Extended-spectrum b-lactamase S U M M A R Y Objectives: This study was performed to determine the local etiologic pattern of blood culture isolates and antibiotic resistance in febrile neutropenic patients with hematological malignancies. Methods: A total of 142 blood culture isolates from febrile neutropenic patients admitted to our hematology unit were examined, particularly for the detection of cefepime resistance, because cefepime, a fourth-generation cephalosporin, has been used in our

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... as initial therapy for febrile neutropenia. Results: Among all isolates, 67 (47.2%) were Gram-positive bacteria, the majority of which were fully sensitive to vancomycin. Gram-negative bacteria accounted for 68 (47.9%) of the isolates. Cefepime resistance was seen in 24 (35.3%) of the Gram-negative isolates, and had significantly increased in 2007. The cefepime-resistant isolates primarily consisted of Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Approximately 60% of the cefepime-resistant isolates were extended-spectrum blactamase (ESBL)-producing organisms. Molecular analysis showed the predominant emergence of CTX-M types. Most of the cefepime-resistant isolates were resistant to third-and various fourth-generation cephalosporins, while having a high susceptibility to carbapenems, particularly meropenem. Conclusions: Cefepime resistance was often detected in the blood culture isolates from febrile neutropenic patients. This result suggests that therapeutic strategies for febrile neutropenia should be modified based on the local antibiotic resistance patterns. ß