Effects of antimicrobial therapy duration and class on risk of antimicrobial-resistant Gram-negative bacillus bloodstream infection in patients with AML.

BACKGROUND

Antimicrobial-resistant Gram-negative bacilli (ARGNB) bloodstream infection (BSI) has been associated with prior antibiotic exposure among hematologic malignancy patients. The relationships between days of therapy (DOT), antimicrobial class, and ARGNB BSI risk are poorly understood.

METHODS

This is a single-center, case-control study of acute myeloid leukemia (AML) patients including 115 cases with ARGNB BSI and 230 matched controls with non-ARGNB BSI between January 1, 2007 and December 31, 2018. Fixed- and mixed-effects logistic regression was used to examine relationships between antibiotic DOT and risk of ARGNB BSI. Admission to an intensive care unit (ICU) within 7 days, 30-day mortality, and Pitt Bacteremia Score (PBS) were secondary outcomes.

RESULTS

Prior isolation of a antimicrobial-resistant organism (ARO) (OR 4.45 95% CI 1.46, 13.54), surgery within 90 days (OR 3.71, 95% CI 1.57, 8.73), aminoglycoside DOT (OR 1.14, 95% CI 1.05, 1.23), cefepime DOT (OR 1.09, 95% CI 1.05, 1.13), and carbapenem DOT (OR 1.10, 95% CI 1.05, 1.16) were associated with increased odds of ARGNB BSI. Days since last antibiotic administration (OR 0.98, 95% CI 0.97, 0.99) and inpatient days within 90 days (OR 0.95, 95% CI 0.93, 0.98) showed reduced odds of ARGNB BSI. Total antimicrobial DOT regardless of class was not associated with ARGNB BSI. ARGNB BSI was associated with increased 30-day mortality (OR 2.86, 95% CI 1.57, 5.22) CONCLUSIONS: Among AML patients with GNB BSI, greater DOT of aminoglycosides, cefepime, and carbapenems in the 90 days prior to BSI were associated with increased odds of ARGNB BSI.