Displaying publications 41 - 60 of 75 in total

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  1. Fulltext Growth inhibition of Candida species by Wickerhamomyces anomalus mycocin and a lactone compound of Aureobasidium pullulans
    Tay ST, Lim SL, Tan HW
    BMC Complement Altern Med, 2014;14:439.
    PMID: 25380692 DOI: 10.1186/1472-6882-14-439
    The increasing resistance of Candida yeasts towards antifungal compounds and the limited choice of therapeutic drugs have spurred great interest amongst the scientific community to search for alternative anti-Candida compounds. Mycocins and fungal metabolites have been reported to have the potential for treatment of fungal infections. In this study, the growth inhibition of Candida species by a mycocin produced by Wickerhamomyces anomalus and a lactone compound from Aureobasidium pullulans were investigated.
    Matched MeSH terms: Biofilms/drug effects
  2. Fulltext Inhibitory effect of Duabanga grandiflora on MRSA biofilm formation via prevention of cell-surface attachment and PBP2a production
    Santiago C, Lim KH, Loh HS, Ting KN
    Molecules, 2015 Mar 10;20(3):4473-82.
    PMID: 25764489 DOI: 10.3390/molecules20034473
    Formation of biofilms is a major factor for nosocomial infections associated with methicillin-resistance Staphylococcus aureus (MRSA). This study was carried out to determine the ability of a fraction, F-10, derived from the plant Duabanga grandiflora to inhibit MRSA biofilm formation. Inhibition of biofilm production and microtiter attachment assays were employed to study the anti-biofilm activity of F-10, while latex agglutination test was performed to study the influence of F-10 on penicillin-binding protein 2a (PBP2a) level in MRSA biofilm. PBP2a is a protein that confers resistance to beta-lactam antibiotics. The results showed that, F-10 at minimum inhibitory concentration (MIC, 0.75 mg/mL) inhibited biofilm production by 66.10%; inhibited cell-surface attachment by more than 95%; and a reduced PBP2a level in the MRSA biofilm was observed. Although ampicilin was more effective in inhibiting biofilm production (MIC of 0.05 mg/mL, 84.49%) compared to F-10, the antibiotic was less effective in preventing cell-surface attachment. A higher level of PBP2a was detected in ampicillin-treated MRSA showing the development of further resistance in these colonies. This study has shown that F-10 possesses anti-biofilm activity, which can be attributed to its ability to reduce cell-surface attachment and attenuate the level of PBP2a that we postulated to play a crucial role in mediating biofilm formation.
    Matched MeSH terms: Biofilms/drug effects
  3. Bacterial adherence and biofilm formation on medical implants: a review
    Veerachamy S, Yarlagadda T, Manivasagam G, Yarlagadda PK
    Proc Inst Mech Eng H, 2014 Oct;228(10):1083-99.
    PMID: 25406229 DOI: 10.1177/0954411914556137
    Biofilms are a complex group of microbial cells that adhere to the exopolysaccharide matrix present on the surface of medical devices. Biofilm-associated infections in the medical devices pose a serious problem to the public health and adversely affect the function of the device. Medical implants used in oral and orthopedic surgery are fabricated using alloys such as stainless steel and titanium. The biological behavior, such as osseointegration and its antibacterial activity, essentially depends on both the chemical composition and the morphology of the surface of the device. Surface treatment of medical implants by various physical and chemical techniques are attempted in order to improve their surface properties so as to facilitate bio-integration and prevent bacterial adhesion. The potential source of infection of the surrounding tissue and antimicrobial strategies are from bacteria adherent to or in a biofilm on the implant which should prevent both biofilm formation and tissue colonization. This article provides an overview of bacterial biofilm formation and methods adopted for the inhibition of bacterial adhesion on medical implants.
    Matched MeSH terms: Biofilms/drug effects
  4. Fulltext Non-antibiotic quorum sensing inhibitors acting against N-acyl homoserine lactone synthase as druggable target
    Chang CY, Krishnan T, Wang H, Chen Y, Yin WF, Chong YM, et al.
    Sci Rep, 2014;4:7245.
    PMID: 25430794 DOI: 10.1038/srep07245
    N-acylhomoserine lactone (AHL)-based quorum sensing (QS) is important for the regulation of proteobacterial virulence determinants. Thus, the inhibition of AHL synthases offers non-antibiotics-based therapeutic potentials against QS-mediated bacterial infections. In this work, functional AHL synthases of Pseudomonas aeruginosa LasI and RhlI were heterologously expressed in an AHL-negative Escherichia coli followed by assessments on their AHLs production using AHL biosensors and high resolution liquid chromatography-mass spectrometry (LCMS). These AHL-producing E. coli served as tools for screening AHL synthase inhibitors. Based on a campaign of screening synthetic molecules and natural products using our approach, three strongest inhibitors namely are salicylic acid, tannic acid and trans-cinnamaldehyde have been identified. LCMS analysis further confirmed tannic acid and trans-cinnemaldehyde efficiently inhibited AHL production by RhlI. We further demonstrated the application of trans-cinnemaldehyde inhibiting Rhl QS system regulated pyocyanin production in P. aeruginosa up to 42.06%. Molecular docking analysis suggested that trans-cinnemaldehyde binds to the LasI and EsaI with known structures mainly interacting with their substrate binding sites. Our data suggested a new class of QS-inhibiting agents from natural products targeting AHL synthase and provided a potential approach for facilitating the discovery of anti-QS signal synthesis as basis of novel anti-infective approach.
    Matched MeSH terms: Biofilms/drug effects
  5. Potential mechanisms for the effects of tea extracts on the attachment, biofilm formation and cell size of Streptococcus mutans
    Wang Y, Lee SM, Dykes GA
    Biofouling, 2013;29(3):307-18.
    PMID: 23528127 DOI: 10.1080/08927014.2013.774377
    Tea can inhibit the attachment of Streptococcus mutans to surfaces and subsequent biofilm formation. Five commercial tea extracts were screened for their ability to inhibit attachment and biofilm formation by two strains of S. mutans on glass and hydroxyapatite surfaces. The mechanisms of these effects were investigated using scanning electron microscopy (SEM) and phytochemical screening. The results indicated that extracts of oolong tea most effectively inhibited attachment and extracts of pu-erh tea most effectively inhibited biofilm formation. SEM images showed that the S. mutans cells treated with extracts of oolong tea, or grown in medium containing extracts of pu-erh tea, were coated with tea components and were larger with more rounded shapes. The coatings on the cells consisted of flavonoids, tannins and indolic compounds. The ratio of tannins to simple phenolics in each of the coating samples was ∼3:1. This study suggests potential mechanisms by which tea components may inhibit the attachment and subsequent biofilm formation of S. mutans on tooth surfaces, such as modification of cell surface properties and blocking of the activity of proteins and the structures used by the bacteria to interact with surfaces.
    Matched MeSH terms: Biofilms/drug effects*
  6. Anti-Candida albicans biofilm activity by Cassia spectabilis standardized methanol extract: an ultrastructural study
    Torey A, Sasidharan S
    Eur Rev Med Pharmacol Sci, 2011 Aug;15(8):875-82.
    PMID: 21845797
    Candida (C.) albicans infection in its biofilm mode of growth has taken centre point with the increasing recognition of its role in human infections due to the development of resistance to the commonly used antibiotic or phenotypic adaptation within the biofilm. Hence, in this study the inhibitory effect of methanol extract of Cassia (C.) spectabilis leaves was evaluated against biofilm forming C. albicans.
    Matched MeSH terms: Biofilms/drug effects*
  7. Fulltext Biopolymers Regulate Silver Nanoparticle under Microwave Irradiation for Effective Antibacterial and Antibiofilm Activities
    Velusamy P, Su CH, Venkat Kumar G, Adhikary S, Pandian K, Gopinath SC, et al.
    PLoS One, 2016;11(6):e0157612.
    PMID: 27304672 DOI: 10.1371/journal.pone.0157612
    In the current study, facile synthesis of carboxymethyl cellulose (CMC) and sodium alginate capped silver nanoparticles (AgNPs) was examined using microwave radiation and aniline as a reducing agent. The biopolymer matrix embedded nanoparticles were synthesized under various experimental conditions using different concentrations of biopolymer (0.5, 1, 1.5, 2%), volumes of reducing agent (50, 100, 150 μL), and duration of heat treatment (30 s to 240 s). The synthesized nanoparticles were analyzed by scanning electron microscopy, UV-Vis spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy for identification of AgNPs synthesis, crystal nature, shape, size, and type of capping action. In addition, the significant antibacterial efficacy and antibiofilm activity of biopolymer capped AgNPs were demonstrated against different bacterial strains, Staphylococcus aureus MTCC 740 and Escherichia coli MTCC 9492. These results confirmed the potential for production of biopolymer capped AgNPs grown under microwave irradiation, which can be used for industrial and biomedical applications.
    Matched MeSH terms: Biofilms/drug effects
  8. Fulltext Prevention of cell-surface attachment and reduction of penicillin-binding protein 2a (PBP2a) level in methicillin-resistant Staphylococcus aureus biofilms by Acalypha wilkesiana
    Santiago C, Lim KH, Loh HS, Ting KN
    BMC Complement Altern Med, 2015;15:79.
    PMID: 25880167 DOI: 10.1186/s12906-015-0615-6
    Formation of biofilm is known to enhance the virulence of methicillin-resistance Staphylococcus aureus (MRSA), which is associated with persistent infections in hospital settings. The biofilm layer essentially forms a protective barrier encapsulating the bacterial colony and thus reduces the effectiveness of chemotherapeutics. We have isolated 9EA-FC-B bioactive fraction from Acalypha wilkesiana Müll. Arg. that reverses ampicillin resistant in MRSA through inhibition of the antibiotic resistant protein, penicillin-binding protein 2a (PBP2a). In this study, we aimed to investigate the effects of 9EA-FC-B on MRSA biofilm forming capacity.
    Matched MeSH terms: Biofilms/drug effects*
  9. Fulltext Biofilm Formation and Antibiotic Resistance Phenotype of Helicobacter pylori Clinical Isolates
    Fauzia KA, Miftahussurur M, Syam AF, Waskito LA, Doohan D, Rezkitha YAA, et al.
    Toxins (Basel), 2020 07 24;12(8).
    PMID: 32722296 DOI: 10.3390/toxins12080473
    We evaluated biofilm formation of clinical Helicobacter pylori isolates from Indonesia and its relation to antibiotic resistance. We determined the minimum inhibition concentration (MIC) of amoxicillin, clarithromycin, levofloxacin, metronidazole and tetracycline by the Etest to measure the planktonic susceptibility of 101 H. pylori strains. Biofilms were quantified by the crystal violet method. The minimum biofilm eradication concentration (MBEC) was obtained by measuring the survival of bacteria in a biofilm after exposure to antibiotics. The majority of the strains formed a biofilm (93.1% (94/101)), including weak (75.5%) and strong (24.5%) biofilm-formers. Planktonic resistant and sensitive strains produced relatively equal amounts of biofilms. The resistance proportion, shown by the MBEC measurement, was higher in the strong biofilm group for all antibiotics compared to the weak biofilm group, especially for clarithromycin (p = 0.002). Several cases showed sensitivity by the MIC measurement, but resistance according to the MBEC measurements (amoxicillin, 47.6%; tetracycline, 57.1%; clarithromycin, 19.0%; levofloxacin, 38.1%; and metronidazole 38.1%). Thus, biofilm formation may increase the survival of H. pylori and its resistance to antibiotics. Biofilm-related antibiotic resistance should be evaluated with antibiotic susceptibility.
    Matched MeSH terms: Biofilms/drug effects
  10. Fulltext Characterization and Transcriptome Studies of Autoinducer Synthase Gene from Multidrug Resistant Acinetobacter baumannii Strain 863
    Ng CK, How KY, Tee KK, Chan KG
    Genes (Basel), 2019 04 08;10(4).
    PMID: 30965610 DOI: 10.3390/genes10040282
    Quorum sensing (QS) is a cell-to-cell communication system that uses autoinducers as signaling molecules to enable inter-species and intra-species interactions in response to external stimuli according to the population density. QS allows bacteria such as Acinetobacter baumannii to react rapidly in response to environmental changes and hence, increase the chances of survival. A. baumannii is one of the causative agents in hospital-acquired infections and the number of cases has increased remarkably in the past decade. In this study, A. baumannii strain 863, a multidrug-resistant pathogen, was found to exhibit QS activity by producing N-acyl homoserine lactone. We identified the autoinducer synthase gene, which we named abaI, by performing whole genome sequencing analysis of A. baumannii strain 863. Using high resolution tandem triple quadrupole mass spectrometry, we reported that abaI of A. baumannii strain 863 produced 3-hydroxy-dodecanoyl-homoserine lactone. A gene deletion mutant was constructed, which confirmed the functionality of abaI. A growth defect was observed in the QS-deficient mutant strain. Transcriptome profiling was performed to determine the possible genes regulated by QS. Four groups of genes that showed differential expression were discovered, namely those involved in carbon source metabolism, energy production, stress response and the translation process.
    Matched MeSH terms: Biofilms/drug effects
  11. Fulltext Imipenem Treatment Induces Expression of Important Genes and Phenotypes in a Resistant Acinetobacter baumannii Isolate
    Dhabaan GN, AbuBakar S, Cerqueira GM, Al-Haroni M, Pang SP, Hassan H
    Antimicrob Agents Chemother, 2015 Dec 14;60(3):1370-6.
    PMID: 26666943 DOI: 10.1128/AAC.01696-15
    Acinetobacter baumannii has emerged as a notorious multidrug-resistant pathogen, and development of novel control measures is of the utmost importance. Understanding the factors that play a role in drug resistance may contribute to the identification of novel therapeutic targets. Pili are essential for A. baumannii adherence to and biofilm formation on abiotic surfaces as well as virulence. In the present study, we found that biofilm formation was significantly induced in an imipenem-resistant (Imp(r)) strain treated with a subinhibitory concentration of antibiotic compared to that in an untreated control and an imipenem-susceptible (Imp(s)) isolate. Using microarray and quantitative PCR analyses, we observed that several genes responsible for the synthesis of type IV pili were significantly upregulated in the Imp(r) but not in the Imp(s) isolate. Notably, this finding is corroborated by an increase in the motility of the Imp(r) strain. Our results suggest that the ability to overproduce colonization factors in response to imipenem treatment confers biological advantage to A. baumannii and may contribute to clinical success.
    Matched MeSH terms: Biofilms/drug effects
  12. Anti-plaque effect of a synergistic combination of green tea and Salvadora persica L. against primary colonizers of dental plaque
    Abdulbaqi HR, Himratul-Aznita WH, Baharuddin NA
    Arch Oral Biol, 2016 Oct;70:117-124.
    PMID: 27343694 DOI: 10.1016/j.archoralbio.2016.06.011
    OBJECTIVE: Green tea (Gt), leafs of Camellia sinensis var. assamica, is widely consumed as healthy beverage since thousands of years in Asian countries. Chewing sticks (miswak) of Salvadora persica L. (Sp) are traditionally used as natural brush to ensure oral health in developing countries. Both Gt and Sp extracts were reported to have anti-bacterial activity against many dental plaque bacteria. However, their combination has never been tested to have anti-bacterial and anti-adherence effect against primary dental plaque colonizers, playing an initial role in the dental plaque development, which was investigated in this study.

    METHODS: Two-fold serial micro-dilution method was used to measure minimal inhibitory concentration (MIC) of aqueous extracts of Gt, Sp and their combinations. Adsorption to hexadecane was used to determine the cell surface hydrophobicity (CSH) of bacterial cells. Glass beads were used to mimic the hard tissue surfaces, and were coated with saliva to develop experimental pellicles for the adhesion of the primary colonizing bacteria.

    RESULTS: Gt aqueous extracts exhibited better anti-plaque effect than Sp aqueous extracts. Their combination, equivalent to 1/4 and 1/2 of MIC values of Gt and Sp extracts respectively, showed synergistic anti-plaque properties with fractional inhibitory concentration (FIC) equal to 0.75. This combination was found to significantly reduce CSH (p<0.05) and lower the adherence ability (p<0.003) towards experimental pellicles.

    CONCLUSION: Combination between Gt and Sp aqueous extracts exhibited synergistic anti-plaque activity, and could be used as a useful active agent to produce oral health care products.

    Matched MeSH terms: Biofilms/drug effects
  13. Fulltext Efficient Double Suzuki Cross-Coupling Reactions of 2,5-Dibromo-3-hexylthiophene: Anti-Tumor, Haemolytic, Anti-Thrombolytic and Biofilm Inhibition Studies
    Ikram HM, Rasool N, Zubair M, Khan KM, Abbas Chotana G, Akhtar MN, et al.
    Molecules, 2016 Jul 27;21(8).
    PMID: 27472312 DOI: 10.3390/molecules21080977
    The present study describes several novel 2,5-biaryl-3-hexylthiophene derivatives (3a-i) synthesized via a Pd(0)-catalyzed Suzuki cross-coupling reaction in moderate to good yields. The novel compounds were also analyzed for their anti-thrombolytic, haemolytic, and biofilm inhibition activities. In addition, the anti-tumor activity was also evaluated in vitro for newly-synthesized compounds, where 3-hexyl-2,5-bis(4-(methylthio)phenyl)thiophene exhibited the best anti-tumor activity against 4T1 cells with IC50 value of 16 μM. Moreover, 2,5-bis(4-methylphenyl)-3-hexylthiophene showed the highest activity against MCF-7 cells with an IC50 value of 26.2 μM. On the other hand, the compound 2,5-bis(4-chloropheny)-3-hexylthiophene exhibited excellent biofilm inhibition activity. Furthermore, the compound 2,5-bis(3-chloro-4-fluorophenyl)-3-hexylthiophene also exhibited better anti-thrombolytic and hemolytic activity results as compared to the other newly-synthesized compounds.
    Matched MeSH terms: Biofilms/drug effects*
  14. Green synthesis of graphene-silver nanocomposites and its application as a potent marine antifouling agent
    Yee MS, Khiew PS, Chiu WS, Tan YF, Kok YY, Leong CO
    Colloids Surf B Biointerfaces, 2016 Dec 01;148:392-401.
    PMID: 27639489 DOI: 10.1016/j.colsurfb.2016.09.011
    Fouling of marine surfaces has been a perpetual problem ever since the days of the early sailors. The tenacious attachment of seaweed and invertebrates to man-made surfaces, notably on ship hulls, has incurred undesirable economic losses. Graphene receives great attention in the materials world for its unique combination of physical and chemical properties. Herein, we present a novel 2-step synthesis method of graphene-silver nanocomposites which bypasses the formation of graphene oxide (GO), and produces silver nanoparticles supported on graphene sheets through a mild hydrothermal reduction process. The graphene-Ag (GAg) nanocomposite combines the antimicrobial property of silver nanoparticles and the unique structure of graphene as a support material, with potent marine antifouling properties. The GAg nanocomposite was composed of micron-scaled graphene flakes with clusters of silver nanoparticles. The silver nanoparticles were estimated to be between 72 and 86nm (SEM observations) while the crystallite size of the silver nanoparticles (AgNPs) was estimated between 1 and 5nm. The nanocomposite also exhibited the SERS effect. GAg was able to inhibit Halomonas pacifica, a model biofilm-causing microbe, from forming biofilms with as little as 1.3wt.% loading of Ag. All GAg samples displayed significant biofilm inhibition property, with the sample recording the highest Ag loading (4.9wt.% Ag) associated with a biofilm inhibition of 99.6%. Moreover, GAg displayed antiproliferative effects on marine microalgae, Dunaliella tertiolecta and Isochrysis sp. and inhibited the growth of the organisms by more than 80% after 96h. The marine antifouling properties of GAg were a synergy of the biocidal AgNPs anchored on the stable yet flexible graphene sheets, providing maximum active contact surface areas to the target organisms.
    Matched MeSH terms: Biofilms/drug effects
  15. Fulltext Methicillin-Resistant Staphylococcus aureus Biofilms and Their Influence on Bacterial Adhesion and Cohesion
    Dakheel KH, Abdul Rahim R, Neela VK, Al-Obaidi JR, Hun TG, Yusoff K
    Biomed Res Int, 2016;2016:4708425.
    PMID: 28078291 DOI: 10.1155/2016/4708425
    Twenty-five methicillin-resistant Staphylococcus aureus (MRSA) isolates were characterized by staphylococcal protein A gene typing and the ability to form biofilms. The presence of exopolysaccharides, proteins, and extracellular DNA and RNA in biofilms was assessed by a dispersal assay. In addition, cell adhesion to surfaces and cell cohesion were evaluated using the packed-bead method and mechanical disruption, respectively. The predominant genotype was spa type t127 (22 out of 25 isolates); the majority of isolates were categorized as moderate biofilm producers. Twelve isolates displayed PIA-independent biofilm formation, while the remaining 13 isolates were PIA-dependent. Both groups showed strong dispersal in response to RNase and DNase digestion followed by proteinase K treatment. PIA-dependent biofilms showed variable dispersal after sodium metaperiodate treatment, whereas PIA-independent biofilms showed enhanced biofilm formation. There was no correlation between the extent of biofilm formation or biofilm components and the adhesion or cohesion abilities of the bacteria, but the efficiency of adherence to glass beads increased after biofilm depletion. In conclusion, nucleic acids and proteins formed the main components of the MRSA clone t127 biofilm matrix, and there seems to be an association between adhesion and cohesion in the biofilms tested.
    Matched MeSH terms: Biofilms/drug effects
  16. Biofilm inhibiting activity of betacyanins from red pitahaya (Hylocereus polyrhizus) and red spinach (Amaranthus dubius) against Staphylococcus aureus and Pseudomonas aeruginosa biofilms
    Yong YY, Dykes G, Lee SM, Choo WS
    J Appl Microbiol, 2019 Jan;126(1):68-78.
    PMID: 30153380 DOI: 10.1111/jam.14091
    AIMS: To investigate the biofilm inhibitory activity of betacyanins from red pitahaya (Hylocereus polyrhizus) and red spinach (Amaranthus dubius) against Staphylococcus aureus and Pseudomonas aeruginosa biofilms.

    METHODS AND RESULTS: The pulp of red pitahaya and the leaves of red spinach were extracted using methanol followed by subfractionation to obtain betacyanin fraction. The anti-biofilm activity was examined using broth microdilution assay on polystyrene surfaces and expressed as minimum biofilm inhibitory concentration (MBIC). The betacyanin fraction from red spinach showed better anti-biofilm activity (MBIC: 0·313-1·25 mg ml-1 ) against five Staph. aureus strains while the betacyanin fraction from red pitahaya showed better anti-biofilm activity (MBIC: 0·313-0·625 mg ml-1 ) against four P. aeruginosa strains. Both betacyanin fraction significantly reduced hydrophobicity of Staph. aureus and P. aeruginosa strains. Numbers of Staph. aureus and P. aeruginosa attached to polystyrene were also reduced without affecting their cell viability.

    CONCLUSION: Betacyanins can act as anti-biofilm agents against the initial step of biofilm formation, particularly on a hydrophobic surface like polystyrene.

    SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first to investigate the use of betacyanin as a biofilm inhibitory agent. Betacyanin could potentially be used to reduce the risk of biofilm-associated infections.

    Matched MeSH terms: Biofilms/drug effects*
  17. Novel targets of pentacyclic triterpenoids in Staphylococcus aureus: A systematic review
    Chung PY
    Phytomedicine, 2020 Jul 15;73:152933.
    PMID: 31103429 DOI: 10.1016/j.phymed.2019.152933
    BACKGROUND: Staphylococcus aureus is an important pathogen both in community-acquired and healthcare-associated infections, and has successfully evolved numerous strategies for resisting the action to practically all antibiotics. Resistance to methicillin is now widely described in the community setting (CMRSA), thus the development of new drugs or alternative therapies is urgently necessary. Plants and their secondary metabolites have been a major alternative source in providing structurally diverse bioactive compounds as potential therapeutic agents for the treatment of bacterial infections. One of the classes of natural secondary metabolites from plants with the most bioactive compounds are the triterpenoids, which comprises structurally diverse organic compounds. In nature, triterpenoids are often found as tetra- or penta-cyclic structures.

    AIM: This review highlights the anti-staphylococcal activities of pentacyclic triterpenoids, particularly α-amyrin (AM), betulinic acid (BA) and betulinaldehyde (BE). These compounds are based on a 30-carbon skeleton comprising five six-membered rings (ursanes and lanostanes) or four six-membered rings and one five-membered ring (lupanes and hopanes).

    METHODS: Electronic databases such as ScienceDirect, PubMed and Scopus were used to search scientific contributions until March 2018, using relevant keywords. Literature focusing on the antimicrobial and antibiofilms of effects of pentacyclic triterpenoids on S. aureus were identified and summarized.

    RESULTS: Pentacyclic triterpenoids can be divided into three representative classes, namely ursane, lupane and oleananes. This class of compounds have been shown to exhibit analgesic, immunomodulatory, anti-inflammatory, anticancer, antioxidant, antifungal and antibacterial activities. In studies of the antimicrobial activities and targets of AM, BA and BE in sensitive and multidrug-resistant S. aureus, these compounds acted synergistically and have different targets from the conventional antibiotics.

    CONCLUSION: The inhibitory mechanisms of S. aureus in novel targets and pathways should stimulate further researches to develop AM, BA and BE as therapeutic agents for infections caused by S. aureus. Continued efforts to identify and exploit synergistic combinations by the three compounds and peptidoglycan inhibitors, are also necessary as alternative treatment options for S. aureus infections.

    Matched MeSH terms: Biofilms/drug effects
  18. Fulltext Biocide susceptibilities and biofilm-forming capacities of Acinetobacter baumannii clinical isolates from Malaysia
    Nor A'shimi MH, Alattraqchi AG, Mohd Rani F, A Rahman NI, Ismail S, Abdullah FH, et al.
    J Infect Dev Ctries, 2019 07 31;13(7):626-633.
    PMID: 32065820 DOI: 10.3855/jidc.11455
    INTRODUCTION: Acinetobacter baumannii is a Gram-negative nosocomial pathogen that has the capacity to develop resistance to all classes of antimicrobial compounds. However, very little is known regarding its susceptibility to biocides (antiseptics and disinfectants) and capacity to form biofilms, particularly for Malaysian isolates.

    AIM: To determine the susceptibility of A. baumannii isolates to commonly-used biocides, investigate their biofilm-forming capacities and the prevalence of biocide resistance and biofilm-associated genes.

    METHODOLOGY: . The minimum inhibitory concentration (MIC) values of 100 A. baumannii hospital isolates from Terengganu, Malaysia, towards the biocides benzalkonium chloride (BZK), benzethonium chloride (BZT) and chlorhexidine digluconate (CLX), were determined by broth microdilution. The isolates were also examined for their ability to form biofilms in 96-well microplates. The prevalence of biocide resistance genes qacA, qacE and qacDE1 and the biofilm-associated genes bap and abaI were determined by polymerase chain reaction (PCR).

    RESULTS: Majority of the A. baumannii isolates (43%) showed higher MIC values (> 50 µg/mL) for CLX than for BZK (5% for MIC > 50 µg/mL) and BZT (9% for MIC > 50 µg/mL). The qacDE1 gene was predominant (63%) followed by qacE (28%) whereas no isolate was found harbouring qacA. All isolates were positive for the bap and abaI genes although the biofilm-forming capacity varied among the isolates.

    CONCLUSION: The Terengganu A. baumannii isolates showed higher prevalence of qacDE1 compared to qacE although no correlation was found with the biocides' MIC values. No correlation was also observed between the isolates' biofilm-forming capacity and the MIC values for the biocides.

    Matched MeSH terms: Biofilms/drug effects*
  19. Fulltext Cationic chitosan-propolis nanoparticles alter the zeta potential of S. epidermidis, inhibit biofilm formation by modulating gene expression and exhibit synergism with antibiotics
    Ong TH, Chitra E, Ramamurthy S, Ling CCS, Ambu SP, Davamani F
    PLoS One, 2019;14(2):e0213079.
    PMID: 30818374 DOI: 10.1371/journal.pone.0213079
    Staphylococcus epidermidis, is a common microflora of human body that can cause opportunistic infections associated with indwelling devices. It is resistant to multiple antibiotics necessitating the need for naturally occurring antibacterial agents. Malaysian propolis, a natural product obtained from beehives exhibits antimicrobial and antibiofilm properties. Chitosan-propolis nanoparticles (CPNP) were prepared using Malaysian propolis and tested for their effect against S. epidermidis. The cationic nanoparticles depicted a zeta potential of +40 and increased the net electric charge (zeta potential) of S. epidermidis from -17 to -11 mV in a concentration-dependent manner whereas, ethanol (Eth) and ethyl acetate (EA) extracts of propolis further decreased the zeta potential from -17 to -20 mV. Confocal laser scanning microscopy (CLSM) depicted that CPNP effectively disrupted biofilm formation by S. epidermidis and decreased viability to ~25% compared to Eth and EA with viability of ~60-70%. CPNP was more effective in reducing the viability of both planktonic as well as biofilm bacteria compared to Eth and EA. At 100 μg/mL concentration, CPNP decreased the survival of biofilm bacteria by ~70% compared to Eth or EA extracts which decreased viability by only 40%-50%. The morphology of bacterial biofilm examined by scanning electron microscopy depicted partial disruption of biofilm by Eth and EA extracts and significant disruption by CPNP reducing bacterial number in the biofilm by ~90%. Real time quantitative PCR analysis of gene expression in treated bacteria showed that genes involved in intercellular adhesion such as IcaABCD, embp and other related genes were significantly downregulated by CPNP. In addition to having a direct inhibitory effect on the survival of S. epidermidis, CPNP showed synergism with the antibiotics rifampicin, ciprofloxacin, vancomycin and doxycycline suggestive of effective treatment regimens. This would help decrease antibiotic treatment dose by at least 4-fold in combination therapies thereby opening up ways of tackling antibiotic resistance in bacteria.
    Matched MeSH terms: Biofilms/drug effects
  20. Fulltext Streptomyces sp.-A Treasure Trove of Weapons to Combat Methicillin-Resistant Staphylococcus aureus Biofilm Associated with Biomedical Devices
    Pusparajah P, Letchumanan V, Law JW, Ab Mutalib NS, Ong YS, Goh BH, et al.
    Int J Mol Sci, 2021 Aug 28;22(17).
    PMID: 34502269 DOI: 10.3390/ijms22179360
    Biofilms formed by methicillin-resistant S. aureus (MRSA) are among the most frequent causes of biomedical device-related infection, which are difficult to treat and are often persistent and recurrent. Thus, new and effective antibiofilm agents are urgently needed. In this article, we review the most relevant literature of the recent years reporting on promising anti-MRSA biofilm agents derived from the genus Streptomyces bacteria, and discuss the potential contribution of these newly reported antibiofilm compounds to the current strategies in preventing biofilm formation and eradicating pre-existing biofilms of the clinically important pathogen MRSA. Many efforts are evidenced to address biofilm-related infections, and some novel strategies have been developed and demonstrated encouraging results in preclinical studies. Nevertheless, more in vivo studies with appropriate biofilm models and well-designed multicenter clinical trials are needed to assess the prospects of these strategies.
    Matched MeSH terms: Biofilms/drug effects*
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