An Uncommon ST1224 NDM-1-Producing Klebsiella pneumoniae Isolated from the Bloodstream of a Leukemia Patient in China.

Aims: This study aimed to analyze the clinical data and characteristics of an NDM-1 (New Delhi metallo-β-lactamase-1)-producing Klebsiella pneumoniae isolated from the bloodstream of a leukemia patient. Materials and Methods: A retrospective analysis was used for the clinical data of the patient. The modified Hodge test (MHT) and ethylenediaminetetraacetic acid (EDTA)-disk synergy test were used for detecting metallo-β-lactamase. Antibiotic resistance was determined using the agar dilution method. PCR was used to identify resistance genes. S1-PFGE (S1 nuclease/pulsedfield gel electrophoresis) and Southern blot hybridization were performed to determine the location of bla NDM-1 . A conjugation experiment was used to confirm the transferable characteristics of the resistant genes. Multilocus sequence typing (MLST) was also performed. Results: The patient developed bloodstream infections caused by this NDM-1-producing strain and died due to worsening of the condition. The strain was highly resistant to β-lactam antibiotics and coharbored bla NDM-1, qnrB, and bla CTX-M-9 genes. Southern blot confirmed that bla NDM-1 was located on a plasmid of approximately 55 kb and could be transferred to Escherichia coli J53. MLST analysis showed that this strain belonged to an uncommon sequence type ST1224. Conclusion: The coexistence of various resistant genes is the mechanism for resistance to most antibiotics. Additionally, infections caused by multi-drug resistant bacteria increase the mortality of patients with immunodeficiency, which alerts clinicians to establish a rational and effective combination drug therapy. [ABSTRACT FROM AUTHOR]