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Journal of Clinical Microbiology, November 2003, p. 5347-5348, Vol. 41, No. 11
0095-1137/03/$08.00+0 DOI: 10.1128/JCM.41.11.5347-5348.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.
Towards "Molecular Esperanto" or the Tower of Babel? (The Need for Harmonization of Techniques for Genotyping Clinical Isolates of Pseudomonas aeruginosa Isolated from Patients with Cystic Fibrosis)

LETTER
We read with interest the letter of Armstrong et al. (D. Armstrong,
S. Bell, M. Robinson, P. Bye, B. Rose, C. Harbour, C. Lee, H.
Service, M. Nissen, M. Syrmis, and C. Wainwright, Letter, J.
Clin. Microbiol.
41:2266-2267, 2003) describing the occurrence
of a clonal type (pulsotype I) of
Pseudomonas aeruginosa at
five cystic fibrosis (CF) centers along the east coast of Australia.
This letter strongly asserts that this clonal type has spread
to CF patients, not from either the hospital or external environments,
but by person-to-person transmission. This letter also describes
some of the recent events that have led to advances in molecular
typing techniques and thus to the identification of a dominant
and hypertransmissible clonal strain of
P. aeruginosa at several
CF centers. What this letter also demonstrates to the CF microbiology
community is that there is an urgent requirement for the standardization
and harmonization of genotyping techniques, both nationally
and internationally, where several methods presently exist for
strain characterization (for a detailed review of
P. aeruginosa typing, see reference
15).
Armstrong et al. (letter) cite several previous studies employing pulsed-field gel electrophoresis (PFGE) typing of P. aeruginosa. A methodological comparison highlighting technical variations in previous PFGE typing studies of P. aeruginosa is detailed in Table 1. Thus, Armstrong et al. were correct and diligent in comparing interlaboratory variability in deciding the relatedness of isolates from five CF centers, when more than one microbiology laboratory was involved in strain analysis.
Recently Jones et al. (
9) have stressed the importance of microbiological
surveillance through molecular fingerprinting, namely, PFGE
typing, in order to ascertain the extent of cross-infection
of
P. aeruginosa among CF patients. PFGE is no longer a method
solely restricted to epidemiological typing research studies,
but is one which is now used in many clinical diagnostic laboratories
to aid with routine epidemiological analysis. Laboratories which
are introducing such techniques for the analysis of their
P. aeruginosa subtypes should adopt protocols that will yield data
for their isolates which can be compared with data from other
CF centers. This strategy has been successfully applied for
typing enteric bacterial pathogens through the PulseNet system
(
www.cdc.gov/pulsenet). The exchange of typing data obtained
by employing standardized and harmonized methods, via an electronic
medium, as has been developed recently by the ESF Network for
Exchange of Microbial Typing Information (
http://lists.nottingham.ac.uk/mailman/listinfo/enemti),
would facilitate our understanding of the molecular epidemiology
of
P. aeruginosa in CF patient populations.
Consensus is thus needed in order to ascertain if such differences, for example, different suppliers of restriction enzymes, internal standards, pulse field parameters, etc., are significant or not. If the effects of such differences are not known, then a feasibility study involving several centers needs to be undertaken to resolve these technical anomalies, so that a robust method may be adopted by the CF microbiology community. If it felt that such a trial is unnecessary, then it will be a relatively easy task to define a consensus PFGE protocol that will gain widespread acceptance.
The real treasure to the CF microbiology community of adopting standardized and harmonized genotyping protocols such as PFGE is that it will allow us to identify transmissible types locally as well as globally and provide a basis for the examination of virulence in common genotypes. If we fail to attempt to learn a form of "molecular Esperanto" in terms of speaking a common language of harmonized and standardized methodology, we will potentially suffer, as befell the Israelites in Old Testament times with the Tower of Babel (Genesis 11), from misunderstanding. Indeed, if we cannot communicate with each other, we can hardly cooperate with each other.

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John E. Moore* Colin E. Goldsmith
Northern Ireland Public Health Laboratory Department of Bacteriology
J. Stuart Elborn
Northern Ireland Regional Adult Cystic Fibrosis Centre Belfast City Hospital Belfast BT9 7AD, Northern Ireland
Philip G. Murphy
Department of Microbiology The Adelaide and Meath Hospital Tallaght Dublin, Ireland
Peter H. Gilligan
Clinical Microbiology-Immunology Laboratories UNC Hospitals Chapel Hill, NC 27514
Séamus Fanning
Faculty of Veterinary Medicine University College Dublin Belfield Dublin 4, Ireland
Graham Hogg
Department of Bacteriology The Royal Group of Hospitals Grosvenor Road Belfast BT12 6BA, Northern Ireland
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* Phone: 44 (28) 9026 3554, Fax: 44 (28) 2589 2887, E-mail: jemoore{at}niphl.dnet.co.uk |
Journal of Clinical Microbiology, November 2003, p. 5347-5348, Vol. 41, No. 11
0095-1137/03/$08.00+0 DOI: 10.1128/JCM.41.11.5347-5348.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.
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