Question

A patient came into the office suffering from flu like symptoms, accompanied by Fever, Abdominal pain, Back pain, Chills, Excessive sweating, Fatigue with joints pain. The fever has been an up and down fever. The patient said he had visited a farm a week ago and had drunk milk. He did not know if the milk or the yoghurt he had caused this. 1. What infection does he have? Name the causative agent. 2. How did he become infected with this microbe? Explain the pathogenesis of this disease. 3. What are the virulence factors for this pathogen? What would be the treatment based on the virulence factors and why? Why is it considered as a food borne illness yet there are no symptoms that indicating it is? 4. Name another agent that also causes infection but in pasteurized dairy products? What are the virulence factors for this pathogen? How would you treat it based on that? 5. The patient does not have diarrhea, however how would the type of diarrhea assist in the identification of diseases. Give at least 3 examples stating the agent its disease, type of diarrhea, virulence factors and treatment.

Answer 1

1. The patient has brucellosis which is a zoonotic infection caused by bacteria Brucella on ingesting unpasteurized milk. Causative agent is Brucella.

2. It is likely that he got this microbe when he drank milk from the farm. After this microbe enters the host body it multiplies and moves through the lymphatic system. Macrophages in the host system are not strong enough to destroy these microbes. They live well in lymph nodes. Endotoxins can be the major virulence factor.

3. Endotoxins are the major virulence factors. It does not bear any clear virulence factors like capsules, lipopolysaccharides etc. Gentamycin an aminoglycoside antibiotic is generally used to fight this bacteria. It does not show symptoms in food poisoning like vomiting or loose motions. But since it is caused by ingesting unpasteurized milk and milk products it is a food borne illness.

4. Salmonella typhi can cause food poisoning due to improper storage of milk and milk products and then consuming them. Virulence factors are endotoxins and a protein called invasin which inhibits the action of leukocytes. Antibiotics like amoxicillin can be used.