Virginia C Gould1, Aki Okazaki, Robin A Howe, Matthew B Avison. 1. Bristol Centre for Antimicrobial Research and Evaluation, Department of Pathology & Microbiology, University of Bristol, School of Medical Sciences, University Walk, Bristol, BS8 1TD, UK.
Abstract
OBJECTIVES: To determine the level of variation in the smeDEF efflux pump and smeT transcriptional regulator genes among three defined 16S rRNA sequence subgroups of clinical Stenotrophomonas maltophilia isolates. METHODS: smeDEF sequencing used a PCR genome walking approach. Determination of the sequence surrounding smeDEF used a flanking primer PCR method and specific primers anchored in smeD or smeF together with random primers. RESULTS: smeDEF is chromosomal and located in the same position in the chromosome in all three subgroups of isolates. Flanking smeD is a gene, smeT, encoding a putative transcriptional repressor for smeDEF. Variation at these loci among the isolates is considerably lower (up to 10%) than at intrinsic beta-lactamase loci (up to 30%) in the same isolates, implying greater functional constraint. The smeD-smeT intergenic region contains a highly conserved section, which maps with previously predicted promoter/operator regions, and a hypervariable untranslated region, which can be used to subgroup clinical isolates. CONCLUSIONS: These data provide further evidence that it is possible to group clinical isolates of the inherently variable species, S. maltophilia, based on genotypic properties. Isolate D457, in which most work concerning smeDEF expression has been performed, does not fall into S. maltophilia subgroup A, which is the most typical.
OBJECTIVES: To determine the level of variation in the smeDEF efflux pump and smeT transcriptional regulator genes among three defined 16S rRNA sequence subgroups of clinical Stenotrophomonas maltophilia isolates. METHODS: smeDEF sequencing used a PCR genome walking approach. Determination of the sequence surrounding smeDEF used a flanking primer PCR method and specific primers anchored in smeD or smeF together with random primers. RESULTS: smeDEF is chromosomal and located in the same position in the chromosome in all three subgroups of isolates. Flanking smeD is a gene, smeT, encoding a putative transcriptional repressor for smeDEF. Variation at these loci among the isolates is considerably lower (up to 10%) than at intrinsic beta-lactamase loci (up to 30%) in the same isolates, implying greater functional constraint. The smeD-smeT intergenic region contains a highly conserved section, which maps with previously predicted promoter/operator regions, and a hypervariable untranslated region, which can be used to subgroup clinical isolates. CONCLUSIONS: These data provide further evidence that it is possible to group clinical isolates of the inherently variable species, S. maltophilia, based on genotypic properties. Isolate D457, in which most work concerning smeDEF expression has been performed, does not fall into S. maltophiliasubgroup A, which is the most typical.
Authors: María Carmen Turrientes; María Rosario Baquero; María Blanca Sánchez; Sylvia Valdezate; Esther Escudero; Gabrielle Berg; Rafael Cantón; Fernando Baquero; Juan Carlos Galán; José Luis Martínez Journal: Appl Environ Microbiol Date: 2010-01-22 Impact factor: 4.792
Authors: Lisa C Crossman; Virginia C Gould; J Maxwell Dow; Georgios S Vernikos; Aki Okazaki; Mohammed Sebaihia; David Saunders; Claire Arrowsmith; Tim Carver; Nicholas Peters; Ellen Adlem; Arnaud Kerhornou; Angela Lord; Lee Murphy; Katharine Seeger; Robert Squares; Simon Rutter; Michael A Quail; Mari-Adele Rajandream; David Harris; Carol Churcher; Stephen D Bentley; Julian Parkhill; Nicholas R Thomson; Matthew B Avison Journal: Genome Biol Date: 2008-04-17 Impact factor: 13.583
Authors: Martin Pilhofer; Andreas Peter Bauer; Martina Schrallhammer; Lothar Richter; Wolfgang Ludwig; Karl-Heinz Schleifer; Giulio Petroni Journal: Nucleic Acids Res Date: 2007-10-16 Impact factor: 16.971