Transcript Interim National Salmonella Reference Laboratory

National Salmonella Reference
Laboratory
(NSRL)
C. O’ Hare, N. Delappe, G. Doran, D. Morris, D. Kilmartin, ,A. Lawlor
Capt. P. Scarlett, M. Cormican, and G. Corbett-Feeney
Department of Bacteriology
Clinical Science Institute
National University of Ireland, Galway
Tel: 353-91-544628
Fax: 353-91-512514
Abstract
The National Salmonella Reference Laboratory (NSRL) was established in
January 2000 with funding through the Western Health Board from the
Department of Health and Children. Dr.Tom Moffat, Minister for State,
officially launched the service in March 2000. The service is provided from
the laboratory of the Department of Bacteriology, National University of
Ireland, Galway on an interim basis pending a decision as to the need for, and
location of, a definitive National Salmonella Reference Laboratory.
The NSRL adds a national public health dimension in support of the work of
the country’s clinical laboratories. The laboratory assists in the epidemiology
and surveillance of Salmonella enterica isolates by the routine testing of
serotyping, extended antimicrobial susceptibilites, phage typing and molecular
analysis of submitted isolates. By assembly of all Salmonella enterica isolates
in a single laboratory, the NSRL facilitates recognition and confirmation of
links between individual cases of infection, even where outbreaks are widely
dispersed. This poster summarises the progress of the NSRL in 2001 and
outlines potential issues for the future.
Introduction
Salmonella infection is a significant global public health problem. The species of
bacterium associated with salmonellosis is Salmonella enterica , of which there are
more than 2000 serotypes. The Salmonella enterica serotypes associated with
gastroenteritis in humans are often present in the gastrointestinal tract of animals
including animals intended for human consumption. The primary source of human
infection is by transfer from animals to humans through the food chain, although
person-to-person transfer may also occur.
Most cases of human infection with salmonella are associated with an
acute self-limiting gastrointestinal illness, characterised by diarrhoea, abdominal
cramps, fever and vomiting. However, in a proportion of cases, especially among
the very young, the elderly and those with impaired immune function, the bacteria
may invade the blood stream and cause very serious life-threatening infection.
The NSRL provides an overview of the epidemiology and burden of
disease caused by salmonella infection in Ireland today. Another important role of
the NSRL is the extended sensitivity testing of salmonella isolates. Resistance of
bacteria to antibiotics is an increasing concern throughout the world and laboratory
susceptibility testing of isolates is important both as a guide to the therapy of
individual patients and as an indicator of the nature and extent of the problem of
resistance. Comprehensive standardised antimicrobial sensitivity testing and
molecular techniques are also applied to strains to determine how closely bacteria
are related.
Introduction
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Salmonella enterica is a global health problem
>2000 serotypes
The primary source of human infection is by transfer from
animals to humans through the food chain
Mostly illness is acute self-limiting gastroenteritis
But can be fatal in old/young or immunosuppressed
Isolation
Clinical: Faeces plated onto Xylose lysine deoxycholate (XLD)
selective agar, 37oC.
Food: Enrichment in peptone water
Subculture to Selective enrichment RVB or Selenite
Plate on selective XLD or BGA media, all 37oC
Materials and Methods
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Serotyping:
- performed by slide agglutination using commercial standard
antisera, according to the Kauffmann-White classification scheme
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Antibiotic Sensitivity testing:
- performed by the NCCLS disk-diffusion method against a panel
of 15 antimicrobial agents.
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Phage typing:
- performed on all S.Typhimurium and S.Enteritidis isolates using
the overlay/ lysis method developed by PHLS, Colindale, UK.
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Pulsed Field Gel Electrophoresis:
- molecular analysis according to standard guidelines by
PulseNet, CDC, USA.
Serotypes of Salmonella enterica
in Ireland in 2001
Heidelberg
1%
Brandenburg
1%
Stanley
1%
Bredeney
2%
Virchow
3%
Kentucky
1%
Hadar
1%
Others
10%
Dublin
2%
Enteritidis
46%
Typhimurium
32%
Enteritidis
Typhimurium
Virchow
Dublin
Bredeney
Heidelberg
Stanley
Brandenburg
Hadar
Kentucky
Others
Phage Typing
Phage lysis areas on a plate overlayed with Salmonella Typhimurium
culture, indicate a specific pattern with is referred to as a Phage type.
Pulse Field Gel Electrophoresis (PFGE)
PFGE analysis of XbaI -digested genomic DNA from phage types of
Salmonella Typhimurium
Quality Assurance
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NSRL is committed to ensuring the highest possible quality of service
and rapid turnaround. Reports are issued on most isolates within 5
days. In the case of isolates that present particular difficulty an interim
report is issued initially and a final report on completion.
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NSRL participates in a European proficiency testing scheme for
serotyping, phage typing and antibiotic susceptibility testing.
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The laboratory collaborates closely with the Laboratory of Enteric
pathogens in London. All phage types that have not previously been
detected or which yield unidentified patterns are sent there for
confirmation.
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The NSRL aspires to accreditation to provide assurance of its quality
of service and is involved in a pilot project with the National
Accreditation Board to achieve NAB accreditation.
Dissemination of Information
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Accumulated data is e-mailed to National Disease Surveillance Centre,
Food Safety Authority of Ireland and clinical microbiologists each
month.
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NDSC publishes updated summary tables in publication Epi-Info each
month
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NSRL is linked to the pan-European network Enternet through which
summary data is provided monthly to a coordinator in the UK.
Through this network, information and isolates for study have been
shared with colleagues in other countries who are investigating
particular incidents or concerns.
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A pilot project to transmit results via encrypted e-mail is being
discussed with the NDSC.
Research
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It is important that a Reference Laboratory should be a focus of research
and development to ensure it can respond rapidly to new developments in
its field of expertise
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A number of Salmonella serotypes are currently under research focus with
regard to molecular analysis (PFGE and Plasmids). These include: S.
Typhimurium, S. Enteritidis, S. Kentucky, S. Kedougou and S. Bredeney
(the latter in association with Dr.S.Fanning, C.I.T., and Dr.J.Moore,
PHLS, N.Ireland).
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In collaboration with other groups, NSRL is operating a pilot study of
PFGE and PCR typing methods for Shigella sonnei, Listeria
monocytogenes, Campylobacter sp. and E.coli O157, and hope to offer a
molecular typing service for S.sonnei in 2003.
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A research ethos is maintained in the NSRL by close association with the
Dept. of Bacteriology in NUIG, e.g. the study of ESBL’s, and also
flouroquinolone resistance in Salmonella serotypes
Martin --Acknowledgements ???
Shea Fanning,
PHLS Colindale
FSAI
NDSC
Jim Moore
Cyril Carroll
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