Background: Ambulatory consolidation chemotherapy for acute myeloid leukemia (AML) is frequently associated with bloodstream infections but the spectrum of bacterial pathogens in this setting has not been well-described.
Methods: We evaluated the emergence of bacteremias and their respective antibiotic susceptibility patterns in AML patients receiving ambulatory-based consolidation therapy. Following achievement of complete remission, 207 patients received the first cycle (C1), and 195 the second cycle (C2), of consolidation on an ambulatory basis. Antimicrobial prophylaxis consisted of ciprofloxacin, amoxicillin and fluconazole.
Results: There were significantly more positive blood cultures for E. coli in C2 as compared to C1 (10 vs. 1, p=0.0045); all E. coli strains for which susceptibility testing was performed demonstrated resistance to ciprofloxacin. In patients under age 60 there was a significantly higher rate of Streptococccus spp. bacteremia in C2 vs. C1; despite amoxicillin prophylaxis all Streptococcus isolates in C2 were sensitive to penicillin. Patients with Staphylococcus bacteremia in C1 had significantly higher rates of Staphylococcus bacteremia in C2 (p=0.009, OR=8.6).
Conclusions: For AML patients undergoing outpatient-based intensive consolidation chemotherapy with antibiotic prophylaxis, the second cycle is associated with higher rates of ciprofloxacin resistant E. coli, penicillin-sensitive Streptococcus bacteremias and recurrent Staphylococcus infections.