JAC Advance Access originally published online on May 5, 2004
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Journal of Antimicrobial Chemotherapy (2004) 53, 1076-1080
© 2004 The British Society for Antimicrobial Chemotherapy
Citrobacter koseri and Citrobacter amalonaticus isolates carry highly divergent ß-lactamase genes despite having high levels of biochemical similarity and 16S rRNA sequence homology
Bristol Centre for Antimicrobial Research and Evaluation, Department of Pathology & Microbiology, University of Bristol, School of Medical Sciences, University Walk, Bristol BS8 1TD, UK
Received 25 February 2004; accepted 12 March 2004
Objectives: Isolates previously identified as Citrobacter diversus are now known as Citrobacter koseri. We measured sequence variation at the ß-lactamase structural gene among a group of clinical isolates originally identified as C. diversus by API 20E profiling.
Methods: ß-Lactamase and 16S rRNA genes were amplified by PCR and sequenced by standard methods. ß-Lactamase induction was attempted in liquid-grown cultures using cefoxitin. Nitrocefin hydrolysis assays were performed using a spectrophotometer.
Results: Analysis of 16S rRNA gene sequences showed that Citrobacter spp. isolates with an inducible ß-lactamase gene, cdiA, closely related to ‘C. koseri ’ NF85 and ULA27 are actually Citrobacter amalonaticus. C. koseri isolates, whose identities were confirmed by 16S rRNA sequencing, produce a class A ß-lactamase, Cko, constitutively at low levels. The cko and cdiA ß-lactamase genes share <45% identity.
Conclusions: We have confirmed that cko is a ß-lactamase gene carried by C. koseri, and that isolates previously identified as ‘C. koseri ’, but carrying the cdiA ß-lactamase gene are C. amalonaticus. Thus, ß-lactamase-gene-specific PCR may provide a valuable tool to differentiate these biochemically homogeneous Citrobacter species.
Keywords: Citrobacter, ß-lactamases, phylogenetics, induction
* Corresponding author. Tel: +44-117-9287897; Fax: +44-117-9287896; E-mail: Matthewb.Avison{at}bris.ac.uk
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  C. Arpin, C. Quentin, F. Grobost, E. Cambau, J. Robert, V. Dubois, L. Coulange, C. Andre, and on behalf of the Scientific Committee of ONERBA Nationwide survey of extended-spectrum {beta}-lactamase-producing Enterobacteriaceae in the French community setting J. Antimicrob. Chemother., June 1, 2009; 63(6): 1205 - 1214. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. A. Jacoby AmpC {beta}-Lactamases Clin. Microbiol. Rev., January 1, 2009; 22(1): 161 - 182. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Naas, D. Aubert, A. Ozcan, and P. Nordmann Chromosome-Encoded Narrow-Spectrum Ambler Class A {beta}-Lactamase GIL-1 from Citrobacter gillenii Antimicrob. Agents Chemother., April 1, 2007; 51(4): 1365 - 1372. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Mugnaioli, F. Luzzaro, F. De Luca, G. Brigante, G. Amicosante, and G. M. Rossolini Dissemination of CTX-M-Type Extended-Spectrum {beta}-Lactamase Genes to Unusual Hosts J. Clin. Microbiol., August 1, 2005; 43(8): 4183 - 4185. [Abstract] [Full Text] [PDF]
|
|