Epidemiology and Antibiotic Resistance of Bacterial Bloodstream Infections in Hematological Malignancies: A 7-Year Study from Northeastern Iran

Background: Bacterial bloodstream infections (BSIs) caused by multidrug-resistant pathogens remain a major concern in cancer patients, particularly those with hematological malignancies. Their increased susceptibility underscores the importance of timely, targeted empirical therapy. This study aimed to describe the epidemiology and antimicrobial resistance of bacterial pathogens in Northeastern Iran.
Methods: A retrospective review was conducted of BSI episodes between 2011 and 2018 in patients with hematological cancers admitted to a tertiary care center in Mashhad, Iran. Clinical and microbiological data were analyzed to determine pathogen distribution and resistance patterns.
Results: Among 107 patients with confirmed bacteremia, 60 (56.1%) were male, with a mean age of 43.8 ± 1.8 years. Acute myeloid leukemia was the most frequent malignancy (41.1%), followed by acute lymphoblastic leukemia (24.3%). The mean hospitalization duration was 20 ± 1.3 days, and 64% of patients survived to discharge. The predominant isolates were Staphylococcus aureus (15.9%), Acinetobacter spp. (15.0%), Enterococcus spp. (13.1%), and Staphylococcus epidermidis (12.1%). Neutropenia occurred in 62 patients (42.1%) and was significantly associated with infections due to S. aureus and Escherichia coli (P < 0.001). Antibiotic susceptibility testing revealed vancomycin was most effective, with susceptibility rates of 92.3% for S. epidermidis and 82.4% for S. aureus. Enterococcus spp. showed 78.6% sensitivity to linezolid, while only 52.9% of S. aureus isolates were susceptible to ciprofloxacin.
Conclusion: The observed resistance patterns differ from global trends, underscoring the importance of region-specific empirical therapy. Ongoing surveillance and tailored treatment strategies are essential to improve outcomes in patients with hematological malignancies.