Question

1.A research group is investigating the potential infectious nature of a disease. From ulcerative skin lesions in mice they were able to grow as pure cultures a Gram negative microorganism. They inoculated this microorganism into the skin of healthy mice and reproduced the same ulcerative skin lesions. According to the Koch’s postulated these experimental evidences are sufficient to confirm that the Gram negative microorganism is the causative agent of the studied disease. (T/F)

2. Exotoxins can cause tissue damage during infection by: a)their ability to directly kill cells of the host and activate the immune system b) Their ability to promote bacterial growth c)Their ability to produce immunosuppression in the host d) Their ability to directly kill cells of the host and produce immunosuppression in the host

Answer 1

1. False

No, these experimental evidences are not sufficient to confirm that Gram negative microorganism is the causative agent of the studied disease. This is because when same ulcerative skin lesions are reproduced by inoculating the microorganism in healthy mice, Gram negative microorganism should be isolated from them.

2. d) Their ability to directly kill cells of the host and produce immunosuppression in the host

Exotoxins are responsible for directly killing cells of the host and produce immunosuppression in host.