A-059. The Effect of Manuka Honey on the Activity of Bacteriolytic Cell Wall Enzymes in MRSA
Background: Manuka honey has been shown to affect the cell
cycle of MRSA by impeding cell division, but the precise mode of action is
unknown. Cell division depends on the formation of septa and cell separation is
facilitated by the cleavage of peptidoglycan. This study was designed to
determine whether manuka honey affected the activity of bacteriolytic enzymes
involved in the hydrolysis of peptidoglycan. Methods: EMRSA-15 (NCTC 13142) was
cultivated at 37°C for up to 24 hours in TSB with 10% (w/v) manuka honey, as
well as 10% (w/v) artificial honey. Cells were harvested at known time
intervals (0, 60, 120, 240, 720, 1080 and 1440 minutes), washed and cell free
extracts were prepared with a French press (intracellular enzymes). Culture
supernatants (extracellular enzymes) were also collected at each time point and
concentrated using Centicon 10 (Millipore). Bacteriolytic activity of cell free
extracts and culture supernatants was determined by a cell wall turbidity assay
using Micrococcus lysodeiktikus cell walls and 200 ug/ml protein from
each sample. It was also determined using zymography gels containing 1mg/ml M.
lysodeikticus cell wall with 15 ug protein of each sample. Results:
Activity of extracellular bacteriolytic enzymes was at undetectable levels in
turbidity assays and zymographs. Intracellular enzymes of untreated cells and
of artificial honey treated cells showed similar patterns of bacteriolytic
activity in both tests. Manuka honey treated cells exhibited markedly reduced
activity compared to controls in cell wall assays and zymographs. After 24
hours turbidity results from manuka honey treated cells compared to control
cells were significantly different (p = 0.001). Conclusion: Activity of
bacteriolytic cell wall enzymes was reduced in MRSA cells exposed to
bactericidal concentrations of manuka honey.
This study was supported by the British Society for Antimicrobial Chemotherapy.