An Outbreak of Salmonella Typhimurium DT49 in Ireland

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An Outbreak of Salmonella Typhimurium DT49 in
Ireland

• C. O Hare
• H. Pelly
• P. McKeown
• M. Di Renzi
• G. Corbett-Feeney
• M. Cormican

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Map Key
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Case Definitions
Probable case Diarrhoea plus or minus one or
more of fever, headache, abdominal pain,
nausea, vomiting, confusion, bloody stools AND
ate at restaurant X between the 4th and the 19th
April 2004 Confirmed case criteria of a
probable case and had laboratory confirmation of
Salmonella Typhimurium
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• Case Ascertainment
• All patients with Salmonella Typhimurium
  infection in Ireland
• with date of onset of symptoms between the 4th
  April and
• the 21st April, were asked if they had eaten in
  restaurant X.
• Contacts of cases who had also eaten at the
  restaurant were
• interviewed and stool samples were obtained.
• Characteristics of Cases
• 9 confirmed cases, 1 probable case
• 8/10 female (1 food handler)
• Mean age 36.5 years (range 8-77 years)
• Hospital admission required in 3/10 cases
• One isolate was invasive and was cultured from
  blood
• No fatalities

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Epidemic curve, by date of onset of symptoms
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Epidemic curve, by date of eating in restaurant X
Foodstuffs analysed by Food laboratory from
Restaurant X
Chicken Stuffing Pepper sauce Red pepper
sauce Meringue Manufactured ice-cream Tiramisu
Egg white Whipped cream Raw shelled
eggs Coleslaw
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• Case control Studies
• 10 Cases (9 confirmed)
• 26 controls (including)
• 13 controls (asymptomatic contacts who dined in
  
• restaurant X during the period 4th to 19th April)
• 13 staff members (asymptomatic contacts who
• confirmed that they consistently ate on the
  premises)

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Relationship between Food exposure and
salmonellosis (Univariate)
Foodstuff Cases Controls OR P
value Tiramisu 5/10 4/26 5.5 0.04 (5th and
11th) Tiramisu 3/7 0/9 /// 0.06 (11th) Foods
containing 9/10 16/26 5.6 0.1 Liquid egg (5th
and 11th) Foods containing 7/7 4/9 /// 0.03 Liq
uid egg (11th)
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• Salmonella Reference laboratory
• Serology (Kauffmann-White scheme)
• Phage type (Anderson scheme)
• Antimicrobial susceptibility (Disk Diffusion
  NCCLS)
• PFGE (Pulse Net, CDC, USA)
• Plasmid profile (Kado and Liu)
• 9/10 patient isolates were received by NSRL

Microbiology
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Antimicrobial Susceptibility Isolates tested
against a panel of 14 antimicrobials Results
8 isolates were susceptible to all
antimicrobials tested 1 sample contained 2
isolates with different antibiograms A
ampicillin, streptomycin and kanamycin
resistant B fully susceptible
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S. Typhimurium DT49 in Europe Ireland From
2001-2004 5 isolates all human. Not travel
associated Enter-net data Austria From
2003-2004 2 probable DT49. Travel to
Turkey? Finland 2003 One isolate DT49.
Travel to Mexico Denmark From 2000-2004 no
human cases. 1998-1999 4 DT49 in pigs England
and Wales From 1984-1988 DT49 was most common
phage type of S. Typhimurium Large hospital
outbreak, House of Lords outbreak
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Molecular Analysis PFGE
XbaI restriction. S. Braenderup control
S. Typhimurium DT49 outbreak Isolates
indistinguishable from each other and also from
isolates from previous years
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Molecular Analysis - Plasmids
Serotype specific plasmid

Extra Plasmid band
90kb marker
60kb marker
l marker 2-16kb
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Discussion First outbreak of DT49 gt2 people
reported in Ireland Prompt Intervention of
Public Health Epidemiological investigation
showed that foods containing liquid egg were
strongly associated with symptoms Cross
contamination ? Role of Salmonella Reference
Laboratory Enter-net collaboration
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Acknowledgements Enter-net National Disease
Surveillance Center (NDSC) Food Safety Authority
of Ireland (FSAI) Area Medical
officers Environmental Health officers Infection
control nurses Surveillance scientists NSRL
Website address http//www.nuigalway.ie/salmone
lla_lab/
From Midland Health Board Western Health
Board Eastern Regional Health board