Epidemiology of the colonization of inpatients and outpatients with ciprofloxacin-resistant coagulase-negative staphylococci

Abstract

We tested the skin staphylococcal flora of inpatients and hospital staff in the orthopedic unit of Turku University Central Hospital (Turku, Finland) for susceptibility to ciprofloxacin. Ciprofloxacin-resistant coagulase-negative staphylococci were detected on the skin of 14 (61%) of the 23 inpatients and 16 (53%) of the 30 members of the hospital staff. Plasmid profiles were highly similar for most of these resistant isolates, thus suggesting that cross infection was responsible for the spread of ciprofloxacin-resistant strains in the orthopedic unit. Colonization of inpatients with ciprofloxacin-resistant coagulase-negative staphylococci was significantly associated with hospitalization longer than 6 days (P = .006) and the use of antibiotics during the hospital stay (P = .009). Twelve of 30 outpatients with venous leg ulcers were treated with ciprofloxacin, and all of these 12 were colonized with ciprofloxacin-resistant coagulase-negative staphylococci; in contrast, only three (33%) of the nine outpatients who were treated with trimethoprim (P = .004) and three (33%) of the nine outpatients who were treated with placebo (P = .004) were colonized with these strains. The ciprofloxacin-resistant strains from the outpatients had distinctly different plasmid profiles, a finding that suggests that, in the community, ciprofloxacin resistance may have emerged in isolates from each treated individual.