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

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



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.


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.


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.


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.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Silverchair Information Systems
Loading ...
Support Center