Daptomycin use in neutropenic patients with documented gram-positive infections

The goal of this study was to describe the outcomes associated with daptomycin treatment of documented gram-positive infections in patients with neutropenia.

All patients with neutropenia (≤500 cells/m(3)) and at least one documented gram-positive culture from 2006-2009 were identified from a retrospective, multicenter, and observational registry (Cubicin(®) Outcome Registry and Experience (CORE(®))). Investigators assessed patient outcome (cured, improved, failed, nonevaluable) at the end of daptomycin therapy. All patients were included in the safety analysis.

The efficacy population had 186 patients; 159 (85 %) patients had either cure (n = 108, 58 %) or improved (n = 51, 27 %) as an outcome. Success rates (cure plus improved) by the lowest WBC during daptomycin were 98/116 (84 %) for ≤100 cells/m(3) and 61/70 (87 %) for 101-499 cells/m(3), P = 0.6. Most patients had cancer; 135/186 (73 %) had hematological malignancy; 26/186 (14 %) had solid tumors, and 9 (5 %) had both. One hundred fifty-six (84 %) patients received other antibiotics before daptomycin treatment; 82 % vancomycin, of which 31 % failed vancomycin. The most common infections were bacteremia (78 %), skin and skin structure infections (8 %), and urinary tract infections/pyelonephritis (6 %). The most common pathogens were vancomycin-resistant Enterococcus faecium (47 %), methicillin-resistant Staphylococcus aureus (20 %), and coagulase-negative staphylococci (19 %). The median (min, max) initial daptomycin dose was 6 mg/kg (3.6, 8.3). The median (min, max) daptomycin duration of therapy was 14 days (1, 86). Possibly related adverse events occurred in 12/209 patients (6 %), and 13 patients (6 %) discontinued daptomycin due to adverse event.

The results suggest that daptomycin appeared useful and well tolerated in neutropenic patients, and the degree of neutropenia did not affect daptomycin success rates. Comparative clinical trials are needed to confirm these findings.