Diarrhea:- Part 1 – Diarrhea Lab findings
October 27, 2022Lab TestsMicrobiology
Diarrhea Lab findings
Sample for diarrhea
- A fresh stool sample is ideal.
- Blood may be needed for antigen and antibody testing
Definition of diarrhea
- This is characterized by 3 loose stools per day and may be accompanied by the following:
- Abdominal pain.
- Nausea and vomiting.
Causes of Diarrhoea:
- Diarrhea may be acute or chronic.
- This may be due to the following:
- Viral infections. The most common cause is retrovirus among children. Other viruses are Adenovirus, cytomegalovirus, and HIV.
- Bacterial infections are due to salmonellosis, Vibrio, Campylobacter, and Yersinia. Other causes are toxigenic bacteria like Staphylococcus and Bacillus cereus, Shigella, and E.Coli.
- Parasitic infestation, e.g., Giardia Lamblia and Entamoeba histolytica.
Pathophysiology of Diarrhea:
- Most of the diarrhea is due to infections.
- Age: Mostly, the young are susceptible due to poor health.
- Poor general health and nutrition will predispose to diarrhea.
- Bacteria leading to diarrhea depend upon the following:
- A dose of the bacterial infection.
- Production of enterotoxin.
- Its ability to attach to the intestinal mucosa and to invade the mucosa.
- Other factors for diarrhea are:
- Poor sanitation.
- Contaminated food and water.
- Personal hygiene, washing hands with soap after defecation, prevents the fecal-oral spread.
- Food stored at room temperature allows rapid bacterial growth and the production of toxins.
- Food stored at 4 °C cannot kill the bacteria; it can only prevent the multiplication of bacteria.
- Avoid keeping the food at room temperature, which leads to the rapid proliferation of the organism.
- AIDS has a prominent feature of diarrhea.
Types of diarrhea:
Diarrhea may be:
Diarrhea may be:
- Watery diarrhea.
- Blood diarrhea.
- Diarrhea with a lot of mucus.
|Presentation of diarrhea||Causative agent||Source of spread||Diagnosis|
Watery diarrhea (Bacterial)
||Associated with traveling||Commercial kits are available|
|Watery diarrhea (Parasitic)||Intestinal parasites:
|Watery diarrhea (Toxin)||There are performed enterotoxin:
||No diagnostic tests available for toxins|
|Gastroenteritis||Due to Enteric viruses
|Antibiotic-associated diarrhea (Colitis)||Drugs associated||Drugs||
Diarrhea causes and diagnosis:
|Causative agent||Source||A common source of infection||Diagnosis|
|Salmonella species||Animal and humans||Milk, eggs, meat, and poultry||The specimen is feces, culture on selective media.|
|Shigella species||Humans||Food, fomites, and feco-oral route||Stool and rectal swab on MacConkey and selective media|
|Escherichia coli||Humans||Food, water, fomites, and feco-oral route||Feces culture on MacConkey medium|
|Bacillus species||Soil||Rice||Suspected food, vomitus, and stool culture on ordinary media|
|Staphylococcus aureus||Septic lesion on food handlers||Dairy products and cooked meat||Suspected food, vomitus, or feces are cultures on ordinary media|
|Campylobacter species||Animals||Meat, milk, and poultry||Feces culture on selective medium|
|Clostridium perfringens||Animal||Meat pies and stews||Feces and suspected food on aminoglycoside blood agar anaerobically|
|Clostridium difficle||Humans||Feco-oral and overgrowth of strains in the colon||Direct detection of toxins and isolation on selective media|
|Vibrio cholerae||Humans||Food and water||Feces on selective medium (TCBS agar).|
|Yersinia species||Animal||Food and water||Isolation from feces or blood or rising antibody titer|
Other types of diarrhea:
Osmotic diarrhea (Malabsorption)
- It is defined as diarrhea with a <3 weeks to 8 weeks duration.
- It is due to increased osmotically active solutes in the stool.
- This type of diarrhea stops during fasting.
- It is due to abnormal electrolyte transport.
- Secretory diarrhea is caused by increased water and chloride secretion.
- There is active inflammation of the intestinal mucosa.
- Primarily due to infective bacteria.
Diarrhea due to motility issues:
- There is decreased motility of the small intestine.
- It may be seen in hypothyroidism, diabetes mellitus, postvagatomy, and amyloidosis.
- There may be increased motility of the small intestine.
- It may be seen in hyperthyroidism, carcinoid syndrome, and irritable bowel syndrome.
Diarrhea due to malabsorption:
- It is due to defective digestion or absorption.
- It may be seen in lymphatic obstruction.
- In surgery where resection of the intestine is done.
- G. lamblia causing impaired absorption.
- Chronic diarrhea is defined when the diarrhea is at least 4 weeks.
- It may be 6 to 8 weeks in duration even.
- It may be seen in infections like giardiasis and amoebiasis.
- It is seen in ulcerative colitis and collagenous colitis.
- In foods that contain sorbitol, fructose, caffeine, and ethanol.
- Drugs like antibiotics, colchicine, chemotherapy, and antihypertensive.
- Hormonal origins include diabetes mellitus, hyperthyroidism, hypothyroidism, and adrenal insufficiency.
- Infiltration of GIT by amyloidosis, scleroderma, and lymphomas.
- Surgery like resection of the intestine, vagotomy, and gastrectomy.
- Celiac sprue.
- Whipple disease.
- Allergy to some foods.
- It may be idiopathic in origin.
Lab. workup of the patient with diarrhea:
- History of the patient as regards the duration of the clinical symptoms.
- Any history of travel to a foreign country.
- Food history of the other people living with the patient.
- Take a stool sample or rectal swab.
- Take a sample of suspected food.
- Get the vomitus sample.
- Stool examination for ova and parasites.
- Stool cultures for pathogenic organisms.
- Bood culture in severe cases. It is advised in very young and old patients.
- Take a sample of the suspected food if possible.
- Antigen tests for G.lamblia and E.Coli.
- Antibodies tests can diagnose parasitic diseases.
- A rapid antigen test can diagnose the retrovirus.
- Causes of noninfectious disease are diagnosed by:
- Fecal fat.
- Lactose intolerance test.
- Celiac disease is diagnosed by anti-endomysial and antigliadin antibodies.
- Tests other than lab are colonoscopy, endoscopy, and sigmoidoscopy.
- In case of an outbreak, advice:
- Fecal samples from the kitchen personnel.
- Food handling practices by the workers in the kitchen.
Electrolytes findings are as follows: