Community-phenotype-methicillin-resistant staphylococcus aureus infections: A retrospective chart review of outcomes after treatment with daptomycin

Background: Daptomycin, a cyclic lipopeptide antibiotic, was approved by the US Food and Drug Administration (FDA) in September 2003 for the treatment of complicated skin and skin structure infections due to susceptible strains of certain gram-positive microorganisms, including methicillin-resistant Staphylococcus aureus (MRSA). In May 2006, daptomycin was approved by the FDA for treatment of bacteremia and right-sided endocarditis due to MRSA and methicillin-sensitive S aureus.Objective: The aim of this study was to assess the use of daptomycin in community-phenotype (CP)-MRSA infections.Methods: This was a retrospective chart review of data from patients enrolled in a postlabeling registry who received daptomycin for MRSA infections from January to December 2005. CP-MRSA was defined as MRSA susceptible to clindamycin and trimethoprim/sulfamethoxazole; all other phenotypes were considered other-phenotype MRSA (OP-MRSA). Success rates were calculated by dividing success (defined as cure plus improved) by success and failure (including non-evaluable patients).Results: A database search identified 352 patients (100 patients with CP-MRSA [57 men; 43 women]; 252 patients with OP-MRSA [136 men, 116 women]) who met study criteria. Most patients (79.2%) received gram-positive antibiotics before daptomycin. Compared with OP-MRSA, a greater proportion of patients with CP-MRSA were <50 years of age (50.0% vs 35.7%; P = 0.014) and had fewer underlying diseases (mean [SD], 1.7 [1.3] vs 2.5 [1.5]; P < 0.001). Success rate, time to clinical response, and duration of therapy were similar in both groups.Conclusion: Daptomycin was found to be equally effective in treating CP-MRSA and OP-MRSA infections in this selected group of patients.