By identifying micro-organism in postoperative patients, we evaluated problems associated with the use of cephalosporin for the prevention of infection, and antibiotic choice in cases, in which causative micro-organisms cannot be islolated.

Eighteen patients, from January 1998 to May 2002, who received arthroplasty, were studied. All cases were administered preoperative first generation cephalosporin one hour before operation. All patients with infection had micro-organisms identified received an antibiotic sensitivity test.

Gram positive cocci were identified in fifteen cases (83%) (staphylococcus was the most common (72%)), and there were eight cases (80%) in acute infections and seven (88%) in chronic. 78-83% were sensitive to vancomycin, teicoplanin and ciprofloxacin, but only 17% were sensitive to cephalothin.

Staphylococcus was found to be the most common organism in postoperative infection, and ciprofloxacin was more effective than cephalosporin. Ciprofloxacin is considered to be an effective antibiotic in patients with unidentified causative organisms.