Food Protection Trends - March/April 2020 - 102

Authority of Thailand, and the Ministry of Interior of Thailand
(47). The purpose was to improve food safety and sanitary
conditions associated with restaurants and street vendors. This
initiative involves inspection of food establishments to screen
for coliform contamination by use of an SI-2 test kit, which
was developed by the Ministry of Public Health, Thailand.
The campaign was said to be helpful in promoting business of
restaurants and food vendors by reassuring tourists and local
consumers (23).
Food handlers play a significant role in either spreading or
preventing foodborne illnesses. Studies and reports indicate
that poor hygienic practices of food handlers are among
the risk factors that contribute to both sporadic cases and
outbreaks of foodborne illnesses around the world (2, 3,
13, 45). Today, ready-to-eat food, convenience stores and
restaurants are important to the Thai culinary culture (20).
Moreover, Thailand is famous for food tourism, with many
of its restaurants located in the area around the Bangkok
Metropolitan Region (9, 42). Hiring migrant workers in
food services and establishments is preferred because of
the lower wages they accept, as compared to those of Thai
workers (14). The Samut Sakhon province, a famous tourism
destination in Thailand, has a high number of migrant
workers (10). With the increasing numbers of migrant food
handlers, it has become a challenge to promote positive
food handling behaviors and practices (31, 45). In addition,
concerns regarding pathogenic contamination should not
focus solely on food. Previous studies have revealed high
pathogen contamination of non-food items, such as tables,
chairs and floors, in restaurants, and good sanitation practices
and effective cleaning processes are required to eliminate
such pathogens (8, 28).
Therefore, it appears to be important to study coliform
contamination in restaurants as well as the hygienic practices
of food handlers. Few such studies have been conducted in
Thailand (19). The purpose of this study was to screen for
coliform contamination in ice and non-food items such as
tabletops and tableware and to determine the quality of food
hygiene practices among migrant food handlers in the Samut
Sakhon province, Thailand.
MATERIALS AND METHODS
Study design, participants and data collection
A cross-sectional study was conducted in the Samut Sakhon
province, which is located in the central part of Thailand,
adjacent to Bangkok province. It is one of the most widely
recognized coastal provinces in Thailand, and its fame as a
tourist destination is due partly to its relatively inexpensive
seafood sold in many well-known restaurants (27, 41).
The sample size (number of restaurants to be included in
the study) was obtained by the formula [n = log10 (1-P)/
log10(1-d)], with P = 95% confidence level and d = the
maximum tolerable fraction of food that is contaminated.
The formula, which is used to detect the fraction of contam-

102

Food Protection Trends March/April

inated food and evaluate restaurant sanitary conditions, is
used for calculation of the sample size needed for a certain
implementation in terms of legal frameworks and a monitoring program in food safety and management systems (44). A
10% non-response rate was added. Therefore, a total sample
size of 32 restaurants was determined to be necessary.
Study participants were selected in a two-step process.
First, restaurants were randomly chosen by using a random-walk method (43). The inclusion criteria for restaurants
were that they had been operating for at least one year and
that they hired migrants as food handlers. One migrant food
handler was recruited from each selected restaurant. The inclusion criteria for migrant food handlers were that they were
able to understand and communicate in Thai or Burmese, had
worked as a food handler in the restaurant for a minimum of
one year prior to data collection, and agreed to participate in
the study. When more than one food handler was willing to
participate, one was randomly selected for a structured faceto-face interview. Eight items were randomly chosen to be
screened for the presence of coliform contamination. These
consisted of two ice samples, a spoon, a fork, a plate, a bowl,
a glass, and a tabletop, all of which were located in the work
station of the selected migrant food handler.
SI-2 test kit
Screening for coliform contamination was performed using
an SI-2 test kit, which contains a culture broth that supports
the growth of coliform bacteria, with bromocresol purple as
a pH indicator, and which was developed by the Ministry of
Public Health, Thailand. Because this test kit was routinely
used in government sectors, especially among provincial
public health officers under the Ministry of Public Health and
as part of the "Clean food good taste project" campaign (39),
it was selected for use in this study so as to further support
and more easily communicate the study's results with the
Ministry of Public Health. The test kit gives a qualitative
result, as positive or negative for contamination with coliform
bacteria. A sterile swab (RLDC, MOPH, Nonthaburi, TH)
wet with an SI-2 medium (RLDC, MOPH, Nonthaburi,
TH) was swabbed onto approximately four square inches of
each tableware surface; each swab was slowly rotated three
times and then left in the bottle of SI-2 medium. For each
ice sample, one milliliter of melted ice was pipetted into the
SI-2 medium. All samples were left at room temperature
(approximately 32°C-35°C) for 24 hours. At the end of 24
hours, if the color of the medium had changed from purple
to yellow, this indicated the presence of coliform bacteria and
was interpreted as positive for contamination (32).
Questionnaire
A face-to-face interview was conducted, using a structured questionnaire to collect information on food hygiene
practices among migrant food handlers. All interviews were
performed by the researchers and a trained Burmese research

Food Protection Trends - March/April 2020

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