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Potential effects of Psidium sp., Mangifera sp., Mentha sp. and its mixture (PEM) in reducing bacterial populations in biofilms, adherence and acid production of S. sanguinis and S. mutans

Shafiei Z, Rahim ZHA, Philip K, Thurairajah N, Yaacob H

Arch Oral Biol, 2020 Jan;109:104554.
PMID: 31563709 DOI: 10.1016/j.archoralbio.2019.104554

OBJECTIVE: Psidium sp., Mangifera sp. and Mentha sp. and its mixture (PEM) are known to have antimicrobial and anti-adherence effects.
DESIGN: Here, we have investigated these individual plant extracts and its synergistic mixture (PEM) for its anti-cariogenic effect to reduce populations of single and mixed-species of Streptococcus sanguinis and Streptococcus mutans in a planktonic or/and biofilm and their others reduced virulence. Bacterial populations in the biofilm after 24 h, hydrophobic cell surface activity to n-hexadecane and pH changes at 5 min' intervals until 90 min of incubation were recorded. Total phenolic content and bioactive compounds in the crude aqueous plant extracts were analysed. Regulatory gene expressions of S. mutans adhesins genes (gtfB, gtfC, gbpB and spaP) upon treatment with PEM were investigated in planktonic and biofilm conditions.
RESULTS: All plant extracts strongly reduced S. mutans in the biofilm compared to S. sanguinis in single and mixed-species. PEM reduced S. mutans by 84% with S. sanguinis 87% in the mixed population. Psidium sp. and PEM highly reduced cell-surface hydrophobicity of the two bacteria thus reducing adherence and biofilm formation. PEM and Mangifera sp. lowered initial pH change in the mixed populations of S. sanguinis and S. mutans. PEM downregulated the S. mutans gtfB gene expression in the single species planktonic and mixed-species biofilms.
CONCLUSIONS: The effectiveness of PEM in reducing S. mutans within the biofilm, cell-surface hydrophobicity, acid production and adhesin gene (gtfB) expression in mixed-species with S. sanguinis indicates its potential as an antibacterial agent against dental caries. This is attributed to the phenolic content in the PEM.

Matched MeSH terms: Biofilms/drug effects*
Fulltext Antibiotic Susceptibility Patterns, Biofilm Formation and esp Gene among Clinical Enterococci: Is There Any Association?

Weng PL, Ramli R, Hamat RA

Int J Environ Res Public Health, 2019 09 17;16(18).
PMID: 31533204 DOI: 10.3390/ijerph16183439

Enterococci are commonly found in humans, animals and environments. Their highly adaptive mechanisms are related to several virulent determinants and their ability to resist antibiotics. Data on the relationship between the esp gene, biofilm formation and antibiotic susceptibility profiles may differ between countries. This cross-sectional study was conducted to determine the proportion of esp gene and biofilm formation among Enterococcus faecalis and Enterococcus faecium clinical isolates. We also investigated the possible association between the esp gene with antibiotic susceptibility patterns and biofilm formation. The isolates were collected from clinical samples and identified using biochemical tests and 16SRNA. Antibiotic susceptibility patterns and a biofilm assay were conducted according to the established guidelines. Molecular detection by PCR was used to identify the esp gene using established primers. In total, 52 and 28 of E. faecalis and E. faecium were identified, respectively. E. faecium exhibited higher resistance rates compared to E. faecalis as follows: piperacillin/tazobactam (100% versus 1.9%), ampicillin (92.8% versus 1.9%), high-level gentamicin resistance (HLGR) (89.3% versus 25.0%) and penicillin (82.1% versus 7.7%). E. faecium produced more biofilms than E. faecalis (59.3% versus 49.0%). E. faecium acquired the esp gene more frequently than E. faecalis (78.6% versus 46.2%). Interestingly, the associations between ampicillin and tazobactam/piperacillin resistance with the esp gene were statistically significant (X2 = 4.581, p = 0.027; and X2 = 6.276, p = 0.012, respectively). Our results demonstrate that E. faecium exhibits high rates of antimicrobial resistance, esp gene acquisition and biofilm formation. These peculiar traits of E. faecium may have implications for the management of enterococcal infections in hospitals. Thus, concerted efforts by all parties in establishing appropriate treatment and effective control measures are warranted in future.

Matched MeSH terms: Biofilms*
Fulltext Physiologically Relevant Alternative Carbon Sources Modulate Biofilm Formation, Cell Wall Architecture, and the Stress and Antifungal Resistance of Candida glabrata

Chew SY, Ho KL, Cheah YK, Sandai D, Brown AJP, Than LTL

Int J Mol Sci, 2019 Jun 28;20(13).
PMID: 31261727 DOI: 10.3390/ijms20133172

Flexibility in carbon metabolism is pivotal for the survival and propagation of many human fungal pathogens within host niches. Indeed, flexible carbon assimilation enhances pathogenicity and affects the immunogenicity of Candida albicans. Over the last decade, Candida glabrata has emerged as one of the most common and problematic causes of invasive candidiasis. Despite this, the links between carbon metabolism, fitness, and pathogenicity in C. glabrata are largely unexplored. Therefore, this study has investigated the impact of alternative carbon metabolism on the fitness and pathogenic attributes of C. glabrata. We confirm our previous observation that growth on carbon sources other than glucose, namely acetate, lactate, ethanol, or oleate, attenuates both the planktonic and biofilm growth of C. glabrata, but that biofilms are not significantly affected by growth on glycerol. We extend this by showing that C. glabrata cells grown on these alternative carbon sources undergo cell wall remodeling, which reduces the thickness of their β-glucan and chitin inner layer while increasing their outer mannan layer. Furthermore, alternative carbon sources modulated the oxidative stress resistance of C. glabrata as well as the resistance of C. glabrata to an antifungal drug. In short, key fitness and pathogenic attributes of C. glabrata are shown to be dependent on carbon source. This reaffirms the perspective that the nature of the carbon sources available within specific host niches is crucial for C. glabrata pathogenicity during infection.

Matched MeSH terms: Biofilms*
Antibiotic resistance, putative virulence factors and curli fimbrination among Cronobacter species

Odeyemi OA, Abdullah Sani N

Microb Pathog, 2019 Nov;136:103665.
PMID: 31404630 DOI: 10.1016/j.micpath.2019.103665

This study aimed to investigate antibiotic resistance and putative virulence factors among Cronobacter sakazakii isolated from powdered infant formula and other sources. The following 9 cultures (CR1-9) were collected from our culture collection: C. sakazakii and 3 Cronobacter species: C. sakazakii ATCC® 29544™, C. muytjensii ATCC® 51329™, C. turicensis E866 were used in this study. Isolates were subjected to antibiotic susceptibility and the following virulence factors (protease, DNase, haemolysin, gelatinase, motility and biofilm formation) using phenotypic methods. All the bacteria were able to form biofilm on agar at 37 °C and were resistant to ampicillin, erythromycin, fosfomycin and sulphamethoxazole. It was observed from this study that tested strains formed weak and strong biofilm with violet dry and rough (rdar), brown dry and rough (bdar), red mucoid and smooth (rmas) colony morphotypes on Congo red agar. Rdar expresses curli and fimbriae, while bdar expresses curli. Both biofilm colony morphotypes are commonly found in Enterobacteriaceae including Salmonella species. This study also reveals a new colony morphotypes in Cronobacter species. Conclusively, there was correlation between putative virulence factors and antibiotic resistance among the tested bacteria. Further study on virulence and antibiotic resistance genes is hereby encouraged.

Matched MeSH terms: Biofilms/growth & development
Synthesis, Bacterial biofilm inhibition and cytotoxicity of new N-Alkyl/aralkyl-N-(2,3-dihydro-1,4-benzodioxin-6-yl)-4-nitrobenzenesulfonamides

Abbasi MA, Zeb A, Rehman A, Siddiqui SZ, Shah SAA, Shahid M, et al.

Pak J Pharm Sci, 2020 Jan;33(1):41-47.
PMID: 32122829

The current research was commenced by reaction of 1,4-benzodioxane-6-amine (1) with 4-nitrobenzenesulfonyl chloride (2) in the presence of aqueous base under dynamic pH control at 9 to yield N-(2,3-dihydro-1,4-benzodioxin-6-yl)-4-nitrobenzenesulfonamide (3) which was further reacted with a series of alkyl/aralkyl halides (4a-i) in polar aprotic solvent using catalytic amount of lithium hydride which acts as base to afford some new N-alkyl/aralkyl-N-(2,3-dihydro-1,4-benzodioxin-6-yl)-4-nitrobenzenesulfonamides (5a-i). The projected structures of all the synthesized derivatives were characterized by contemporary techniques i.e., IR, 1H-NMR and EIMS. The biofilm Inhibitory action of all synthesized molecules was carried out against Escherichia coli and Bacillus subtilis. It was inferred from their results that 5f and 5e exhibited suitable inhibitory action against the biofilms of these bacterial strains. Moreover, their cytotoxicity was also checked and it was concluded that these synthesized molecules displayed docile cytotoxicity.

Matched MeSH terms: Biofilms/drug effects*
Fulltext First reported case of Gilbertella persicaria in human stool: outcome of a community study from Segamat, Johor, Malaysia

Huët MAL, Wong LW, Goh CBS, Ong KS, Dwiyanto J, Reidpath D, et al.

Braz J Microbiol, 2020 Dec;51(4):2067-2075.
PMID: 32572838 DOI: 10.1007/s42770-020-00323-z

Species of fungi belonging to the order Mucorales can be found everywhere in the environment. Gilbertella persicaria, which belongs to this order, have often been isolated from fruits and in water systems. However, there has been no report of isolation of this fungus from human samples. During a gut mycobiome study, from the Segamat community, Gilbertella persicaria was isolated from a human fecal sample and was characterized through a series of morphological assessment, biochemical tests, and molecular techniques. The isolate produced a white velvety surface that turned grayish after 24 h. Although no biofilm production was observed, the results indicated that the isolate could form calcium oxalate crystals, produced urease, and was resistant to low pH. The isolate was sensitive to amphotericin but resistant to voriconazole and itraconazole. The features of this fungus that could help in its survival in the human gut are also discussed.

Matched MeSH terms: Biofilms/growth & development
Betacyanin-inhibited biofilm formation of co-culture of Staphylococcus aureus and Pseudomonas aeruginosa on different polymer surfaces

Yong YY, Ong MWK, Dykes G, Choo WS

FEMS Microbiol Lett, 2021 01 26;368(1).
PMID: 33338235 DOI: 10.1093/femsle/fnaa214

Staphylococcus aureus and Pseudomonas aeruginosa are bacteria that cause biofilm-associated infections. The aim of this study was to determine the activity of combined betacyanin fractions from Amaranthus dubius (red spinach) and Hylocereus polyrhizus (red pitahaya) against biofilms formed by co-culture of S. aureus and P. aeruginosa on different polymer surfaces. Various formulations containing different concentrations of the betacyanin fractions were investigated for biofilm-inhibiting activity on polystyrene surfaces using crystal violet assay and scanning electron microscopy. A combination of each betacyanin fraction (0.625 mg mL-1) reduced biofilm formation of five S. aureus strains and four P. aeruginosa strains from optical density values of 1.24-3.84 and 1.25-3.52 to 0.81-2.63 and 0.80-1.71, respectively. These combined fractions also significantly inhibited dual-species biofilms by 2.30 and reduced 1.0-1.3 log CFU cm-2 bacterial attachment on polymer surfaces such as polyvinyl chloride, polyethylene, polypropylene and silicone rubber. This study demonstrated an increase in biofilm-inhibiting activity against biofilms formed by two species using combined fractions than that by using single fractions. Betacyanins found in different plants could collectively be used to potentially decrease the risk of biofilm-associated infections caused by these bacteria on hydrophobic polymers.

Matched MeSH terms: Biofilms/drug effects*
Fulltext Efficient Synthesis of Novel Pyridine-Based Derivatives via Suzuki Cross-Coupling Reaction of Commercially Available 5-Bromo-2-methylpyridin-3-amine: Quantum Mechanical Investigations and Biological Activities

Ahmad G, Rasool N, Ikram HM, Gul Khan S, Mahmood T, Ayub K, et al.

Molecules, 2017 Jan 27;22(2).
PMID: 28134790 DOI: 10.3390/molecules22020190

The present study describes palladium-catalyzed one pot Suzuki cross-coupling reaction to synthesize a series of novel pyridine derivatives 2a-2i, 4a-4i. In brief, Suzuki cross-coupling reaction of 5-bromo-2-methylpyridin-3-amine (1) directly or via N-[5-bromo-2-methylpyridine-3-yl]acetamide (3) with several arylboronic acids produced these novel pyridine derivatives in moderate to good yield. Density functional theory (DFT) studies were carried out for the pyridine derivatives 2a-2i and 4a-4i by using B3LYP/6-31G(d,p) basis with the help of GAUSSIAN 09 suite programme. The frontier molecular orbitals analysis, reactivity indices, molecular electrostatic potential and dipole measurements with the help of DFT methods, described the possible reaction pathways and potential candidates as chiral dopants for liquid crystals. The anti-thrombolytic, biofilm inhibition and haemolytic activities of pyridine derivatives were also investigated. In particular, the compound 4b exhibited the highest percentage lysis value (41.32%) against clot formation in human blood among all newly synthesized compounds. In addition, the compound 4f was found to be the most potent against Escherichia coli with an inhibition value of 91.95%. The rest of the pyridine derivatives displayed moderate biological activities.

Matched MeSH terms: Biofilms/drug effects
Plant-derived Compounds as Potential Source of Novel Anti-Biofilm Agents Against Pseudomonas aeruginosa

Chung PY

Curr Drug Targets, 2017;18(4):414-420.
PMID: 27758704 DOI: 10.2174/1389450117666161019102025

Pseudomonas aeruginosa is the most common Gram-negative bacterium associated with nosocomial and life-threatening chronic infections in cystic fibrosis patients. This pathogen is wellknown for its ability to attach to surfaces of indwelling medical devices to form biofilms, which consist of a regular array of extracellular polymers. Tenaciously bound to the surface of devices and inherently resilient to antibiotic treatment, P. aeruginosa poses a serious threat in clinical medicine and contributes to the persistence of chronic infections. Studies on microbial biofilms in the past decade involved mainly the understanding of environment signals, genetic elements and molecular mechanisms in biofilm formation, tolerance and dispersal. The knowledge obtained from the studies of these mechanisms is crucial in the establishment of strategies to eradicate or to prevent biofilm formation. Currently, biofilm infections are usually treated with combinations of antibiotics and surgical removal, in addition to frequent replacement of the infected device. More recently, specific natural sources have been identified as antibiofilm agents against this pathogen. This review will highlight the recent progress made by plant-derived compounds against P. aeruginosa biofilm infections in both in vitro or in vivo models.

Matched MeSH terms: Biofilms/drug effects
Antibiofilm activity and mode of action of DMSO alone and its combination with afatinib against Gram-negative pathogens

Yahya MFZR, Alias Z, Karsani SA

Folia Microbiol (Praha), 2018 Jan;63(1):23-30.
PMID: 28540585 DOI: 10.1007/s12223-017-0532-9

Biofilms are complex microbial communities that tend to attach to either biotic or abiotic surface. Enclosed in a self-produced extracellular polymeric substance (EPS) matrix, the biofilms often cause persistent infections. The objective of this study was to investigate the antibiofilm activity of dimethyl sulfoxide (DMSO) and afatinib against Gram-negative pathogens. Test microorganisms used in this study were Escherichia coli ATCC 1299, Pseudomonas aeruginosa ATCC 10145, and Salmonella typhimurium ATCC 14028. Biofilms were developed in 96-well microplate at 37°C for 24 h. Following removal of non-adherent cells, analysis of biofilm viability, biofilm biomass, and extracellular polymeric substances (EPS) matrix were performed using resazurin assay, crystal violet assay, and attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy, respectively. Bradford protein assay was conducted to determine the total amount of EPS proteins. The results demonstrated that both 32% DMSO alone and its combination with 3.2 μg/mL afatinib were effective in killing biofilm cells and reducing biofilm biomass. IR spectral variations of EPS matrix of biofilms in the range between 1700 and 900 cm-1 were also observed. Reduction in EPS proteins verified the chemical modifications of EPS matrix. In conclusion, 32% DMSO alone and its combination with 3.2 μg/mL afatinib showed remarkable antibiofilm activities against Gram-negative pathogens. It was suggested that the biofilm inhibition was mediated by the chemical modification of EPS matrix.

Matched MeSH terms: Biofilms/drug effects*
Fulltext Potential of Superhydrophobic Surface for Blood-Contacting Medical Devices

Wu XH, Liew YK, Mai CW, Then YY

Int J Mol Sci, 2021 Mar 24;22(7).
PMID: 33805207 DOI: 10.3390/ijms22073341

Medical devices are indispensable in the healthcare setting, ranging from diagnostic tools to therapeutic instruments, and even supporting equipment. However, these medical devices may be associated with life-threatening complications when exposed to blood. To date, medical device-related infections have been a major drawback causing high mortality. Device-induced hemolysis, albeit often neglected, results in negative impacts, including thrombotic events. Various strategies have been approached to overcome these issues, but the outcomes are yet to be considered as successful. Recently, superhydrophobic materials or coatings have been brought to attention in various fields. Superhydrophobic surfaces are proposed to be ideal blood-compatible biomaterials attributed to their beneficial characteristics. Reports have substantiated the blood repellence of a superhydrophobic surface, which helps to prevent damage on blood cells upon cell-surface interaction, thereby alleviating subsequent complications. The anti-biofouling effect of superhydrophobic surfaces is also desired in medical devices as it resists the adhesion of organic substances, such as blood cells and microorganisms. In this review, we will focus on the discussion about the potential contribution of superhydrophobic surfaces on enhancing the hemocompatibility of blood-contacting medical devices.

Matched MeSH terms: Biofilms/drug effects
An overview of Acinetobacter baumannii pathogenesis: Motility, adherence and biofilm formation

Mea HJ, Yong PVC, Wong EH

Microbiol Res, 2021 Jun;247:126722.
PMID: 33618061 DOI: 10.1016/j.micres.2021.126722

The Gram-negative opportunistic pathogen Acinetobacter baumannii has gain notoriety in recent decades, primarily due to its propensity to cause nosocomial infections in critically ill patients. Its global spread, multi-drug resistance features and plethora of virulence factors make it a serious threat to public health worldwide. Though much effort has been expended in uncovering its successes, it continues to confound researchers due to its highly adaptive nature, mutating to meet the needs of a given environment. Its persistence in the clinical setting allows it to be in close proximity to a potential host, where contact can be made facilitating infection and colonization. In this article, we aim to provide a current overview of the bacterial virulence factors, specifically focusing on factors involved in the initial stages of infection, highlighting the role of adaptation facilitated by two-component systems and biofilm formation. Finally, the study of host-pathogen interactions using available animal models, their suitability, notable findings and some perspectives moving forward are also discussed.

Matched MeSH terms: Biofilms/growth & development*
Fulltext Effect of Propolis Nanoparticles against Enterococcus faecalis Biofilm in the Root Canal

Parolia A, Kumar H, Ramamurthy S, Madheswaran T, Davamani F, Pichika MR, et al.

Molecules, 2021 Jan 30;26(3).
PMID: 33573147 DOI: 10.3390/molecules26030715

To determine the antibacterial effect of propolis nanoparticles (PNs) as an endodontic irrigant against Enterococcus faecalis biofilm inside the endodontic root canal system. Two-hundred-ten 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 seven groups, with 30 dentinal blocks in each group including: group I-saline; group II-propolis 100 µg/mL; group III-propolis 300 µg/mL; group IV-propolis nanoparticle 100 µg/mL; group V-propolis nanoparticle 300µg/mL; group VI-6% sodium hypochlorite; group VII-2% chlorhexidine. Dentin shavings were collected at 200 and 400 μm depths, and total numbers of CFUs were determined at the end of one, five, and ten minutes. The non-parametric Kruskal-Wallis and Mann-Whitney tests were used to compare the differences in reduction in CFUs between all groups, and probability values of p < 0.05 were set as the reference for statistically significant results. The antibacterial effect of PNs as an endodontic irrigant was also assessed against E. faecalis isolates from patients with failed root canal treatment. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were also performed after exposure to PNs. A Raman spectroscope, equipped with a Leica microscope and lenses with curve-fitting Raman software, was used for analysis. The molecular interactions between bioactive compounds of propolis (Pinocembrin, Kaempferol, and Quercetin) and the proteins Sortase A and β-galactosidase were also understood by computational molecular docking studies. PN300 was significantly more effective in reducing CFUs compared to all other groups (p < 0.05) except 6% NaOCl and 2% CHX (p > 0.05) at all time intervals and both depths. At five minutes, 6% NaOCl and 2% CHX were the most effective in reducing CFUs (p < 0.05). However, no significant difference was found between PN300, 6% NaOCl, and 2% CHX at 10 min (p > 0.05). SEM images also showed the maximum reduction in E. faecalis with PN300, 6% NaOCl, and 2% CHX at five and ten minutes. CLSM images showed the number of dead cells in dentin were highest with PN300 compared to PN100 and saline. There was a reduction in the 484 cm-1 band and an increase in the 870 cm-1 band in the PN300 group. The detailed observations of the docking poses of bioactive compounds and their interactions with key residues of the binding site in all the three docking protocols revealed that the interactions were consistent with reasonable docking and IFD docking scores. PN300 was equally as effective as 6% NaOCl and 2% CHX in reducing the E. faecalis biofilms.

Matched MeSH terms: Biofilms/drug effects
Fulltext Comparative characterisation of genotypically different clones of MRSA in the production of biofilms

Atshan SS, Shamsudin MN, Lung LT, Sekawi Z, Ghaznavi-Rad E, Pei CP

J Biomed Biotechnol, 2012;2012:417247.
PMID: 22529705 DOI: 10.1155/2012/417247

The ability to adhere and produce biofilms is characteristic of enhanced virulence among isolates of methicillin-resistant Staphylococcus aureus (MRSA). The aim of the study is to find out whether these characteristics are consistently similar among isolates variations of MRSA. The study used 30 various isolates of MRSA belong to 13 spa types and 5 MLST types and determined the aggregation, the adherence, and the production of biofilms and slime for each isolate. The methods used to evaluate these characteristics were a modified Congo red agar assay (MCRA), a microtiter plate assay (MPA), high-magnification light microscopy, scanning electron microscopy (SEM), and PCR. The study found that isolates belonging to similar Spa, SCCmec, and ST types have similar abilities to produce biofilms; however, their ability to produce slime on CRA was found to be different. Moreover, isolates that have different Spa types showed high variation in their ability to produce biofilms. The results of light microscope revealed the isolates that produced strong and weak biofilms and formed similar aggregation on the glass surfaces. SEM results showed that all 30 MRSA isolates that were tested were 100% positive for biofilm formation, although to varying degrees. Further testing using PCR confirmed that 100% of the 30 isolates tested were positive for the presence of the icaADBC, fnbA, eno, ebps, clfA, and clfB genes. The prevalence of fib, cna, fnbB, and bbp in MRSA clones was 90, 93.33, 53.33, and 10%, respectively. This study indicate that differences in biofilm production capacities are caused by the differences in surface protein A (Spa) type and are not due to differences in MLST and SCCmec types.

Matched MeSH terms: Biofilms/classification*
The inhibitory effects of aureobasidin A on Candida planktonic and biofilm cells

Tan HW, Tay ST

Mycoses, 2013 Mar;56(2):150-6.
PMID: 22882276 DOI: 10.1111/j.1439-0507.2012.02225.x

Aureobasidin A (AbA) is a cyclic depsipeptide antifungal compound that inhibits a wide range of pathogenic fungi. In this study, the in vitro susceptibility of 92 clinical isolates of various Candida species against AbA was assessed by determining the planktonic and biofilm MICs of the isolates. The MIC(50) and MIC(90) of the planktonic Candida yeast were 1 and 1 μg ml(-1), respectively, whereas the biofilm MIC(50) and MIC(90) of the isolates were 8 and ≥64 μg ml(-1) respectively. This study demonstrates AbA inhibition on filamentation and biofilm development of C. albicans. The production of short hyphae and a lack of filamentation might have impaired biofilm development of AbA-treated cells. The AbA resistance of mature Candidia biofilms (24 h adherent population) was demonstrated in this study.

Matched MeSH terms: Biofilms/drug effects*
Fulltext Detection of quorum sensing signal molecules and identification of an autoinducer synthase gene among biofilm forming clinical isolates of Acinetobacter spp

Anbazhagan D, Mansor M, Yan GO, Md Yusof MY, Hassan H, Sekaran SD

PLoS One, 2012;7(7):e36696.
PMID: 22815678 DOI: 10.1371/journal.pone.0036696

Quorum sensing is a term that describes an environmental sensing system that allows bacteria to monitor their own population density which contributes significantly to the size and development of the biofilm. Many gram negative bacteria use N-acyl-homoserine lactones as quorum sensing signal molecules. In this study, we sought to find out if the biofilm formation among clinical isolates of Acinetobacter spp. is under the control of autoinducing quorum sensing molecules.

Matched MeSH terms: Biofilms/growth & development*
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: Biofilms/growth & development
Fulltext Anti-Candida activity and biofilm inhibitory effects of secreted products of tropical environmental yeasts

Tan HW, Tay ST

Trop Biomed, 2011 Apr;28(1):175-80.
PMID: 21602784

This study describes the killer phenotypes of tropical environmental yeasts and the inhibition effects of the culture filtrates on the biofilm of Candida albicans. A total of 26 (10.5%) of 258 yeast isolates obtained from an environmental sampling study demonstrated killer activity to Candida species. The killer yeasts were identified as species belonging to the genus Aureobasidium, Pseudozyma, Ustilago and Candida based on sequence analysis of the ITS1-5.8S-ITS2 region of the yeasts. Pseudozyma showed the broadest killing effects against sensitive strains of Candida. New species of Ustilago and Pseudozyma demonstrating killer phenotypes were identified in this study. Interestingly, more than 50% reduction in the metabolic activity of Candida albicans biofilm was noted after exposure to the culture filtrates of the nine killer yeasts. Purification and characterization of toxin and metabolites are essential for understanding the yeast killing effects.

Matched MeSH terms: Biofilms/drug effects*
Proteinase, phospholipase, biofilm forming abilities and antifungal susceptibilities of Malaysian Candida isolates from blood cultures

Tay ST, Abidin IA, Hassan H, Ng KP

Med Mycol, 2011 Jul;49(5):556-60.
PMID: 21254967 DOI: 10.3109/13693786.2010.551424

This study was conducted to determine the proteinase, phospholipase, and biofilm forming abilities of Candida isolates in blood cultures of specimens from patients at the University Malaya Medical Center, Kuala Lumpur, Malaysia. Proteinase and phospholipase activities were detected in 93.7% and 73.3%, respectively, of 15 Candida albicans isolates. Amongst the 26 non-C. albicans Candida isolates, proteinase and phospholipase activities were detected in 88.5% and 7.7% of the isolates, respectively. There was no significant difference in the expression levels of proteinase amongst the Candida isolates studied (P = 0.272), but the phospholipase activity of C. albicans was significantly higher than that of the non-C. albicans Candida isolates (P = 0.003). There was no significant difference in the biofilm forming abilities of C. albicans and non-C. albicans Candida isolates on the polystyrene microtiter wells (P = 0.379). In addition, the findings of this study demonstrate increased resistance of Candida isolates in biofilms to amphotericin and fluconazole, as compared to their planktonic counterparts.

Matched MeSH terms: Biofilms/growth & development*
Microbial colonization of medical devices and novel preventive strategies

Shunmugaperumal T

Recent Pat Drug Deliv Formul, 2010 Jun;4(2):153-73.
PMID: 20236065

Upon implantation or insertion into patient's body for exerting the intended purpose like salvage of normal functions of vital organs, the medical devices are unfortunately becoming the sites of competition between host cell integration and microbial adhesion. Moreover, since there is an increased use of implanted medical devices, the incidence of biofilm-and medical devices-related nosocomial infections is also increasing progressively. To control microbial colonization and subsequent biofilm formation of the medical devices, different approaches either to enhance the efficiency of certain antimicrobial agents or to disrupt the basic physiology of the pathogenic microorganisms including novel small molecules and antipathogenic drugs are being explored. In addition, the various lipid-and polymer-based drug delivery carriers are also investigated for applying antibiofilm coating of the medical devices especially over catheters. The main intention of this review is therefore to summarize the major and/breakthrough inventions disclosed in patent literature as well as in research papers related to microbial colonization of medical devices and novel preventive strategies. This review starts with an overview of the preventive strategies followed by a short description about the potential of different lipidic-and polymeric-drug delivery carriers in eradicating the biofilm-associated infections from the medical devices.

Matched MeSH terms: Biofilms/drug effects

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