Different susceptibility of coagulase-positive and coagulase-negative staphylococci to ciprofloxacin.

Ciprofloxacin susceptibility was evaluated in 573 clinical staphylococcal isolates (Staphylococcus aureus 230, methicillin-resistant (MR) 36%; coagulase-negative strains 343, MR 66%) collected from 1989 to 1995. Resistance to ciprofloxacin for MR Staphylococcus aureus was 25% until 1991 when ciprofloxacin was introduced into the hospital formulary, and rose progressively to 90% in 1994-1995. MR Staphylococcus haemolyticus showed a ciprofloxacin resistance of 46% until 1991 and of 73% from 1992 to 1995. In contrast MR Staphylococcus epidermidis and other coagulase-negative strains showed a constant susceptibility to this agent (80%). Ciprofloxacin has limited usefulness against MR Staphylococcus aureus but can be still used to treat Staphylococcus epidermidis infections.