trimethoprim--sulfamethoxazole-drug-combination and quinupristin-dalfopristin

Following an initial response to vancomycin therapy, a patient with meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia developed endocarditis, failed a second course of vancomycin and then failed daptomycin therapy. An increase in the vancomycin minimum inhibitory concentrations of four consecutive MRSA blood isolates from 2 microg/mL to 8 microg/mL was shown by Etest. Population analysis of four successive blood culture isolates recovered over the 10-week period showed that the MRSA strain became progressively less susceptible to both vancomycin and daptomycin. Retrospectively, the macro Etest method using teicoplanin indicated a decrease in vancomycin susceptibility in the second blood isolate. The patient improved after treatment with various courses of trimethoprim/sulfamethoxazole, quinupristin/dalfopristin and linezolid. Early detection of vancomycin-heteroresistant S. aureus isolates, which appeared to have clinical significance in this case, continues to be a challenge for the clinical laboratory. Development of suitable practical methods for this should be given priority. Concurrent development of resistance to vancomycin and daptomycin, whilst rare, must be considered in a patient who is unresponsive to daptomycin following vancomycin therapy.

Topics: Acetamides; Anti-Bacterial Agents; Bacteremia; Daptomycin; Drug Resistance, Bacterial; Endocarditis, Bacterial; Humans; Linezolid; Male; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Oxazolidinones; Staphylococcal Infections; Trimethoprim, Sulfamethoxazole Drug Combination; Vancomycin; Virginiamycin

Topics: Anti-Bacterial Agents; Anti-Infective Agents; Fluoroquinolones; Germany; Hospitals; Humans; Longitudinal Studies; Methicillin Resistance; Microbial Sensitivity Tests; Minocycline; Staphylococcus aureus; Teicoplanin; Trimethoprim, Sulfamethoxazole Drug Combination; Vancomycin; Virginiamycin