This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow E-mail this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Jacoby, G. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Jacoby, G. A.

 Previous Article  |  Next Article 

Clinical Microbiology Reviews, January 2009, p. 161-182, Vol. 22, No. 1
0893-8512/09/$08.00+0     doi:10.1128/CMR.00036-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

AmpC β-Lactamases

George A. Jacoby*

Lahey Clinic, Burlington, Massachusetts

Summary: AmpC β-lactamases are clinically important cephalosporinases encoded on the chromosomes of many of the Enterobacteriaceae and a few other organisms, where they mediate resistance to cephalothin, cefazolin, cefoxitin, most penicillins, and β-lactamase inhibitor-β-lactam combinations. In many bacteria, AmpC enzymes are inducible and can be expressed at high levels by mutation. Overexpression confers resistance to broad-spectrum cephalosporins including cefotaxime, ceftazidime, and ceftriaxone and is a problem especially in infections due to Enterobacter aerogenes and Enterobacter cloacae, where an isolate initially susceptible to these agents may become resistant upon therapy. Transmissible plasmids have acquired genes for AmpC enzymes, which consequently can now appear in bacteria lacking or poorly expressing a chromosomal blaAmpC gene, such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. Resistance due to plasmid-mediated AmpC enzymes is less common than extended-spectrum β-lactamase production in most parts of the world but may be both harder to detect and broader in spectrum. AmpC enzymes encoded by both chromosomal and plasmid genes are also evolving to hydrolyze broad-spectrum cephalosporins more efficiently. Techniques to identify AmpC β-lactamase-producing isolates are available but are still evolving and are not yet optimized for the clinical laboratory, which probably now underestimates this resistance mechanism. Carbapenems can usually be used to treat infections due to AmpC-producing bacteria, but carbapenem resistance can arise in some organisms by mutations that reduce influx (outer membrane porin loss) or enhance efflux (efflux pump activation).

* Mailing address: Lahey Clinic, 41 Mall Road, Burlington, MA 01805. Phone: (781) 744-2928. Fax: (781) 744-5486. E-mail: george.a.jacoby{at}lahey.org

Clinical Microbiology Reviews, January 2009, p. 161-182, Vol. 22, No. 1
0893-8512/09/$08.00+0     doi:10.1128/CMR.00036-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Dallenne, C., Da Costa, A., Decre, D., Favier, C., Arlet, G. (2010). Development of a set of multiplex PCR assays for the detection of genes encoding important {beta}-lactamases in Enterobacteriaceae. J Antimicrob Chemother 65: 490-495 [Abstract] [Full Text]  
  • Jorgensen, R. L., Nielsen, J. B., Friis-Moller, A., Fjeldsoe-Nielsen, H., Schonning, K. (2010). Prevalence and molecular characterization of clinical isolates of Escherichia coli expressing an AmpC phenotype. J Antimicrob Chemother 65: 460-464 [Abstract] [Full Text]  
  • Drawz, S. M., Bonomo, R. A. (2010). Three Decades of {beta}-Lactamase Inhibitors. Clin. Microbiol. Rev. 23: 160-201 [Abstract] [Full Text]  
  • Zhao, S., Blickenstaff, K., Glenn, A., Ayers, S. L., Friedman, S. L., Abbott, J. W., McDermott, P. F. (2009). {beta}-Lactam Resistance in Salmonella Strains Isolated from Retail Meats in the United States by the National Antimicrobial Resistance Monitoring System between 2002 and 2006. Appl. Environ. Microbiol. 75: 7624-7630 [Abstract] [Full Text]  
  • Jeong, S. H., Song, W., Kim, J.-S., Kim, H.-S., Lee, K. M. (2009). Broth Microdilution Method To Detect Extended-Spectrum {beta}-Lactamases and AmpC {beta}-Lactamases in Enterobacteriaceae Isolates by Use of Clavulanic Acid and Boronic Acid as Inhibitors. J. Clin. Microbiol. 47: 3409-3412 [Abstract] [Full Text]  
  • Mataseje, L. F., Xiao, J., Kost, S., Ng, L.-K., Dore, K., Mulvey, M. R., on behalf of the Canadian Public Health Laboratory, (2009). Characterization of Canadian cefoxitin-resistant non-typhoidal Salmonella isolates, 2005-06. J Antimicrob Chemother 64: 723-730 [Abstract] [Full Text]  
  • Petrosino, J. F., Galhardo, R. S., Morales, L. D., Rosenberg, S. M. (2009). Stress-Induced {beta}-Lactam Antibiotic Resistance Mutation and Sequences of Stationary-Phase Mutations in the Escherichia coli Chromosome. J. Bacteriol. 191: 5881-5889 [Abstract] [Full Text]  
  • Gordon, N. C., Wareham, D. W. (2009). Failure of the MicroScan WalkAway System To Detect Heteroresistance to Carbapenems in a Patient with Enterobacter aerogenes Bacteremia. J. Clin. Microbiol. 47: 3024-3025 [Abstract] [Full Text]  
  • Hawkey, P. M., Jones, A. M. (2009). The changing epidemiology of resistance. J Antimicrob Chemother 64: i3-i10 [Abstract] [Full Text]  
  • Kotsakis, S. D., Papagiannitsis, C. C., Tzelepi, E., Tzouvelekis, L. S., Miriagou, V. (2009). Extended-Spectrum Properties of CMY-30, a Val211Gly Mutant of CMY-2 Cephalosporinase. Antimicrob. Agents Chemother. 53: 3520-3523 [Abstract] [Full Text]  
  • Pope, C. E., Carter, P. E., Heffernan, H. M. (2009). CMY-29 and CMY-30, Two Novel Plasmid-Mediated AmpC {beta}-Lactamases. Antimicrob. Agents Chemother. 53: 3178-3178 [Full Text]  


Copyright © 2010 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»