This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
The endotoxin of the following gram negative bacteria does not play any pa in the pathogenesis of the natural disease. 
Select and explain. 
A. E. coli, B. E. coli, C. Vibrio cholerae, D. Pseudomonas
C: Vibrio cholerae
Answer: C: Vibrio cholerae 
Explanation: Ans. is 'c' i.e., Vibrio cholerae . Cholera vibrios possess the lipopolysaccharide 0 antigen (LPS endotoxin), but it has no role in pathogenesis. About other options . Somatic lipopolysaccharide surface 0 antigen of E.coli has endotoxic activity and also protect the bacilli from phagocytosis . Long chain lipopolysaccharide (endotoxin) of klebsiella protects it from the action of serum complement . Endotoxin of pseudomonas causes fever, leukocytosis or leukopenia, shock, DIC, hypotension, ARDS, SIRS.