Clinical factors affecting the efficacy of vancomycin in methicillin-resistant Staphylococcus aureus pneumonia

Obiective: Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen. Patients with risk factors such as long hospital admission and compromised hosts are prone to MRSA infection, particularly MRSA pneumonia that is not resolved effectively and causes significant mortality. To identify the factors affecting the efficacy of vancomycin (VCM) therapy on MRSA pneumonia, a retrospective investigation was carried out. Methods: Severity rating of pneumonia, pharmacokinetic parameters of VCM, clinical improvement following VCM therapy, clinical data and patient's background were investigated in 40 patients from January 2003 to March 2008. The outcome was evaluated 30 days after the initiation of VCM therapy, and multivariate logistic regression analysis was performed. Results: The 30 day mortality rate was 15.0% (6 patients). As a result of multivariate logistic regression analysis, underlying malignancy and parenteral nutrition as the route of feeding during VCM therapy (odds ratio (OR) = 22.3, 95% confidence interval (CI) = 1.55 - 322; OR = 12.6, 95% CI = 1.15 - 139, respectively) were found to be significant factors affecting the survival. No pharmacokinetic parameters of VCM and severity of pneumonia were significant. Conclusion: Underlying malignancy and parenteral nutrition, which were associated with nutrition and the immune system, were found to affect the survival after 30 days of VCM therapy.