Clinical experiences of bacteremia caused by metallo-?-lactamase-producing Gram-negative organisms

Nan-Yao Lee¹, Jing-Jou Yan^2,3, Hsin-Chun Lee^1,3, Kung-Hung Liu¹, Shao-Tsung Huang¹, Wen-Chien Ko^1,3
Division of Infectious Diseases, Departments of ¹Internal Medicine and ²Pathology, National Cheng Kung University Hospital, Tainan; and ³Department of Medicine, Medical College, National Cheng Kung University, Tainan, Taiwan, ROC

Received: March 23, 2004 Revised: April 26, 2004 Accepted: May 17, 2004

Corresponding author: Wen-Chien Ko, Department of Internal Medicine, National Cheng Kung University Hospital, No. 138, Sheng Li Road, 704, Tainan, Taiwan, ROC. E-mail:

The emergence of acquired metallo-?-lactamase (MBL) in Gram-negative bacilli is regarded as a therapeutic challenge since such enzymes are capable of hydrolyzing all ?-lactams in vitro except the monobactams. The clinical characteristics and outcome of 8 episodes of Gram-negative bacteremia caused by MBL-producing isolates from January 1997 through December 2000 (Klebsiella pneumoniae, 6 isolates; Pseudomonas stutzeri, 4; Pseudomonas aeruginosa, 1; and Pseudomonas putida, 1) were analyzed. The median age of the patients was 61 years (range, 2-95 years). Most patients (n = 6, 75%) had more than 1 comorbid illness or condition and 6 patients acquired bacteremia in the intensive care unit. The median time from admission to the first positive culture was 34.5 days (range, 1-99 days). Pneumonia was the most common site of infection. Five patients (62.5%) received a carbapenem to treat bacteremia. The median time to defervescence was 6 days (range, 2-12 days). No bacteriologic failure was noted during or after antimicrobial therapy. The overall mortality rate from bacteremia caused by Gram-negative, MBL-producing organisms was nil at 14 or 28 days.