The potential antimicrobial properties of tannins from Phyllanthus columnaris stem bark were evaluated against three Gram-positive cariogenic bacteria (Streptococcus salivarius ATCC 13419, Streptococcus oralis ATCC 6249 and Streptococcus mutans ATCC 25175), two obligate anaerobic Gram-negative periodontopathic bacteria (Porphyromonas gingivalis ATCC 33277, and Fusobacterium spp ATCC 25586), and five Candida spp (C. albicans ATCC 14053, C. parapsilosis ATCC 22019, C. tropicalis ATCC 750, C. krusei ATCC 6258 and C. glabrata ATCC 2001). Antimicrobial activities of tannins were determined using the disc diffusion test as well as minimum inhibitory concentration and minimum bactericidal/fungicidal concentration tests. The chemical composition of tannins was analysed by direct infuse mass spectrometry. Tannins inhibited the growth of all tested pathogens at MIC value ranging from 0.16 to 1.25 mg/mL. All tested bacteria showed similar higher level of susceptibility against tannins as the lowest MIC value was detected (0.16 mg/mL) except for S. oralis (0.63 mg/mL). However, both Gram negative anaerobes recorded the lowest MBC value at 0.32 mg/mL as compared to the Gram positive cariogenic bacteria (2.5->5.0 mg/mL). DIMS analysis of precursor ions detected four compounds present in tannins namely punicafolin, (S)-Nerolidol 3-O-[a-L-Rhamnopyranosyl-(1->4)-a-L-rhamnopyranosyl-(1->2)-[4-(4-hydroxy-3 methoxycinnamoyl)-(E)-a-L-rhamnopyranosyl-(1->6)]-b-D-glucopyranoside], ent-Epicatechin-(4alpha->8)-ent-epicatechin-(4alpha->8)-ent-epicatechin 3',3''-digallate and pavetannin C1 respectively.

Accumulation of mixed oral microflora appears to be one of the contributing factors to pericoronitis, an inflammation of the oral soft tissues surrounding the crown of a partially erupted, or impacted mandibular third molars.This study was aimed to identify the predominant infectious bacteria related to pericoronitis and their coexistence with other bacterial species at the infection site.Plaque from pericoronal pockets of lower wisdom teeth of 25 patients that have been diagnosed with pericoronitis were sampled and subjected to a standard microbiological procedure for identification of bacterial species including cultivation on enriched agar plates, biochemical profiling and 16s rRNA PCR analysis. A total of 97 microorganisms were isolated and identified from the cultured samples and 94.73% were Gram-positive bacteria; with the highest incidence of Streptococcus gordonii, Streptococcus mitis, and Streptococcus anginosus. This study also revealed that facultative anaerobes were the predominant group causing pericoronitis (89%). The high occurence of multi-strain bacteria ranging from facultative anaerobic to aerobic bacteria display the importance of their infection networks in pericoronitis.Knowledge gained from this study increases our understanding on the role of different pathogens in pericoronitis and provides new insight into the clinical management of patients and in the prevention of its recurrence. Keywords:Pericoronitis, Oral bacteria, Mandibular third molar.

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.

In our previous study, we isolated eight bacterial endophytes with positive antimicrobial activity out of 82 isolates from five different places in Pulau Langkawi. The antimicrobial activity of the endophytes secondary metabolite although moderate, was further explored for the prospect to be enhanced by incorporating to silver nitrates. Only two isolates were able to synthesise silver nanoparticles namely Bacillus subtilis (B7b) and Pseudomonas resinovorans (B2c) within 72 hours of incubation at room temperature via extracellular method. Antimicrobial assay against Staphylococcus aureus, methicilin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermis, Escherichia coli and Pseudomonas aeruginosa was performed. Synthesised silver nanoparticles (AgNPs) showed excellent inhibitory effect against both Gram positive and Gram negative bacteria but secondary metabolites without AgNPs showed positive activity only against Gram positive bacteria. The results suggested that incorporation of AgNPs was able to enhance antimicrobial activity of secondary metabolites of B7b and B2c against test bacteria. � 2019, Malaysian Society of Applied Biology. All rights reserved.

Aims: The aim of the study was to isolate and characterise bacteriophages specific to Pseudomonas aeruginosa carrying virulence genes. Methodology and results: Four clinical strains of P. aeruginosa CL1, CL2, CL3 and CL4 were obtained from Queen Elizabeth Hospital, Kota Kinabalu, Sabah. The bacterial strains were screened for virulence genes exoS, toxA and oprI and biofilm production. Six P. aeruginosa specific bacteriophages, namely PAtk1, PAtk2, PAtk3, PAtk4, PAtk5 and PAtk6, were isolated from Tasik Kejuruteraan, Universiti Kebangsaan Malaysia. These bacteriophages were screened for lytic spectrum against P. aeruginosa and two species of Enterobacteriaceae (Escherechia coli and Salmonella Typhi). PCR results showed that all strains possessed exoS, toxA and oprI genes except CL2 that lacked exoS. Nevertheless, it was CL2 that produced the highest biofilm density. Further, based on Transmission Electron Microscopy, PAtk15 and PAtk6 were classified into the family Myoviridae and Siphoviridae, respectively. Among all six isolated phages, only PAtk4 and PAtk6 showed the broadest lytic spectrum in which lytic activity was observed against all clinical P. aeruginosa strains. Conclusion, significance and impact of study: In this study we reported the isolation of six bacteriophages from Myoviridae and Siphoviridae that are specific to P. aeruginosa possessing exoS, toxA and oprI genes. Bacteriophages Patk4 and PAtk6 were able to infect all four strains of P. aeruginosa, making these phages potential agents in combating infections by the bacterium.

Objective: Aim: Klebsiella pneumonia has emerged as an increasingly important cause of community-acquired nosocomial infections and many of these strains are highly virulent and exhibit a strong propensity to spread. Infections cause by K. pneumonia produces carbapen¬emase (KPC) enzyme and can be difficult to treat since only a few antibiotics are effective against them. Bacteriophage targeting this strain can be an alternative treatment. Characterisation of bacteriophage is utmost important in assisting the application of bacteriophage in phage therapy. Patients and methods: Materials and methods: In the present study, the lytic bacteriophage, k3w7, isolated by the host Klebsiella pneumoniae kP2 was characterised using transmission electron microscope (TEM), plaque assay, and restriction digestive enzyme to investigate mor¬phology, host spectrum, bacteriophage life cycle and stability accordingly. Results: Results and conclusions: As shown by TEM, k3w7 was observed to have the characteristic of icosahedral heads 100 nm and contractile sheaths 120 nm suggesting it belongs to the family of myoviridae.The Investigation has done on the phage growth cycle showed a short latent period of 20 min and a burst size of approximately 220 plaque forming units per infected cell. Stability test showed the phage was stable over a wide range of pH and temperatures. According to restriction analysis, k3w7 had 50 -kb double-stranded DNA genome as well as the heterogeneous nature of genetic material. These findings suggest that K3W7 has a potential use in therapy against infections caused by K. pneumonia produces carbapenemase.

Aim:Phyllanthus columnarisMüll.Arg. was found to possess anti-methicillin resistant Staphylococcus aureus(anti-MRSA) activities. This study aimed at isolating, identifying and evaluating the active compounds from the stem bark of Phyllanthus columnarisMüll.Arg. against MRSA. Methodology and results:Stem bark extracts (methanol, acetone and aqueous) of Phyllanthus columnaris were subjected to anti-MRSA screening by disc diffusion method. MIC and MBC tests were carried out to compare the lowest concentration to inhibit and kill the sixteen MRSA tested among the three extracts. TLC bioautography were performed to detect the bioactive compounds. Isolation of the two active compounds was performed by means of preparative TLC. Morphological and ultra-structure alterations of the MRSA treated with bioactive compounds after 24 h were revealed by scanning and transmission electron microscopy.Both methanol and acetone extracts exhibited good anti-MRSA activity with the lowest minimum inhibitory concentration (MIC) value for both extracts were 0.78 mg/mLand the lowest minimum bactericidal concentration (MBC) were 1.56 mg/mL. Bioassay-guided chromatography by bioautography revealed two active anti-MRSA compounds from both tannin-free methanol and acetone extracts and characterized as stigmasterol and lupeol by nuclear magnetic resonance (NMR) spectral data. Scanning and transmission electron microscopy of MRSA treated with stigmasterol and lupeol showed cell wall disruption, release of cytoplasmic com-pounds and decreased in cellular volume. Conclusion,significance and impact of study:Results obtained herein, may suggest that the stem bark of Phyllanthus columnaris possess anti-MRSA and the two of the active compounds isolated were stigmasterol and lupeol. Their anti-MRSA effects up to the morphological and ultra-structure studies were not reported earlier.

Phage therapy is the therapeutic use of bacteriophages to treat highly drug resistant bacterial infections. Klebsiella pneumonia (KP) has emerged as an increasingly important cause of community-acquired nosocomial infections and many of these strains are highly virulent with multidrug resistance (MDR) ability and exhibit a strong propensity to spread making infection cause by it difficult to treat. Treatment utilizing bacteriophage specific to KP (KP phage) can be used as an alternative counter measure. Characterization of bacteriophage is utmost important in assisting the application of bacteriophage in phage therapy. In the present study, samples from sewage water and cockles were screened for KP phage. Enrichment detection methods followed by isolation of phage by double agar layers method was done using 9 strains of MDR-KP as host system. KP phages were characterized on the basis of plaque morphology, host range and transmission electron microscope (TEM). A total of 58 lytic KP phages were isolated from sewage (42) and cockle (16). Investigation done on host range showed that 52 were KP phage and 6 have broad host range. Further identification by transmission electron microscopy (TEM) was done to 10 selected phages that showed potent lytic activity against MDR-KP. Image from TEM show selected phages were from subfamily caudovirales (7) with icosahedral head and pentagonal structure with short non-contractile tail suggesting it belongs to the family of Podoviridae. Two phages belonged to the family Myoviridae with isometric head and contractile tail and one from the family Siphoviridae with icosahedral and a non-contractile tail. Therefore, this study has partially characterized and revealed 10 potential lytic bacteriophages as therapeutic agent against MDR-KP which mostly resembles Podoviridae family.

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.

The aim of this study was to determine the prevalence of Staphylococcus aureus in the oral cavity of healthy adults and the factors that may influence the presence of the bacteria. A cross-sectional study was conducted on a number of selected healthy adults in a district in Malaysia, during which, information about their socio-demographic background and oral hygiene practices was obtained. Oral rinse samples of the respondents were also collected using phosphate buffered saline and the data obtained was subsequently analyzed using SPSS A total of 140 oral rinse samples were collected and the results of the analysis conducted showed a prevalence of approximately 40% of the Staphylococcus aureus in the oral cavity of the participants. There was no significant association observed between both the socio-demographic factor and oral hygiene practices with the presence of Staphylococcus aureus. The use of prostheses was found to be a significant factor for a higher prevalence of Staphylococcus aureus in the oral cavity (OR 5.13; P<0.05, 95%CI 1.410 - 18.76). The prevalence of Staphylococcus aureus in the oral cavity of healthy adults was high and the use of prostheses was a factor associated with the presence of the bacteria. This accentuates the importance of a good oral hygiene, as oral cavity can be the primary route for Staphylococcus aureus to cause potential systemic infections.

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.