Comparative Study on the Antibacterial Activity and Efficacy of Linezolid and Vancomycin in Methicillin-Resistant Staphylococcus aureus Rat Pneumonia Model

Abstract

Methieillin-resistant Staphylococcus aureus (MRSA) can lead to pneumonia and septicemia with a rising incidence. As the first choice drug of MRSA, vancomycin causes more side effects and reduces sensitivity. Oxazolidinone antibiotics linezolid is confirmed to be used in the treatment of MRSA infection. This study compared the antibacterial activity and efficacy of linezolid and vancomycin on rat MRSA pneumonia model. SD rats were randomly separated into pneumonia group; vancomycin group and linezolid group. Survival rate was calculated and compared. PaO2 and pH were tested by blood gas analysis. Pulmonary wet/dry (W/D) ratio was determined. Serum TNF-α and IL-1β contents were detected by ELISA. Colony counting was performed by pulmonary tissue homogenate. Diameter of inhibition zone was measured. Minimum inhibition concentration (MIC) was evaluated by broth microdilution method. Both vancomycin and linezolid significantly improved survival rate, elevated PaO2 and pH, decreased W/D, and reduced TNF-α and IL-1β (P < 0.05). Bacterial inhibition diameter was 28±2 mm, colony counting was 22±6, and MIC was 1.2±0.3 μg/ml in linezolid group, which was obviously than that bacterial inhibition diameter at 21±3 mm, colony counting at 85±12, and MIC at 2.5±0.7 μg/ml in vancomycin group (P < 0.05). Both vancomycin and linezolid can treat MRSA pneumonia, inhibit inflammation, and improve survival rate. Linezolid exhibited stronger antibacterial action than vancomycin.