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Introduction
Various infectitios diseases can be produced from ingestion of pathogens. These are
either probably cramped to gastrointestinal tract or initiated in the gut before scattering to
other parts of the body. However, there are numerous microbial pathogens that are able to
infect the gastrointestinal tract. These microbial pathogens can be identified and
segmented into different categories based on their size, characteristics and so on. Bacteria
are the most common microbes; after all, they cause gastrointestinal tract infection. They
can be got hold of by the fecal-oral route through fecal-contaminated food, water and
fingers. The pathogens must usually be ingested in sufficient number so that it can cause
to infection. There are several terms of indications used to describe the gastrointestinal
tract infection. Like gastroenteritis, diarrhea, dysentery, enterocolitis etc.
Gastroenteritis can be distinguished by gastrointestinal symptoms, for instance,
nausea, vomiting, diarrhea and abdominal discomfort. Salmonella, Shigella,
Staphylococcus, Campylobacter jejuni, Clostridium, Escherichia coli and yersinia
are the most common species of bacteria that cause gastroenteritis.
Diarrhea refers to blood or mucus in the stool may mean inflammatory bowel
disease or bacterial infection. Moreover, it occurs due to loose bowel movements
with bloating or flatus are often caused by lactose (in nonfermented dairy
products) or complex carbohydrates (often found in beans).
Dysentery is an inflammation of the intestine characterized by the frequent
passage of feces, usually with blood and mucus. The two most common causes of
dysentery are infection with a bacillus of the Shigella group, and infestation by an
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ameba, Entamoeba histolytica. Pain, fever, and abdominal cramps are symptoms
of this disorder and usually resulting from large intestine disease.
Enterocolitis is an inflammation involving the mucosa of both the small and large
intestine (1).
All of these terms are beneficial in identifying the cases and come to conclusion with an
effective outcome. The clinical history of the patient as usual plays an important role to
make the diagnosis effectively on track and maintaining towards right procedures. For
example, there were three cases that we had to investigate:
Case #1:
Along with 2 days history of gastroenteritis a16-year old boy was presented to the
doctor, his symptoms were nausea, vomiting followed by abdominal pains and
diarrhea. Those information were enough to go for diagnosis because it seemed to be
one of the pathogens that cause gastrointestinal symptoms.
Case #2:
the patient was suffering from fever, night sweat, severe headache and non productive
cough. There was also a history for a cluster of cases of typhoid fever occurred in the
country side of patient. These symptoms and history would give hint that the case
supposed to be salmonella typhi although we could not exclude other species unless
we had gone for further investigations.
Case #3:
A 22-year old patient was presented to the local doctor with a history abdominal
pains, fever and watery diarrhea followed by classical dysentery including blood and
mucus in his/her stool. These symptoms were typical for the third categorical
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description (dysentery) and doing further investigations were suggested to reach the
final diagnosis.
Clinical history is the great tool to enhance the opportunity and chance of absolute test
function and procedure to generate a meaningful and satisfactory outcome to represent in
front of the doctor to step into next phase for his patient. After all, clinical history is the
reflection of patients symptoms. It is very important to get the correct diagnosis of the
case to can prescribe the treatment accurately; this will help the patient to recover
quickly, moreover avoiding any complication of the disease. Therefore, to rashes that
identifying the above organisms by examining their gram morphology and colony
characteristics, with prime importance being given to simple biochemical tests, aims of
the practical exercises is to provide practical knowledge and skills to work at graduate
level in a diagnostic laboratory on the Enterics bench. Undoubtedly, to work most
effectively in order to interpret results and troubleshoot, it is essential for scientists to
understand the basic principles of diagnostic microbiology and recognizing and selecting
potential pathogens in mixed culture. However, a good understanding of microbial
pathogenesis is becoming increasingly important with the use of tests to detect potential
virulence factors, e.g. toxins.
Discussion
While working in the lab, we had gone through three organism which were unknown to
us; meanwhile, we finally managed to isolate them through proper identification
successfully. After all, as we know, there is no other best possible way rather than
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isolating organism through its accurate detection and identification. During this isolation
procedure, we did mark properly and made sure that is not ging to affect other with its
any kind of infected mode of effects. However, pathogens all kinds of investigation of
sampling work require to follow certain procedure and executing all of them correctly.
That is why, it is obvious and definite to maintain this standard from the beginning till
the last stage of its procedure; for example, history collection to the stage of result
generating stage. In this case, the first hit is the foundation of any furher steps; that
means, if there is anything wronly recorded or mentioned in the clinical history, then
automatically, it will create a barrier to generate a realistic and true outcome. So for lab
scientist the first important thing in the lab after consider the clinical not was the
selection of right media, for example, in case study one, no growth on the plate of
skirrows medium (SK) would exclude campylobacter spp, whereas the growth of bacteria
on desoxycholate citrate agar (DCA), xylose lysine desoxycholate agar (XLD) and
hektoen agar (HEK) would rule in salmonella and shigella spp. The morphological
features might give a clue of the suspected bacteria. For the sake of differentiation in
between salmonella and shigella, we had to undergo through biochemical test and in
response we explored salmonella spp. In addition, API 10S and serology were supposed
to give the exact serotype and if then sending the report to the reference lab for the
confirmation that would be more accurate to reach the correct identification. In case #1, it
was pretty good, nothing was surprising and all the outcomes were familier to us. There
were similarity between case #1 and case #2 outcomes; the only exception was in gas;
from glucose the gas was showing negative outcome; as a result, there was a
differentiation in between salmonella typhi and other salmonella serotypes. Ornithine
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decarboxylase was identified due to reverse response in between salmonella typhi and
other salmonella serotypes (3). Urea gave us a bit hectic moment with its unusual
outcome; from the second colony that had been choosen from the media, it showed its
response as positive. Therefore, we thought of its reflection on non pathogenic disorders;
as a result, it was excluded.
In case #3, the selective media, morphological features and biochemical tests were
reflecting more likely shigella spp. The serology test did represent a positive response
with shigella flexneri. In this practical exercise, we did choose two colons in each case
study; because, we saw slightly different colonies with size from what we normally
suspected in these cases. So in case #1, we did choose two colonies from XLD agar; first-
one was red colonies with black center and the second-one was red colonies very small in
size to be more accurate in identifying the bacteria; but the result was the same for the
both colonies that had been picked. But in case #2 we did choose two colonies but the
result was different. In case #2, two different colones was first choosen from HEK agar
which was green most raised colonies and the second-one was blue green colonies with
black center and the result were the same for both colonies exabte in urea test was
positive in the second colony and negative in the first-one; so we excluded the second
colony; because it was might reflect non pathogenic disorders and that thing was not in
our interest in this practical exrsaus. Finally, in case #3, we also did choose two different
colonies first one from XLD agar red colony and green colonies from HEK agar and the
result were different from each other as it shown in table 3 above but we excluded the
second colonies because it gave us positive urea test and that reflect non pathogenic
disorders. The purity plat for all cases were checked and it was pure with no other
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bacteria growth but if it was not pure all the biochemical test could not be readied and
that would also mean that we were needed to do the exrsaus from the beginning.
Moreover, infectivity of the specimens also did carry wrong diagnosis. That is why extra
measures were taken before any steps initiated, especially the cleanliness was in the
priority. Flame played a major role to avoid any kind of giving chance of allowing
infectivity during the working hours in the lab.
In the end, it can be shared that all the procedures during the tests and throughout this
case study were followed accurately or atleast tried to be acurate. Undoubtedly, we had to
follow the appropriate steps in a right time with right justifications rather than making the
situation in a twisted-manner. Often, we realized that prper time management and usage
of its best in a systematic way would have given us more confidence on claiming the true
and accurate outcomes of any results; but still we are hopeful with our approach and
mode of operations.
After analyzing all the above facts and figures, throughout the experience, we would like
to recommend the followings as per our understanding:
While doing all the tests, it is very essential to keep all the information and data.
Therefore, recording all the data properly is must. Moreover, we assume, tests
must be conducted in a sequential and systematic manner.
Organism is the key factor to generate result or come up with a conclusion;
sometimes or often the result can frustrate us through its positivity or negativity.
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To be well organsied and uptodated with the standard of procedure, time is the
key factor; it is understandable that the free of time usage can provide us that
opportunity in generating best result.