Prevalence and risk factors of Gram-negative bacilli causing blood stream infection in patients with malignancy.

OBJECTIVES: To evaluate the epidemiology, risk factors, and antibiotic resistance of Gram negative bacteria (GNB) in patients with hematologic or solid organ malignancies.  

METHODS: This is a retrospective study of 61 episodes of GNB bacteremia occurring in 56 patients with malignancy admitted to the Oncology Units in King Khalid University Hospital, Riyadh. Kingdom of Saudi Arabia during the period from January 2013 to October 2015. Data were retrieved from the computerized database of the microbiology laboratory and the patient's medical records.  

RESULTS:  Hematological malignancies accounted for 30 (54%) and solid tumors accounted for 26 (46%). The most common hematological malignancies were leukemia 23 (77%), followed by lymphoma 6 (20%). Among solid tumors, colorectal cancer 9 (34.6) and breast cancer 6 (23%) were the most common. The most predominant pathogen was Escherichia coli (E. coli) (29.5%) followed by Acinetobacter baumannii (A. baumannii) (18%). The extended-spectrum beta-lactamases producers rate of E. coli and Klebsiella pneumonia was (34.6%). Imipenem resistance among Pseudomonas aeruginosa/ A. baumannii was high (52.4%). The multi-resistant organisms rate was (43.5%). Risk factors associated with the bacteremia were ICU admission (32.1%), post-surgery (23.2%), and placement of central line (21.4%). The overall 30-day mortality rate of the studied population was high (32.1%). 

CONCLUSION: In light of the high resistant rate among the GNB isolated from malignancy patients from our institution, careful selection of antimicrobial treatment based on antimicrobial susceptibility testing is recommended.