BlaSHV genes in Klebsiella pneumoniae: Different allele distributions are associated with different promoters within individual isolates

Hammond, David S., Schooneveldt, Jacqueline M., Nimmo, Graeme R., Huygens, Flavia and Giffard, Philip M. (2005) BlaSHV genes in Klebsiella pneumoniae: Different allele distributions are associated with different promoters within individual isolates. Antimicrobial Agents and Chemotherapy, 49 1: 256-263. doi:10.1128/AAC.49.1.256-263.2005

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Author Hammond, David S.
Schooneveldt, Jacqueline M.
Nimmo, Graeme R.
Huygens, Flavia
Giffard, Philip M.
Title BlaSHV genes in Klebsiella pneumoniae: Different allele distributions are associated with different promoters within individual isolates
Formatted title
BlaSHV genes in Klebsiella pneumoniae: Different allele distributions are associated with different promoters within individual isolates
Journal name Antimicrobial Agents and Chemotherapy   Check publisher's open access policy
ISSN 0066-4804
1098-6596
Publication date 2005-01
Sub-type Article (original research)
DOI 10.1128/AAC.49.1.256-263.2005
Open Access Status File (Publisher version)
Volume 49
Issue 1
Start page 256
End page 263
Total pages 8
Place of publication Washington, DC, United States
Publisher American Society for Microbiology
Language eng
Subject 1108 Medical Microbiology
1115 Pharmacology and Pharmaceutical Sciences
Formatted abstract
Extended-spectrum ß-lactamases (ESBLs) emerge by point mutation from non-extended-spectrum precursors. The aims of this study were to reveal the basis for variations in resistance levels found in a collection of 21 Klebsiella pneumoniae clinical isolates from Brisbane, Australia. Previous studies have shown that 20 of these isolates possess blaSHV-11, blaSHV-2a, and/or blaSHV-12, and there is an association between the copy numbers of the ESBL-encoding genes and resistance levels. In this study, a real-time PCR method for interrogating the polymorphic sites at codons 238 and 240 was developed, and this confirmed the relationship between mutant gene copy numbers and resistance levels. The blaSHV promoter region was cloned from one of the ESBL-expressing isolates, and this showed that blaSHV genes exist downstream of two different promoters within this single isolate. These promoters have both been reported previously, and they differ by virtue of the presence or absence of an IS26 insertion. The blaSHV copy numbers in cis with the different promoters were measured, and the copy number of the IS26 promoter was correlated with resistance levels. Cloning and analysis of PCR products showed that different blaSHV variants existed in cis with individual promoters in individual isolates but that mutant genes were more abundant downstream of the IS26 promoter. There were no ESBL-positive isolates without this promoter. It was concluded that blaSHV in cis with the IS26 promoter is located on an amplifiable replicon, and the presence of the IS26 insertion may facilitate the acquisition of an ESBL-positive phenotype. Copyright © 2005, American Society for Microbiology
Keyword blaSHV Genes
Alleles
Klebsiella pneumoniae
Isolates
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Medicine Publications
 
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Created: Tue, 19 Jan 2010, 14:39:40 EST by Gerald Martin on behalf of Faculty Of Health Sciences