Background: The epidemiology of Gram-negative bacteria in patients with febrile neutropenia (FN) and their susceptibility to initial empirical antibiotic therapy is key to successful treatment during the treatment of hematologic malignancies.
Methods: A retrospective study was conducted. Patients with FN and confirmed laboratory results of Gram-negative bacteria infections were included. If no direct sensitivity of the identified pathogen to the initially prescribed antibiotic regimen was confirmed, it was defined as inappropriate initial antibiotic treatment (IIAT).
Results: A total of  247 patients with FN were proven to be infected with Gram-negative bacteria, and  200 were diagnosed with acute leukemia. The most commonly detected bacteria were Escherichia coli  (40%), Klebsiella pneumoniae  (20%), and Pseudomonas aeruginosa  (11%). In sum, 176 patients were classified as IIAT. The mortality rate in the IIAT group was significantly higher (37.7% vs 23.9%, P =0.038). With monotherapy as empirical treatment, high possibility of IIAT with fluoroquinolones (52%) and cephalosporins (35%) was detected, while more sensitivity to carbapenems (16%) and glycopeptides antibiotics (19%) was noticed. With combined treatment, cephalosporins/carbapenems had with the lowest percentage of IIAT (18%).
Conclusion: In conclusion, inappropriate initial empirical antibiotic treatments were associated with higher mortality in patients with hematologic malignancies. The current empirical antibiotic regimen needs to be further optimized.
Keywords: febrile neutropenia, Gram-negative bacteria, hematologic malignancy, empirical antibiotic treatment, inappropriate initial antibiotic treatment