Ans. is 'c' i.e., Campylobacter jejuni This is a case of dysentery (RBC in stools along with WBC). Among the given options, 'b', 'c' and 'd' can cause dysentery. But, coma shaped organism is campylobactor jejuni. Based on the depth of intestinal invasion, there are different clinical manifestations of infection with organisms causing diarrhea:- No cell invesion (noninflammatory) The bacteria bind to intestinal epithelial cells but do not enter the cell. Diarrhea is caused by the release of enterotoxins. Watery diarrhea with no fecal leukocytes and no systemic symptoms (e.g. fever) occurs. Organisms are : V cholerae Clostridium perfringens Cryptosporidia Adenovirus ETEC B. cereus Microsporidia Staph. aureus Giardia Rotavirus Invasion of the intestinal epithelial cells (Inflammatory) The organisms have virulence factors that allow binding and invasion into cells. Toxins may be then released that destroy the cell. The cell penetration results in a systemic immune response with fecal leukocytes as well as fever. The cell death results in RBC leakage into the stool (dysentery).