Food Protection Trends - November/December 2024 - 421

fresh and perishable foods are primarily sold in informal
markets (10).
Fresh food markets (or informal markets) are a large
collection of open-air stalls where fruits, vegetables, and
animal source foods are sold (22). In LMICs, fresh food
markets are the daily destination of millions of consumers
because food products are often less expensive and fresher
than foods in supermarkets (29). However, vendors often
sell animal source foods, fresh fruits, and fresh vegetables
at the same stand, favoring potential cross-contamination
due to extensive food handling during market operations.
Food items are often displayed at ambient temperature and
are directly exposed to the open-air environment, thereby
increasing the risk of microbial contamination (19). In
several studies, microbial contamination of food products
sold in fresh food markets has been documented (2, 20,
26, 28, 33). In Cambodia, various food products sold in
fresh food markets were reported to be contaminated
with foodborne pathogens, including Campylobacter spp.,
Salmonella, Escherichia coli, and Staphylococcus aureus (7,
15, 21, 32). Lay et al. (15) reported that raw poultry sold
in fresh food markets in Phnom Penh (Cambodia) had
a high prevalence of Salmonella (88% of 152 samples)
and Campylobacter spp. (81% of 129 samples). In a study
conducted in two northeast provinces of Cambodia, Desiree
et al. (7) suggested that approximately 28% and 22% of
312 vegetable samples collected from fresh food markets
were contaminated with Salmonella and E. coli, respectively.
Environmental contamination is also a concern in these
settings (23, 31). Schwan et al. (31) reported that foodcontact
surfaces sampled in fresh food markets could be
more than twice as likely to be contaminated with Salmonella
compared with non food-contact surfaces in the dry season;
the estimated probabilities of detection (95% confidence
interval) were 0.41 (0.25, 0.59) and 0.17 (0.08, 0.32),
respectively (P = 0.002). In these studies, the presence of
Salmonella on these food-contact surfaces was associated
with poor personal hygiene and poor sanitizing practices
among vendors (23, 31).
Banana leaves and bamboo baskets are natural and
sustainable food-contact surfaces commonly used to display,
store, and transport food products in Cambodian fresh food
markets. Banana leaves are typically harvested from trees
grown in rural areas and are minimally processed by simply
rinsing with water or wiping with cloths to maintain their
freshness; thus, they could serve as vehicles for pathogens
transmission. Banana leaves are favored for food use due
to their local abundance and growing global concerns over
the environmental impacts of plastics. Bamboo baskets,
cardboard, grass mats, styrofoam boxes, lotus flower leaves,
and banana leaves are commonly used in fresh food markets
in Cambodia to store, display, and transport food products.
Chua and Dykes (6) reported that foodborne pathogens are
capable of attaching to banana leaf surfaces despite their high
wax content (3% of leaf), which could reduce attachment
(6, 36). Bamboo baskets can harbor diverse Salmonella
serotypes; Rissen, Weltevreden, and Altona are the most
commonly isolated (31). Schwan et al. (32) found that
Salmonella serotype abundance differed depending on the
surface type. These researchers evaluated the diversity of
serotypes on floors (13 serotypes) baskets (11), mats (5),
scales (5), and lotus flower leaves (4). Baskets, scales, and
lotus leaves were the top three surfaces with the highest
diversity of Salmonella serotypes. These findings suggest
that food-contact surfaces such as bamboo baskets and
banana leaves used to store, display, and transport food
products in fresh food markets in Cambodia might be a
vehicle of food contamination.
Cleaning and sanitation can play an important role in
preventing foodborne illnesses and reducing foodborne
outbreaks (16). Improved sanitation also has positive effects
on human health and national economies. According to a
2012 study conducted by the World Health Organization,
every dollar invested in sanitation had a $5.50 return
in reduced health costs, decreased premature deaths,
and increased productivity (12). Often in LMICs, poor
hygiene and sanitation practices and insufficient food
safety infrastructures can increase the risk of bacterial
contamination of food and lead to foodborne outbreaks.
Maintaining a clean and sanitary food environment is
essential for reducing the prevalence of foodborne pathogens.
The objectives of this study were to evaluate the efficacy
of cleaning and sanitizing methods for reducing Salmonella
experimentally inoculated onto banana leaf and bamboo
basket surfaces and to investigate the attachment of
Salmonella on these food-contact surfaces.
MATERIALS AND METHODS
Salmonella strains
Three serotypes of Salmonella enterica subsp. enterica
isolated from food and non food-contact surfaces in fresh
food markets during a previous research study conducted in
Cambodia (31) were used in this study: Rissen, Corvallis,
and 4,[5],12,:i:-. Salmonella stock cultures were maintained
at −80°C in a CryoCare Organism Preservation System (Key
Scientific, Stamford, TX) until used for experiments.
Inoculum preparation
A single frozen bead of each Salmonella strain was
transferred into 10 ml of tryptic soy broth (TSB; BD Difco,
Sparks, MD) and grown overnight (16 to 18 h) at 37°C on
an orbital shaker at 70 rpm. A loopful of Salmonella culture
was then streaked on tryptic soy agar (TSA; BD Difco) and
incubated at 37°C for 24 h. A single colony from the streak
plate was inoculated into10 ml of freshly prepared TSB and
incubated overnight at 37°C on an orbital shaker at 70 rpm.
Overnight cultures were centrifuged at 4,000 rpm for 10 min.
Supernatant was discarded, and the pellet resuspended in 1
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