severe complications induced by these wounds can lead to limb amputation or even death and urgently require more effective treatments. Electrospun scaffolds have great potential for improving wound healing treatments by providing controlled drug delivery. Previously, we developed fibrous scaffolds from complex carbohydrate polymers [i.e. chitin-lignin (CL) gels]. However, their application was limited by solubility and undesirable burst drug release. Here, a coaxial electrospinning is applied to encapsulate the CL gels with polycaprolactone (PCL). Presence of a PCL shell layer thus provides longer shelf-life for the CL gels in a wet environment and sustainable drug release. Antibiotics loaded into core-shell fibrous platform effectively inhibit both gram-positive and -negative bacteria without inducting observable cytotoxicity. Therefore, PCL coated CL fibrous gel platforms appear to be good candidates for controlled drug release based wound dressing applications.

Matched MeSH terms: Gram-Positive Bacteria/drug effects; Gram-Positive Bacteria/growth & development

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