This Article Full Text Full Text (PDF) An author's correction has been published Other Versions of this Article: AAC.00576-07v1 51/11/4015    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lewis, J. S. Articles by Jorgensen, J. H. Search for Related Content PubMed PubMed Citation Articles by Lewis, J. S., II Articles by Jorgensen, J. H.

 Previous Article  |  Next Article 

Antimicrobial Agents and Chemotherapy, November 2007, p. 4015-4021, Vol. 51, No. 11
0066-4804/07/$08.00+0     doi:10.1128/AAC.00576-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

First Report of the Emergence of CTX-M-Type Extended-Spectrum ß-Lactamases (ESBLs) as the Predominant ESBL Isolated in a U.S. Health Care System

Department of Pharmacy, University Health System, San Antonio, Texas,¹ Departments of Microbiology,² Medicine,³ Pathology, University of Texas Health Science Center, San Antonio, Texas 78229⁴

Received 2 May 2007/ Returned for modification 30 May 2007/ Accepted 16 August 2007

CTX-M-type extended-spectrum ß-lactamases (ESBLs) have become increasingly common worldwide, with the notable exception of the United States, where TEM- and SHV-type ESBLs have appeared to predominate. We have noted the emergence of ESBLs in our health care system (the University Health System in San Antonio, TX), especially in Escherichia coli isolates, that preferentially hydrolyze cefotaxime rather than ceftazidime, suggesting the possibility of CTX-M-type enzymes. Microbiology laboratory records were reviewed to identify ESBL-producing isolates and to compare the diameters of ceftazidime disk diffusion zones of inhibition to cefotaxime zone diameters. All isolates had been initially detected and confirmed using the procedures recommended by the Clinical and Laboratory Standards Institute. A total of 94 stored ESBL-producing isolates recovered between January 2000 and June 2006 (predominately from blood and normally sterile fluids) were retrieved for further study and screened using PCR primers specific for the presence of CTX-M, TEM, and SHV ESBLs. Only small numbers of retained ESBL-producing isolates were available for study in 2000 and 2002. The percentages of available ESBL-producing organisms in the following years were found to produce CTX-M enzymes: 2000, 25%; 2001, 10%; 2002, 0%; 2003, 60%; 2004, 69%; 2005, 89%; and 2006, 70%. The most common CTX-M-type ESBL was CTX-M-15, followed by CTX-M-16, CTX-M-8, and CTX-M-14. Comparing the disk diffusion zone diameters of cefotaxime and ceftazidime was helpful with the initial recognition of CTX-M-producing E. coli, which had an average cefotaxime zone diameter 7 mm smaller than the ceftazidime zone. However, comparing ceftazidime and cefotaxime zones for CTX-M-producing Klebsiella spp. was not helpful with initial recognition. CTX-M enzymes were also identified in Proteus mirabilis, Enterobacter spp., and Morganella morganii. Based on pulsed-field gel electrophoresis typing of the E. coli isolates, the CTX-M-producing isolates did not represent the spread of a single clone in the institution or in the community. In conclusion, CTX-M-type ESBLs are now the most common ESBL type isolated from patients in our health care system and may also be present but unrecognized in other U.S. locales.

Published ahead of print on 27 August 2007.

This article has been cited by other articles:

• Hanson, N. D., Moland, E. S., Hong, S. G., Propst, K., Novak, D. J., Cavalieri, S. J. (2008). Surveillance of Community-Based Reservoirs Reveals the Presence of CTX-M, Imported AmpC, and OXA-30 {beta}-Lactamases in Urine Isolates of Klebsiella pneumoniae and Escherichia coli in a U.S. Community. Antimicrob. Agents Chemother. 52: 3814-3816 [Abstract] [Full Text]  
• Livermore, D. M., Mushtaq, S., Warner, M., Miossec, C., Woodford, N. (2008). NXL104 combinations versus Enterobacteriaceae with CTX-M extended-spectrum {beta}-lactamases and carbapenemases. J Antimicrob Chemother 0: dkn320v1-4 [Abstract] [Full Text]  
• Zhanel, G. G., DeCorby, M., Laing, N., Weshnoweski, B., Vashisht, R., Tailor, F., Nichol, K. A., Wierzbowski, A., Baudry, P. J., Karlowsky, J. A., Lagace-Wiens, P., Walkty, A., McCracken, M., Mulvey, M. R., Johnson, J., The Canadian Antimicrobial Resistance Alliance (CA, , Hoban, D. J. (2008). Antimicrobial-Resistant Pathogens in Intensive Care Units in Canada: Results of the Canadian National Intensive Care Unit (CAN-ICU) Study, 2005-2006. Antimicrob. Agents Chemother. 52: 1430-1437 [Abstract] [Full Text]