Posternotomy mediastinitis due to Staphyloccocus aureus: comparison of clinical and pharmacoeconomical aspects

Abstract

Aims To evaluate clinical and pharmacoeconomical outcomes of posternotomy mediastinitis (PSM) caused by methicillin-resistant and methicillin-susceptible Staphylococcus aureus (MRSA and MSSA, respectively). Methods We reviewed hospital records of 61 pts. with S. aureus PSM who were treated from 1999 to 2002 in Kaunas University Hospital. Staphylococcus aureus was the infectious agent identified in wound secretion or in the mediastinum, or both. PSM was caused by MRSA in 12 pts and by MSSA in 49. Results Duration in-hospital stays for pts. with MRSA mediastinitis 63 days (63.33 ± 5.8) vs. 43 days (43.88 ± 4.18) for pts. with MSSA mediastinitis (P ¼ 0.0169). In-hospital mortality rate in MRSA mediastinitis group was significantly higher 33% vs. 4% of MSSA group respectively [relative risk (RR), 8.17; 95% confidence interval (CI), (1.89–34.57). Number needed to treat (NNT) ¼ )3.42 95% CI] ()12.37 to)1.74). Multivariate analysis using of the stepwise logistic regression method showed a relationship between mortality and the following variables: the MRSA infection itself (OR 9.152), and the duration of stay in intensive care unit (OR 1.085). 18-day treatment with vancomycin and fucid acid or rifampicin was more effective than 9-day treatment with vancomycin alone. Relative risk reduction 0.65; CI (0.56–0.94) of PSM-related death and treatment failure). Direct costs for antibiotic treatment for one patient in MRSA group was 880.85 ± 158.86euro; 95%CI (534.72–1226.99) vs. 249.63euro; 95%CI (123.52–375.75), P < 0.001. Incremental cost per one death avoided for antibiotic treatment (ICER) 2176.62euro. Conclusions MRSA infection causes worse outcomes and its treatment is more expensive than treatment of MSSA infection.