Enhancement of antibacterial activity against microorganisms involved in diabetes foot ulcer by virgin coconut oil

The purpose of this study was to evaluate the enhancement of the antibacterial activity by virgin coconut oil (VCO) against microorganisms involved in diabetes foot ulcer including Methicillin resistant Staphylococcus aureus (MRSA) ATCC 43300, S. aureus ATCC 6538 and Escherichia coli ATCC 8739. Virgin coconut oil cream (VCOC) was developed and composed of all ingredients following non-ionic buffered cream base pH 5.5 (Thai National Hospital Formulary, 2016) (NBCB), except 10%w/w of liquid paraffin was replaced with VCO. Chitosan (10%w/w) as microparticle form, prepared by the ionic gelation with the use of sodium tripolyphosphate, and gentamicin sulfate (0.1%w/w) were incorporated into both creams. The antibacterial activities of all creams were evaluated by agar well diffusion method.

It was found that VCOC as well as NBCB did not showed antibacterial activities against all bacteria tested as they produced no zone of inhibition. On the other hand, the antibacterial activities of chitosan and gentamicin incorporated in VCOC were significantly increased compared to the NBCB used. The inhibition zone diameter of 10% w/w chitosan in VCOC against MRSA, S. aureus and E. coli were 8.23 ± 0.06 mm, 8.43 ± 0.15 mm and 8.87 ± 0.12 mm, respectively, while there were no inhibition zone of the chitosan in NBCB. In addition, 0.1% w/w gentamicin in VCOC had better antibacterial activities than the gentamicin in NBCB. The inhibition zone diameters of the gentamicin in VCOC against MRSA, S. aureus and E. coli (25.73 ± 0.42 mm, 26.17 ± 0.92 mm, 24.80 ± 0.80 mm, respectively) were significantly higher than those of antibiotic in NBCB (and 21.57 ± 1.72 mm, 20.67 ± 0.76 mm, 21.60 ± 0.35 mm, respectively) (p value < 0.05). The findings of this study indicated that VCO could enhance the antibacterial activity of chitosan and gentamicin.