Selection of SHV extended-spectrum-beta-lactamase-dependent cefotaxime and ceftazidime resistance in Klebsiella pneumoniae requires a plasmid-borne blaSHV gene
Hammond, David S., Harris, Tegan M., Bell, Jan, Turnidge, John, & Giffard, Philip M. (2008) Selection of SHV extended-spectrum-beta-lactamase-dependent cefotaxime and ceftazidime resistance in Klebsiella pneumoniae requires a plasmid-borne blaSHV gene. Antimicrobial Agents and Chemotherapy, 52(2), pp. 441-445.
In Klebsiella pneumoniae, it is common for plasmid-located and chromosome-located bla(SHV) copies to coexist within single cells. The plasmid-borne genes are mainly derived from two separate IS26-mediated mobilizations of bla(SHV). The objective of this study was to test the hypothesis that the presence of a non-extended-spectrum beta-lactamase (non-ESBL) encoding plasmid-borne form of bla(SHV) facilitates the cefotaxime (CTX)-mediated selection of ESBL-expressing mutants, even when there is a chromosomal copy of the same gene. Twenty-one diverse ESBL-negative, bla(TEM)-negative K. pneumoniae clinical isolates were tested for the IS26 insertions characteristic of the two mobilization events. The isolates were then tested for their ability to be selected for ESBL-mediated CTX resistance by serial subculturing with a doubling of the CTX concentration at every subculture. Fourteen isolates possessed neither of the IS26 insertions. None of these became ESBL positive, and all died during the course of the experiment, despite possessing chromosomal bla(SHV) copies. The other isolates all became ESBL positive and grew abundantly up to a CTX concentration of 128 microg/ml. Similar results were obtained with ceftazidime. ESBL expression was associated with the appearance of the expected G-->A mutation at position 1 of codon 238 and also with bla(SHV) copy number amplification. It was concluded that plasmid-borne bla(SHV) greatly facilitates the selection of ESBL expression, even when the same gene is on the chromosome, and that gene dosage effects are likely to contribute to this phenomenon.
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|Item Type:||Journal Article|
|Additional Information:||The contents of this journal can be freely accessed online via the journal's web page (see hypertext link) 4 months after publication.|
|Keywords:||infectious diseases, cells and tissue, ihbi, Anti, Bacterial Agents, Cefotaxime, Ceftazidime, Cephalosporin Resistance, DNA Transposable Elements, Klebsiella pneumoniae, Microbial Sensitivity Tests, Plasmids, genetics, beta, Lactamases|
|Subjects:||Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > MICROBIOLOGY (060500) > Microbiology not elsewhere classified (060599)|
Australian and New Zealand Standard Research Classification > TECHNOLOGY (100000) > MEDICAL BIOTECHNOLOGY (100400) > Medical Biotechnology not elsewhere classified (100499)
Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > MICROBIOLOGY (060500) > Infectious Agents (060502)
Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > GENETICS (060400) > Genetics not elsewhere classified (060499)
|Divisions:||Past > QUT Faculties & Divisions > Faculty of Science and Technology|
Current > Institutes > Institute of Health and Biomedical Innovation
|Copyright Owner:||Copyright 2008 American Society for Microbiology|
|Deposited On:||10 Jun 2008|
|Last Modified:||11 Oct 2012 14:24|
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