Category Archives: Diarrhea

Ophthalmologists Discuss Methods to Help Physicians See What Patients Can’t See(part 10)

Glaucoma Detection Glaucoma patients may have lost up to 50% of the nerve fibers in the optic nerve before the damage is noticed with a visual field test, says Harry A. Quigley, MD. That means, he says, that if the damage could be picked up early, and therapy instituted, then more vision could be saved. Since 1975, Quigley, a professor in the Department of Ophthalmology, Johns … Continue reading

Pathogenesis of infectious diarrhea: CONCLUSIONS AND ADDENDUM

CONCLUSIONS In this overview, a range of organisms have been considered, and examples of how the normal function of the gut is perturbed were provided. The emphasis has been on the microbial determinants and mechanisms involved in the primary interaction of pathogen with gut epithelia (Figure 9). Allusions have been made to subsequent involvement of host responses such as the inflammatory response, the production and … Continue reading

Pathogenesis of infectious diarrhea: GUT PHYSIOLOGY Part 16

Clostridium difficile : C difficile is established as the most common nosocomial enteric pathogen, causing pseudomembranous colitis, antibiotic-associated colitis and antibiotic-associated diarrhea. The most important defence against this opportunistic pathogen is the normal colonic microflora, although the microbial species responsible for C difficile and the mechanisms whereby their growth is suppressed are still not understood. Disruption of the normal ecosystem by antibiotics can result in colonization by … Continue reading

Pathogenesis of infectious diarrhea: GUT PHYSIOLOGY Part 15

Yersinia species : Yersinia pestis is transmitted from rats to humans by a flea bite, but Yersinia pseudotuberculosis and Yersinia enterocolitica are foodborne pathogens. Y pseudotuberculosis gives rise to mesenteric adenitis and septicemia, and Y enterocolitica causes a broad range of gastrointestinal syndromes. From an enteric point of view, Y enterocolitica appears to cross the intestinal epithelium via M cells, destroying Peyer’s patches in the process. This … Continue reading

Pathogenesis of infectious diarrhea: GUT PHYSIOLOGY Part 14

S dysenteriae : S dysenteriae causes dysentery, an acute infectious rectocolitis resulting in low volume bloody diarrhea that is often preceded by a watery diarrhea phase. While the precise mechanism of watery diarrhea induction is not entirely clear, in particular the role played by Stx, the pathogenesis of the colitic phase of the infection has been well studied. It is essentially an invasive process, with the chromosomally … Continue reading

Pathogenesis of infectious diarrhea: GUT PHYSIOLOGY Part 13

Campylobacter species : While the clinical picture of Campylobacter jejuni infection, the transmission of the pathogen and epidemiology of disease are all fairly well understood, attempts to understand the genetic and molecular basis of the virulence of this pathogen and of the factors that poise the host toward susceptibility to infection and severity of clinical enterocolitic disease, are only beginning. The clinical picture of the pathogenesis of … Continue reading

Pathogenesis of infectious diarrhea: GUT PHYSIOLOGY Part 12

The main conclusions of these integrated studies may be summarized as follows. First, the rapid onset of ischemia (triggered by an unknown mechanism) after initial entry of the virus causes hypoxia, cytopathic changes in enterocytes and hence atrophy of villi. These are precisely the kinds of changes induced by experimental ischemia. The ensuing increased rate of cell division, necessary for the reconstitution of villi, results … Continue reading

Pathogenesis of infectious diarrhea: GUT PHYSIOLOGY Part 11

Both quantitative and histochemical studies of alkaline phosphatase, thymidine kinase (a marker for DNA synthesis and hence crypt cell activity), lactase, maltase, sucrase and sodium/potassium ATPase were undertaken. Three points emerged from these gut enzyme studies. First, while the levels of lactase fell, the residual level of lactase was demonstrably sufficient to handle most of the lactose load delivered from the stomach to the small intestine … Continue reading

Pathogenesis of infectious diarrhea: GUT PHYSIOLOGY Part 10

Rotavirus : In this section, a closer look is taken at the phenomenon of villus shortening and its consequences, and the subsequent host response of villus resynthesis. For this we draw on a multidisciplinary study of a naturally occurring infection of seven-day-old neonatal mice (rotavirus-anti-body free) with the homologous murine epizootic diarrhea of infant mice (EDIM) strain of rotavirus. These studies were carried out from oral … Continue reading

Pathogenesis of infectious diarrhea: GUT PHYSIOLOGY Part 9

Third, because the virulence of Salmonella species is multifactorial, the choice of model system is crucial. For example, S typhimurium in the mouse is equivalent to Salmonella typhi in humans and, therefore, is not the best model for localized gastroenteritic infections caused by Salmonella species in humans. The rabbit ileal loop model and the in vitro organ culture system derived from it were chosen for … Continue reading