The aim of this work was to determine the antibiotic susceptibility pattern of the Staphylococcus aureus isolates from orthopaedic patients and their plasmid carriage. A total number of 39 S. aureus were isolated from wound, skin and bed of orthopaedic patients in Ahmadu Bello University Teaching Hospital Zaria, Nigeria with the use of API STAPH identification kit. Antibiotics susceptibility test was done using disc agar diffusion test, plasmid analysis was also carried out. A high percentage (97.4%) of the S. aureus isolates were susceptible to both vancomycin and gentamicin followed by ciprofloxacin (94.9%) and pefloxacin (84.6%). The S. aureus isolates were highly resistant to the following antibiotics: ampicilin (94.9%), ceftriaxone (79.5%), cefoxitin (64.1%) and amoxicillin - clavulanic acid (59%). The antibiotic susceptibility tests showed that 29.4% of S. aureus with plasmids were multi-drug resistant being resistant to three or more classes of antibiotics. In the plasmid analysis 60.7% of the S. aureus isolates had plasmids with size range 9.2 to 13.3 kb. Plasmid-coded antibiotic resistance encompasses most classes of antibiotics commonly used at the forefront of clinical antibiotic therapy.
Key words: Staphylococcus aureus, plasmid, orthopaedic, susceptibility.