Risk factors for therapeutic failure in adults with methicillin-resistant Staphylococcus aureus (MRSA) infection treated with vancomycin in a high-complexity hospital in Cali, Colombia

Objective: To determine the risk factors associated with therapeutic failure of vancomycin in hospitalized adult patients with methicillin-resistant Staphylococcus aureus (MRSA) infections. Design: Case-control study. Setting: Conducted in a high complexity hospital in Cali, Colombia. Participants: Adult hospitalized from January 1, 2015, to December 31, 2021, with MRSA infections with confirmed microbiological isolation. Methods: Cases were patients with therapeutic failure of vancomycin (mortality, poor clinical improvement, change of antibiotic used, early relapse, or persistence of positive blood cultures) and control patients were those who did not present failure. Significant variables from the bivariate analysis were included in a multiple analysis with an asymmetric logistic regression model. Results: A total of 105 patients were included in the study, 28 in the treatment group and 77 in the control group. The median age was 49 years and 59 (56%) of participants were men. The following variables: age (OR 1.034; 95% CI 1.007-1.061, p=0.011), osteomyelitis/ septic arthritis (OR 6.035; 95% CI 2.282-15.956, p=0.000) and minimum inhibitory concentration (MIC) (OR 5.971; 95% CI 1.321-26.979, p=0.020) were found to be independent risk factors associated with therapeutic failure of vancomycin. Vancomycin trough levels were not different between cases and controls (OR 0.976; 95% CI 0.911-1.044, p=0.478). Conclusions: When a multiple analysis was performed to control for confounding factors, only 3 variables were found to be significant and were considered risk factors for therapeutic failure of vancomycin in adult patients with MRSA infection: age, MIC, and osteomy-elitis/septic arthritis.