Displaying publications 41 - 60 of 66 in total

Abstract:
Sort:
  1. Biofilm production by pathogens associated with canine otitis externa, and the antibiofilm activity of ionophores and antimicrobial adjuvants
    Chan WY, Hickey EE, Page SW, Trott DJ, Hill PB
    J Vet Pharmacol Ther, 2019 Nov;42(6):682-692.
    PMID: 31503362 DOI: 10.1111/jvp.12811
    Otitis externa (OE) is a frequently reported disorder in dogs associated with secondary infections by Staphylococcus, Pseudomonas and yeast pathogens. The presence of biofilms may play an important role in the resistance of otic pathogens to antimicrobial agents. Biofilm production of twenty Staphylococcus pseudintermedius and twenty Pseudomonas aeruginosa canine otic isolates was determined quantitatively using a microtiter plate assay, and each isolate was classified as a strong, moderate, weak or nonbiofilm producer. Minimum biofilm eradication concentration (MBEC) of two ionophores (narasin and monensin) and three adjuvants (N-acetylcysteine (NAC), Tris-EDTA and disodium EDTA) were investigated spectrophotometrically (OD570nm ) and quantitatively (CFU/ml) against selected Staphylococcus and Pseudomonas biofilm cultures. Concurrently, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of planktonic cultures were assessed. 16/20 of the S. pseudintermedius clinical isolates were weak biofilm producers. 19/20 P. aeruginosa clinical isolates produced biofilms and were distributed almost equally as weak, moderate and strong biofilm producers. While significant antibiofilm activity was observed, no MBEC was achieved with narasin or monensin. The MBEC for NAC ranged from 5,000-10,000 µg/ml and from 20,000-80,000 µg/ml against S. pseudintermedius and P. aeruginosa, respectively. Tris-EDTA eradicated P. aeruginosa biofilms at concentrations ranging from 6,000/1,900 to 12,000/3,800 µg/ml. The MBEC was up to 16-fold and eightfold higher than the MIC/MBC of NAC and Tris-EDTA, respectively. Disodium EDTA reduced biofilm growth of both strains at concentrations of 470 µg/ml and higher. It can be concluded that biofilm production is common in pathogens associated with canine OE. NAC and Tris-EDTA are effective antibiofilm agents in vitro that could be considered for the treatment of biofilm-associated OE in dogs.
    Matched MeSH terms: Biofilms/growth & development*
  2. Fulltext Iron and Virulence in Stenotrophomonas Maltophilia: All We Know So Far
    Kalidasan V, Joseph N, Kumar S, Awang Hamat R, Neela VK
    Front Cell Infect Microbiol, 2018;8:401.
    PMID: 30483485 DOI: 10.3389/fcimb.2018.00401
    Stenotrophomonas maltophilia is a multi-drug-resistant global opportunistic nosocomial pathogen, which possesses a huge number of virulence factors and antibiotics resistance characteristics. Iron has a crucial contribution toward growth and development, cell growth and proliferation, and pathogenicity. The bacterium found to acquire iron for its cellular process through the expression of two iron acquisition systems. Two distinct pathways for iron acquisition are encoded by the S. maltophilia genome-a siderophore-and heme-mediated iron uptake system. The entAFDBEC operon directs the production of the enterobactin siderophore of catecholate in nature, while heme uptake relies on hgbBC and potentially hmuRSTUV operon. Fur and sigma factors are regulators of S. maltophilia under iron-limited condition. Iron potentially act as a signal which plays an important role in biofilm formation, extracellular polymeric substances (EPS), extracellular enzymes production, oxidative stress response, diffusible signal factor (DSF) and siderophore production in S. maltophilia. This review summarizes the current knowledge of iron acquisition in S. maltophilia and the critical role of iron in relation to its pathogenicity.
    Matched MeSH terms: Biofilms/growth & development
  3. Fulltext Association of some Campylobacter jejuni with Pseudomonas aeruginosa biofilms increases attachment under conditions mimicking those in the environment
    Teh AHT, Lee SM, Dykes GA
    PLoS One, 2019;14(4):e0215275.
    PMID: 30970009 DOI: 10.1371/journal.pone.0215275
    Campylobacter jejuni is a microaerophilic bacterial species which is a major food-borne pathogen worldwide. Attachment and biofilm formation have been suggested to contribute to the survival of this fastidious bacteria in the environment. In this study the attachment of three C. jejuni strains (C. jejuni strains 2868 and 2871 isolated from poultry and ATCC 33291) to different abiotic surfaces (stainless steel, glass and polystyrene) alone or with Pseudomonas aeruginosa biofilms on them, in air at 25°C and under static or flow conditions, were investigated using a modified Robbins Device. Bacteria were enumerated and scanning electron microscopy was carried out. The results indicated that both C. jejuni strains isolated from poultry attached better to Pseudomonas aeruginosa biofilms on abiotic surfaces than to the surfaces alone under the different conditions tested. This suggests that biofilms of other bacterial species may passively protect C. jejuni against shear forces and potentially oxygen stress which then contribute to their persistence in environments which are detrimental to them. By contrast the C. jejuni ATCC 33291 strain did not attach differentially to P. aeruginosa biofilms, suggesting that different C. jejuni strains may have alternative strategies for persistence in the environment. This study supports the hypothesis that C. jejuni do not form biofilms per se under conditions they encounter in the environment but simply attach to surfaces or biofilms of other species.
    Matched MeSH terms: Biofilms/growth & development*
  4. Antimicrobial activity of Lactobacillus spp. isolated from fermented foods and their inhibitory effect against foodborne pathogens
    Hussein AO, Khalil K, Mohd Zaini NA, Al Atya AK, Aqma WS
    PeerJ, 2025;13:e18541.
    PMID: 39790459 DOI: 10.7717/peerj.18541
    Lactic acid bacteria (LAB), known for their health benefits, exhibit antimicrobial and antibiofilm properties. This study investigated the cell-free supernatant (CFS) of Lactobacillus spp., particularly L. plantarum KR3, against the common foodborne pathogens S. aureus, E. coli and Salmonella spp. Lactobacillus strains were isolated from cheese, pickles and yoghurt. They were then identified by morphological, physiological and biochemical characteristics and confirmed by 16S rRNA gene sequencing. Culture supernatants from seven lactobacilli isolates showed varying inhibitory activities. Notably, L. plantarum KR3 and L. pentosus had the highest bacteriocin gene counts. L. plantarum KR3 CFS demonstrated significant antibacterial activity, with inhibition zones of 20 ± 0.34 mm for S. aureus, 23 ± 1.64 mm for E. coli, and 17.1 ± 1.70 mm for Salmonella spp. The CFS also exhibited substantial antibiofilm activity, with 59.12 ± 0.03% against S. aureus, 83.50 ± 0.01% against E. coli, and 60. ± 0.04% against Salmonella spp., which were enhanced at the minimum inhibitory concentration (MIC). These results highlighted the potential of L. plantarum KR3 in antimicrobial applications, however, further research is needed to evaluate its viability and functional properties for probiotic use. Additionally, the CFS demonstrated exceptional thermal stability, reinforcing its promise as an antimicrobial agent.
    Matched MeSH terms: Biofilms/growth & development
  5. 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/growth & development*
  6. Quantitative PCR analysis of genes expressed during biofilm development of methicillin resistant Staphylococcus aureus (MRSA)
    Atshan SS, Shamsudin MN, Karunanidhi A, van Belkum A, Lung LT, Sekawi Z, et al.
    Infect Genet Evol, 2013 Aug;18:106-12.
    PMID: 23669446 DOI: 10.1016/j.meegid.2013.05.002
    Staphylococcus aureus biofilm associated infections remains a major clinical concern in patients with indwelling devices. Quantitative real-time PCR (qPCR) can be used to investigate the pathogenic role of such biofilms. We describe qPCRs for 12 adhesion and biofilm-related genes of four S. aureus isolates which were applied during in vitro biofilm development. An endogenous control (16S rRNA) was used for signal normalization. We compared the qPCR results with structural analysis using scanning electron microscopy (SEM). The SEM studies showed different cellular products surrounding the aggregated cells at different times of biofilm formation. Using qPCR, we found that expression levels of the gene encoding fibronectin binding protein A and B and clumping factor B (fnbA/B and clfB), which involves in primary adherence of S. aureus, were significantly increased at 24h and decreased slightly and variably at 48 h when all 4 isolates were considered. The elastin binding protein (ebps) RNA expression level was significantly enhanced more than 6-fold at 24 and 48 h compared to 12h. Similar results were obtained for the intercellular adhesion biofilm required genes type C (icaC). In addition, qPCR revealed a fluctuation in expression levels at different time points of biofilm growth of other genes, indicating that different parameter modes of growth processes are operating at different times.
    Matched MeSH terms: Biofilms/growth & development*
  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/growth & development*
  8. 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/growth & development
  9. Polymicrobial biofilm formation by Candida albicans, Actinomyces naeslundii, and Streptococcus mutans is Candida albicans strain and medium dependent
    Arzmi MH, Alnuaimi AD, Dashper S, Cirillo N, Reynolds EC, McCullough M
    Med Mycol, 2016 Nov 01;54(8):856-64.
    PMID: 27354487 DOI: 10.1093/mmy/myw042
    Oral biofilms comprise of extracellular polysaccharides and polymicrobial microorganisms. The objective of this study was to determine the effect of polymicrobial interactions of Candida albicans, Actinomyces naeslundii, and Streptococcus mutans on biofilm formation with the hypotheses that biofilm biomass and metabolic activity are both C. albicans strain and growth medium dependent. To study monospecific biofilms, C. albicans, A. naeslundii, and S. mutans were inoculated into artificial saliva medium (ASM) and RPMI-1640 in separate vials, whereas to study polymicrobial biofilm formation, the inoculum containing microorganisms was prepared in the same vial prior inoculation into a 96-well plate followed by 72 hours incubation. Finally, biofilm biomass and metabolic activity were measured using crystal violet and XTT assays, respectively. Our results showed variability of monospecies and polymicrobial biofilm biomass between C. albicans strains and growth medium. Based on cut-offs, out of 32, seven RPMI-grown biofilms had high biofilm biomass (HBB), whereas, in ASM-grown biofilms, 14 out of 32 were HBB. Of the 32 biofilms grown in RPMI-1640, 21 were high metabolic activity (HMA), whereas in ASM, there was no biofilm had HMA. Significant differences were observed between ASM and RPMI-grown biofilms with respect to metabolic activity (P <01). In conclusion, biofilm biomass and metabolic activity were both C. albicans strain and growth medium dependent.
    Matched MeSH terms: Biofilms/growth & development*
  10. Fulltext Discovery of New Genes Involved in Curli Production by a Uropathogenic Escherichia coli Strain from the Highly Virulent O45:K1:H7 Lineage
    Nhu NTK, Phan MD, Peters KM, Lo AW, Forde BM, Min Chong T, et al.
    mBio, 2018 08 21;9(4).
    PMID: 30131362 DOI: 10.1128/mBio.01462-18
    Curli are bacterial surface-associated amyloid fibers that bind to the dye Congo red (CR) and facilitate uropathogenic Escherichia coli (UPEC) biofilm formation and protection against host innate defenses. Here we sequenced the genome of the curli-producing UPEC pyelonephritis strain MS7163 and showed it belongs to the highly virulent O45:K1:H7 neonatal meningitis-associated clone. MS7163 produced curli at human physiological temperature, and this correlated with biofilm growth, resistance of sessile cells to the human cationic peptide cathelicidin, and enhanced colonization of the mouse bladder. We devised a forward genetic screen using CR staining as a proxy for curli production and identified 41 genes that were required for optimal CR binding, of which 19 genes were essential for curli synthesis. Ten of these genes were novel or poorly characterized with respect to curli synthesis and included genes involved in purine de novo biosynthesis, a regulator that controls the Rcs phosphorelay system, and a novel repressor of curli production (referred to as rcpA). The involvement of these genes in curli production was confirmed by the construction of defined mutants and their complementation. The mutants did not express the curli major subunit CsgA and failed to produce curli based on CR binding. Mutation of purF (the first gene in the purine biosynthesis pathway) and rcpA also led to attenuated colonization of the mouse bladder. Overall, this work has provided new insight into the regulation of curli and the role of these amyloid fibers in UPEC biofilm formation and pathogenesis.IMPORTANCE Uropathogenic Escherichia coli (UPEC) strains are the most common cause of urinary tract infection, a disease increasingly associated with escalating antibiotic resistance. UPEC strains possess multiple surface-associated factors that enable their colonization of the urinary tract, including fimbriae, curli, and autotransporters. Curli are extracellular amyloid fibers that enhance UPEC virulence and promote biofilm formation. Here we examined the function and regulation of curli in a UPEC pyelonephritis strain belonging to the highly virulent O45:K1:H7 neonatal meningitis-associated clone. Curli expression at human physiological temperature led to increased biofilm formation, resistance of sessile cells to the human cationic peptide LL-37, and enhanced bladder colonization. Using a comprehensive genetic screen, we identified multiple genes involved in curli production, including several that were novel or poorly characterized with respect to curli synthesis. In total, this study demonstrates an important role for curli as a UPEC virulence factor that promotes biofilm formation, resistance, and pathogenesis.
    Matched MeSH terms: Biofilms/growth & development
  11. The emerging problems of Klebsiella pneumoniae infections: carbapenem resistance and biofilm formation
    Chung PY
    FEMS Microbiol Lett, 2016 10;363(20).
    PMID: 27664057
    Klebsiella pneumoniae is an opportunistic pathogen that commonly causes nosocomial infections in the urinary tract, respiratory tract, lung, wound sites and blood in individuals with debilitating diseases. Klebsiella pneumoniae is still a cause of severe pneumonia in alcoholics in Africa and Asia, and the predominant primary pathogen of primary liver abscess in Taiwan and Southeast Asia, particularly in Asian and Hispanic patients, and individuals with diabetes mellitus. In the United States and Europe, K. pneumoniae infections are most frequently associated with nosocomial infections. The emergence of antibiotic-resistant strains of K. pneumoniae worldwide has become a cause of concern where extended-spectrum β-lactamases (ESBLs) and carbapenemase-producing strains have been isolated with increasing frequency. The pathogen's ability to form biofilms on inserted devices such as urinary catheter has been proposed as one of the important mechanisms in nosocomially acquired and persistent infections, adding to the increased resistance to currently used antibiotics. In this review, infections caused by K. pneumoniae, antibiotic resistance and formation of biofilm will be discussed.
    Matched MeSH terms: Biofilms/growth & development*
  12. 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/growth & development*
  13. Fulltext In silico Identification of the Indispensable Quorum Sensing Proteins of Multidrug Resistant Proteus mirabilis
    Pawar S, Ashraf MI, Mujawar S, Mishra R, Lahiri C
    Front Cell Infect Microbiol, 2018;8:269.
    PMID: 30131943 DOI: 10.3389/fcimb.2018.00269
    Catheter-associated urinary tract infections (CAUTI) is an alarming hospital based disease with the increase of multidrug resistance (MDR) strains of Proteus mirabilis. Cases of long term hospitalized patients with multiple episodes of antibiotic treatments along with urinary tract obstruction and/or undergoing catheterization have been reported to be associated with CAUTI. The cases are complicated due to the opportunist approach of the pathogen having robust swimming and swarming capability. The latter giving rise to biofilms and probably inducible through autoinducers make the scenario quite complex. High prevalence of long-term hospital based CAUTI for patients along with moderate percentage of morbidity, cropping from ignorance about drug usage and failure to cure due to MDR, necessitates an immediate intervention strategy effective enough to combat the deadly disease. Several reports and reviews focus on revealing the important genes and proteins, essential to tackle CAUTI caused by P. mirabilis. Despite longitudinal countrywide studies and methodical strategies to circumvent the issues, effective means of unearthing the most indispensable proteins to target for therapeutic uses have been meager. Here, we report a strategic approach for identifying the most indispensable proteins from the genome of P. mirabilis strain HI4320, besides comparing the interactomes comprising the autoinducer-2 (AI-2) biosynthetic pathway along with other proteins involved in biofilm formation and responsible for virulence. Essentially, we have adopted a theoretical network model based approach to construct a set of small protein interaction networks (SPINs) along with the whole genome (GPIN) to computationally identify the crucial proteins involved in the phenomenon of quorum sensing (QS) and biofilm formation and thus, could be therapeutically targeted to fight out the MDR threats to antibiotics of P. mirabilis. Our approach utilizes the functional modularity coupled with k-core analysis and centrality scores of eigenvector as a measure to address the pressing issues.
    Matched MeSH terms: Biofilms/growth & development
  14. 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/growth & development*
  15. 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/growth & development
  16. 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/growth & development
  17. A study on Candida biofilm growth characteristics and its susceptibility to aureobasidin A
    Munusamy K, Vadivelu J, Tay ST
    Rev Iberoam Micol, 2018 03 12;35(2):68-72.
    PMID: 29544734 DOI: 10.1016/j.riam.2017.07.001
    BACKGROUND: Biofilm is known to contribute to the antifungal resistance of Candida yeasts. Aureobasidin A (AbA), a cyclic depsipeptide targeting fungal sphingolipid biosynthesis, has been shown to be effective against several Candida species.

    AIMS: The aim of this study was to investigate Candida biofilm growth morphology, its biomass, metabolic activity, and to determine the effects of AbA on the biofilm growth.

    METHODS: The biofilm forming ability of several clinical isolates of different Candida species from our culture collection was determined using established methods (crystal violet and XTT assays). The determination of AbA planktonic and biofilm MICs was performed based on a micro-broth dilution method. The anti-biofilm effect of AbA on Candida albicans was examined using field emission scanning electron microscope (FESEM) analysis.

    RESULTS: A total of 35 (29.7%) of 118 Candida isolates were regarded as biofilm producers in this study. Candida parapsilosis was the largest producer, followed by Candida tropicalis and C. albicans. Two morphological variants of biofilms were identified in our isolates, with 48.6% of the isolates showing mainly yeast and pseudohyphae-like structures, while the remaining ones were predominantly filamentous forms. The biofilm producers were divided into two populations (low and high), based on the ability in producing biomass and their metabolic activity. Candida isolates with filamentous growth, higher biomass and metabolic activity showed lower AbA MIC50 (at least fourfold), compared to those exhibiting yeast morphology, and lower biomass and metabolic activity. The observation of filament detachment and the almost complete removal of biofilm from AbA-treated C. albicans biofilm in FESEM analysis suggests an anti-biofilm effect of AbA.

    CONCLUSIONS: The variability in the growth characteristics of Candida biofilm cultures affects susceptibility to AbA, with higher susceptibility noted in biofilm cultures exhibiting filamentous form and high biomass/metabolic activity.

    Matched MeSH terms: Biofilms/growth & development
  18. Fulltext Genotypically different clones of Staphylococcus aureus are diverse in the antimicrobial susceptibility patterns and biofilm formations
    Atshan SS, Nor Shamsudin M, Lung LT, Sekawi Z, Pei Pei C, Karunanidhi A, et al.
    Biomed Res Int, 2013;2013:515712.
    PMID: 24455699 DOI: 10.1155/2013/515712
    This study evaluated whether genotypically different clinical isolates of S. aureus have similar susceptibilities to individual antibiotics. It further aims to check the impact of biofilm on the in vitro activity of vancomycin, daptomycin, linezolid, and tigecycline against S. aureus clones. The study used a total of 60 different clinical MSSA and MRSA isolates. Susceptibilities were performed in planktonic cultures by macrobroth dilution and epsilon-test (E test) system. Biofilm production was determined using an adherent plate assay. The efficacy of antimicrobial activities against biofilms formation was checked using confocal laser scanning microscopy (CLSM). The study found that similar and different spa, MLST, and SCCmec types displayed high variation in their susceptibilities to antibiotics with tigecycline and daptomycin being the most effective. The biofilms were found resistant to high concentrations of most antibiotics tested with daptomycin being the most effective drug used in adhesive biofilms. A considerable difference exists among similar and various clone types against antibiotics tested. This variation could have contributed to the degree of virulence even within the same clonal genotype and enhanced heterogeneity in the infection potential. Thus, the development of a rapid and precise identification profile for each clone in human infections is important.
    Matched MeSH terms: Biofilms/growth & development*
  19. Novel phage-based bio-processing of pathogenic Escherichia coli and its biofilms
    Jassim SA, Abdulamir AS, Abu Bakar F
    World J Microbiol Biotechnol, 2012 Jan;28(1):47-60.
    PMID: 22806779 DOI: 10.1007/s11274-011-0791-6
    To explore new approaches of phage-based bio-process of specifically pathogenic Escherichia coli bacteria in food products within a short period. One hundred and forty highly lytic designed coliphages were used. Escherichia coli naturally contaminated and Enterohemorrhagic Escherichia coli experimentally inoculated samples of lettuce, cabbage, meat, and egg were used. In addition, experimentally produced biofilms of E. coli were tested. A phage concentration of 10(3) PFU/ml was used for food products immersion, and for spraying of food products, 10(5) PFU/ml of a phage cocktail was used by applying a 20-s optimal dipping time in a phage cocktail. Food samples were cut into pieces and were either sprayed with or held in a bag immersed in lambda buffer containing a cocktail of 140 phages. Phage bio-processing was successful in eliminating completely E. coli in all processed samples after 48 h storage at 4°C. Partial elimination of E. coli was observed in earlier storage periods (7 and 18 h) at 24° and 37°C. Moreover, E. coli biofilms were reduced >3 log cycles upon using the current phage bio-processing. The use of a phage cocktail of 140 highly lytic designed phages proved highly effective in suppressing E. coli contaminating food products. Proper decontamination/prevention methods of pathogenic E. coli achieved in this study can replace the current chemically less effective decontamination methods.
    Matched MeSH terms: Biofilms/growth & development*
  20. Fulltext Anti-biofilm agents: recent breakthrough against multi-drug resistant Staphylococcus aureus
    Chung PY, Toh YS
    Pathog Dis, 2014 Apr;70(3):231-9.
    PMID: 24453168 DOI: 10.1111/2049-632X.12141
    Staphylococcus aureus is a Gram-positive pathogen that causes potentially life-threatening nosocomial- and community-acquired infections, such as osteomyelitis and endocarditis. Staphylococcus aureus has the ability to form multicellular, surface-adherent communities called biofilms, which enables it to survive in various sources of stress, including antibiotics, nutrient limitations, heat shock, and immune responses. Biofilm-forming capacity is now recognized as an important virulence determinant in the development of staphylococcal device-related infections. In light of the projected increase in the numbers of elderly patients who will require semi-permanent indwelling medical devices such as artificial knees and hips, we can anticipate an expanded need for new agents and treatment options to manage biofilm-associated infections in an expanding at-risk population. With better understanding of staphylococcal biofilm formation and growth, novel strategies that target biofilm-associated infections caused by S. aureus have recently been described and seem promising as future anti-biofilm therapies.
    Matched MeSH terms: Biofilms/growth & development
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links