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Sequences of small blaTEM-encoding plasmids in Haemophilus influenzae and description of variants falsely negative for blaTEM by PCR


Tristram, SG and Franks, LR and Harvey, GL, Sequences of small blaTEM-encoding plasmids in Haemophilus influenzae and description of variants falsely negative for blaTEM by PCR, Journal of Antimicrobial Chemotherapy, 67, (11) pp. 2621-2625. ISSN 0305-7453 (2012) [Refereed Article]

Copyright Statement

Copyright 2012 the authors.

DOI: doi:10.1093/jac/dks264


Objectives: To characterize an unidentified β-lactamase and associated genetic background in a blaTEM and blaROB PCR-negative Haemophilus influenzae isolate, and characterize small blaTEM-encoding plasmids in a collection of H. influenzae.

Methods: The unidentified β-lactamase gene was identified by cloning and sequencing the encoding plasmid. Strains with small blaTEM plasmids were identified using negative PCR for integrative conjugative elements, but positive blaTEM PCR; plasmids from selected isolates were sequenced. PCR for rep and divergent blaTEM were evaluated for detecting small plasmids on selected H. influenzae isolates.

Results: Small plasmids (4.8-5.5 kb) encoding blaTEM appear to be associated with remnants of Tn2 on a conserved plasmid core. The unidentified β-lactamase was actually a TEM-1, with negative blaTEM PCR associated with a previously unrecognized deletion of bp 1-27 of bla(TEM) (Sutcliffe numbering) associated with a larger deletion within Tn2. This deletion was found in other isolates and may be more common than previously thought. PCR for the conserved rep gene appears useful for screening for small blaTEM-encoding plasmids or associated cryptic plasmids in H. influenzae.

Conclusions: Small blaTEM-encoding plasmids in H. influenzae appear relatively conserved, but require further study to confirm this. PCR associated with the rep gene may be useful for studying these small plasmids. A deletion in part of blaTEM in some strains may interfere with some PCRs; therefore, care should be taken with primer selection or design and, preferably, regions within the open reading frame should be targeted.

Item Details

Item Type:Refereed Article
Keywords:b-lactamases, TEM, transposons
Research Division:Biomedical and Clinical Sciences
Research Group:Medical microbiology
Research Field:Medical bacteriology
Objective Division:Health
Objective Group:Clinical health
Objective Field:Clinical health not elsewhere classified
UTAS Author:Tristram, SG (Dr Stephen Tristram)
UTAS Author:Franks, LR (Miss Lauren Franks)
UTAS Author:Harvey, GL (Mr Gareth Harvey)
ID Code:80267
Year Published:2012
Web of Science® Times Cited:9
Deposited By:Health Sciences A
Deposited On:2012-10-25
Last Modified:2014-11-25

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