An Outbreak of An Outbreak of SalmonellaSalmonella Typhimurium DT49 in Typhimurium DT49 in

IrelandIrelandC. O’ HareC. O’ Hare

H. PellyH. Pelly

P. McKeownP. McKeown

M. Di RenziM. Di Renzi

G. Corbett-FeeneyG. Corbett-Feeney

M. CormicanM. Cormican

Map & KeyMap & Key

County Dublin

County Longford

County Roscommon

1 dot = 1 case of Salmonellosis (random placing)

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

Case Ascertainment• All patients with Salmonella Typhimurium infection in Irelandwith 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

Epidemic curve, by date of onset of symptoms

10 Number of cases9 Restaurant closed8

7

6 Member of the staff5

4

3

2

1

Date of onset of symptoms

1915 16 17 1811 12 13 14 20 21

April4 5 6 7 8 9 10

Chicken Stuffing Pepper sauceRed pepper sauce Meringue Manufactured ice-creamTiramisu Egg white Whipped creamRaw shelled eggs Coleslaw

Foodstuffs analysed by Food laboratory from Restaurant X

10 Number of cases9 Voluntary Closure Order 8 Restaurant closed all day7

6

5

4

3

2

1

20 2116 17 18 1912 13 14 158 9 10 114 5 6 7

Epidemic curve, by date of eating in restaurant X

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)

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 0.1Liquid egg(5th and 11th)

Foods containing 7/7 4/9 /// 0.03Liquid egg (11th)

Relationship between Food exposure and salmonellosis (Univariate)

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

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 antibiogramsA : ampicillin, streptomycin and kanamycin resistantB: fully susceptible

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. TyphimuriumLarge hospital outbreak, House of Lords outbreak

Molecular Analysis – PFGE

S. Typhimurium DT49 outbreak Isolates indistinguishable from each other andalso from isolates from previous years

XbaI restriction. S. Braenderup control

Molecular Analysis - Plasmids

marker 2-16kb

* ExtraPlasmidband

60kbmarker

90kbmarker

Serotype specific plasmid

Discussion

First outbreak of DT49 >2 people reported in Ireland

Prompt Intervention of Public Health

Epidemiological investigation showed that foods containing liquidegg were strongly associated with symptomsCross contamination ?

Role of Salmonella Reference Laboratory

Enter-net collaboration

Acknowledgements

Enter-netNational Disease Surveillance Center (NDSC)Food Safety Authority of Ireland (FSAI)

Area Medical officersEnvironmental Health officersInfection control nursesSurveillance scientists

NSRL Website address: http://www.nuigalway.ie/salmonella_lab/

From Midland Health BoardWestern Health BoardEastern Regional Health board