First case report of vancomycin-intermediate sequence type 72 Staphylococcus aureuswith nonsusceptibility to daptomycin

BACKGROUND: Sequence type 72 methicillin-resistant Staphylococcus aureus (MRSA) SCCmec type IV (ST72-MRSA-IV) is the most common community-acquired MRSA clone in Korea. Resistance to daptomycin or vancomycin among community-acquired MRSA clones is not well described in the literature. We herein report the first case of vancomycin-intermediate, daptomycin-nonsusceptible ST72-MRSA-IV. CASE PRESENTATION: A 45-year-old Japanese man underwent aortic arch prosthesis implantation for treatment of a dissecting aortic aneurysm. Fourteen months later, he developed a prosthetic graft infection of the aortic arch and an anterior mediastinal abscess caused by ST72-MRSA-IV. First-line treatment with vancomycin and rifampicin failed, and daptomycin was thus administered. After several days, the treatment was changed to linezolid because of the re-emergence of fever. The patient's condition resolved and no recurrence or other problems were seen for 1 year post-treatment. The infectious agent was definitively identified as vancomycin-intermediate, daptomycin-nonsusceptible, rifampicin-resistant ST72-MRSA-IV based on culture results and minimum inhibitory concentration testing. CONCLUSION: This case report illustrates the importance of fully understanding the changing epidemiology of infectious agents and the risk factors for the development of antibiotic resistance. Such information will help to minimize the emergence and spread of antibiotic-resistant strains. This report concerns one particular bacterial strain; however, the basic concepts involved in this case translate to all infectious disease fields.