Hyperbaric oxygen as adjunctive therapy in experimental mediastinitis.

BACKGROUND: Mediastinitis is a dreaded complication of cardiac surgical procedures. The purpose of our study was to research the role of hyperbaric oxygen therapy (HBO) in the treatment of experimental mediastinitis and to investigate whether it potentiates the antibiotic effects of linezolid, teicoplanin, and vancomycin. METHODS: The study included nine groups; an uncontaminated and a contaminated untreated control groups, and seven contaminated groups that received HBO or systemic antibiotics with linezolid, vancomycin, or teicoplanin, or a combination therapy consisting of one of these antibiotics and HBO. There were six adult male Wistar rats in each group. Contaminated groups were inoculated with 0.5 mL 10(8) CFU/mL methicillin resistant Staphylococcus aureus in the mediastinal and in the sternal layers. The antibiotic treatment continued 7 d. Twelve hours later at the end of the treatment, the rats were sacrificed, a sternotomy was performed for each rat and tissue samples from the upper ends of the sternum were aseptically obtained and evaluated microbiologically. RESULTS: There was no difference between the therapeutic efficacy of linezolid, teicoplanin, or vancomycin (P>0.05). When the groups were analyzed separately, treatment with a combination of HBO and antibiotic therapy reduced the bacterial count in comparison with HBO or antibiotic treatment alone (P<0.05). The combination of teicoplanin or vancomycin and HBO, respectively, was not more effective in reducing the bacterial count in comparison with the combination of linezolid and HBO (P>0.05). CONCLUSIONS: Linezolid and teicoplanin therapy was found as effective as standard vancomycin therapy for methicillin resistant Staphylococcus aureus (MRSA) mediastinitis. Adjunctive HBO offered additional benefit to the antibiotic treatment of mediastinitis.