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Research Article
Microbiological Safety of Kitchen Sponges Used in
Food Establishments
Tesfaye Wolde1,2 and Ketema Bacha2
1AppliedBiologyDepartment,WolkiteUniversity,Wolkite,Ethiopia
2Biology Department, Jimma University, Jimma, Ethiopia
Correspondence should be addressed to Tesfaye Wolde; tesfalem atnafu@yahoo.com
Received June ; Accepted September
Academic Editor: Marie Walsh
Copyright © T. Wolde and K. Bacha. is is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Kitchen sponges are among the possible sources of contaminants in food establishments. e main purpose of the current study
was, therefore, to assess the microbiological safety of sponges as it has been used in selected food establishments of Jimma town.
Accordingly, the microbiological safety of a total of kitchen sponges randomly collected from food establishments was evaluated
against the total counts of aerobic mesophilic bacteria (AMB), Enterobacteriaceae, coliforms, and yeast and molds. e mean
counts of aerobic mesophilic bacteria ranged from . to . log CFU/mm3. e isolated genera were dominated by Pseudomonas
(.%), Bacillus (.%), Micrococcus (.%), Streptococcus (.%), and Lactobacillus (%) excluding the unidentied Gram positive
rods (.%) and Gram negative rods (.%). e high microbial counts (aerobic mesophilic bacteria, coliforms, Enterobacteriaceae,
and yeast and molds) reveal the existence of poor kitchen sponge sanitizationpract ice.Awareness creation training on basic hygienic
practices to food handlers and periodic change of kitchen sponges are recommended.
1. Introduction
During the cleaning of kitchen utensils, the prewashing and
washing steps are usually carried out using sponges in order
to remove food residues. In due course, some parts of the food
residues could adhere to the sponges. Food remains, together
with humidity retained in sponges, tender a positive envi-
ronment for growth and survival of bacteria. Report shows
that such heavily contaminated sponges could be the main
vehicle that signicantly contributes to the dissemination
of potentially pathogenic bacteria in back of house setting
[]. Research on the signicance of bacterial contamination
of kitchen environments started years ago. According to
the early studies, uncooked material is the major cause of
contaminants in kitchen although the area nearby the kitchen
could contribute free-living bacteria. Accordingly, numerous
studies revealed that sponges can be vital disseminators of
pathogensandcantransferbacteriatosurfacesandutensils,
leading to cross-contamination of food [, ].
Earlier studies conducted to evaluate microbial safety
of kitchens utensils and its environment [, ] showed that
bacterial proles of hand towels, dishcloths, tea towels, steel
sinks, and working surfaces are signicant and contributed
to food contamination. Foodborne illness related to foods
prepared in unhygienic kitchen is recurrently associated with
Salmonella [–]. Several other bacterial infections associ-
ated with contaminated kitchen environment are Listeria,
Campylobacter Bacillus cereus,Staphylococcus aureus,and
Escherichia coli [, ]. S. aureus is one of the pathogenic
bacteria isolated from .% used synthetic washing sponges
[].
Jimma town, the study site, has been visited by many
travelers as the town is a strategic place for the southwest
part of the country in terms of transportation and trading.
As a result, many visitors are coming to the town for several
reasons. us, the town and its food establishments are visited
by many individuals from dierent parts of the country
traveling to and away from the city. In addition, the numbers
of food vendors are currently increasing faster. Nevertheless,
thereisascarcityofreportsonthemicrobiologicalsafetyof
kitchen sponges of food establishments in Ethiopia including
Jimma town. is prompted the current study to evaluate
Hindawi Publishing Corporation
International Journal of Food Science
Volume 2016, Article ID 1659784, 7 pages
http://dx.doi.org/10.1155/2016/1659784
International Journal of Food Science
the microbial wellbeing of synthetic sponges from food
establishments of Jimma town. Assessment was made in
terms of prevalence and load of aerobic mesophilic bacteria,
coliforms, Enterobacteriaceae, and yeast and molds.
2. Methods
A total of kitchen sponge samples were collected from
food establishments ( restaurants, hotels, cafeterias,
and pastry shops) in Jimma town using simple random
sampling technique during the months of October to
June . Sponges from the selected food establishments
were collected aseptically in germ-free polythene bags dis-
cretely and transported to Postgraduate Microbiology Lab-
oratory, Department of Biology, Jimma University. Samples
wereprocessedinanhour.Questionnairewasusedto
obtain rst-hand information about personal history/status
assessments of the establishment owners, food handlers, food
servers, and care being taken during washing steps of kitchen
sponges.
Ofthecollectedkitchenspongesamples,anamountof
mm3was aseptically cut using sterile blade and the pieces
were blended separately in mm3of sterile peptone water
(OXOID). Kitchen sponges were mixed and proper dilutions
of peptone water were plated in triplicate on dried surfaces
of relevant media for microbial enumeration. erefore,
standard plate counts were counted on Standard Plate Count
Agar (SPCA) (OXOID) following incubation at thirty-two
degrees Celsius for forty-eight hours; VRBA (OXOID) was
used to enumerate coliforms following incubation for forty-
eight hours at thirty-two degrees Celsius. Enterobacteriaceae
were enumerated on MacConkey agar (OXOID) following
incubation at thirty-two degree Celsius for forty-eight hours
(pink-to-red purple colonies with/without haloes of precip-
itation were counted as Enterobacteriaceae. Similarly, yeast
and molds were counted on Chloramphenicol Bromophenol
blue agar incubated at degrees Celsius for days. Media
composition (Gram per ml distilled water) includes yeast
extracts (OXOID) ., glucose , chloramphenicol .,
Bromophenol blue ., and agar .; pH .). Smooth
colony-forming units with no extension at margin were
considered as yeasts. Furry colony-forming units with elon-
gations at edge were considered as molds. All the microbio-
logical media used for this study were OXOID products.
Following record, een colonies were indiscriminately
singled out from enumerable plates of SPCA. Culture charac-
teristics on solid media, cell morphology, and Gram reaction
were performed following usual microbiological techniques:
lipopolysaccharide test was made to dierentiate between
Gram negative and Gram positive bacteria using the quick
method suggested by Gregersen []. Catalase test was done
by applying little drops of % H2O2on agar plates containing
an overnight initiated culture for production of air bubbles.
Cytochrome oxidase test was conducted as suggested by
Kovacs [] using newly ready kovac’s reagents for revelation
of a blue colour on recently activated colonies in seconds—
few minutes as a positive reaction.
T : Demographic features of proprietors/workers in food
enterprise, Jimma, .
Demographic features Incidence Percent
Sex
Women .
Men .
Age
– .
– .
> .
Educational status
Illiterate .
Literate .
Marital status
Single .
Married .
3. Results
e median service period of the food establishments was
yrs, arraying from months to years (data not shown).
Middle age of the establishments’ proprietors was years,
varying from to yrs. Majorities (.%) of the hotel
managers were literate (Table ). More than half (.%) of
the study participants had received training on food hygiene
and safe handling, although .% did not get any training
opportunity.
Majority (.%) of the food establishments were found
using dierent kinds of detergents for dish washing while
.% use warm (–∘C) water to clean the dishware at
least two times per a week. Among the food prepar-
ing personnel who were asked about their familiarity and
practices related to food cleanliness, about (.%) were
foundfamiliarwithatleastonetypeoffoodborneillness
(Table ). e proportion of food handlers who said that
foodbornediseasesareduetopathogenswas(.%),
with even more numbers (.%) associating the vehicle
of transmission of foodborne diseases with contaminated
food. Moreover, (%) of the food handlers had serious
concerns on the risks of dirty hands in contaminating food.
It was observed that all of the food establishments were
washing their kitchen utensils using sponges. Mean service
time of a kitchen sponge was days. Majority, (%),
oftherespondentshadnoknowledgeofthepresenceof
antimicrobial chemicals in kitchen sponges (Table ).
e average enumerations (log CFU/mm3) of bacteria
which are aerobic mesophiles of kitchen sponge samples
were the highest in pastry shop samples (.), followed
by hotel (.), cafeteria (.), and restaurant (.). With
mean counts of high margin (> log CFU/mm3)inallsam-
ple sources, the actual gures fall within the ranges (log
CFU/mm3) of . to . (restaurant), . to . (hotel), .
to . (cafeteria), and . to . (pastry shop) (Table ).
Irrespectiveofthemicrobialgroupsandfoodestablishment
International Journal of Food Science
T : Food handlers’ familiarity with foodborne illness, Jimma,
(𝑛 = 201).
Familiarity and practice Incidence Percent
Had information about foodborne diseases .
Causes of foodborne illness
(i) Microbes .
(ii) Substance .
(iii) Unhygienic food preparation .
(iv) Others .
Vehicle for transmission of foodborne disease
(i) Contaminated food .
(ii) Contaminated water .
(iii) Vectors like ies and cockroaches .
Factors contributing to food contamination
(i) Unclean hands .
(ii) Grimy food handlers .
(iii) Dirty utensils .
(iv) Unhygienic working environment .
(v) Infestation by insects and rats .
Dish washing and kitchen cleaning material
(i) Sponge
(ii) Cloth .
(iii) Towel .
Life span of a kitchen sponge (days)
(i) – .
(ii) – .
(iii) – .
types, there were statistically signicant variations in micro-
bial counts within groups (CV >%).
A total of , , , and bacterial strains
were isolated from kitchen sponge samples collected from
restaurants, hotels, pastry shops, and cafeterias, respectively,
and characterized with various genera and bacterial groups
(Table ). Pseudomonas (.%), Bacillus (.%), Micrococ-
cus (.%), Streptococcus (.%), and Lactobacillus (%)
were among the dominant bacterial genera besides the
unidentied Gram positive rods (.%) and Gram negative
rods (.%). In general, .% of the sponges were Gram
positive organisms, with about .% of the total
aerobic mesophilic bacterial grouped as Gram negative. e
proportion of Pseudomonas spp. (.%) among the aerobic
mesophilic bacterial ora of kitchen sponges was relatively
high.
Out of dierent kitchen sponges examined, .%
had coliform counts of greater than . LOG CFU (mm3)−1
with % of the kitchen sponges’ samples containing col-
iform counts above log CFU/mm3.Likewise,about.%
of the samples had Enterobacteriaceae count greater than
log CFU/mm3. e counts of yeasts were relatively low
where .% of the samples had yeast counts greater than
log CFU/mm3with % of the samples having yeast counts
below detectable number. About .% of the kitchen sponges
120
100
80
60
40
20
0
Cumulative frequency
<2.00
>2.00
>3.00
>4.00
>5.00
>6.00
>7.00
>8.00
>9.00
>10.0
>11.0
>12.0
Log CFU (mm3)
AMB
S. aureus
Coliform
E. coli
Ye a s t
Mold
in percent (%)
F : Cumulative frequency of microbial groups from kitchen
sponges (𝑛 = 201).
had mold count greater than log CFU/mm3with only .%
of the samples having counts below detectable level (Figure ).
4. Discussion
e current report on microbiology of synthetic kitchen
sponges worn in food establishments is the rst of its kind
from Ethiopia, particularly from Jimma town. Unhygienic
handling and use of the same sponges for extended period of
time contributed to the observed gross contamination with
aerobic mesophilic counts as high as .log cfu/mm3.Other
related studies also indicate that food establishments that
lack basic sanitary facilities and utensils used for handling
of food are grossly contaminated with microorganisms and
could contribute to the occurrence of foodborne diseases
[]. Recently, increase in population mobility for business or
leisure purposes and visiting food establishments has become
common practice. On the other hand, kitchen sponges are
unhygienic with disease causing bacteria and indicator bac-
teria owing to cross-contamination, inappropriate handling
and storage, or improper sanitizing, leading to foodborne
illness []. us, pattern of disease development data are
required to update community health authorities about the
nature and extent of the problem and to keep an eye on
trends over time. Result of the current study clearly revealed
limitation of experience on hygienic handling of kitchen
utensils and poor sanitization strategies tracked to diminish
pathogenic bacteria in the kitchen sponges as experienced by
the food establishments.
e most extensively used and usual methods of washing
of tools for food handling are the three-partition sink or
holder system []; conversely, a reduced amount of half
(%) of the enterprises had been washing utensils by means
of this system. Almost three-fourth (%) of the food serving
institutions, particularly those who prepare food in their own
kitchen and dish up meals, and .% of the establishments
portioning both meals and drinks had been using three
compartments and sponge to clean utensils. Even if the
washing practices in Jimma were superior to the practices
International Journal of Food Science
T : Microbial count (log CFU/mm3) of dierent microbial groups detected in kitchen sponge samples, Jimma, .
Microbial group
Source of kitchen sponge
Restaurant Hotel Pastry Cafeteria
Avg SD CV% Min Max Avg SD CV% Min Max Avg SD CV% Min Max Avg SD CV% Min Max
AMB . . . . . . . . . . . . . . . . . . . .
Coliform . . . <. . . . . . . . . . . . . . . .
Yeast . . . <. . . . . <. . . . . . . . . . <. .
EB . . . . . . . . . . . . . . . . . . . .
Molds . . . <. . . . <. . . . . <. . . . . <. .
AMB = aerobic mesophilic bacteria; EB = Enterobacteriaceae.
International Journal of Food Science
T : Frequency distribution (%) of dominant bacteria in kitchen sponges collected from food establishments of Jimma town, .
Food establishment Number of isolates Pseudomonas Enterobacteriaceae Bacillus Micrococcus Gram negative coccus Streptococcus Lactobacillus Other Gram
positive rods
Restaurant
Hotel
Pastry shop
Cafeteria
Total
% . . . . . . . .
International Journal of Food Science
elsewhere[],theyarestillbelowmeetingthesanitary
standard and necessitate extra advance.
From this study, food handlers had good knowledge or
awareness of the basis of foodborne disease transmission
mechanisms, aggravating factors for food contamination,
and as a whole foodborne disease. ough they have good
acquaintance, they did not keep up with the poor sanitary
conditions of the facilities where they have been working,
predominantly with the neatness and maintenance of the
kitchens and food utensils and the reduced storage of orga-
nized foods and food utensils. e observed discrepancy
between comprehension and practice could be accounted to
reluctance to practice what they know due to negligence, lack
of commitment, and attitudinal change. Equally important,
they might also not be operational and/or supplied with
the essential materials that would allow them to uphold
the sanitary excellence of their property. In fact, all food
handlers have duty to keep high degree of personal hygiene
and be preinformed about hygienic and nondangerous food
handling; failure to do so could contribute to contamination
of food sources with pathogens []. In this report the
food handlers’ hygiene and food management practices were
found below standard and not satisfactory. Such condition
facilitates the spread of foodborne diseases if corrective
hygienic procedures are not set in place.
e detection of high counts of coliforms, Enterobacte-
riaceae, and aerobic mesophilic bacteria in kitchen sponge
samples was an indication of underprivileged sanitary emi-
nence of utensils used for food handling. Outbreaks of food
poisoning recurrently happen as a result of unacceptable food
preparation in which cross-contamination in combination
with insucient storage or cooking was concerned in many
occasions []. Kitchen sponges and dishcloths could lead
to cross-contamination in kitchens since they can transfer
microorganisms to surfaces where microorganisms can sur-
vive for hours or days and contaminate food persisting in
these disease vehicles [].
In the current report, diverse microorganisms including
probably pathogenic microbes were encountered in kitchen
sponges. Among these microbes are Pseudomonas sp., Bacil-
lus sp., and Streptococcus sp. As reported earlier [], microor-
ganisms, together with pathogenic species, frequently exist
in all areas of the home surroundings. Accordingly, wet sites
including kitchen sink areas, toilets, and nappy buckets are
most commonly associated with heavy contamination and
the occurrence of potentially harmful species. Other wet sites,
such as dishcloths and similar cleaning materials, were also
found to be frequently and heavily contaminated by microbes
of dierent arrays. As to Keeratipibul and his colleagues [],
thepresenceofcoliformsisunacceptablebecauseitreveals
poor sanitary conditions. Contamination in sponges may
come from leovers, inadequate hygienic practices during
food preparation, cross-contamination due to contaminated
surfaces, and storage in places. ese results imply that, in
kitchen environment, although raw food is most likely the
main source of contamination, the sink, waste trap, and the
surrounding areas can also act as reservoirs of dierent arrays
of microorganisms which harbor and promote the concern of
free-living bacteria and fungi populations.
Among kitchen sponges evaluated, .% of
them had aerobic mesophilic bacterial count greater than
log CFU/mm3, a value comparable to the . log CFU/mm3
count reported elsewhere [] but much lower than the
log CFU/mm3reported by Erdogrul and Erbilir [] from
Turkey. e signicantly high count could be accounted
to failure to use sanitizing chemicals to clean kitchen
sponges, extended use of the same sponge for cleaning, and
underprivileged hygienic conditions of the food serving
establishments as observed during data collection.
Resultsofthisstudyindicatedthatthecountsofcol-
iform ranged between . and . log CFU/mm3with an
average count of .log CFU/mm3.Furthermore,.%
of the restaurants, % of the hotels, and % each of
the pastry shops and cafeterias kitchen sponge samples had
coliform count greater than detectable level. In a related
study [], it was reported that the coliform load of kitchen
sponges was within the range of below detectable level
to . log CFU/mm3. is indicates that signicantly high
proportion of synthetic kitchen sponges in many food serv-
ing establishments at Jimma town was contaminated with
microorganisms of fecal origin because of poor hygienic
practices. Coliform should be eliminated during washing
steps using hot water. Presence of such high counts among
the kitchen sponge samples could indicate either inappro-
priatenessoftheheatingtemperatureusedduringwashing
or postwashing contamination because of inadequate storage
conditions being practiced in the food establishments accom-
panied by proliferation of those wash-surviving microorgan-
isms during storage.
e Enterobacteriaceae count of the present study ranged
between . and . log CFU/mm3with mean number
. log CFU/mm3. Of the total kitchen sponge samples eval-
uated, .% of restaurants samples, % of hotels, and %
each of pastry shops and cafeterias samples had Enterobacte-
riaceae count greater than 3CFU/mm3. In addition, among
thetotalcharacterizedaerobicmesophilicbacteria,
.% were Enterobacteriaceae. If not necessarily at all, many
of the Enterobacteriaceae could be potentially pathogenic as
indicated by the presence high counts of indicator coliforms
as discussed above. e members of Enterobacteriaceae
isolated in a related study conducted by Scott et al. []
included Klebsiella,Enterobacter,Proteus,andCitrobacter.
Speirs et al. [] also reported almost similar isolates from
domestic kitchens.
About .% and .% of the kitchen sponge samples
had yeast and mold counts greater than 3CFU/mm3with
only % and .% of the samples with yeast and mold
count below detectable level, respectively. In general, the
mean counts of aerobic mesophilic bacteria, Enterobacte-
riaceae, coliforms, and yeast and molds of kitchen sponge
samples were signicantly dierent among the dierent food
establishments. Relatively, high counts of these microbial
groups were obtained in samples from pastry shops. is
might indicate the prolonged usage of kitchen sponge when
compared to other food establishment types. In fact, the
hygienic practice and sanitary conditions of kitchen envi-
ronment among pastry shops were better than kitchens of
International Journal of Food Science
other food establishment types as observed during sample
collection.
In conclusion, high microbial load of any sort is clear indi-
cator for below standard handling practice in a given setting
and calls for regular monitoring of the practice by owners and
sta working at the same food establishment besides timely
supervision by concerned government bodies to ensure safety
of customers.
Competing Interests
eauthorsarmthattherearenocompetinginterests.
Acknowledgments
e authors would like to thank Jimma University for nan-
cial support. e study participants of all food establishments
deserve special thanks for genuine provision of information
and cooperation during sample collection.
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