Current epidemiology of microbiologically documented infections and risk factors for multidrug resistance in hematologic patients presenting to the emergency department with suspected bacteremia.

Objective: To describe the microbiological isolates obtained from hematologic patients seen in the emergency department (ED) who had blood cultures requested and identify the risk factors associated with the isolation of multidrug-resistant bacteria (MDR).

Methods: We conducted a retrospective, observational, and descriptive study of all consecutive patients with hematologic malignancies who presented to the ED and had, at least, 1 blood culture requested within the first 72 hours following admission from January 2020 through March 2022. The decision on the number of blood cultures and other requested samples was made by the attending physician. A descriptive analysis was performed on the microbiological isolates from blood cultures and, when applicable, from other requested samples. A multivariate analysis was conducted to determine the variables associated with MDR isolation.

Results: A total of 679 ED visits were included. The median patient age was 66 years (IQR, 52-76), with lymphoma being the most prevalent hematologic disease (35.6%). A significant proportion of patients had prior hospitalizations (47%), were colonized by multidrug-resistant gram-negative bacilli (MDR-GNB) (14%), and/or were neutropenic (27%). In addition to blood cultures, at least, 1 more culture was requested in 556 visits, 202 of which had > 1 blood culture, resulting in a total of 1,751 microbiological cultures in the ED. Most samples came from blood (936; 53.5%), followed by urine (567; 32.4%), respiratory tract (88; 5%), and stool (88; 5%). A total of 211 (12.1%) cultures tested positive in 179 ED visits (26.4%). Of these, 99 (10.6%) blood cultures tested positive in 88 (13%) visits. Among patients with bacteremia, gram-negative bacilli (GNB) were the most common microorganisms (48%), with 12 (25%) categorized as MDR-GNB. Gram-positive microorganisms were documented in 47 (47%) episodes of bacteremia. MDR bacteria were isolated in 40 (5.9%) visits. A past medical history of MDR was associated with MDR isolation in the ED [OR, 4.13; 95%CI, 1.99-8.50].

Conclusions: The proportion of positive cultures and MDR isolates is relatively high in patients with hematologic malignancies presenting to the ED. A past medical history of MDR is an independent risk factor for MDR isolation.