Comparison of the efficacy of tigecycline and teicoplanin in an experimental methicillin-resistant Staphylococcus aureus osteomyelitis model

We evaluated the efficacy of tigecycline and teicoplanin in a rat model of MRSA osteomyelitis. Osteomyelitis was induced with an intramedullary injection of 10(8) colony-forming units (cfu) of MRSA. After osteomyelitis formation was confirmed on Day 14, infected rats were randomly divided into three groups: tigecycline (n=13), teicoplanin (n=13), and no-treatment control (n=14). A 28-day antibiotic therapy with a subcutaneous injection of tigecycline (14 mg/kg twice daily) or intramuscular administration of teicoplanin (20 mg/kg daily) was administered. Rats were then sacrificed, and the tibias were harvested. The bones were weighed and then cultured. Our results indicated that bacterial growth was significantly reduced in teicoplanin and tigecycline groups, compared to the control group (p=0.019 and p=0.006, respectively). However, no difference was detected between the two antibiotic groups (p=1.000). No bacterial growth was detected in 7 out of 13 and 9 out of 13 specimens of the teicoplanin and tigecycline treated groups, respectively. Although this result was numerically in favor of tigecycline, the difference was not statistically significant (p=0.427). In conclusion, tigecycline, a novel antibiotic, appears as an effective alternative to teicoplanin in the treatment of osteomyelitis caused by MRSA.