Format

Send to

Choose Destination
J Antimicrob Chemother. 2009 Nov;64(5):960-4. doi: 10.1093/jac/dkp338. Epub 2009 Sep 12.

Plasmid-borne blaSHV genes in Klebsiella pneumoniae are associated with strong promoters.

Author information

1
Institute of Heath and Biomedical Innovation, Queensland University of Technology, Musk Ave., Kelvin Grove, QLD 4059, Australia.

Abstract

BACKGROUND:

Extended-spectrum beta-lactamases (ESBLs) belonging to the SHV family remain a major cause of ESBL-positive phenotypes in Klebsiella pneumoniae. The bla(SHV) gene is a normal constituent of the K. pneumoniae chromosome. However, most ESBL-encoding bla(SHV) genes found in K. pneumoniae are plasmid borne. The objective was to determine the contribution of promoter variants to the expression of plasmid-borne bla(SHV) genes.

METHODS:

K. pneumoniae clinical isolates were analysed for the presence of IS26 insertions characteristic of plasmid-borne bla(SHV), and differences in their bla(SHV) promoter sequences and expression levels. A high resolution melting (HRM)-based method for rapid promoter analysis was developed.

RESULTS:

An IS26 insertion characteristic of the plasmid-borne bla(SHV-1)/bla(SHV-2)/bla(SHV-5) family was 100% linked to a promoter mutated in the -10 region, a mutation previously only found on the chromosome. The mutation was shown by real-time reverse transcriptase PCR to be associated with increased bla(SHV) expression.

CONCLUSIONS:

Plasmid-borne bla(SHV) is associated with strong promoters. It is likely that an SHV-dependent ESBL-positive phenotype requires both a strong promoter and a coding sequence mutation. An HRM assay can indicate bla(SHV) expression.

PMID:
19749204
DOI:
10.1093/jac/dkp338
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Silverchair Information Systems
Loading ...
Support Center