Some research findings on the antibacterial activity of honey

P. C. Molan B.Sc. Ph.D.

Honey Research Unit, Department of Biological Sciences, University of Waikato, Hamilton, New Zealand

Related Article: Honey as a dressing for wounds, burns and ulcers: a brief review of clinical reports and experimental studies
Related Bibliography: Use of Honey in Medicine
Related Article: Selection and Use of Honey on Wounds

Summarised below are results from published work carried out with standardised honeys of average-level antibacterial potency (as are available commercially):

Minimum concentration of honey (%, v/v) in the growth medium needed to completely inhibit the growth of various species of wound-infecting bacteria.

Species	Manuka honey + catalase	Other honey
Escherichia coli	3.7	7.1
Proteus mirabilis	7.3	3.3
Pseudomonas aeruginosa	10.8	6.8
Salmonella typhimurium	6.0	4.1
Serratia marcescens	6.3	4.7
Staphylococcus aureus	1.8	4.9
Streptococcus pyogenes	3.6	2.6

(Note: the manuka honey had catalase added to remove hydrogen peroxide, so that only the phytochemical antibacterial component was being tested. MIC values would be approximately halved if the catalase were not added and the hydrogen peroxide were also involved in the antibacterial activity.)

Minimum inhibitory concentration of honey for 20 strains of Pseudomonas isolated from infected wounds:

5.5%-8.7% (v/v) for manuka honey
5.8%-9.0% (v/v) for pasture honey

Minimum inhibitory concentration of honey for some MRSA strains

(Note: MR96 808 is resistant to Methicillin, Mupirocin, Erythromycin, Clindamycin, Gentamicin, Trimethoprim/Sulphamethoxazole, and Ciprofloxacin)

Manuka Honey Pasture Honey

MIC MBC MIC MBC

MRSA strain (% v/v) (% v/v) (% v/v) (% v/v)

[Acc 2243, sensitive control] 2 4 2 2

MR97 284, WSPP1 strain 2 4 2 2

MR97 285, WSPP2 strain 2 4 2 2

ST86 203, PNPH strain 2 4 4 4

ST85 653, WNWH strain 2 4 2 4

Acc 1056 1 4 2 2

Acc 2891, SK18 strain 2 4 2 2

MR96 808 1 4 2 2

Minimum inhibitory concentration of honey for 58 strains of coagulase-positive Staphylococcus aureus isolated from infected wounds:

2%-3% (v/v) for manuka honey
3%-4% (v/v) for pasture honey

(Thus growth of S. aureus would still be prevented if honeys were diluted by body fluids 7- to 14-fold beyond the point where the sugar content was ineffective.)

Summary of some unpublished work (just completed), isolates tested at the Central Public Health Laboratory, Colindale, London:

(With standardised honeys of average-level antibacterial potency, as are available commercially)

MIC of honey (% v/v) No. of isolates with that MIC

MRSA (82 isolates tested)

Manuka honey 4% 81

7% 1

Pasture honey 3% 55

4% 20

5% 3

6% 1

>6% 3

VRE

Manuka honey (56 isolates tested) <5% 1

6% 2

<7% 3

7% 2

8% 30

9% 16

10% 2

Pasture honey (34 isolates tested) 8% 2

12% 6

14% 2

16% 15

18% 3

>18% 1

20% 4

>20% 1

Acinetobacter (5 isolates tested)

Manuka honey 6% 2

7% 1

8% 1

>8% 1

MIC for pasture honey >7% 5

Stenotrophomonas maltophilia (4 isolates tested)

Manuka honey 3% 3

4% 1

Pasture honey <4% 1

5% 1

6% 2

Home NZ Bkpg Bee Diseases Organisation Information Contacts

	Manuka Honey		Pasture Honey
	MIC	MBC	MIC	MBC
MRSA strain	(% v/v)	(% v/v)	(% v/v)	(% v/v)
[Acc 2243, sensitive control]	2	4	2	2
MR97 284, WSPP1 strain	2	4	2	2
MR97 285, WSPP2 strain	2	4	2	2
ST86 203, PNPH strain	2	4	4	4
ST85 653, WNWH strain	2	4	2	4
Acc 1056	1	4	2	2
Acc 2891, SK18 strain	2	4	2	2
MR96 808	1	4	2	2

	MIC of honey (% v/v)	No. of isolates with that MIC
MRSA (82 isolates tested)
Manuka honey	4%	81
	7%	1
Pasture honey	3%	55
	4%	20
	5%	3
	6%	1
	>6%	3
VRE
Manuka honey (56 isolates tested)	<5%	1
	6%	2
	<7%	3
	7%	2
	8%	30
	9%	16
	10%	2
Pasture honey (34 isolates tested)	8%	2
	12%	6
	14%	2
	16%	15
	18%	3
	>18%	1
	20%	4
	>20%	1
Acinetobacter (5 isolates tested)
Manuka honey	6%	2
	7%	1
	8%	1
	>8%	1
MIC for pasture honey	>7%	5
Stenotrophomonas maltophilia (4 isolates tested)
Manuka honey	3%	3
	4%	1
Pasture honey	<4%	1
	5%	1
	6%	2