Multiresistant Pseudomonas aeruginosa in a pediatric cystic fibrosis center:

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Pediatric Pulmonology

Volume 35, Issue 4, 2003. Pages: 253-256

Published Online: 5 Mar 2003

Copyright © 2003 Wiley-Liss, Inc.

Multiresistant Pseudomonas aeruginosa in a pediatric cystic fibrosis

center: Natural history and implications for segregation

G. Davies, MBChB, D. McShane, MBChB, MRCPCH, J.C. Davies, MD, MRCPCH, A.

Bush, MD, FRCPCH *

Department of Paediatric Respiratory Medicine, Royal Brompton and

Harefield NHS Trust, London, UK

email: A. Bush (A.Bush@...)

*Correspondence to A. Bush, Department of Paediatric Respiratory

Medicine, Royal Brompton and Harefield NHS Trust, London SW3 6NP,

UK.setDOI( " ADOI=10.1002/ppul.10262 " )Keywords

cystic fibrosis • Pseudomonas aeruginosa • segregation

Abstract

It has been suggested that cystic fibrosis (CF) patients harboring

multiresistant (MR) Pseudomonas aeruginosa (PA) should be seen in

separate clinics. The aim of this study was to test the feasibility of

this by longitudinally studying the consistency of isolates of MRPA in

individuals. We analyzed all respiratory tract cultures undertaken in 1

year from a pediatric CF clinic population (n = 367). PA was classified

as MR according to the definition of the American CF Foundation:

resistance to all agents in at least two of the following groups of

antibiotics: -lactams, aminoglycosides, and fluroquinolones. PA was

cultured from 96 children during the year of study. Thirty-six were

infected with at least one MR strain. Following initial identification of

MRPA, MR in subsequent cultures was highly variable. Twenty-three of 36

patients had subsequent cultures in which PA was identified. However, 21

of 23 patients had at least one isolate that was not MR following

detection of MRPA. The variability with time in isolation of MR strains

from individuals demonstrates the potential difficulties in designing

segregation policies based on antibiotic sensitivity patterns. Pediatr

Pulmonol. 2003; 35:253-256. © 2003 Wiley-Liss, Inc

Received: 13 July 2002; Accepted: 21 November 2002Digital Object

Identifier (DOI)

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Journal of Bacteriology, April 2003, p. 2080-2095, Vol. 185, No. 7

Copyright © 2003, American Society for Microbiology. All Rights Reserved.

Microarray Analysis of Pseudomonas aeruginosa Quorum-Sensing Regulons:

Effects of Growth Phase and Environment

E. Wagner,1 Bushnell,1 Luciano Passador,1 I.

,2 and Barbara H. Iglewski1* Department of Microbiology and

Immunology, University of Rochester School of Medicine and Dentistry,1

Department of Environmental Medicine and Center for Functional Genomics,

University of Rochester Medical Center, Rochester, New York

146422Received 6 September 2002/ Accepted 30 December 2002Bacterial

communication via quorum sensing (QS) has been reported to be important

in the production of virulence factors, antibiotic sensitivity, and

biofilm development. Two QS systems, known as the las and rhl systems,

have been identified previously in the opportunistic pathogen Pseudomonas

aeruginosa. High-density oligonucleotide microarrays for the P.

aeruginosa PAO1 genome were used to investigate global gene expression

patterns modulated by QS regulons. In the initial experiments we focused

on identifying las and/or rhl QS-regulated genes using a QS signal

generation-deficient mutant (PAO-JP2) that was cultured with and without

added exogenous autoinducers [N-(3-oxododecanoyl) homoserine lactone and

N-butyryl homoserine lactone]. Conservatively, 616 genes showed

statistically significant differential expression (P  0.05) in response

to the exogenous autoinducers and were classified as QS regulated. A

total of 244 genes were identified as being QS regulated at the

mid-logarithmic phase, and 450 genes were identified as being QS

regulated at the early stationary phase. Most of the previously reported

QS-promoted genes were confirmed, and a large number of additional

QS-promoted genes were identified. Importantly, 222 genes were identified

as being QS repressed. Environmental factors, such as medium composition

and oxygen availability, eliminated detection of transcripts of many

genes that were identified as being QS regulated. * Corresponding author.

Mailing address: Department of Microbiology and Immunology, Box 672,

University of Rochester School of Medicine and Dentistry, Rochester, NY

14642. Phone: . Fax: . E-mail:

bigl@....  For a commentary on this article, see page 2061

in this issue. Journal of Bacteriology, April 2003, p. 2080-2095, Vol.

185, No. 7

Copyright © 2003, American Society for Microbiology. All Rights Reserved.

Becki

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