Salmonella and Staphylococcus Contamination in
Pork and Chicken in Cambodian Markets
SFFF CambodiaTaskforce and Stakeholder Meeting
Siem Reap, 24-25 October2019

Objective:
• To assess microbial contamination in Cambodia food products
• To test for antimicrobial resistance
• Overall aim:
– to improve food safety and AMR awareness in Cambodia
– to reduce risk foodborne bacteria and AMR.
• Conducted from October 2018 to August 2019 in 25 provinces,
with repeat sampling in 4 provinces: Phnom Penh, Siem Reap,
Shihanouk and Battambong.

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• Samples: 496 (from markets, 25 provinces of
Cambodia, including pork, chicken and swab of
cutting boards)
• Predictors: knowledge, practice, pathogens,
• Bacteria pathogen: Salmonella and Staphylococcus
• Protocol:
– Detection Salmonella species (ISO 6579-1_2017)
– Analysis of QMRA: Most Probable Number of
Salmonella (Pavic et al., 2010)
– Enumeration and Detection Staphylococcus (ISO-
6888-1, 1999)
– AST profiles in both species (CLSIVET 01 A4; CLSI-
VET08, 4th ed, 2018)
• Expected Result: microbial contamination in food,
AMR profiles, knowledge practice which related to
microbial hazard identified.
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Interview: knowledge, practice

Why we are doing this?
• Salmonella is 1 of 4 key global causes of diarrheal diseases, while
staphylococcus aureus is a leading cause of food poisoning
pathogen;
• Most cases of salmonellosis are mild; however, sometimes it can be
life-threatening.The severity of the disease depends on host factors
and the serotype of Salmonella.
• Basic food hygiene practices, such as "cook thoroughly", are
recommended as a preventive measure against salmonellosis
• Antimicrobial resistance is a global public health concern and
Salmonella is one of the microorganisms in which some resistant
serotypes have emerged, affecting the food chain.
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Samples collection
Specimen type
N Sample First
Round
N Sample Second
Round
Total
Pork 156 30 186
Pork cutting board 52 10 62
Chicken 156 30 186
Chicken cutting
board
52 10 62
Total 416 80 496
• Meat samples were collected from meat retails in wet markets by trained
staff on specimen collection, packaging and transportation,
• In each market, specimen was purchased from 3 pork retailers, 3 chicken
meat retailers for about 300 gram each. In addition, swab samples from the
cutting boards of 1/3 vendors (one selling only pork, one selling only chicken),
• Samples collected at 9-11 am of each day, stored in ice box and sent for
testing immediately within 24 hrs.

Sampling activities

Result of Multi-pathogen Survey in Cambodian Markets
• In general, the prevalence of
salmonella was 43%, while
staphylococcus was 31%
• For salmonella, the highest
contamination was in Mondulkiri
followed by PreahVihear, Siem Riep,
Kampot, Kep, Kampong Chhnang,
Sihanouk, KampongThom,Takeo…
No salmonella detected in samples
from Koh Kong
• For staphylococcus, the highest
prevalence was in Kampong Speu
followed by Kampong Chhnang,
Kampong Cham, Svay Rieng, Steung
Treng, Kratie… No staphylococcus
detected in samples collected from
Oddor Meanchey.

Number of positive samples from difference sampling season

Result
The rate of sample that shown positive with Salmonella and S. aureus
Sample type
N.
Specimen
N.positiveboth
Salmonella andS.aureus
Salmonella
positive
S. aureus
positive
Chicken 186 38 (20.4%) 84 (45.2%) 78 (41.9%)
Cuttingboard chicken 62 6 (9.7%) 26 (41.9%) 12 (19.4%)
Cuttingboard pork 62 1 (1.6%) 19 (30.6%) 7 (11.3%)
Pork 186 33 (17.7%) 85 (45.7%) 58 (31.2%)
Grand Total 496 78 (15.7%) 214 (43.1%) 155 (31.3%)

Sample types <0.3 0.3–3.0 3.1–30.0 30.1–110 >110
Chicken 19 21 17 2 3
Pork 20 22 15 1 4
Sample type No. positive n Prevalence
Chicken 84 186 45.2
Cuttingboard chicken 26 62 41.9
Cuttingboard pork 19 62 30.6
Pork 85 186 45.7
Grand Total 214 496 43.1
Prevalence of Salmonella in chicken and pork in Cambodia
The MPN profiles of Salmonella from the 124 positive samples

Cross contamination of Salmonella in Chicken Salad
Scenario ID
No. of samples/one experiment (or trial, equal to one household prepares a chicken salad
for their meal)
Number of
repetitions
Sum
Raw chicken
after washing
twice and right
after cutting
into 3-6 pieces,
before boiling
(swab 25 cm2)
Raw
vegetable
after
washing
and
preparation
Cutting
boards
before
sliding
boiled
chicken
(25cm2)
Knife
before
sliding
boiled
chicken
(25cm2 of
both sides)
Hands after
sliding boiled
chicken (two
hands: surface,
palms, fingers,
webbing)
Chicken
salad right
after finish
(25 gram)
Scenario 2 1 0 0 0 1 1 6 18
Scenario 1 1 0 1 1 1 1 6 30
Scenario 3 1 1 1 1 1 1 6 36
Scenario 4 1 1 0 0 1 1 6 24
Total 108
• Experimental design for Salmonella cross contamination

Cross Contamination Experiment
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6- mix with vegetable (1 sample
collected for MPN).
Possible sample:
1 sample from swab of meat
after wash twice
2 sample from cutting aboard
3 sample from hand
4 sample from knife,
5 sample from chicken salad for
Salmonella isolation and MPN.
6.Vegetable
1- Meat was inoculated with
Salmonella typhi and Salmonella
london
2- wash meat twice (1 sample)
3- Cut to three pieces & wash knife,
cutting board and hand with only
water.
5- Using same knife, cutting board and
hand to slide meat to small pieces
(three samples were collected).
4- Cook for 20 min and take out
for 30 min to cool down and
prepare vegetable.

Cross contamination Study
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Number and percentage of sample positive with Salmonella in scenario1 of chicken salad
Sample type
Tested sample
per experiment
number of
experiments
Positive
Salmonella
Percentage
%
Chicken wash twice with
water
1 6 4 66.7
Hand wash properly with soap 1 6 1 16.7
Chicken salad S1 1 6 0 0.0
Total 18 6 5 27.8
Result• The experiments were conducted at the laboratory of bacteriology and
mycology of NAHPRI from sinceAugust 2019.To date, experiments have
been conducted for 12 times, including 6 for scenario 1 and 6 for scenario 2.
• The experiment of other scenarios will be performed afterward.The result
of experiment in scenario 1 was presented inTable 1, as the specimen

Sample type
Tested sample
per experiment
Number of
experiments
Positive
Salmonella
Percentage
%
chicken wash twice with water 1 6 5 83.3
cutting board wash only with
water
1 6 3 50.0
hand wash with only water 1 6 3 50.0
knife was only with water 1 6 0 0.0
chicken salad S2 1 6 5 83.3
Total 30 6 16 53.3
Number and percentage of sample positive with Salmonella in scenario2 of chicken salad

Most probable number of Salmonella from chicken salad from scenario 1 and 2
Scenarios
<0.3 0.3–3.0 3.1–30.0
30.1–
110
>110
Scenario 1 5 0 0 0 0
Scenario 2 2 1 2 1 0