Linezolid, Vancomycin Compared for MRSA Pneumonia

SAN DIEGO, CA—There was no statistically significant difference in clinical outcomes between patients with methicillin-resistant Staphylococcus aureus (MRSA) pneumonia who were treated with linezolid and those treated with vancomycin except mortality, reported ManShan Celica Tong, PharmD, MPH, from Medical University of South Carolina, Charleston, SC, at IDWeek 2015.

The only statistically significant difference found in the retrospective comparison study was seen in all-cause mortality, which was lower among patients in the linezolid treatment group over the vancomycin treatment group (10% vs. 19.5%; P=0.046).

“While suggestive of clinical superiority, these results must be interpreted with caution,” noted Dr. Tong. “They could be due to a number of factors beyond antibiotic use.” Dr. Tong cited the team’s use of all-cause mortality at the end of hospitalization, rather than 30-day mortality data, as one such possible factor.

“Cost was not significantly different between the two groups, despite the higher acquisition cost of linezolid” Dr. Tong noted.

Dr. Tong and colleagues conducted a retrospective cohort study (n=227) to compare outcomes and costs of linezolid treated patients (n=150) with those treated with vancomycin (34%). Study authors utilized retrospective chart and database review of eligible patients that were admitted to the University between May 1, 2011 and August 31, 2014 with an ICD-9 code for MRSA and pneumonia. Study patients were ≥18 years, had vancomycin or linezolid initiated ≥2 days after admission and continued for ≥3 consecutive days.

The two treatment groups were similar in regards to gender, age, ethnicity, and Charleston Comorbidity Index. Hospital length of stay was 10 days for the linezolid group vs. 12 for the vancomycin group (P=0.318), and intensive care unit (ICU) length of stay was 4 days for both treatment groups (P=0.199). Mechanical ventilation was 10 vs. 7 in each of the groups, respectively (P=0.335). Other outcomes including thrombocytopenia, nephrotoxicity, 30-day readmission, and patient charge were all similar for both treatment groups.