The Effect of Manuka Honey on the Cell Cycle of MRSA

 

Preliminary studies have shown that manuka honey affects the cell cycle of MRSA by

impeding cell division, but mode of action was unknown. Cell division depends on the

formation of septa and cleavage of peptidoglycan at cytokinesis. This study investigated

how manuka honey might alter the cell cycle of EMRSA-15.

Physiological and chemical changes in the bacteria exposed to manuka honey were

determined using time to kill studies, confocal and electron microscopy. Data indicated that

honey had a bactericidal effect on MRSA, inhibiting the cell cycle cytokinesis. Increased

septum formation was noted in honey treated cells by transmission electron microscopy.

Cell division components including FtsZ and Endo-B-N-Acetylglucosaminidase were

investigated using cell wall turbidity assays, zymography, immunofluorescence and

immuno gold labelling. Manuka honey treated MRSA cells showed a marked reduction in

hydrolase activity after 12 hours compared to untreated cells. The immunofluorescence

indicated an initial increase in FtsZ production followed by a significant decrease by 24

hours. PCR of FtsZ showed a 10% increase in production after 1 and 4 hours. Localization

by gold labelling gave inconclusive results.

Immunofluorescence of Endo-B-N-Acetylglucosaminidase showed a decrease in the

amount of enzyme over 24 hours and localization by gold labelling indicated altered

distribution of this enzyme. PCR showed no significant difference in expression.

2-D electrophoresis showed a differing proteomic profile between control cells and those

treated with honey, with a potential target protein being identified.

Methylglyoxal (an antibacterial component of manuka honey) was investigated after a

report named this as potentially the active component of manuka honey. Results showed it

has an effect but is not wholly responsible for the effects induced by manuka honey.

It was concluded that increased numbers of cells with septa were formed and alteration in

production of proteins and enzymes resulted in MRSA cells exposed to bactericidal

concentrations of manuka honey. The work was also carried out with artificial honey

controls, indicating that effects seen were not due to sugar content within honey or

methylglyoxal content.