OBJECTIVES : Infections are a major complication for patients with haematological malignancies. The aim of this study was to assess antimicrobial utilization and resistance in patients with haematological malignancies.

METHODS : We conducted a cross-sectional study using administrative claims data and antimicrobial susceptibility data in Japan. We included patients diagnosed with haematological malignancies who were hospitalized in a haematology ward between 1 April 2015 and 30 September 2017 in 37 hospitals. Descriptive statistics were used to summarize patient characteristics, antimicrobial utilization, Gram-negative bacterial infections, and antimicrobial resistance.

RESULTS : A total of 8064 patients were identified (median age 70 years; 56.8% men). Approximately half of patients were diagnosed as non-Hodgkin lymphoma (49.9%), followed by myeloid leukaemia (15.2%), multiple myeloma (14.3%), myelodysplastic syndromes (11.3%), lymphoid leukaemia (6.9%), and Hodgkin lymphoma (2.5%). The following broad-spectrum antimicrobial agents showed a higher antimicrobial use density (AUD): fourth-generation cephalosporins (155.8), carbapenems (103.8), and piperacillin/tazobactam (28.4). Glycopeptides (47.8) also showed a high AUD, whereas third generation cephalosporins, quinolones, penicillins, first/second-generation cephalosporins, and others showed AUD values of 16.7, 8.7, 7.1, 3.9, and 22.1, respectively. Especially, patients with lymphoid leukaemia, myeloid leukaemia, or myelodysplastic showed higher AUD than Hodgkin lymphoma, non-Hodgkin lymphoma, or multiple myeloma. The most frequent bacterial species in all specimens was Escherichia coli (15.4%), and this trend also was observed in blood specimens. Fluoroquinolone-resistant E. coli (6.0%) and third-generation cephalosporin-resistant E. coli (3.5%) was frequently observed antimicrobial-resistant strain, while other strains rarely occurred.

CONCLUSIONS : Patients with haematological malignancies showed a high AUD for broad-spectrum antimicrobial agents. Furthermore, we found a clear difference of AUD by underlying diseases among hematological malignancies. However, antimicrobial resistant was not much high in the group of high AUD, and we could not find association between AUD and antimicrobial resistance.