Evaluation of the Clinical Course of Methicillin-resistant Staphylococcus Aureus Infections in Consideration of the Efficacy of Linezolid

Abstract

Linezolid is used as a first-line treatment for methicillin-resistant Staphylococcus aureus (MRSA) infections. We aimed to analyze the clinical courses of patients who received linezolid therapy in order to determine the most appropriate point for assessing the validity of linezolid therapy and identify predictors of the clinical outcomes of linezolid therapy for early stage MRSA infections.

We retrospectively retrieved demographic and laboratory data from the medical records of 123 patients who underwent linezolid therapy for proven MRSA infections. We compared the post-linezolid therapy clinical courses of the clinical success and clinical failure groups, and the most appropriate point for assessing the validity of linezolid therapy was investigated.

Clinical success was achieved in 99 patients. The maximum body temperature of the clinical success group was significantly lower than that of the clinical failure group at 3, 5, and 7 days after the initiation of linezolid therapy. Among the patients who achieved clinical success, hemodialysis (adjusted odds ratio [OR] = 5.36 [1.41-20.30], P = 0.014), an elevated baseline C-reactive protein (CRP) level (adjusted OR = 1.09 [1.01-1.17], P = 0.023), and non-respiratory infections (adjusted OR = 0.09 [0.01-0.76], P = 0.027) were found to be significant risk factors for late-appearing effects of linezolid.

In conclusion, we suggest that patients' maximum body temperature and CRP levels should be carefully monitored for at least 3-4 days to assess the effects of linezolid against early stage MRSA infections; however, they should be monitored for 7 days in patients without the above-mentioned risk factors for late-appearing linezolid effects in order to obtain more accurate information about the outcomes of such treatment.