PMID:18234876
| Citation |
Biendo, M, Canarelli, B, Thomas, D, Rousseau, F, Hamdad, F, Adjide, C, Laurans, G and Eb, F (2008) Successive emergence of extended-spectrum beta-lactamase-producing and carbapenemase-producing Enterobacter aerogenes isolates in a university hospital. J. Clin. Microbiol. 46:1037-44 |
|---|---|
| Abstract |
Sixty-two clinical isolates of Enterobacter aerogenes resistant to expanded-spectrum cephalosporins were collected between July 2003 and May 2005. Among these isolates, 23 (37.1%) were imipenem (IPM) susceptible, and 39 (62.9%) were IPM insusceptible, of which 89.7% (35/39) were resistant and 10.3% (4/39) were intermediate. Isolate genotypes were compared by pulsed-field gel electrophoresis. Of 62 isolates, 48 belonged to epidemic pulsotype A (77.4%). This pulsotype included 37.5% and 58.4% of beta-lactam phenotypes b and a, respectively. Nine isolates (14.5%) belonged to pulsotype E, which included 22.3% and 77.7% of phenotypes b and a, respectively. The beta-lactamases with pIs of 5.4, 6.5, 8.2, and 8.2 corresponded to extended-spectrum beta-lactamases (ESBLs) TEM-20, TEM-24, SHV-5, and SHV-12, respectively. Of 39 IPM-insusceptible E. aerogenes isolates, 26 (66.6%) were determined to be metallo-beta-lactamase producers, by using a phenotypic method. Of these isolates, 24 harbored a bla(IMP-1) gene encoding a protein with a pI of >9.5, and two carried the bla(VIM-2) gene encoding a protein with a pI of 5.3, corresponding to beta-lactamases IMP-1 and VIM-2, respectively. The remaining 13 (33.4%) isolates were negative for the bla(IMP-1) and bla(VIM-2) genes but showed an alteration of their outer membrane proteins (OMPs). Ten of these isolates produced the two possible OMPs (32 and 42 kDa), with IPM MICs between 8 and 32 microg/ml, and three others produced only a 32-kDa OMP with IPM MICs >32 microg/ml. This work demonstrates that, in addition to resistance to expanded-spectrum cephalosporins, IPM resistance can occur in ESBL-producing E. aerogenes isolates by carbapenemase production or by the loss of porin in the outer membrane. |
| Links |
PubMed PMC2268331 Online version:10.1128/JCM.00197-07 |
| Keywords |
Adult; Aged; Aged, 80 and over; Anti-Bacterial Agents/pharmacology; Bacterial Outer Membrane Proteins/chemistry; Bacterial Outer Membrane Proteins/metabolism; Bacterial Proteins/biosynthesis; Bacterial Proteins/genetics; Cephalosporin Resistance; Enterobacter aerogenes/drug effects; Enterobacter aerogenes/enzymology; Enterobacter aerogenes/isolation & purification; Enterobacteriaceae Infections/epidemiology; Enterobacteriaceae Infections/microbiology; Female; France/epidemiology; Hospitals, University; Humans; Isoelectric Focusing; Male; Microbial Sensitivity Tests; Middle Aged; Polymerase Chain Reaction; Porins/analysis; Sequence Analysis, DNA; beta-Lactamases/biosynthesis; beta-Lactamases/genetics |
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