Beth Daly, MPH Communicable Disease Epidemiologist Communicable Disease Surveillance Section

NH Department of Health and Human ServicesDivision of Public Health Services

Salmonella Oranienburg Infections associated with Fruit Salad Served in Healthcare Settings—Northeastern

United States, June-July 2006

Beth Daly, MPH

Communicable Disease Epidemiologist

Communicable Disease Surveillance Section


Salmonellosis• US: >30,000 infections reported each year

• NH: 2nd most common bacterial foodborne illness with 150-200 cases each year

• >2500 different serotypes

• Poultry and cattle serve as reservoirs

• Source of outbreaks include meat, produce, ill food service workers, etc.

• Primarily diarrheal illness

• Illness lasts 2-5 days

• Incubation period 6-72 hours


Salmonella Oranienburg

• 13th most common serotype of Salmonella reported to CDC

– 495 cases reported in 2004 (1.4%)

• 9 outbreaks reported to CDC since 1996

• Outbreaks associated with meats and produce

– Ground beef, chicken, pizza, mango


Salmonella Surveillance

• Mandated reporting of salmonellosis in NH

• Reports received from HCP, ICP, laboratories

• For each case reported there are an estimated 38 cases that go unreported



Pulsed Field Gel Electrophoresis

• Isolated bacteria from each case used

• DNA from the bacteria is restricted by an enzyme and undergoes electophoresis to produce a pattern or DNA fingerprint

• Patterns compared to determine if isolated organisms are different, similar, or indistinguishable

• Two-enzyme approach used


PFGE Analysis


Use of PFGE in Surveillance• NH PHL performs PFGE on all isolates of:– Campylobacter– Salmonella– Shigella– Listeria– E. coli O157:H7

• These patterns are entered into a national and state database to look for “matches”

• This allows for recognize of local and multi-state outbreaks


Nosocomial Salmonellosis

• Uncommon in developed countries

• Healthcare facilities (HCF) don’t test for salmonellosis in patients hospitalized >72 hours with diarrhea

– C. diff the most common cause of hospital acquired diarrhea

• Since 1960, 56 outbreaks have been described– Most often associated with food, feed, visitors, staff

– 9 occurred in the US, most recent in 2002 and 1996


NH Outbreak• July 19th: NH DHHS investigated a

salmonellosis outbreak at a local hospital

• Initially 5 cases identified

– 2 patients, 2 HCP, 1 cafeteria patron

• 3 of 5 cases determined to be S. Oranienburg

• Concerns about medical devices, ill HCP, or ill FSW

• Challenging disease control approach


Immediate Infection Control

• Active surveillance and exclusion among staff in affected units– Shift change sign-in

• Mandatory in-service training to staff

• Alert hospital-wide email

• Inspection of hospital kitchen

• Routine salmonellosis testing for patients with diarrhea


Multistate Outbreak Recognition

• July 19th: NH DHHS and MHD investigated outbreak of S. Oranienburg at local hospital

• July 21st: MA DPH reported S. Oranienburg cases at local LTCF

• NH cases and other northeastern states report cases with the same PFGE pattern as MA cases

• Xbal pattern uncommon and seen only 14 times prior to this cluster

• BlnI pattern not seen before


Frequency of BlnI Patterns in S. Oranienburg with the Xbal JJXX01.0056 Pattern, 1998-2006

0

10

20

30

40

50

60

1998 1999 2000 2001 2002 2003 2004 2005 2006

Unknown JJXA26.0005 JJXA26.0017


Methods- Case Finding• Case Definition: culture-confirmed cases of S.

Oranienburg with

– Illness onset after June 1st

– Xbal pattern JJXX01.0056 and Blnl pattern JJA26.0017 if available

• PulseNet queried weekly

• Announcements on listserves: foodborne outbreaks, promed mail, SHEA, APIC, EIN

• Active case finding in affected facilities


Methods- Hypothesis Generation

• Routine surveillance questionnaires reviewed

• Extended questionnaires administered to small subset of cases– 300 exposures including 234 food items

• Facilities with cases surveyed to determine brand and distributor information for fruit salad served in the facility

• 26 unaffected facilities in NH surveyed for comparison


Methods- Case Control Study• Case control study conducted between August

15th and September 6th

• Cases were eligible if– Onset between June 15th and July 31st

– Experienced diarrhea– Two enzyme match– Could be interviewed

• Control selection was based on type of case and eligible if– No diarrhea since June 1st

– Must be on a solid diet


Control Selection• Patients exposed in HCF

– 7 day period before onset calculated– Dates of hospitalization during these 7 days– List of patients hospitalized on same days created– List randomized and selected until 3 controls found

• Healthcare Employees– 7 day period before onset calculated– Dates case worked during these 7 days– List of coworkers on same days created– List randomized and selected until 3 controls found

• Community Cases– List of neighbors generated using reverse phone– Closest neighbors called until 3 controls found


Results- Geographic Distribution

• 42 cases in 10 states and Canada:

MA (12) NH (10)NY (4) PA (3) VT (3) Canada (2) KY (2)MD (2)ME (2)CT (1)NJ (1)


Results- Case Details

• Age: 8 months to 96 years (median=59)31% over age 70

• Sex: 28 females (67%)• Healthcare Relationship:– 21 hospitalized patients or LTCF residents– 9 healthcare employees– 1 case who ate in hospital cafeteria

• Illness onset dates ranged from June 15th to July 25th


Culture Confirmed Cases of Salmonella Oranienburg by Date of Onset (n=22)

0

1

2

3

4

6/15

/06

6/17

/06

6/19

/06

6/21

/06

6/23

/06

6/25

/06

6/27

/06

6/29

/06

7/1/

067/

3/06

7/5/

067/

7/06

7/9/

067/

11/0

67/

13/0

67/

15/0

67/

17/0

67/

19/0

67/

21/0

67/

23/0

67/

25/0

67/

27/0

67/

29/0

67/

31/0

6

Date of Onset

Nu

mb

er o

f C

ases


Results- Hypothesis Generation

• Interviews showed a high proportion of cases consumed fruit salad in healthcare facilities

– 23 of 33 cases (70%) consumed fruit salad

– 19 of 23 consumed Brand X fruit in a HCF

• 10 (91%) of 11 facilities with cases served Brand X fruit salad from Ontario, Canada

– Cantaloupe and honeydew melon

• 3 (15%) of 20 control facilities served Brand X (OR=57, p-value=0.0005)


Results- Case Control Study

• Illness significantly associated with fruit salad consumption– Any Fruit Salad= OR: 8.9, 95% CI: 2.3 - 35.5

– Fruit Salad in a HCF= OR: 6.0, 95% CI: 1.5 - 23.5

• Many fruit salad components also significant

• Significant correlations between many individual components

• Multivariate analysis not feasible

• Specific component not statistically implicated


Results- Matched UnivariateFood Item Cases

(n=21)

Controls (n=33)

Matched OR

95% CI

N % N %

Any Fruit Salad 14/20 70% 4/30 13% 8.9 2.3-35.5

Fruit Salad in a Healthcare Facility

12/20 60% 4/30 13% 6.0 1.5-23.5

Cantaloupe in Fruit Salad 12/20 60% 2/30 7% 9.9 2.2-44.5

Honeydew in Fruit Salad 11/20 55% 1/30 3% 16.9 2.4-119.6

Watermelon in Fruit Salad 9/19 47% 2/30 7% 6.9 1.4-33.7

Pineapple in Fruit Salad 8/19 42% 1/29 4% 40.6 3.0-548.4

Red Grapes in Fruit Salad 7/20 35% 0/30 0% 9.8* 1.5-65.6

*Uses a 0.5 continuity correction


Traceback and Product Investigation• Several recent outbreaks of Salmonella

associated with cantaloupe and honeydew – > 25 since 1984, 16 since 1998– 1998 outbreak of S. Oranienburg in Ontario

Canada associated with cantaloupe• FDA and CFIA conducted traceback and

traceforward investigations on August 24th

• Brand X Canadian facility inspected• Cantaloupe and honeydew from California• Unable to traceback to farm due to large

number of supplying brokers


Challenges

• Affected population– Other significant medical issues

– Age

– Mental status

• Distinguishing between primary and secondary cases

• Infection control

• Identification of the source within the fruit salad components


Conclusions

• Interventions on farm may prevent produce-associated outbreaks

• Nosocomial salmonellosis rare in US

– Recognition is difficult due to stool testing practices in hospitals

– May be difficult to distinguish between primary and secondary cases

– Foodborne outbreaks in healthcare settings can cause significant illness, costs, fear


Acknowledgements

• Hospital ICP• NH Disease Control and Laboratory Staff

• Collaborating States:MA, NY, PA, VT, KY, MD, ME, CT, NJ

• CDC: Dr. Christine Olson, MD, MPH, EISODr. Michael Lynch, MD, MPH

Documents

Beth Daly, MPH Communicable Disease Epidemiologist Communicable Disease Surveillance Section