Table 10.

qac genes and susceptibility of S. aureus strains to some antiseptics and disinfectants

qacgeneaMIC ratiosb ofc:
ProflavineCHGPtPiCTABBZKCPCDC
qacA >162.5>16>164>3>42
qacB 81>422>3>22
qacC 11ca. 116>3>41
qacD 11ca. 116>3>41
MIC (μg/ml) for sensitive strain400.8<5050d 1<2<14
  • a qac genes are otherwise known as nucleic acid binding (NAB) compound resistance genes (88).

  • b Calculated from the data in reference289. Ratios are MICs for strains of S. aureus carrying various qac genes divided by the MIC for a strain carrying no gene (the actual MIC for the test strain is shown in the bottom row).

  • c CHG, chlorhexidine diacetate; Pt, pentamidine isethionate; Pi, propamidime isethionate; CTAB, cetyltrimethylammonium bromide; BZK, benzalkonium chloride; CPC, cetylpyridinium chloride; DC, dequalinium chloride.

  • d The MIC of propamidine isethionate for the sensitive S. aureus is considerably higher than the normal quoted value (ca. 2 μg/ml [Table 6]).