Lewis Acidity and Bacteria
A review on $\ce{Ag+}$ quotes the following situations, which may be provoked by the Lewis acidic behavior of a metal cation.



  Silver treated cells exhibited electron-light regions in
  their cytoplasm thus forcing DNA to condense. Authors state that
  condensed DNA molecules lose their ability to replicate.



I presume that $\ce{Ag+}$, acting as a Lewis acid, will reduce the negative charge on DNA, thus inducing DNA aggregation.



  Electron-dense region were also observed around the cell wall inside
  the cytoplasm, and the cytoplasmic membrane experienced  shrinkage 
  and  detachment  from  the  cell wall.


  There was also indication  that  silver  ions  interact  with  thiol
  groups leading to the deactivation of enzymatic proteins.



Here one sees the action of $\ce{Ag+}$ on thiols which may be interpreted as an acid-base interaction of the Lewis type.



  Also the effect of $\ce{Ag+}$ on the respiratory electron chain of E. coli was stressed, since $\ce{Ag+}$ is toxic to microorganisms due to inhibition of the
  respiratory chain at multiple sites.



It appears that in many cases, one can link the antibacterial function of metal ions to their acidic properties. And certainly, those discussed above are not the only ones.