Microbiological Profile and Predictors of Multidrug- Resistant Organisms among Cancer Patients Admitted with Bacteremia: A Retrospective Cohort Study in Jordan.

Introduction: Bacteremia is a life-threatening complication in cancer patients. However, there are limited studies evaluating bacteremia in this patient population. The objective of this study was to evaluate the microbiological profile as well as the prevalence and predictors of multidrug-resistant organisms (MDROs) among cancer patients admitted with bacteremia.

Patients and methods: A retrospective cohort study which included adult cancer patients admitted with bacteremia, between July 2020 and September 2022, at a comprehensive cancer center in Jordan. Patients under the palliative or bone marrow transplant services were excluded, as well as patients with blood cultures deemed as contaminants. Using the electronic medical records, patients' characteristics and the types of pathogens and susceptibilities were recorded. MDROs were defined as intrinsic or acquired non-susceptibility to at least one agent in = 3 antimicrobial categories. Logistic regression was used to identify predictors of bacteremia due to MDROs.

Results: A total of 651 cases of bacteremia for 531 patients were included. The mean age of the patients was 58±16 (SD) years, 290 (55%) were males, and 373 (70%) had solid tumors while the remaining had hematologic malignancies. Gram-negative bacteria were reported in most cases (n = 439, 65%), the most common being Escherichia coli (n = 252, 57%), followed by Klebsiella species (n = 63, 14%). For gram-positive bacteremia, Coagulase-negative staphylococci were the most common (n = 64, 28%) followed by Streptococcus species (n = 62, 27%) and Staphylococcus aureus (n = 49, 21%). MDROs were reported in 309 cultures (48%), with extendedspectrum- beta-lactamase-producing Enterobacterales and methicillin-resistant Staphylococcus aureus being the most common MDROs, reported in 149 (34%) and 22 (45%), of the cultures, respectively. Use of antibiotics within the previous 90 days (OR 1.5, 95% CI 1.00-2.34) and hematologic malignancy (OR 1.8 CI 1.26 - 2.67) were identified as predictors of MDRO bacteremia.

Discussion: Our study investigated the microbiological profile, prevalence, and predictors of MDRO bacteremia in a substantial cohort of adult patients with solid and hematologic malignancies admitted with bacteremia. Similar to findings from a study conducted in Lebanon, almost two-thirds of the cultures in our cohort were gram-negative. Interestingly, about half of the cases consisted of MDROs, a finding comparable to existing data as well. Additionally, we identified two predictors of MDRO bacteremia: antibiotics use within the past 90 days, which aligns with previous literature on the subject, and hematologic malignancies, which can be explained by the course of the disease, particularly the prolonged neutropenia episodes. Given the high percentage of MDROs among cancer patients with bacteremia, this study emphasizes the importance of establishing and adhering to an antimicrobial stewardship program at each healthcare institution. Furthermore, the findings of this study can serve as data sets that can be utilized to advance predictive models for MDRO bacteremia.

Conclusion: Among cancer patients admitted with bacteremia, gram-negative bacteria were the most common. About half of the bacteria were multidrugresistant. The use of antibiotics within the past 90 days and hematologic malignancy were predictors of MDRO bacteremia. Further predictive models for MDRO bacteremia are needed to help guide the empiric antibiotic prescribing decisions.