What is the role of extended-spectrum beta-lactamases (ESBLs) in the treatment of Enterobacter infections?

Updated: Jun 18, 2019
  • Author: Susan L Fraser, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

The production of extended-spectrum beta-lactamases (ESBLs) has been documented in Enterobacter. Usually, these ESBLs are TEM1 -derived or SHV1 -derived enzymes, and they have been reported since 1983 in Klebsiella pneumoniae, Klebsiella oxytoca, and E coli. Bush et al classify these ESBLs in group 2be and in molecular class A in their beta-lactamase classification. [34] The location of these enzymes on plasmids favors their transfer between bacteria of the same and of different genera. Many other gram-negative bacilli may also possess such resistant plasmids.

Bacteria-producing ESBLs should be considered resistant to all generations of cephalosporins, all penicillins, and to the monobactams such as aztreonam, even if the in vitro susceptibilities are in the sensitive range according to the CLSI breakpoints. In the past, the CLSI has cautioned physicians regarding the absence of a good correlation with susceptibility when its breakpoints are applied to ESBL-producing bacteria.


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