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International Journal of Microbiology
Volume 2011, Article ID 712618, 6 pages
http://dx.doi.org/10.1155/2011/712618
Research Article

The Effect of Sub-MIC β-Lactam Antibiotic Exposure of Pseudomonas aeruginosa Strains from People with Cystic Fibrosis in a Desiccation Survival Model

1Regional Adult Cystic Fibrosis Unit, St James University Hospital, Leeds LS9 7TF, UK
2Department of Microbiology, Leeds General Infirmary, Leeds LS1 3EX, UK

Received 9 May 2011; Accepted 20 July 2011

Academic Editor: Haichun Gao

Copyright © 2011 I. J. Clifton et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Prior to modern typing methods, cross-infection of P. aeruginosa between people with cystic fibrosis (CF) was felt to be rare. Recently a number of studies have demonstrated the presence of clonal strains of P. aeruginosa infecting people with CF. The aim of this study was to determine whether strains of P. aeruginosa demonstrated differences in resistance to desiccation and whether preincubation in subminimum inhibitory concentrations (MICs) of β-lactam affected desiccation resistance. The experimental data were modelled to a first-order decay model and a Weibull decay model using least squares nonlinear regression. The Weibull model was the preferred model for the desiccation survival. The presence of a mucoid phenotype promoted desiccation survival. Preincubation with antibiotics did not have a consistent effect on the strains of P. aeruginosa. Meropenem reduced desiccation resistance, whereas ceftazidime had much less effect on the strains studied.