Characterization of Staphylococcus aureus mutants expressing reduced susceptibility to common house-cleaners.
OBJECTIVE
To characterize mutants of Staphylococcus aureus expressing reduced susceptibility to house cleaners (HC), assess the impact of the alternative sigma factor SigB on HC susceptibility, and determine the MIC of clinical methicillin-resistant S. aureus (MRSA) to a HC.


RESULTS
Susceptibility to HC, HC components, H2O2, vancomycin and oxacillin and physiological parameters were determined for HC-reduced susceptibility (HCRS) mutants, parent strain COL and COLsigB::kan. HCRS mutants selected with three HC expressed reduced susceptibility to multiple HC, HC components, H2O2 and vancomycin. Two unique HCRS mutants also lost the methicillin resistance determinant. In addition, all HCRS mutants exhibited better growth at two temperatures, and one HCRS mutant expressed reduced carotenoid production. COLsigB::kan demonstrated increased susceptibility to all HC and many HC components. sigB operon mutations were not detected in one HCRS mutant background. Of 76 clinical MRSA, 20 exhibited reduced susceptibility to a HC.


CONCLUSIONS
HCRS mutants demonstrate altered susceptibility to multiple antimicrobials. While sigB is required for full HC resistance, one HCRS mechanism does not involve sigB operon mutations. Clinical MRSA expressing reduced susceptibility to a common HC were detected.


CONCLUSIONS
This study suggests that HCRS mutants are not protected against, nor selected by, practical HC concentrations.
Davis
A O
AO
Microbiology Group, Department of Biology, New Mexico State University, Las Cruces, NM 88003-8001, USA.
O'Leary
J O
JO
Muthaiyan
A
A
Langevin
M J
MJ
Delgado
A
A
Abalos
A T
AT
Fajardo
A R
AR
Marek
J
J
Wilkinson
B J
BJ
Gustafson
J E
JE
D004202:Disinfectants / Q000494:pharmacology*; D004351:Drug Resistance / Q000235:genetics; D004787:Environmental Pollution; D005798:Genes, Bacterial; D006798:Housing; D008826:Microbial Sensitivity Tests; D009154:Mutation; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics*
D004202:Disinfectants