A comparative study on the effects of vancomycin, enrofloxacin, and trimethoprim/sulfamethoxazole on methicillin-resistant Staphylococcus aureus osteomyelitis in an animal model

Abstract

Osteomyelitis is a serious medical issue that is refractory to treatments. Methicillin-resistant Staphylococcus aureus (MRSA) is a major problem in cases with osteomyelitis. These S. aureus have recently developed a resistance to vancomycin, which is a choice antibiotic for osteomyelitis. Therefore, finding alternative antibiotics is highly essential for treatment of methicillin-resistant S. aureus osteomyelitis. Twenty-four New Zealand adult white rabbits were experimentally infected by the injection of 106 colony-forming unit of Staphylococcus aureus in diaphysis of the tibia. Two weeks after injection, the animals were checked by microbiological and radiological tests for osteomyelitis. All infected rabbits were randomly divided into four groups of 6 including control, vancomycin, enrofloxacin, and trimethoprim/sulfamethoxazole, and every 12 h were administered with 30, 15, and 20 mg/kg, for treatment groups, respectively. Body weight, body temperature, and heterophil/lymphocyte ratio were assessed before and after inducing osteomyelitis. Then, the animals were treated in experimental groups for 2 weeks post infection. All of the experiment and control groups were humanely sacrificed. Subsequently, the bone specimens were separated for microbiological tests. The groups treated with vancomycin and enrofloxacin had significantly lower colony counts, and lower heterophil/lymphocyte ratio than control groups after treatment (P < 0.05). In this study, enrofloxacin had comparable efficacy to that of the vancomycin-treated group. However, trimethoprim/sulfamethoxazole did not show such efficacy. It can be inferred that enrofloxacin can be an effective antibiotic for the treatment of acute osteomyelitis caused by methicillin-resistant Staphylococcus aureus.