Basrah Journal of Veterinary Research,Vol.17, No.3,2018
Proceeding of 6th International Scientific Conference,College of Veterinary Medicine
University of Basrah,Iraq
665
CONTAMINATION OF TABLE EGG SHELL WITH
COLIFORM BACTERIA IN MOSUL CITY MARKETS
Yones, N. Ab. J. and Jwher, Dh. M.
Department of Veterinary Public Health, College Veterinary Medicine,
University of Mosul,mosul.Iraq
Key word: Egg-Shell, Bacterial Contamination, Mosul City
Corresponding author: Deea@gmx.us
ABSTRACT
The study was designed to assess the hygienic condition of local and imported table
egg-shell at Mosul markets. Two hundred local and imported eggs were randomly
collected from the markets and transferred immediately to the scientific research unit
in the college of Veterinary medicine / University of Mosul for bacteriological
examination. Total counts using four types of medias were used: Standard Plate Count
ager (SPC), Mac Conkey ager, Violet Red Bile Glucose ager (VRBG) and Tryptone
Bile X-glucoronide (TBX) for Escherichia coli and fecal coliform bacteria. Results
showed that the means of total viable coliform and E. coli bacterial count in the local
egg-shell at different markets ranged from 0.3 to 3 x107 on SPC agar, 0.08-10x107 on
Mac Conkey ager, 0.014-3x105 on (VRBG) and 0.3-7x104 on (TBX) compared with
0.032-5x107 on SPC agar, 0.03-3.3x105 on Mac Conkey ager, 0.014-5.9x104 on
(VRBG) with no growth on (TBX) for coliform and E. coli in the imported table-egg
shell at different markets. Biochemical tests for local and imported table egg-shell
were performed. It was concluded that the rate of contamination in the local table
eggs was more than the imported one and the isolates of E. coli bacteria were obtained
only from local eggs on the TBX medium.
INTRODUCTION
Table egg production are regarded as a significant economic source in several
countries of the world. However, it is estimated that annual global production of table
egg is about 69 millions in the year of 2010 which exceeds its production percentage
by 2.5% from the year 2000. Interestingly, China is considered as the most table egg
producing country in the world, producing more than 28 million tons of egg per year,
Basrah Journal of Veterinary Research,Vol.17, No.3,2018
Proceeding of 6th International Scientific Conference,College of Veterinary Medicine
University of Basrah,Iraq
666
followed by USA which produces 5.4 million tons, then India which produces 3.4
million tons and finally Japan which produces 2.5 million tons. Other important
countries with regard to table egg production include Mexico, Brazil and Russia,
which produces more than two million tons per year (1).
Concerning Iraq, table egg production has reached 46 thousand tons in the year
2010 with 8.1% decrease as compared to the year 2000. Annual egg production in the
neighboring countries surrounding Iraq i.e. Turkey, Iran, Saudi Arabia, Jordan and
Kuwait was 741, 740, 193, 163, 69 and 40 thousand tons, respectively (1).
Owing to the certain characters and traits of the egg, it is rapidly prone to perish
and spoil, partially due to factors related to the ambient environment and its condition
surrounding the eggs. However, fresh eggs lose its quality with lowering grades as
well as shelf life alongside with prolonged storage (2). Keeping and storing of such
eggs for long periods may alter the physical and chemical and hygienic qualities due
to its exposure to droughts, high temperature, unpleasant odors and other
contaminants (3).
Basically, the egg is affected through its formation in the ovary pre and post laying
by several agents i.e. management, husbandry, feeding, the health status of the layers,
practice of egg harvestmen, egg package and transportation, condition of storing and
keeping quality, handling, manipulation, marketing and finally the type of its offering
to the consumer (4). Shell contamination of the egg has received great care and
attention of many workers which usually occurs by either pathogenic or nonpathogenic
bacteria existed on the shell with subsequent invasion into the inner parts
of the egg. The critical sources of such harmful bacteria is the litter and droppings of
the layer itself (5).
Hence, such microorganisms invading egg content may cause food poisoning and
spoilage inside the concerned egg causing serious health risk and hazards to the
consumer (2,4,6).
Bacteria of Enterobacteriacae family are one of the pathogenic microorganisms
which is the target of this study. So, the aim of the study is to elucidate the possible
role of these bacteria causing food spoilage. The parameter of assessment includes
total viable bacteria count as well as an attempt to isolate coliform and Escherichia
coli present on the local and imported table egg-shell in the different Mosul city
markets.
Basrah Journal of Veterinary Research,Vol.17, No.3,2018
Proceeding of 6th International Scientific Conference,College of Veterinary Medicine
University of Basrah,Iraq
667
MATERIALS AND METHODS
Two hundred of local and imported table eggs were randomly collected from
Mosul markets during the period from 1st till 20th March 2014. The collection
involved 10 eggs from each region which were put in aseptic sterile packs. Bags were
transferred to scientific research laboratory/ department of Veterinary Public health,
College of Veterinary Medicine/ University of Mosul for bacteriological examination
. Each egg sample was placed in sterile bag, then they were further washed with
Ringer’s solution in 100 ml glass beaker. Serial decimal dilution of the aliquots was
performed from 102 to 107. Then 0.1 ml of the aliquots was transferred to four types
of media; standard plate count ager (SPC), Mac Conkey ager, violet red bile glucose
ager (VRBG) and finally using Tryptone bile X glucoronide (TBX), in duplicates.
Media were incubated for 24 h. at 37c0. Dilutions show 30 to 300 colonies were
counted for calculation CFUml-1 of coliform and E-coli bacteria (7).
Biochemical test for the positive results isolates of both local and imported eggs
were examined using Simmon’s citrate, Motility, Gas formation and indole tests as
described by (8).
RESULTS
The results of the study revealed bacterial contamination of the local egg-shell
ranged from 0.3 to 3 x107 CFUml-1 on SPC agar, 0.08-10x107 CFUml-1 on
MacConkey ager, 0.014-3x105 CFUml-1 on (VRBG) and 0.3-7x104 CFUml-1 on
(TBX), comparable with 0.032-5x107 CFUml-1 on SPC agar,0.03-3.3x105 CFUml-1 on
MacConkey ager and 0.014-5.9x104 CFUml-1 on (VRBG) while no growth on (TBX)
was detected for quantitative test and on and VRBG for biochemical tests as shown in
table 1and 2.
Table (1): Means of total viable bacteria, coliform and E. coli counts in the local eggshell
in different markets.
Basrah Journal of Veterinary Research,Vol.17, No.3,2018
Proceeding of 6th International Scientific Conference,College of Veterinary Medicine
University of Basrah,Iraq
668
Region CFU/ml
(SPC)
CFU/ml (Mac
Conkey)
CFU/ml
(VRBG)
CFU/ml
(TBX)
1 3.2x107 0.67 x105 - -
2 0.7x107 8.7 x105 5.9x105 3 x104
3 0.87x107 7.3 x105 - -
4 1.07x107 0.081 x105 - -
5 0.36x107 0.71 x105 - -
6 0.3x107 0.62 x105 0.034 x105 0.3x104
7 0.3x107 9.1 x105 0.3 x105 3.3 x104
8 0.46x107 1.0 x105 0.3 x105 -
9 0.42x107 0.95 x105 0.3 x105 0.3x 104
10 0.41x107 10.5 x105 0.014 x105 7 x104
Table (2): Means of total viable bacteria, coliform and E. coli count in the imported
table egg-shell in different markets.
Region CFU/ml (SPC) CFU/ml
(Mac
Conkey)
CFU/ml
(VRBG)
CFU/ml
(TBX)
1 0.43x107 - 0.22x106 -
2 5x107 0.3x105 - -
3 3x107 0.33x105 - -
4 1.45x107 0.03x105 - -
5 0.133x107 3.3x105 - -
6 1.22x107 - - -
7 1.41x107 - - -
8 0.032x107 - - -
9 0.5x107 - 3 x106 -
10 0.081x107 - 0.35 x106 -
Table (3), demonstrates the results of biochemical tests of E. coli, Klebsiella and
non-Klebsiella isolates contaminated shells of local eggs.
Table (3): The results of biochemical tests of the cultured bacterial isolates of local
table egg-shell.
Basrah Journal of Veterinary Research,Vol.17, No.3,2018
Proceeding of 6th International Scientific Conference,College of Veterinary Medicine
University of Basrah,Iraq
669
genus SIM Simmon,s
citrate
No. of
sample
No.of
isolate
Total
Motility Indol H2s
E-coli + + - - 6 12 10
Klebsiella - - - + 6 12 2
Non-
Klebsiella
- - - + 6 12 0
Also, table 4 states the biochemical tests of isolates of E. coli, Klebsiella and non-
Klebsiella bacteria of the imported table egg shells cultured on different media.
Table (4): The results of biochemical tests of the cultured bacterial isolates of the
imported table egg-shell.
genus SIM Simmon,s
citrate
No. of
sample
No.of
isolate
Total
Motility Indol H2s
E-coli + + - - 10 20 0
Klebsiella - - - + 10 20 8
Non-
Klebsiella
- - - + 10 20 12
DISCUSSION
Due to the increased transportation and movement of both peoples and agricultural
products among countries, foods began to be produced in countries to be consumed in
others. This process witnesses acceleration and expansion in commercial relations
among countries (3). However, table eggs represent one of the important staple with
subsequent increase in the trade of such food due to proportional increase in human
population. The frequent and urgent demand on the egg has led to increase their
production reaching about 2 million egg / day (1).
Other factors contributing the increase of egg production is the improvement of
modern mechanical gathering and conveying of eggs as well as improvement of
washing, cleansing, grading, packaging and other operations which will lead to
notable improved view of the consumer (9).
Owing to these processes, the eggs can be exposed to different bacterial
contamination through different stages of processing causing a significant decrease in
quality and shelf-life and storage of the eggs as well as occurrence of food spoilage(2)
.
The increased probability for further contamination of the eggs can cause
putrefaction and spoilage when the eggs are stored for prolonged period to avoid such
Basrah Journal of Veterinary Research,Vol.17, No.3,2018
Proceeding of 6th International Scientific Conference,College of Veterinary Medicine
University of Basrah,Iraq
670
adverse effect on the stored eggs, many countries enacts and legislate laws and
directions to flush the raw eggs once in order to supply intact and clean eggs. This
practice is aimed to supply safe eggs to the consumer (10).
Flushing of eggs is carried out using water containing diluted concentrations of
antiseptic and disinfectants with rapid drying of the eggs. Although this practice is
commonly followed by several obstacles impede the provision of sale eggs to
consumers. Hence, such obstacles are contributing in the existence of coliform
bacteria with further growth and multiplication on egg-shell which was recorded in
the study were in accordance with (4,11,12).
The study focused on the concentration and their counts of table egg-shell (local
and imported) with bacteria of Entrobacteriacea and the findings revealed high counts
of bacterial contamination in the local table egg-shells as compared with imported
table eggs concerning both qualitative and quantitative assessment. As mentioned
earlier, bacterial contamination is present in local table egg, but absent in imported
table eggs as shown in table 1 and 2. According to the findings shown in tables 1 and
2, the numbers of growing bacterial colonies cultured on VRBG media one more than
those growing on MacConkey agar for both types of table eggs (local and imported).
The excessive growth of bacteria on VRBG agar can be described to the fact that this
medium is selective for coliform entero-bacteria (13). Identification and description of
these bacteria were preliminary fulfilled as shown in tables 3 and 4, based on the
results of biochemical test as mentioned by (14), The differences in the bacterial
counts between local and imported table eggs may be due to several factors such as
system of rearing and type of handling the eggs pas laying. It is known that egg laying
is taking place on the litter or on the nests in the local rearing of the hens and layers.
On the contrary, layers of imported eggs one often reared by the modern technology
(batteries), hence egg gathering and harvesting is taking place mechanically with great
decrease of the change of bacterial contaminating as compared with those of bedding,
litter or nests (12).
The numbers and counts of the obtained entero-bacteria in this work exceed those
recorded as permissible and the maximum acceptable limit for enterobacteriaecae
counts present on the egg-shell according to the European specification is 102
CFU/gm (15).
Basrah Journal of Veterinary Research,Vol.17, No.3,2018
Proceeding of 6th International Scientific Conference,College of Veterinary Medicine
University of Basrah,Iraq
671
The excessive counts in the numbers of coliform entero-bacteria may be in part
related to unhygienic conditions in local poultry forms. However, techniques and
methods followed for identification and diagnosis of coliform entero-bacteria play on
important role in reflecting the real total bacterial counts for both domestic and
imported eggs. Application of different techniques used for culturing and
identification of bacteria and their subsequent variations in the results is the subject of
several studies. However, the recent techniques used for identification of bacteria is
the application of molecular biology mentioned that the upper total count of bacteria
is 102 CFU/gm. This figure is less than those obtained in the cement study (16).
Undoubtedly, relative humidity of the air has great role in the growth and
multiplication of microorganisms existing on the surface of egg-shell. The moisture is
related to several factors such as degree of nest cleanliness, frequency of egg
gathering and finally with the period and type of egg storing in the poultry form
(16,17).
Contamination of egg-shell is proportionally related to the bacterial load of air and
environment of layer forms and such condition may lead to microbial contamination
since the ambient environment is regarded as a crucial agent, which increases
bacterial counts. The results of the study ascertained these findings mentioned by
several researchers who are in agreement with (12).
The high level of egg contamination of external environment source greatly affect
the suitability of eggs and its nutritional value (18).
The microorganism in the bacterial counts present on egg surface with frequent
increase can cause spoilage of the egg due to their increase inside the egg content
(19).
This alteration in egg quality may lead to lessen the nutritional value and hygienic
quality of the eggs with serious reflection on consumer’s health (20).
CONCLUSIONS
Existence of bacterial contamination of the local and imported eggshell. The rate of
contamination in local table egg exceeded the rate of imported table egg
Basrah Journal of Veterinary Research,Vol.17, No.3,2018
Proceeding of 6th International Scientific Conference,College of Veterinary Medicine
University of Basrah,Iraq
672
contamination, and isolates of E. coli bacteria were obtained only from local eggs on
the TBX medium.
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