Understanding antibiotic resistance
Understanding antibiotic resistance

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Understanding antibiotic resistance

4.1 Natural honey

Honey is a natural product that has been widely used in traditional medicine for centuries and is still used in modern medicine.

The antibacterial properties of honey were first reported by the Dutch scientist van Ketel in 1892 (Dustmann, 1979) and it is active against up to 60 types of bacteria. Table 1 summarises some of the clinically important bacteria mentioned in this course that honey has antibacterial activity against.

Table 1 Antibacterial activity of honey against clinically important infections.

Bacterial typeClinical importance
Staphylococcus aureusHospital and community acquired infections
Vibrio cholerae Cholera
Escherichia coliUrinary tract infections, septicaemia, wound infections
Pseudomonas aeruginosaWound and urinary infections

Honey can be both bacteriostatic and bactericidal, depending on the concentration used. Its antibacterial activity is related to the following four properties.

  • High hydroscopicity

    Honey has a high sugar content and is hydroscopic; that is, it absorbs moisture from its environment. This causes bacteria to dehydrate in the presence of honey.

  • Acidity

    Honey is acidic, with a pH between 3.2 and 4.5. At this acidic pH, many bacteria cannot grow.

  • Hydrogen peroxide content

    When it is diluted, honey produces the chemical hydrogen peroxide (H2O2) from glucose. This chemical reaction requires the enzyme glucose oxidase (Figure 10). H2O2 can kill bacterial cells.

Described image
Figure 9 Conversion of glucose to hydrogen peroxide (H2O2) and D-glucono-1,5-lactone, catalysed by glucose oxidase. You do not need to study the chemical structures in this figure in detail.
  • Phytochemical factors

    Honey contains a large number of phytochemicals which are chemicals produced by plants. Many phytochemicals have antibacterial properties. For example, allicin (Figure 10), produced by crushing garlic, has antibacterial activity against several bacterial pathogens, including MRSA and P. aeruginosa.

Described image
Figure 10 (a) Allicin is produced from (b) crushed garlic and has antibacterial activity against several pathogens. You do not need to study the chemical structure in this figure in detail.

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