Medical Microbiology Assignment: Gastroenteritis Diagnosis & Tests

This medical microbiology assignment addresses the diagnosis and analysis of infective gastroenteritis. It explores various diagnostic tests, including fecal cultures, antigen detection tests for pathogens like C. difficile, STEC, and Campylobacter, and blood tests such as Full Blood Count (FBC), Erythrocyte Sedimentation Rate (ESR), and C-reactive protein (CRP). The assignment details the importance of each test and the specimens required. It also discusses sample processing and potential causes of the patient's condition, including food poisoning, traveler's diarrhea, and food poisoning associated with seafood, providing insights into the causative agents and pathogenesis. The assignment references relevant literature to support its findings, offering a comprehensive understanding of the topic.

Running head: MEDICAL MICROBIOLOGY
Medical Microbiology
Name of Student
Name of University
Author Note

1MEDICAL MICROBIOLOGY
Question 1:
The patient is diagnosed with infective gastroenteritis, for which the general diagnostic
tests include:
 A faecal culture is generally recommended to determine the causative pathogen for the
condition. An antigen detection tests to check presence of C. difficile, STEC and Campylobacter. Full Blood Count (FBC) test to monitor the number of monocytes, lymophocytes and
RBC. Erythrocyte Sedimentation Rate or ESR C- reactive protein (CRP) test
Question 2:
Faecal Culture- This culture would provide all the necessary information, whether the
pathogen is of viral, bacterial or fungal origin.
The antigen Test for C. difficile, STEC and Campylobacter all will provide information
about the presence of toxin from these pathogens which cause even more harm (Humphries and
Linscott 2015).
The specimens required for faecal culture is preferably acute phase stool collection,
approximately 5 ml in collection tubes. Rectal swabs can also be considered, but they are
generally less sensitive to culture tests. The specimens for C. difficile toxin test can be done by
Enzyme Linked Immunosorbant assay by using faecal sample (Humphries and Linscott 2015).

2MEDICAL MICROBIOLOGY
Question 3:
Sample processing is done before culturing the bacteria, if the fecal specimen is provided
without any preservative, it is advisable to macroscopically analyze the sample first for presence
of blood or mucus, these areas mainly contain the bulk of pathogen and that can be used for
culture. Gram staining procedure is not necessary unless Campylobacter is suspected to be
present. Selective media culture for Staphylococcus, Shigella et cetra are advised for differential
analysis (Humphries and Linscott 2015).
Question 4:
It is suspected that the patient RP could be suffering from food poisoning, basing on the
observed symptoms that the patient came up with. This could have suffered food poisoning
involving a bacterium, most probably E. coli (Wills et al 2015). Another possible reason could be
that the patient is suffering from “Traveler’s Diarrhea”, which occurs when one encounters a
pathogen in foreign countries where hygiene is low (Steffen Hill and DuPont 2015). The last
suspected pathogenesis is food poisoning associated with sea-food which the patient has said to
have eaten in a few restaurants. This kind of food poisoning can happen due to presence of gram-
negative bacteria in fin-fish products. Pathogens like Morganella morganii and M
psychrotolerans are particularly strong histamine producers which induce toxicity and diarhea is
one of the symptoms along with vomiting, inflammation, abdominal cramps and flushing in
extremities (Schirone Visciano Tofalo and Suzzi 2016).
Question 5:
The specimen for full blood count, ESR and CRP are generally preferred to be peripheral
blood.

3MEDICAL MICROBIOLOGY
FBC will provide information about the inflammatory condition of the guts
caused by increase in the number of white blood cells (Leukocytosis). ESR is a diagnostic test
that determines the presence of inflammation but not specifically differentiates between chronic
and acute inflammation. It is generally coupled with CRP test which acts a marker for
inflammation produced in the liver (Zareifar Farahmand Far Golfeshan and Cohan 2014).

4MEDICAL MICROBIOLOGY
References:
Humphries, R.M. and Linscott, A.J., 2015. Laboratory diagnosis of bacterial
gastroenteritis. Clinical microbiology reviews, 28(1), pp.3-31.
Schirone, M., Visciano, P., Tofalo, R. and Suzzi, G., 2016. Histamine Food Poisoning.
In Histamine and Histamine Receptors in Health and Disease (pp. 217-235). Springer, Cham.
Steffen, R., Hill, D.R. and DuPont, H.L., 2015. Traveler’s diarrhea: a clinical
review. Jama, 313(1), pp.71-80.
Wills, W.J., Meah, A., Dickinson, A.M. and Short, F., 2015. ‘I don’t think I ever had food
poisoning’. A practice-based approach to understanding foodborne disease that originates in the
home. Appetite, 85, pp.118-125.
Zareifar, S., Farahmand Far, M.R., Golfeshan, F. and Cohan, N., 2014. Changes in platelet count
and mean platelet volume during infectious and inflammatory disease and their correlation with
ESR and CRP. Journal of clinical laboratory analysis, 28(3), pp.245-248.
.