Comparison of the therapeutic efficacy of linezolid and vancomycin and correlation of serum and tissue malondialdehyde and myeloperoxidase in an experimental mediastinitis model.

BACKGROUND

We aimed to investigate the therapeutic efficacy of linezolid in an experimental mediastinitis model and to compare it with vancomycin, which is commonly used. The objective of this study was also to evaluate the role of the immune system in mediastinitis.

MATERIALS AND

METHODS

Fifty adult Wistar rats were randomly divided into five groups: an uncontaminated and contaminated untreated control groups; a group that received sefazolin prophylaxis; and two groups treated with vancomycin or linezolid. Median sternotomy without access to pleural spaces was performed on all rats. All groups, except the uncontaminated one, were inoculated with 0.5 mL 10(8) colony-forming units/mL methicillin-resistant Staphylococcus aureus in the mediastinal and sternal layers. Postoperatively, vancomycin and linezolid groups were given antibiotic treatment for 7 d, starting 24 h after the end of the procedure. After 7-d treatment tissue samples from the upper ends of the sternotomy line and mediastinum were obtained and evaluated microbiologically. Additionally, serum, heart, lung, liver, kidney, and mediastinal tissues samples were obtained to determine malondialdehyde (MDA) and myeloperoxidase (MPO).

RESULTS

The study showed that either vancomycin or linezolid successfully reduced bacterial counts in mediastinum and sternotomy line. MDA and MPO levels were found to be decreased in the treated groups. There was a positive correlation between serum and tissues MDA and MPO in all of the groups.

CONCLUSIONS

Our study showed that linezolid appears to be a promising option for treating mediastinitis due to methicillin-resistant S. aureus. Additionally, it was demonstrated that a wide inflammatory process occurred after mediastinitis.