Bacterial bloodstream infections and patterns of resistance in patients with haematological malignancies at a tertiary centre in Lebanon over 10 years.

Objectives: Bacterial bloodstream infections (BSIs) with resistant pathogens in patients with haematological malignancies are rising due to increased use of novel chemotherapeutic agents and prophylactic antibiotics. Our goal was to understand the epidemiology and resistance patterns of bacterial pathogens in patients with haematological malignancies to help tailor empirical antibiotics and to limit resistance.

Methods: This was a retrospective chart review looking at bacterial BSI episodes between 2007-2017 in patients previously diagnosed with haematological malignancy at a tertiary-care centre in Lebanon.

Results: Among 165 hospitalised patients with haematological malignancy and bacterial BSI over 10 years, Gram-negative bacteria (GNB) caused 65.0% of all episodes, with the most common pathogens being Escherichia coli (45.6%), 79.6% of which were ESBL-producers, Pseudomonas aeruginosa (7.5%) and Acinetobacter baumannii (4.0%). The majority of the organisms (61.0%) were multidrug-resistant (MDR), with ANC < 100 neutrophils/μL (OR = 0.12, 95% CI 0.03-0.54) identified as an independent marker for increased multidrug resistance. The risk factors associated with increased mortality included recent use of amikacin (p<0.001) and infections with organisms resistant to amikacin (p<0.001) or ciprofloxacin (p=0.04). Our results reflect a persistent pattern of Gram-negative predominance with E. coli remaining the most common isolated pathogen in bacterial BSIs in patients with haematological malignancies. The relative frequency of GNB to Gram-positive bacteria remains similar to our data from 2007.

Conclusion: The persistent divergence between worldwide data and the results observed in our centre and the increasing rates of MDR pathogens emphasise the importance of tailoring empirical antimicrobial therapy according to the centre's epidemiology.