Antimicrobial and Antibiofilm Activities of Natural and Synthetic Compounds Against Oral and Skin Pathogens - an In-Vitro Study

Siew, Noa Noelle (2023) Antimicrobial and Antibiofilm Activities of Natural and Synthetic Compounds Against Oral and Skin Pathogens - an In-Vitro Study. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Concerns have been raised about the rise in antimicrobial-resistant bacteria, especially with the formation of biofilm amongst bacteria which further reduce the sensitivity of antibiotics. Porphyromonas gingivalis is the predominant pathogen of periodontal disease. Conversely, Staphylococcus aureus is the major pathogen responsible for skin and soft tissue infections (SSTIs) alongside Proteus mirabilis, Klebsiella pneumoniae, and Pseudomonas aeruginosa. An alternative antimicrobial and antibiofilm agent from a natural source or repurposed drug is necessary as the current gold standard method of treatment, antibiotic therapy is no longer effective against these oral and skin pathogens. The main objective of this study was to evaluate the antimicrobial and antibiofilm properties of Cratoxylum cochinchinense extract and flucytosine against the aforementioned oral and skin pathogens using the broth microdilution, agar well diffusion, and crystal violet staining methods. The minimum inhibitory concentration (MIC) of C. cochinchinense extract against P. gingivalis and S. aureus obtained were 0.6 mg/ml and 0.4 mg/ml, respectively whereas flucytosine did not exhibit any antibacterial properties against the tested bacteria. Agar well diffusion assay verified the antibacterial property of C. cochinchinense extract towards S. aureus with a zone of inhibition of 7.17±0.76 mm and a dose dependent inhibitory action of C. cochinchinense extract (6, 12, 24 mg/ml) towards S. aureus, producing zones of inhibition of 7.17±1.15, 9.00±1.00 and 9.50±1.00 mm. Antibiofilm assays were conducted with concentrations of C. cochinchinense extract and flucytosine of 0.2-1.0 mg/ml and 0.03125-0.5 mg/ml, respectively. C. cochinchinense extract inhibited biofilm formation in P. mirabilis (16±6%) and K. pneumoniae (21±6%) whereas flucytosine inhibited biofilm formation in S. aureus (18±4%), P. mirabilis (46±5%) and K. pneumoniae (35±21%). In addition, C. cochinchinense extract eradicated mature biofilm of S. aureus (49±7%) whereas flucytosine eradicated mature biofilms for S. aureus (26±6%), and P. mirabilis (41±7%). The FTIR spectrum displayed the functional groups of xanthones and other phytochemicals in the C. cochinchinense extract. Further studies should be conducted on C. cochinchinense as both an antibacterial and antibiofilm agent whereas flucytosine has more potential as an antibiofilm agent than an antibacterial agent. Keywords: Oral pathogen, skin pathogens, antibiofilm, Cratoxylum cochinchinense, flucytosine.