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Candida and invasive candidiasis: back to basics

Lim CS, Rosli R, Seow HF, Chong PP

Eur J Clin Microbiol Infect Dis, 2012 Jan;31(1):21-31.
PMID: 21544694 DOI: 10.1007/s10096-011-1273-3

The ubiquitous Candida spp. is an opportunistic fungal pathogen which, despite treatment with antifungal drugs, can cause fatal bloodstream infections (BSIs) in immunocompromised and immunodeficient persons. Thus far, several major C. albicans virulence factors have been relatively well studied, including morphology switching and secreted degradative enzymes. However, the exact mechanism of Candida pathogenesis and the host response to invasion are still not well elucidated. The relatively recent discovery of the quorum-sensing molecule farnesol and the existence of quorum sensing as a basic regulatory phenomenon of the C. albicans population behavior has revolutionized Candida research. Through population density regulation, the quorum-sensing mechanism also controls the cellular morphology of a C. albicans population in response to environmental factors, thereby, effectively placing morphology switching downstream of quorum sensing. Thus, the quorum-sensing phenomenon has been hailed as the 'missing piece' of the pathogenicity puzzle. Here, we review what is known about Candida spp. as the etiological agents of invasive candidiasis and address our current understanding of the quorum-sensing phenomenon in relation to virulence in the host.

Matched MeSH terms: Biofilms
Effect of full and partial-bed configuration on carbon removal performance of biological aerated filters

Suja F, Donnelly T

Water Sci Technol, 2008;58(5):977-83.
PMID: 18824794 DOI: 10.2166/wst.2008.454

A comparative study to explore the characteristics of partially and fully packed biological aerated filters (BAFs) in the removal of carbon pollutant, reveals that the partial-bed reactor can perform comparably well with the full-bed reactor. The organic removal rate was 5.34 kg COD m(-3) d(-1) at Organic Loading Rates (OLR) 5.80+/-0.31 kg COD m(-3) d(-1) for the full-bed, and 5.22 kg COD m(-3) d(-1) at OLR 5.79+/-0.29 kg COD m(-3) d(-1) for the partial-bed. In the partial-bed system, where the masses of biomass were only 41-51% of those of the full-bed, the maximum carbon removal limit was still between 5 to 6 kg COD m(-3) d(-1). At organic loadings above 5.0 kg COD m(-3) d(-1), the carbon removal capacity in both systems was limited by the mass and activity of microorganisms. The SRT in the full and partial-bed reactors was primarily controlled by the biomass loss in the effluent and during backwash operation. The SRT was reduced from 20.08 days at OLR 4.18+/-0.20 kg COD m(-3) d(-1) to 7.62 days at OLR 5.80+/-0.31 kg COD m(-3) d(-1) in the full-bed, and from 7.17 days to 4.21 days in the partial-bed. After all, SRT values in the partial-bed were always lower than those in the full-bed.

Matched MeSH terms: Biofilms
Fulltext Porphyromonas gingivalis: An Overview of Periodontopathic Pathogen below the Gum Line

How KY, Song KP, Chan KG

Front Microbiol, 2016;7:53.
PMID: 26903954 DOI: 10.3389/fmicb.2016.00053

Periodontal disease represents a group of oral inflammatory infections initiated by oral pathogens which exist as a complex biofilms on the tooth surface and cause destruction to tooth supporting tissues. The severity of this disease ranges from mild and reversible inflammation of the gingiva (gingivitis) to chronic destruction of connective tissues, the formation of periodontal pocket and ultimately result in loss of teeth. While human subgingival plaque harbors more than 500 bacterial species, considerable research has shown that Porphyromonas gingivalis, a Gram-negative anaerobic bacterium, is the major etiologic agent which contributes to chronic periodontitis. This black-pigmented bacterium produces a myriad of virulence factors that cause destruction to periodontal tissues either directly or indirectly by modulating the host inflammatory response. Here, this review provides an overview of P. gingivalis and how its virulence factors contribute to the pathogenesis with other microbiome consortium in oral cavity.

Matched MeSH terms: Biofilms
Fulltext Curcumin rescues Caenorhabditis elegans from a Burkholderia pseudomallei infection

Eng SA, Nathan S

Front Microbiol, 2015;6:290.
PMID: 25914690 DOI: 10.3389/fmicb.2015.00290

The tropical pathogen Burkholderia pseudomallei requires long-term parenteral antimicrobial treatment to eradicate the pathogen from an infected patient. However, the development of antibiotic resistance is emerging as a threat to this form of treatment. To meet the need for alternative therapeutics, we proposed a screen of natural products for compounds that do not kill the pathogen, but in turn, abrogate bacterial virulence. We suggest that the use of molecules or compounds that are non-bactericidal (bacteriostatic) will reduce or abolish the development of resistance by the pathogen. In this study, we adopted the established Caenorhabditis elegans-B. pseudomallei infection model to screen a collection of natural products for any that are able to extend the survival of B. pseudomallei infected worms. Of the 42 natural products screened, only curcumin significantly improved worm survival following infection whilst not affecting bacterial growth. This suggested that curcumin promoted B. pseudomallei-infected worm survival independent of pathogen killing. To validate that the protective effect of curcumin was directed toward the pathogen, bacteria were treated with curcumin prior to infection. Worms fed with curcumin-treated bacteria survived with a significantly extended mean-time-to-death (p < 0.0001) compared to the untreated control. In in vitro assays, curcumin reduced the activity of known virulence factors (lipase and protease) and biofilm formation. To determine if other bacterial genes were also regulated in the presence of curcumin, a genome-wide transcriptome analysis was performed on curcumin-treated pathogen. A number of genes involved in iron acquisition and transport as well as genes encoding hypothetical proteins were induced in the presence of curcumin. Thus, we propose that curcumin may attenuate B. pseudomallei by modulating the expression of a number of bacterial proteins including lipase and protease as well as biofilm formation whilst concomitantly regulating iron transport and other proteins of unknown function.

Matched MeSH terms: Biofilms
Nitrogen nutrient removals from wastewater and river water

Abdul-Rahman R, Tsuno H, Zainol N

Water Sci Technol, 2002;45(12):197-204.
PMID: 12201103

Elevated levels of nutrients in agroindustry wastewaters, and higher reliance on chlorination pose health threats due to formation of chlorinated organics as well as increased chlorination costs. Removals of ammonium and nitrate compounds were studied using activated carbon from palm shells, as adsorbent and support media. Experiments were carried out at several loadings, F:M from 0.31 to 0.58, and hydraulic residence times (HRT) of 24 h, 12 h and 8 h. Results show that the wastewater treatment process achieved removals of over 90% for COD and 62% for Total-N. Studies on removals from river water were carried out in sequencing batch reactor (SBR) and activated carbon biofilm (ACB) reactor. Removals achieved by the SBR adsorption-biodegradation combination were 67.0% for COD, 58.8% for NH3-N and 25.5% for NO3-N while for adsorption alone the removals were only 37.0% for COD, 35.2% for NH3-N and 13.8% for NO3-N. In the ACB reactor, at HRT of 1.5 to 6 h, removals ranged from 12.5 to 100% for COD, 16.7 to 100% for NO3-N and 13.5 to 100% for NH3-N. Significant decrease in removals was shown at lower HRT. The studies have shown that substantial removals of COD, NO3-N and NH3-N from both wastewater and river water may be achieved via adsorption-biodegradation by biofilm on activated carbon processes.

Matched MeSH terms: Biofilms
Fulltext Characterization of salt-tolerant plant growth-promoting rhizobacteria and the effect on growth and yield of saline-affected rice

Shultana R, Kee Zuan AT, Yusop MR, Saud HM

PLoS One, 2020;15(9):e0238537.
PMID: 32886707 DOI: 10.1371/journal.pone.0238537

In this study, we characterized, identified, and determined the effect of salt-tolerant PGPR isolated from coastal saline areas on rice growth and yield. A total of 44 bacterial strains were isolated, and 5 were found to be tolerant at high salt concentration. These isolates were further characterized for salinity tolerance and beneficial traits through a series of quantitative tests. Biochemical characterization showed that bacterial survivability decreases gradually with the increase of salt concentration. One of the strains, UPMRB9, produced the highest amount of exopolysaccharides when exposed to 1.5M of NaCl. Moreover, UPMRB9 absorbed the highest amount of sodium from the 1.5M of NaCl-amended media. The highest floc yield and biofilm were produced by UPMRE6 and UPMRB9 respectively, at 1M of NaCl concentration. The SEM observation confirmed the EPS production of UPMRB9 and UPMRE6 at 1.5M of NaCl concentration. These two isolates were identified as Bacillus tequilensis and Bacillus aryabhattai based on the 16S rRNA gene sequence. The functional group characterization of EPS showed the presence of hydroxyl, carboxyl, and amino groups. This corresponded to the presence of carbohydrates and proteins in the EPS and glucose was identified as the major type of carbohydrate. The functional groups of EPS can help to bind and chelate Na+ in the soil and thereby reduces the plant's exposure to the ion under saline conditions. The plant inoculation study revealed significant beneficial effects of bacterial inoculation on photosynthesis, transpiration, and stomatal conductance of the plant which leads to a higher yield. The Bacillus tequilensis and Bacillus aryabhattai strains showed good potential as PGPR for salinity mitigation practice for coastal rice cultivation.

Matched MeSH terms: Biofilms
Fulltext Can Herbal Extracts Serve as Antibacterial Root Canal Irrigating Solutions? Antimicrobial Efficacy of Tylophora indica, Curcumin longa, Phyllanthus amarus, and Sodium Hypochlorite on Enterococcus faecalis Biofilms Formed on Tooth Substrate: In Vitro Study

Sainudeen S, Nair VS, Zarbah M, Abdulla AM, Najeeb CM, Ganapathy S

J Pharm Bioallied Sci, 2020 Aug;12(Suppl 1):S423-S429.
PMID: 33149499 DOI: 10.4103/jpbs.JPBS_127_20

Aim: The purpose of this study was to evaluate the antimicrobial efficacy of Tylophora indica, Curcumin longa, and Phyllanthus amarus on Enterococcus faecalis biofilms formed on the tooth substrate. Sodium hypochlorite was used as a positive control. DMSO (dimethyl sulfoxide), the vehicle for the herbal extracts, was used as the negative control.
Materials and Methods: Extracted human teeth were biomechanically prepared, vertically sectioned, placed in the tissue culture wells exposing the root canal surface to E. faecalis to form a biofilm. At the end of the third week, all groups were treated for 15 min with the test solutions and the control. The results were analyzed both quantitatively and qualitatively.
Results: Statistical analysis was performed by using one-way analysis of variance and compared by the Mann-Whitney test using the Statistical Package for the Social Sciences (SPSS) software, version 20.0. The qualitative assay with the 3-week biofilm on the canal portion showed complete inhibition of bacterial growth for NaOCl, whereas samples treated with herbal solutions showed significant reduction of bacterial growth compared to control group, which showed 139.9 × 109 CFU/mL among the experimental herbal solutions groups. P. amarus has shown maximum bacterial count followed by C. longa and T. indica.
Conclusion: NaOCl 5% showed maximum antibacterial activity against 3-week biofilm on tooth substrate. T. indica, P. amarus, and C. longa showed statistically significant antibacterial activity against 3-week biofilm. The use of herbal alternatives might prove to be advantageous considering the several undesirable characteristics of NaOCl.

Matched MeSH terms: Biofilms
Fulltext Biofilm in endodontics: A review

Jhajharia K, Parolia A, Shetty KV, Mehta LK

J Int Soc Prev Community Dent, 2015 Jan-Feb;5(1):1-12.
PMID: 25767760 DOI: 10.4103/2231-0762.151956

Endodontic disease is a biofilm-mediated infection, and primary aim in the management of endodontic disease is the elimination of bacterial biofilm from the root canal system. The most common endodontic infection is caused by the surface-associated growth of microorganisms. It is important to apply the biofilm concept to endodontic microbiology to understand the pathogenic potential of the root canal microbiota as well as to form the basis for new approaches for disinfection. It is foremost to understand how the biofilm formed by root canal bacteria resists endodontic treatment measures. Bacterial etiology has been confirmed for common oral diseases such as caries and periodontal and endodontic infections. Bacteria causing these diseases are organized in biofilm structures, which are complex microbial communities composed of a great variety of bacteria with different ecological requirements and pathogenic potential. The biofilm community not only gives bacteria effective protection against the host's defense system but also makes them more resistant to a variety of disinfecting agents used as oral hygiene products or in the treatment of infections. Successful treatment of these diseases depends on biofilm removal as well as effective killing of biofilm bacteria. So, the fundamental to maintain oral health and prevent dental caries, gingivitis, and periodontitis is to control the oral biofilms. From these aspects, the formation of biofilms carries particular clinical significance because not only host defense mechanisms but also therapeutic efforts including chemical and mechanical antimicrobial treatment measures have the most difficult task of dealing with organisms that are gathered in a biofilm. The aim of this article was to review the mechanisms of biofilms' formation, their roles in pulpal and periapical pathosis, the different types of biofilms, the factors influencing biofilm formation, the mechanisms of their antimicrobial resistance, techniques to identify biofilms.

Matched MeSH terms: Biofilms
The bactericidal potential of LLDPE with TiO2/ZnO nanocomposites against multidrug resistant pathogens associated with hospital acquired infections

Harun NH, Mydin RBSMN, Sreekantan S, Saharudin KA, Basiron N, Seeni A

J Biomater Sci Polym Ed, 2020 10;31(14):1757-1769.
PMID: 32498665 DOI: 10.1080/09205063.2020.1775759

The emerging polymer nanocomposites have received industrial interests in diverse fields because of their added value in metal oxide-based nanocomposites, such as titanium (TiO2) and zinc oxide (ZnO). Linear low-density polyethylene (LLDPE)-based polymer has recently generated a huge market in the healthcare industry. TiO2 and ZnO are well known for their instant photocatalytic killing of hospital-acquired infections, especially multidrug-resistant (MDR) pathogens. This study investigated the actions of LLDPE/TiO2/ZnO (1:3) nanocomposites in different weight% against two representative MDR pathogens, namely, methicillin-resistant Staphylococcus aureus (MRSA) and Klebsiella pneumonia (K.pneumoniae). Antibacterial activities were quantified according to international standard guidelines of CLSI MO2-A11 (static condition) and ASTM E-2149 (dynamic condition). Preliminary observation via a scanning electron microscope revealed that LLDPE matrix with TiO2/ZnO nanocomposites changed the bacterial morphology and reduced the bacterial adherence and biofilm formation. Furthermore, a high ZnO weight ratio killed both types of pathogens. The bactericidal potential of the nanocomposite is highlighted by the enhancements in photocatalytic activity, zinc ion release and reactive species, and bacteriostatic/bactericidal activity against bacterial growth. This study provides new insights into the MDR-bactericidal potential of LLDPE with TiO2/ZnO nanocomposites for targeted healthcare applications.

Matched MeSH terms: Biofilms
In vitro antimicrobial activity of narasin and monensin in combination with adjuvants against pathogens associated with canine otitis externa

Chan WY, Hickey EE, Khazandi M, Page SW, Trott DJ, Hill PB

Vet Dermatol, 2020 Apr;31(2):138-145.
PMID: 31710159 DOI: 10.1111/vde.12803

BACKGROUND: The emergence of antimicrobial resistance represents a serious human and animal health risk. Good antimicrobial stewardship is essential to prolong the lifespan of existing antibiotics, and new strategies are required to combat infections in man and animals.
HYPOTHESIS/OBJECTIVES: To determine the in vitro interaction of ionophores (narasin or monensin) with antimicrobial adjuvants (N-acetylcysteine (NAC), Tris-EDTA or disodium EDTA) against bacterial strains representing pathogens associated with canine otitis externa (OE).
ANIMAL/ISOLATES: American Type Culture Collection (ATCC) strains Staphylococcus aureus 29213, Pseudomonas aeruginosa 27853 and P. aeruginosa biofilm producer PAO1, and a clinical isolate of Proteus mirabilis from a case of canine OE were tested.
METHODS AND MATERIALS: A 2D microdilution checkerboard method was used, allowing calculation of fractional inhibitory concentration index (FICI), dose reduction index (DRI) and plotting of isobolograms.
RESULTS: The combination of narasin with either Tris-EDTA or disodium EDTA produced additive effects (FICI = 0.75) against P. aeruginosa ATCC 27853 and P. aeruginosa biofilm producer ATCC PAO1. An additive effect (FICI = 0.53-0.75) was found against S. aureus ATCC 29213 when narasin or monensin were combined with NAC. The highest DRI (32-fold) was found with monensin/NAC where the MIC of monensin was reduced from 4 to 0.125 μg/mL.
CONCLUSIONS AND CLINICAL IMPORTANCE: The combination of narasin with Tris-EDTA or disodium EDTA is a promising strategy to inhibit the intrinsic resistance elements of Gram-negative bacteria. These novel combinations potentially could be useful as a multimodal approach to treat mixed infections in canine OE.

Matched MeSH terms: Biofilms
Fulltext The antibacterial efficacy of silver diamine fluoride (SDF) is not modulated by potassium iodide (KI) supplements: A study on in-situ plaque biofilms using viability real-time PCR with propidium monoazide

Abdullah N, Al Marzooq F, Mohamad S, Abd Rahman N, Rani KGA, Chi Ngo H, et al.

PLoS One, 2020;15(11):e0241519.
PMID: 33141868 DOI: 10.1371/journal.pone.0241519

Silver diamine fluoride (SDF) is commonly used to arrest caries lesions, especially in early childhood caries. Recently, it was suggested that SDF can be combined with potassium iodide (KI) to minimize the discoloration of demineralized dentine associated with SDF application. However, the antibacterial efficacy of SDF alone or combined with KI on in-situ biofilm is unknown. Hence, we compared the anti-plaque biofilm efficacy of two different commercially available SDF solutions, with or without KI, using an in-situ biofilm, analysed using viability real-time PCR with propidium monoazide (PMA). Appliance-borne in-situ biofilm samples (n = 90) were grown for a period of 6 h in five healthy subjects who repeated the experiment on three separate occasions, using a validated, novel, intraoral device. The relative anti-biofilm efficacy of two SDF formulations; 38.0% Topamine (SDFT) and 31.3%, Riva Star (SDFR), KI alone, and KI in combination with SDFR (SDFR+KI) was compared. The experiments were performed by applying an optimized volume of the agents onto the biofilm for 1min, mimicking the standard clinical procedure. Afterwards the viability of the residual biofilm bacteria was quantified using viability real-time PCR with PMA, then the percentage of viable from total bacteria was calculated. Both SDF formulations (SDFT and SDFR) exhibited potent antibacterial activities against the in-situ biofilm; however, there was non-significant difference in their efficacy. KI alone did not demonstrate any antibacterial effect, and there was non-significant difference in the antibacterial efficacy of SDF alone compared to SDF with KI, (SDFT v SDFR/KI). Thus, we conclude that the antibacterial efficacy of SDF against plaque biofilms is not modulated by KI supplements. Viability real-time PCR with PMA was successfully used to analyze the viability of naturally grown oral biofilm; thus, the same method can be used to test the antimicrobial effect of other agents on oral biofilms in future research.

Matched MeSH terms: Biofilms
Fulltext Bioactive Compounds from the Bornean Endemic Plant Goniothalamus longistipetes

Teo SP, Bhakta S, Stapleton P, Gibbons S

Antibiotics (Basel), 2020 Dec 16;9(12).
PMID: 33339285 DOI: 10.3390/antibiotics9120913

The present study aimed to screen plants for bioactive compounds with potential antibacterial activities. In our efforts to evaluate plants from Borneo, we isolated and elucidated the structures of four natural products from the bioactive fraction of a chloroform extract of Goniothalamus longistipetes using various chromatographic and spectroscopic techniques. The bioactive compounds were identified as a known styryllactone, (+)-altholactone ((2S,3R,3aS,7aS)-3-hydroxy-2-phenyl-2,3,3a,7a-tetrahydrobenzo-5(4H)-5-one) (1), a new styryllactone, (2S,3R,3aS,7aS)-3-hydroxy-2-phenyl-2,3,3a,7a-tetrahydrobenzo-5(4H)-5-one) (2) as well as a new alkaloid, 2,6-dimethoxyisonicotinaldehyde (3) and a new alkenyl-5-hydroxyl-phenyl benzoic acid (4). 1 and 4 showed broad-spectrum anti-bacterial activities against Gram-positive and Gram-negative bacteria as well as acid-fast model selected for this study. Compound 2 only demonstrated activities against Gram-positive bacteria whilst 3 displayed selective inhibitory activities against Gram-positive bacterial strains. Additionally, their mechanisms of anti-bacterial action were also investigated. Using Mycobacterium smegmatis as a fast-growing model of tubercle bacilli, compounds 1, 2 and 4 demonstrated inhibitory activities against whole-cell drug efflux and biofilm formation; two key intrinsic mechanisms of antibiotic resistance. Interestingly, the amphiphilic compound 4 exhibited inhibitory activity against the conjugation of plasmid pKM101 in Escherichia coli using a plate conjugation assay. Plasmid conjugation is a mechanism by which Gram-positive and Gram-negative-bacteria acquire drug resistance and virulence. These results indicated that bioactive compounds isolated from Goniothalamus longistipetes can be potential candidates as 'hits' for further optimisation.

Matched MeSH terms: Biofilms
Burkholderia vietnamiensis isolated from root tissues of Nipa Palm (Nypa fruticans) in Sarawak, Malaysia, proved to be its major endophytic nitrogen-fixing bacterium

Tang SY, Hara S, Melling L, Goh KJ, Hashidoko Y

Biosci Biotechnol Biochem, 2010;74(9):1972-5.
PMID: 20834139

Root-associating bacteria of the nipa palm (Nypa fruticans), preferring brackish-water affected mud in Sarawak, Malaysia, were investigated. In a comparison of rhizobacterial microbiota between the nipa and the sago (Metroxylon sagu) palm, it was found that the nipa palm possessed a group of Burkholderia vietnamiensis as its main active nitrogen-fixing endophytic bacterium. Acetylene reduction by the various isolates of B. vietnamiensis was constant (44 to 68 nmol h(-1) in ethylene production rate) in soft gel medium containing 0.2% sucrose as sole carbon source, and the bacterium also showed motility and biofilm-forming capacity. This is the first report of endophytic nitrogen-fixing bacteria from nipa palm.

Matched MeSH terms: Biofilms
Fulltext LC-MS Data set on the Malayan Deer (Cervus timorensis) Antler Velvet and its antibiofilm activity against Candida species: LC-MS Data set on the Malayan Deer (Cervus timorensis) Antler Velvet and its antibiofilm properties against Candida species

Arzmi MH, John A, Rismayuddin NAR, Kenali NM, Darnis DS

Data Brief, 2021 Apr;35:106769.
PMID: 33537383 DOI: 10.1016/j.dib.2021.106769

Deer antler velvet (DAV) has been traditionally used in Chinese medicine, including treatment on toothache [1]. Due to its rapid and regenerative capacity, deer antlers were proposed to be the good model for bone remodelling in mammals [2]. The data presented in this work is on the liquid chromatography and mass spectrometry (LC-MS) profile and bioactive potential of Malayan deer antler velvet (DAV) on different Candida species that has clinical importance. Aqueous extraction of DAV samples was subjected to Liquid chromatography quadrupole time of flight mass spectrometry (LC-QTOF-MS) profiling. Reverse phase (RP) separation was used due to the process extraction using water as a solvent to separate polar compound. The data was interpreted using Profile Analysis 2.1V. The DAV samples were also tested for the effect on the biofilm formation of seven Candida species in a 96 well plate [3]. The biofilms were developed for 72 h in aerobic environment. Following that, the biofilms biomass was determined using crystal violet assay.

Matched MeSH terms: Biofilms
Fulltext Prevalence, virulence and antifungal activity of C. albicans isolated from infected root canals

Abraham SB, Al Marzooq F, Himratul-Aznita WH, Ahmed HMA, Samaranayake LP

BMC Oral Health, 2020 12 01;20(1):347.
PMID: 33256696 DOI: 10.1186/s12903-020-01347-5

BACKGROUND: There is limited data on the prevalence of Candida species in infected root canal systems of human teeth. We attempted to investigate the prevalence, genotype, virulence and the antifungal susceptibility of Candida albicans isolated from infected root canals of patients with primary and post-treatment infections in a UAE population.
METHODS: Microbiological samples from 71 subjects with infected root canals were aseptically collected, and cultured on Sabouraud dextrose agar, and C. albicans was identified using multiplex polymerase chain reaction, and the isolates were further subtyped using ABC genotyping system. Their relative virulence was compared using further four archival samples of endodontic origin from another geographical region, and four more salivary isolates, as controls. The virulence attributes compared were biofilm formation, and production of phospholipase and haemolysin, and the susceptibility to nystatin, amphotericin B, ketoconazole, and fluoconazole was also tested.
RESULTS: 4 out of 71 samples (5.6%) yielded Candida species. On analysis of variance among the groups, the intracanal isolates, mainly Genotype A, possessed a high degree of phospholipase and haemolysin activity (p

Matched MeSH terms: Biofilms
Fulltext Effectiveness of chitosan-propolis nanoparticle against Enterococcus faecalis biofilms in the root canal

Parolia A, Kumar H, Ramamurthy S, Davamani F, Pau A

BMC Oral Health, 2020 11 25;20(1):339.
PMID: 33238961 DOI: 10.1186/s12903-020-01330-0

BACKGROUND: The successful outcome of endodontic treatment depends on controlling the intra-radicular microbial biofilm by effective instrumentation and disinfection using various irrigants and intracanal medicaments. Instrumentation alone cannot effectively debride the root canals specially due to the complex morphology of the root canal system. A number of antibiotics and surfactants are being widely used in the treatment of biofilms however, the current trend is towards identification of natural products in disinfection. The aim of the study was to determine the antibacterial effect of chitosan-propolis nanoparticle (CPN) as an intracanal medicament against Enterococcus faecalis biofilm in root canal.
METHODS: 240 extracted human teeth were sectioned to obtain 6 mm of the middle third of the root. The root canal was enlarged to an internal diameter of 0.9 mm. The specimens were inoculated with E. faecalis for 21 days. Following this, specimens were randomly divided into eight groups (n = 30) according to the intracanal medicament placed: group I: saline, group II: chitosan, group III: propolis100 µg/ml (P100), group IV: propolis 250 µg/ml (P250), group V: chitosan-propolis nanoparticle 100 µg/ml (CPN100), group VI: chitosan-propolis nanoparticle 250 µg/ml (CPN250), group VII: calcium hydroxide(CH) and group VIII: 2% chlorhexidine (CHX) gel. Dentine shavings were collected at 200 and 400 μm depths, and total numbers of CFUs were determined at the end of day one, three and seven. The non-parametric Kruskal Wallis and Mann-Whitney tests were used to compare the differences in reduction of CFUs between all groups and probability values of p

Matched MeSH terms: Biofilms
Fulltext Transcriptome Analysis of Pseudomonas aeruginosa Biofilm Following the Exposure to Malaysian Stingless Bee Honey

Seder N, Abu Bakar MH, Abu Rayyan WS

Adv Appl Bioinform Chem, 2021;14:1-11.
PMID: 33488102 DOI: 10.2147/AABC.S292143

Introduction: Malaysian stingless bee honey (Trigona) has been aroused as a potential antimicrobial compound with antibiofilm activity. The capability of the gram-negative bacillus P. aeruginosa to sustain a fatal infection is encoded in the bacterium genome.
Methods: In the current study, a transcriptome investigation was performed to explore the mechanism underlying the biofilm dispersal of P. aeruginosa after the exposure to Trigona honey.
Results: Microarray analysis of the Pseudomonas biofilm treated by 20% Trigona honey has revealed a down-regulation of 3478 genes among the 6085 screened genes. Specifically, around 13.5% of the down-regulated genes were biofilm-associated genes. The mapping of the biofilm-associated pathways has shown an ultimate decrease in the expression levels of the D-GMP signaling pathway and diguanylate cyclases (DGCs) genes responsible for c-di-GMP formation.
Conclusion: We predominantly report the lowering of c-di-GMP through the down-regulation of DGC genes as the main mechanism of biofilm inhibition by Trigona honey.

Matched MeSH terms: Biofilms
Fulltext The microbiological quality of water from dental unit waterlines in Malaysian Armed Forces dental centres

Ma, Mei Siang, Zalini Yunus, Ahmad Razi Mohammad Yunus, Zukri Ahmad, Haryanti Toosa

Archives of Orofacial Sciences, 2012;7(1):1-7.
MyJurnal

Abstract Water quality in the dental unit waterlines (DUWLs) is important to the patients and dental health care personnel as they are at risk of being infected with opportunistic pathogens such as Pseudomonas or Legionella species. In this study, a total of 86 samples were collected from DUWLs of 19 dental units in 11 Malaysian Armed Forces dental centres (MAFDC). 350 ml water sample was collected in sterile thiosulphite bags from the outlets of 3–way syringe, high speed handpiece, scaler, cup filler, independent water reservoir or the tap of the same surgery respectively. Samples were transported to the laboratory within 24 hours and kept in the refrigerator at 40C. 100ml of each sample was filtered through a 0.45 μm polycarbonate membrane filter. The filter was then inoculated onto plate count agar and incubated at 370 C for 24 hours, after which the formed colonies were enumerated. Another separate 100ml of water sample was poured onto buffered charcoal yeast extract agar and cetrimide agar to culture Legionnella and Pseudomonas respectively. Identification of these bacteria were confirmed by polymerase chain reaction and sequencing. Pseudomonas aeruginosa was detected in 9.5% of the samples but Legionnella was not detected in any of the samples. 77% of the samples met American Dental Association (ADA) recommendation of less than 200 cfu/ml. The result of this study showed that it is difficult if not impossible to eliminate biofilm from the DUWLs. Regular monitor of water quality from DUWL is required to maximise the health of the dental patients and dental health care personnel.

Matched MeSH terms: Biofilms
Fulltext Changes in the Carbon Metabolism of Escherichia coli During the Evolution of Doxycycline Resistance

Yang Y, Mi J, Liang J, Liao X, Ma B, Zou Y, et al.

Front Microbiol, 2019;10:2506.
PMID: 31736928 DOI: 10.3389/fmicb.2019.02506

Despite our continuous improvement in understanding the evolution of antibiotic resistance, the changes in the carbon metabolism during the evolution of antibiotic resistance remains unclear. To investigate the evolution of antibiotic resistance and the changes in carbon metabolism under antibiotic pressure, Escherichia coli K-12 was evolved for 38 passages under a concentration gradient of doxycycline (DOX). The 0th-passage sensitive strain W0, the 20th-passage moderately resistant strain M20, and the 38th-passage highly resistant strain E38 were selected for the determination of biofilm formation, colony area, and carbon metabolism levels, as well as genome and transcriptome sequencing. The MIC of DOX with E. coli significantly increased from 4 to 96 μg/ml, and the IC50 increased from 2.18 ± 0.08 to 64.79 ± 0.75 μg/ml after 38 passages of domestication. Compared with the sensitive strain W0, the biofilm formation amount of the resistant strains M20 and E38 was significantly increased (p < 0.05). Single-nucleotide polymorphisms (SNPs) were distributed in antibiotic resistance-related genes such as ribosome targets, cell membranes, and multiple efflux pumps. In addition, there were no mutated genes related to carbon metabolism. However, the genes involved in the biosynthesis of secondary metabolites and carbon metabolism pathway were downregulated, showing a significant decrease in the metabolic intensity of 23 carbon sources (p < 0.05). The results presented here show that there may be a correlation between the evolution of E. coli DOX resistance and the decrease of carbon metabolism, and the mechanism was worthy of further research, providing a theoretical basis for the prevention and control of microbial resistance.

Matched MeSH terms: Biofilms
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: Biofilms

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