Displaying publications 21 - 40 of 70 in total

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  1. Fulltext In vitro assessment of Pediococcus acidilactici Kp10 for its potential use in the food industry
    Abbasiliasi S, Tan JS, Bashokouh F, Ibrahim TAT, Mustafa S, Vakhshiteh F, et al.
    BMC Microbiol, 2017 May 23;17(1):121.
    PMID: 28535747 DOI: 10.1186/s12866-017-1000-z
    BACKGROUND: Selection of a microbial strain for the incorporation into food products requires in vitro and in vivo evaluations. A bacteriocin-producing lactic acid bacterium (LAB), Pediococcus acidilactici Kp10, isolated from a traditional dried curd was assessed in vitro for its beneficial properties as a potential probiotic and starter culture. The inhibitory spectra of the bacterial strain against different gram-positive and gram-negative bacteria, its cell surface hydrophobicity and resistance to phenol, its haemolytic, amylolytic and proteolytic activities, ability to produce acid and coagulate milk together with its enzymatic characteristics and adhesion property were all evaluated in vitro.

    RESULTS: P. acidilactici Kp10 was moderately tolerant to phenol and adhere to mammalian epithelial cells (Vero cells and ileal mucosal epithelium). The bacterium also exhibited antimicrobial activity against several gram-positive and gram-negative food-spoilage and food-borne pathogens such as Listeria monocytgenes ATCC 15313, Salmonella enterica ATCC 13311, Shigella sonnei ATCC 9290, Klebsiella oxytoca ATCC 13182, Enterobacter cloaca ATCC 35030 and Streptococcus pyogenes ATCC 12378. The absence of haemolytic activity and proteinase (trypsin) and the presence of a strong peptidase (leucine-arylamidase) and esterase-lipase (C4 and C8) were observed in this LAB strain. P. acidilactici Kp10 also produced acid, coagulated milk and has demonstrated proteolytic and amylolactic activities.

    CONCLUSION: The properties exhibited by P. acidilactici Kp10 suggested its potential application as probiotic and starter culture in the food industry.

    Matched MeSH terms: Bacterial Adhesion
  2. Biofilm formation enhances Helicobacter pylori survivability in vegetables
    Ng CG, Loke MF, Goh KL, Vadivelu J, Ho B
    Food Microbiol, 2017 Apr;62:68-76.
    PMID: 27889168 DOI: 10.1016/j.fm.2016.10.010
    To date, the exact route and mode of transmission of Helicobacter pylori remains elusive. The detection of H. pylori in food using molecular approaches has led us to postulate that the gastric pathogen may survive in the extragastric environment for an extended period. In this study, we show that H. pylori prolongs its survival by forming biofilm and micro-colonies on vegetables. The biofilm forming capability of H. pylori is both strain and vegetable dependent. H. pylori strains were classified into high and low biofilm formers based on their highest relative biofilm units (BU). High biofilm formers survived longer on vegetables compared to low biofilm formers. The bacteria survived better on cabbage compared to other vegetables tested. In addition, images captured on scanning electron and confocal laser scanning microscopes revealed that the bacteria were able to form biofilm and reside as micro-colonies on vegetable surfaces, strengthening the notion of possible survival of H. pylori on vegetables for an extended period of time. Taken together, the ability of H. pylori to form biofilm on vegetables (a common food source for human) potentially plays an important role in its survival, serving as a mode of transmission of H. pylori in the extragastric environment.
    Matched MeSH terms: Bacterial Adhesion/physiology
  3. Sonication reduces the attachment of Salmonella Typhimurium ATCC 14028 cells to bacterial cellulose-based plant cell wall models and cut plant material
    Tan MSF, Rahman S, Dykes GA
    Food Microbiol, 2017 Apr;62:62-67.
    PMID: 27889167 DOI: 10.1016/j.fm.2016.10.009
    This study investigated the removal of bacterial surface structures, particularly flagella, using sonication, and examined its effect on the attachment of Salmonella Typhimurium ATCC 14028 cells to plant cell walls. S. Typhimurium ATCC 14028 cells were subjected to sonication at 20 kHz to remove surface structures without affecting cell viability. Effective removal of flagella was determined by staining flagella of sonicated cells with Ryu's stain and enumerating the flagella remaining by direct microscopic counting. The attachment of sonicated S. Typhimurium cells to bacterial cellulose-based plant cell wall models and cut plant material (potato, apple, lettuce) was then evaluated. Varying concentrations of pectin and/or xyloglucan were used to produce a range of bacterial cellulose-based plant cell wall models. As compared to the non-sonicated controls, sonicated S. Typhimurium cells attached in significantly lower numbers (between 0.5 and 1.0 log CFU/cm2) to all surfaces except to the bacterial cellulose-only composite without pectin and xyloglucan. Since attachment of S. Typhimurium to the bacterial cellulose-only composite was not affected by sonication, this suggests that bacterial surface structures, particularly flagella, could have specific interactions with pectin and xyloglucan. This study indicates that sonication may have potential applications for reducing Salmonella attachment during the processing of fresh produce.
    Matched MeSH terms: Bacterial Adhesion*
  4. Fulltext Influences of proton pump inhibitor on Helicobacter pylori adherence to the gastrointestinal cell lines
    Omar MS, Damanhuri NS, Kumolosasi E
    Turk J Gastroenterol, 2017 Jan;28(1):53-59.
    PMID: 27991853 DOI: 10.5152/tjg.2016.0409
    BACKGROUND/AIMS: Helicobacter pylori is a carcinogenic bacterium that could induce P-glycoprotein expression in the human gastrointestinal tract. Bacterial adherence to the gastrointestinal cell lines could be influenced by the level of P-glycoprotein. This study aimed to determine the influence of proton pump inhibitors that exhibit an inhibitory effect on P-glycoprotein in gastrointestinal carcinoma cell lines, namely Caco-2 and LS174T, in relation to H. pylori adherence.

    MATERIALS AND METHODS: Caco-2 and LS174T cells lines treated with omeprazole and esomeprazole were used in this study to assess the bacterial attachment of H. pylori within certain incubation periods.

    RESULTS: The presence of proton pump inhibitors increased the H. pylori adherence in a time-dependent manner in both Caco-2 and LS174T cell lines. The double inhibition of P-glycoprotein using proton pump inhibitor and P-glycoprotein inhibitor caused low P-glycoprotein expression in the cell lines, resulting in higher H. pylori adherence compared to the control cell lines.

    CONCLUSION: Proton pump inhibitors may alter P-glycoprotein expression in the gastrointestinal tract, and subsequently H. pylori adherence on the cell lines, and may contribute to resistance to drug therapy.

    Matched MeSH terms: Bacterial Adhesion/drug effects*
  5. Analysis of biofilms formation by cronobacter sp. During growth in infant formula milk
    Aishah Faiqah Mohd Yusof, Prabhakaran P, Nur Diyana Azli, Norrakiah Abdullah Sani, Wan Syaidatul Aqma
    Sains Malaysiana, 2017;46:903-908.
    Pacifier nipples are in permanent contact with saliva and with the oral microflora therefore, act as a favoured site for the growth of biofilms. This research was conducted to identify the bacterial biofilms that has been found on the pacifiers that collected from local child nursery and to analyse the formation of biofilms by Cronobacter sp. during growth in infant formula milk. Pacifiers collected were analysed to obtain colony forming unit (CFU) and isolated bacteria were identified using several biochemical tests according to Bergey's Manual. Biofilm assay of three Cronobacter sp. were conducted using 24 wells microtiter plate and stained with 1% of crystal violet solution at different time interval: 6, 12, 18 and 24 h. The hydrophobicity of the bacterial cell suspension was evaluated using bacterial adhesion to hydrocarbons (BATH) method. Extracellular polymeric substances (EPS) analysis was done to identify percentage of carbohydrate and protein content by using phenol sulphuric acid method and Bradford method, respectively. The results obtained showed that the normal microflora bacteria were the most abundant microorganisms that were found on the pacifier with the main genus isolated was Staphylococcus sp., Enterobacteriaceae sp. and Clostridium sp. Based on biofilm and EPS analysis, Cronobacter sakazakii formed a strong biofilms after 18 h, with carbohydrate was identified as main component of EPS.
    Matched MeSH terms: Bacterial Adhesion
  6. The Influence of Prior Modes of Growth, Temperature, Medium, and Substrate Surface on Biofilm Formation by Antibiotic-Resistant Campylobacter jejuni
    Teh AH, Lee SM, Dykes GA
    Curr Microbiol, 2016 Dec;73(6):859-866.
    PMID: 27623781
    Campylobacter jejuni is one of the most common causes of bacterial gastrointestinal food-borne infection worldwide. It has been suggested that biofilm formation may play a role in survival of these bacteria in the environment. In this study, the influence of prior modes of growth (planktonic or sessile), temperatures (37 and 42 °C), and nutrient conditions (nutrient broth and Mueller-Hinton broth) on biofilm formation by eight C. jejuni strains with different antibiotic resistance profiles was examined. The ability of these strains to form biofilm on different abiotic surfaces (stainless steel, glass, and polystyrene) as well as factors potentially associated with biofilm formation (bacterial surface hydrophobicity, auto-aggregation, and initial attachment) was also determined. The results showed that cells grown as sessile culture generally have a greater ability to form biofilm (P 
    Matched MeSH terms: Bacterial Adhesion
  7. 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: Bacterial Adhesion/drug effects
  8. Fulltext Attachment of Salmonella strains to a plant cell wall model is modulated by surface characteristics and not by specific carbohydrate interactions
    Tan MS, Moore SC, Tabor RF, Fegan N, Rahman S, Dykes GA
    BMC Microbiol, 2016 09 15;16:212.
    PMID: 27629769 DOI: 10.1186/s12866-016-0832-2
    BACKGROUND: Processing of fresh produce exposes cut surfaces of plant cell walls that then become vulnerable to human foodborne pathogen attachment and contamination, particularly by Salmonella enterica. Plant cell walls are mainly composed of the polysaccharides cellulose, pectin and hemicelluloses (predominantly xyloglucan). Our previous work used bacterial cellulose-based plant cell wall models to study the interaction between Salmonella and the various plant cell wall components. We demonstrated that Salmonella attachment was favoured in the presence of pectin while xyloglucan had no effect on its attachment. Xyloglucan significantly increased the attachment of Salmonella cells to the plant cell wall model only when it was in association with pectin. In this study, we investigate whether the plant cell wall polysaccharides mediate Salmonella attachment to the bacterial cellulose-based plant cell wall models through specific carbohydrate interactions or through the effects of carbohydrates on the physical characteristics of the attachment surface.

    RESULTS: We found that none of the monosaccharides that make up the plant cell wall polysaccharides specifically inhibit Salmonella attachment to the bacterial cellulose-based plant cell wall models. Confocal laser scanning microscopy showed that Salmonella cells can penetrate and attach within the tightly arranged bacterial cellulose network. Analysis of images obtained from atomic force microscopy revealed that the bacterial cellulose-pectin-xyloglucan composite with 0.3 % (w/v) xyloglucan, previously shown to have the highest number of Salmonella cells attached to it, had significantly thicker cellulose fibrils compared to other composites. Scanning electron microscopy images also showed that the bacterial cellulose and bacterial cellulose-xyloglucan composites were more porous when compared to the other composites containing pectin.

    CONCLUSIONS: Our study found that the attachment of Salmonella cells to cut plant cell walls was not mediated by specific carbohydrate interactions. This suggests that the attachment of Salmonella strains to the plant cell wall models were more dependent on the structural characteristics of the attachment surface. Pectin reduces the porosity and space between cellulose fibrils, which then forms a matrix that is able to retain Salmonella cells within the bacterial cellulose network. When present with pectin, xyloglucan provides a greater surface for Salmonella cells to attach through the thickening of cellulose fibrils.

    Matched MeSH terms: Bacterial Adhesion*
  9. Adhesion of Pseudomonas fluorescens biofilms to glass, stainless steel and cellulose
    Wan Dagang WR, Bowen J, O'Keeffe J, Robbins PT, Zhang Z
    Biotechnol Lett, 2016 May;38(5):787-92.
    PMID: 26892223 DOI: 10.1007/s10529-016-2047-x
    The adhesion of colloidal probes of stainless steel, glass and cellulose to Pseudomonas fluorescens biofilms was examined using atomic force microscopy (AFM) to allow comparisons between surfaces to which biofilms might adhere.
    Matched MeSH terms: Bacterial Adhesion
  10. Simultaneous acid red 27 decolourisation and bioelectricity generation in a (H-type) microbial fuel cell configuration using NAR-2
    Kardi SN, Ibrahim N, Rashid NA, Darzi GN
    Environ Sci Pollut Res Int, 2016 Feb;23(4):3358-64.
    PMID: 26490910 DOI: 10.1007/s11356-015-5538-8
    Microbial fuel cells (MFCs) represent one of the most attractive and eco-friendly technologies that convert chemical bond energy derived from organic matter into electrical power by microbial catabolic activity. This paper presents the use of a H-type MFC involving a novel NAR-2 bacterial consortium consisting of Citrobacter sp. A1, Enterobacter sp. L17 and Enterococcus sp. C1 to produce electricity whilst simultaneously decolourising acid red 27 (AR27) as a model dye, which is also known as amaranth. In this setup, the dye AR27 is mixed with modified P5 medium (2.5 g/L glucose and 5.0 g/L nutrient broth) in the anode compartment, whilst phosphate buffer solution (PBS) pH 7 serves as a catholyte in the cathode compartment. After several electrochemical analyses, the open circuit voltage (OCV) for 0.3 g/L AR27 with 24-h retention time at 30 °C was recorded as 0.950 V, whereas (93%) decolourisation was achieved in 220-min operation. The maximum power density was reached after 48 h of operation with an external load of 300 Ω. Scanning electron microscopy (SEM) analysis revealed the surface morphology of the anode and the bacterial adhesion onto the electrode surface. The results of this study indicate that the decolourisation of AR27 dye and electrical power generation was successfully achieved in a MFC operated by a bacterial consortium. The consortium of bacteria was able to utilise AR27 in a short retention time as an electron acceptor and to shuttle the electrons to the anode surface for bioelectricity generation.
    Matched MeSH terms: Bacterial Adhesion
  11. Fulltext Pectin and Xyloglucan Influence the Attachment of Salmonella enterica and Listeria monocytogenes to Bacterial Cellulose-Derived Plant Cell Wall Models
    Tan MS, Rahman S, Dykes GA
    Appl Environ Microbiol, 2016 01 15;82(2):680-8.
    PMID: 26567310 DOI: 10.1128/AEM.02609-15
    Minimally processed fresh produce has been implicated as a major source of foodborne microbial pathogens globally. These pathogens must attach to the produce in order to be transmitted. Cut surfaces of produce that expose cell walls are particularly vulnerable. Little is known about the roles that different structural components (cellulose, pectin, and xyloglucan) of plant cell walls play in the attachment of foodborne bacterial pathogens. Using bacterial cellulose-derived plant cell wall models, we showed that the presence of pectin alone or xyloglucan alone affected the attachment of three Salmonella enterica strains (Salmonella enterica subsp. enterica serovar Enteritidis ATCC 13076, Salmonella enterica subsp. enterica serovar Typhimurium ATCC 14028, and Salmonella enterica subsp. indica M4) and Listeria monocytogenes ATCC 7644. In addition, we showed that this effect was modulated in the presence of both polysaccharides. Assays using pairwise combinations of S. Typhimurium ATCC 14028 and L. monocytogenes ATCC 7644 showed that bacterial attachment to all plant cell wall models was dependent on the characteristics of the individual bacterial strains and was not directly proportional to the initial concentration of the bacterial inoculum. This work showed that bacterial attachment was not determined directly by the plant cell wall model or bacterial physicochemical properties. We suggest that attachment of the Salmonella strains may be influenced by the effects of these polysaccharides on physical and structural properties of the plant cell wall model. Our findings improve the understanding of how Salmonella enterica and Listeria monocytogenes attach to plant cell walls, which may facilitate the development of better ways to prevent the attachment of these pathogens to such surfaces.
    Matched MeSH terms: Bacterial Adhesion*
  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: Bacterial Adhesion/drug effects*; Bacterial Adhesion/genetics
  13. Fulltext Role of Fimbriae, Flagella and Cellulose on the Attachment of Salmonella Typhimurium ATCC 14028 to Plant Cell Wall Models
    Tan MS, White AP, Rahman S, Dykes GA
    PLoS One, 2016;11(6):e0158311.
    PMID: 27355584 DOI: 10.1371/journal.pone.0158311
    Cases of foodborne disease caused by Salmonella are frequently associated with the consumption of minimally processed produce. Bacterial cell surface components are known to be important for the attachment of bacterial pathogens to fresh produce. The role of these extracellular structures in Salmonella attachment to plant cell walls has not been investigated in detail. We investigated the role of flagella, fimbriae and cellulose on the attachment of Salmonella Typhimurium ATCC 14028 and a range of isogenic deletion mutants (ΔfliC fljB, ΔbcsA, ΔcsgA, ΔcsgA bcsA and ΔcsgD) to bacterial cellulose (BC)-based plant cell wall models [BC-Pectin (BCP), BC-Xyloglucan (BCX) and BC-Pectin-Xyloglucan (BCPX)] after growth at different temperatures (28°C and 37°C). We found that all three cell surface components were produced at 28°C but only the flagella was produced at 37°C. Flagella appeared to be most important for attachment (reduction of up to 1.5 log CFU/cm2) although both cellulose and fimbriae also aided in attachment. The csgD deletion mutant, which lacks both cellulose and fimbriae, showed significantly higher attachment as compared to wild type cells at 37°C. This may be due to the increased expression of flagella-related genes which are also indirectly regulated by the csgD gene. Our study suggests that bacterial attachment to plant cell walls is a complex process involving many factors. Although flagella, cellulose and fimbriae all aid in attachment, these structures are not the only mechanism as no strain was completely defective in its attachment.
    Matched MeSH terms: Bacterial Adhesion*
  14. Calcium is required for ixotrophy of Aureispira sp. CCB-QB1
    Furusawa G, Hartzell PL, Navaratnam V
    Microbiology (Reading), 2015 Oct;161(10):1933-1941.
    PMID: 26306656 DOI: 10.1099/mic.0.000158
    Ixotrophy is a process that enables certain microbes to prey on other cells. The ability of cells to aggregate or adhere is thought to be a significant initial step in ixotrophy. The gliding, multicellular filamentous bacterium Aureispira sp. CCB-QB1 belongs to the family Saprospiraceae and preys on bacteria such as Vibrio sp. in seawater. Adhesion and cell aggregation were coincident with preying and were hypothesized to play an important role in the ixotrophy in this bacterium. To test this hypothesis, experiments to elucidate the mechanisms of aggregation or adhesion in this bacterium were performed. The ability of Aureispira QB1 to adhere and aggregate to prey bacterium, Vibrio sp., required divalent cations, especially calcium ions. In the presence of calcium, Aureispira QB1 cells captured 99 % of Vibrio sp. cells after 60 min of incubation. Toluidine blue O, which binds acidic polysaccharides, bound to Aureispira QB1 and inhibited adhesion of Aureispira QB1. These results suggest that acidic polysaccharides are needed for aggregation or adhesion of Aureispira and that calcium ions play a significant role in these phenomena.
    Matched MeSH terms: Bacterial Adhesion*
  15. Fulltext Molecular analysis of asymptomatic bacteriuria Escherichia coli strain VR50 reveals adaptation to the urinary tract by gene acquisition
    Beatson SA, Ben Zakour NL, Totsika M, Forde BM, Watts RE, Mabbett AN, et al.
    Infect Immun, 2015 May;83(5):1749-64.
    PMID: 25667270 DOI: 10.1128/IAI.02810-14
    Urinary tract infections (UTIs) are among the most common infectious diseases of humans, with Escherichia coli responsible for >80% of all cases. One extreme of UTI is asymptomatic bacteriuria (ABU), which occurs as an asymptomatic carrier state that resembles commensalism. To understand the evolution and molecular mechanisms that underpin ABU, the genome of the ABU E. coli strain VR50 was sequenced. Analysis of the complete genome indicated that it most resembles E. coli K-12, with the addition of a 94-kb genomic island (GI-VR50-pheV), eight prophages, and multiple plasmids. GI-VR50-pheV has a mosaic structure and contains genes encoding a number of UTI-associated virulence factors, namely, Afa (afimbrial adhesin), two autotransporter proteins (Ag43 and Sat), and aerobactin. We demonstrated that the presence of this island in VR50 confers its ability to colonize the murine bladder, as a VR50 mutant with GI-VR50-pheV deleted was attenuated in a mouse model of UTI in vivo. We established that Afa is the island-encoded factor responsible for this phenotype using two independent deletion (Afa operon and AfaE adhesin) mutants. E. coli VR50afa and VR50afaE displayed significantly decreased ability to adhere to human bladder epithelial cells. In the mouse model of UTI, VR50afa and VR50afaE displayed reduced bladder colonization compared to wild-type VR50, similar to the colonization level of the GI-VR50-pheV mutant. Our study suggests that E. coli VR50 is a commensal-like strain that has acquired fitness factors that facilitate colonization of the human bladder.
    Matched MeSH terms: Bacterial Adhesion
  16. 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: Bacterial Adhesion/drug effects
  17. 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: Bacterial Adhesion/drug effects*
  18. 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: Bacterial Adhesion/drug effects; Bacterial Adhesion/physiology*
  19. Effect of electroporation on bioconversion of isoflavones and probiotic properties of parents and subsequent passages of Bifidobacterium longum
    Yeo SK, Ong JS, Liong MT
    Appl Biochem Biotechnol, 2014 Oct;174(4):1496-1509.
    PMID: 25119552 DOI: 10.1007/s12010-014-1141-6
    This study aimed to evaluate the effects of electroporation on growth, bioconversion of isoflavones, and probiotic properties of parent organisms and subsequent passages of Bifidobacterium longum FTDC 8643. Electroporation with the strength of electric field at 7.5 kV cm(-1) for 3.5 ms was applied on B. longum FTDC 8643. The viability of B. longum FTDC 8643 increased significantly upon treatment with electroporation. Such treatment also enhanced the intracellular and extracellular β-glucosidase activity, leading to enhanced production of bioactive isoflavone aglycones in mannitol-soymilk (P 
    Matched MeSH terms: Bacterial Adhesion/drug effects
  20. Extraintestinal pathogenic Escherichia coli (ExPEC) of human and avian origin belonging to sequence type complex 95 (STC95) portray indistinguishable virulence features
    Nandanwar N, Janssen T, Kühl M, Ahmed N, Ewers C, Wieler LH
    Int J Med Microbiol, 2014 Oct;304(7):835-42.
    PMID: 25037925 DOI: 10.1016/j.ijmm.2014.06.009
    Extraintestinal pathogenic Escherichia coli (ExPEC) strains of certain genetic lineages are frequently implicated in a wide range of diseases in humans and birds. ExPEC strains belonging to the phylogenetic lineage/sequence type complex 95 (STC95) are one such prominent lineage that is commonly isolated from extraintestinal infections such as systemic disease in poultry and urinary tract infections (UTIs), neonatal meningitis and sepsis in humans. Several epidemiological studies have indicated that ST95 strains obtained from such infections may share similar virulence genes and other genomic features. However, data on their ability to establish infections in vivo as deduced from the manifestation of similar virulence phenotypes remain elusive. In the present study, 116 STC95 ExPEC isolates comprising 55 human and 61 avian strains, possessing similar virulence gene patterns, were characterized in vitro using adhesion, invasion, biofilm formation and serum bactericidal assays. Overall, STC95 strains from both groups, namely human and birds, were equally capable of adhering to and invading the two mammalian kidney cell lines. Similarly, these strains were able to form strong biofilms in M63 medium. Furthermore, they were equally resistant to the bactericidal activity of human and avian serum. Our cumulative data reinforce the understanding that ST95 strains from poultry present a potential zoonotic risk and therefore need a One Health strategy for a successfull intervention.
    Matched MeSH terms: Bacterial Adhesion
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