Epidemiology and genotypes of plasmid-mediated AmpC b-lactamase produced by clinical isolates of Klebsiella pneumoniae in Korea

Abstract number: 1733_167

Song W., Lee C.H., Kim J.S., Kim H.S., Uh Y., Lee J., Lee K.

Objectives: Plasmid-mediated AmpC b-lactamases (pAmpCs) are cephalosporinases that confer resistance to a wide variety of b-lactam drugs and that may thereby create serious therapeutic problems. The pAmpC-producing organisms are a major concern in nosocomial infections and should therefore be monitored in surveillance studies. The present study was conducted to determine the epidemiology and genotypic distributions of pAmpCs among Klebsiella pneumoniae isolates in Korea.

Methods: During the period May to July 2004, 60 cefoxitin non-susceptible isolates of 735 consecutive, nonrepeat isolates of K. pneumoniae at five Korean university hospitals were tested for antimicrobial susceptibility by broth microdilution methodology. The cefoxitin non-susceptible isolates were further investigated by AmpC disk tests, double disk synergy and antagonism tests, isoelectric focusing, multiplex AmpC PCR, allele-specific PCR, DNA sequencing, and pulsed-field gel electrophoresis (PFGE)

Results: pAmpC producers were found at all the 5 sites in 48/735 K. pneumoniae (6.5%). Thirty-one of 48 pAmpC producers (64.6%) also positive tested by double disk synergy tests for extended-spectrum b-lactamases. Susceptibilities of the pAmpC producers were as follows: ceftazidime 2%, aztreonam 19%, cefepime 49%, and imipenem 96%. Among the 48 K. pneumoniae isolates, there were 47 DHA-1 and 1 CMY-1 b-lactamase. Ten PFGE patterns were shown by the DHA-1-producing K. pneumoniae isolates.

Conclusion: pAmpC producers widespread among Korean medical institutions. A DHA-1 type in K. pneumoniae was the predominant enzyme detected. Overall, despite many different PFGE patterns of the pAmpC producers, some outbreak and epidemic clones appear to be prevalent according to the hospitals in Korea. Prevention of the spread of pAmpC producers requires clinical laboratories test for this resistance mechanism.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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