Development of a green chemistry process for the synthesis of silver nanoparticles has become a focus of interest. This would offer numerous benefits, including ecofriendliness and compatibility for biomedical applications. Here we report the synthesis of silver nanoparticles from the reduction of silver nitrate and an aqueous extract of the lichen Parmotrema praesorediosum as a reductant as well as a stabilizer. The physical appearance of these silver nanoparticles was characterized using ultraviolet-visible spectroscopy, electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction techniques. The results show that silver nanoparticles synthesized using P. praesorediosum have an average particle size of 19 nm with a cubic structure. The antibacterial activity of the synthesized silver nanoparticles was tested against eight micro-organisms using the disk diffusion method. The results reveal that silver nanoparticles synthesized using P. praesorediosum have potential antibacterial activity against Gram-negative bacteria.
This study aims to evaluate the optimum duration of flushing dental unit waterlines (DUWLs) in Universiti Sains Islam Malaysia (USIM) dental polyclinics for removal of heterotrophic bacteria. Water samples were obtained from triple air syringes at each dental chair from oral surgery clinic, outpatient clinic and polyclinic 17 at Faculty of Dentistry, USIM after 16 and 64 hours of not operating the dental units as baseline samples. This is followed by sampling after continuous flushing at 30 seconds, 1 minute, 2 minutes and 3 minutes of flushing duration. The levels of heterotrophic plate count (HPC) for each flushing duration were determined by quantification of colony forming units (CFUs) after cultivation of samples on plate count agar (PCA), R2A agar and 5% sheep blood agar (SBA). Statistically, there was no significant reduction in CFUs of HPC for all flushing duration compared to baseline (P > 0.05) with the most notable HPC reducing level after 1 minute and 3 minutes of flushing DUWLs. However, HPC level at USIM dental clinics is still exceeding the recommendation by Centers for Disease Control and Prevention (CDC) which should be less than 500 CFU/mL. The existing method of controlling DUWLs contamination in USIM dental clinics is only by flushing DUWLs 1 minute every morning prior to dental treatment as recommended by Malaysian Dental Council (MDC) without the use of chemical germicides. Thus, the flushing method alone is not reliable to reduce the number of microorganisms in the DUWLs.
Background: This study investigated the antibacterial effect of ginger (Zingiber officinale) oil against a common resistant root canal pathogen known as Enterococcus faecalis. The aim of the study was to determine the inhibition of E. faecalis growth in culture suspension and ability to inhibit growth of bacteria through disruption of pre-formed monospecies biofilm. Methods: Ginger rhizome oil was prepared in two-fold concentration series from 0.04 to 5.00 mg/mL and mixed with brain heart infusion broth inoculated with E. faecalis in anaerobic condition. Among the antibacterial tests performed were the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations using microdilution assays, and anti-biofilm assay on 3-day old pre-form monospecies biofilm on a 94 well-plate. Ampicillin was used as a positive control. Results: The result showed an in vitro dose-dependent bacteriostatic activity towards E. faecalis in suspension broth (MIC 0.04mg/mL) but no bactericidal activity within the tested concentration range. It was also found that the ginger oil inhibitory activity against E. faecalis was comparably less in anti-biofilm activity than against bacteria cultured in suspension solution. Conclusion: The study suggests that at determined concentrations, ginger oil has the potential to be used as an antibacterial agent in the management of root canal infections particularly where newly formed E. faecalis is involved.
Background: Members of the genus Klebsiella are among the leading microbial pathogens associated with nosocomial infection. The increased incidence of antimicrobial resistance in these species has propelled the need for alternate/combination therapeutic regimens to aid clinical treatment, including bacteriophage therapy. Bacteriophages are considered very safe and effective in treating bacterial infections. In this study, we characterize eight lytic bacteriophages that were previously isolated by our team against carbapenem-resistant Klebsiella pneumoniae. Methods: The one-step-growth curves, stability and lytic ability of eight bacteriophages were characterized. Restriction fragment length polymorphism (RFLP), random amplification of polymorphic DNA (RAPD) typing analysis and protein profiling were used to characterize the microbes at the molecular level. Phylogenetic trees of four important proteins were constructed for the two selected bacteriophages. Results and conclusions: All eight bacteriophages showed high efficiency for reducing bacterial concentration with high stability under different physical and chemical conditions. We found four major protein bands out of at least ten 15–190 KDa bands that were clearly separated by SDS-PAGE, which were assumed to be the major head and tail proteins. The genomes were found to be dsDNA, with sizes of approximately 36–87 Kb. All bacteriophages reduced the optical density of the planktonic K. pneumoniae abruptly, indicating great potential to reduce K. pneumoniae infection. In this study, we have found that tail fiber protein can further distinguished closely related bacteriophages. The characterised bacteriophages showed promising potential as candidates against carbapenem-resistant Klebsiella pneumoniae via bacteriophage therapy.
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