Table 1: Parameters obtained from the ANS binding studies in ATCC 29213 and clinical strain S.  aureus.

n Ψ (mV)ΔΨ (mV)

S. aureus ATCC 29213 sensitive to CIP and CMP
Control without antibiotic143251603028−306
Ciprofloxacin 256 μg/mL7092752983−406−100
Chloramphenicol 4 μg/mL6284648332−331−25

Clinical strain S. aureus  resistant to CIP

Control without antibiotic7790245110−287
Ciprofloxacin 256 μg/mL 7793746865−302−15

is the fluorescence intensity (related to the maximum concentration of bound ANS), n is the number of binding sites of ANS to the membrane, is the dissociation constant, Ψ is the potential at the surface of the membrane and ΔΨ is the change in surface potential of the membrane in the control without antibiotic.