Frequency of microbial isolates and pattern of antimicrobial resistance in patients with hematological malignancies:...

Infections are the main cause of death in patients with hematologic malignancies. This study aims to determine the microbial profile of infections in patients with hematologic malignancies and to determine the antimicrobial resistance patterns for these pathogens.

A retrospective descriptive cross-sectional study was conducted from January 2018 to December 2019 at a large hematological center in Palestine. The medical data of hematologic malignancy patients with positive cultures were collected from the hematology/oncology department using the hospital information system, and data regarding the microbial isolates and their antimicrobial resistance were collected from the microbiology laboratory.

A total of 144 isolates were identified from different types of specimens, mostly blood samples. Of all isolates, 66 (45.8%) were gram-negative bacteria (GNB), 57 (39.6%) were gram-positive bacteria (GPB), and 21 (14.6%) were fungal isolates. The GNB that were most frequently isolated were Pseudomonas aeruginosa (27, 40.9%), followed by Escherichia coli (E. coli) (20, 30.3%). Fourteen isolates (24.6%) of GPB were Staphylococcus epidermidis followed by Enterococcus faecium (10, 17.5%) and Staphylococcus hemolyticus (10, 17.5%). The most frequent fungal pathogens were Candida species (20, 95.2%). GNB were found to be resistant to most antibiotics, mainly ampicillin (79.3%). Pseudomonas aeruginosa exhibited high resistance to ciprofloxacin (60%) and imipenem (59.3%). Among GPB, high resistance rates to oxacillin (91.1%) and amikacin (88.8%) were found. All isolated strains of Staphylococcus epidermidis were resistant to cephalosporins and oxacillin. Approximately half of the GNB isolates (34, 51.5%) were multi-drug resistant organisms (MDRO), and 16.7% (11 isolates) were difficult-to-treat resistance (DTR). Furthermore, 68.4% (39 isolates) of GPB were MDRO. The proportion of staphylococci (CoNS and S. aureus) resistant to oxacillin was 91.7%, while 88.6% of enterococci were resistant to vancomycin.

The findings of this study confirm the predominant microorganisms seen in patients with hematologic malignancies, and show a high percentage of antibiotic resistance. Policies regarding antibiotic use and proper infection control measures are needed to avert the ever-growing danger of antimicrobial resistance. This may be achieved by developing antibiotic stewardship programs and local guidelines based on the hospital's antibiogram.