Objective: Methicillin resistance and infections caused by methicillin-resistant Staphylococcus aureus represent a growing problem and a challenge for health-care institutions. We evaluated risk factors, morbidity and cost of infections caused by methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) Staphylococcus aureus.
Design: We performed an un-matched case-control study in an 20-bed medical intensive care unit from 1994-2001 at Nantes teaching hospital, France. All patients with pneumonia, bacteraemia and urinary MRSA (cases) or MSSA (controls) nosocomial infections were included in the study.
Results: Twenty four patients with MRSA infection were compared to 64 patients with MSSA infections. Patients with MRSA infection were older (56 vs. 45 years, P < 0.01), had longer length of stay (47 vs. 35 days, P < 0.05) and were infected later (22 vs. 10 days, P < 0.00001) than patients with MSSA infection. No difference was observed between the two groups according to the Omega index, acute simplify index and mortality. MRSA infections involved extra cost due to antimicrobial treatment (184 vs. 72 Euros, P < 0.005) and length of stay (37,278 vs. 27,755 Euros, P < 0.05).
Conclusion: Patient infected by MRSA seems to be different from patient infected by MSSA but without consequence on Omega index and mortality. But methicillin-resistance involves extra cost due to antimicrobial treatment and length of stay.