LAUSR

OBJECTIVE Bacterial bloodstream infections (BSI) with resistant pathogens in patients with hematological malignancies are rising due to the increased use of novel chemotherapeutic agents and prophylactic antibiotics. Gram-negative bacteria (GNB) have been the predominant causative agents in BSI in this population, yet a recent increase in Gram-positive bacteria (GPB) is being observed. In Lebanon, old data on BSI in cancer patients has not differentiated between hematological and oncological malignancies. Our goal is to understand the epidemiology and resistance patterns of bacterial pathogens in patients with hematologic malignancies to help tailor the empiric choice of antibiotics and limit resistance. METHODS This study is a retrospective chart review looking at bacterial BSI episodes between 2007 and 2017 in patients previously diagnosed as having a hematological malignancy at a tertiary care center in Lebanon. RESULTS Among the 165 hospitalized patients with hematological malignancies and bacterial BSI over 10 years, GNB caused 65% of all episodes, with the most common pathogens being Escherichia coli (45.5%),79.5 % of which were extended spectrum beta lactamase (ESBL) producers, Pseudomonas aeruginosa (7.5%) and Acinetobacter baumannii (3.9%). The majority of the organisms (61%) were multidrug-resistant (MDR), with ANC<100 neutrophils/µL (OR=0.12; 95% CI [0.03;0.54]) identified as independent marker for increased multidrug resistance. Mortality was higher with MDR pathogens (p=0.009), prior steroid use (p=0.02), and treatment with meropenem (p=0.04). Our results reflect a persistent pattern of Gram-negative predominance with E. coli remaining as the most common isolated pathogen in bacterial BSI in patients with hematologic malignancies with high rates of ESBL producers. The relative frequency of GNB to GPB remains similar to our data from 2007. CONCLUSIONS The persistent divergence between worldwide data and the results observed in our center and the increasing rates of MDR pathogens emphasize the importance of tailoring empiric antimicrobial therapy as per the center's epidemiology.