1. Case 2-A

2. 2 year old child 3 days diarrhea Stool – blood-streaked, 3-4x per day Moderate grade fever, tenesmus, abdominal pain PE –Conscious, slightly febrile, no signs of dehydration

3. Diagnosis diarrhea that can contain blood as well as fecal leukocytes in association with abdominal cramps, tenesmus, and fever these features suggest bacterial dysentery

4. Common Etiologic Agents Bacterial Dysentery –Salmonella –Shigella –Campylobacter jejuni –Yersinia enterocolitica –enteroinvasive E. coli –Vibrio parahaemolyticus

5. Bacillary Dysentery Also known as Shigellosis Infection of the colon which can cause severe diarrhea Shigellae are small, gram-negative, nonmotile bacilli Facultative anaerobe but grow best aerobically Four species: S. Dysenteriae, S. Flexneri, S. Boydii, S. Sonnei

6. Bacillary Dysentery Characterized by its ability to invade intestinal epithelial cell and cause infection and illness in humans with a very small numbers of ingested bacteria Transmitted via fecal-oral route Occurs most commonly in children

7. Mode of Transmission Pediatric age group (1-10 y/o) Ingestion of contaminated water, food, hands Food borne Vegetables Flies Water borne Contact with a contaminated inanimate object Sexual contact

8. Pathogenesis – 1 st stage Ingestion Infectivity dose – 10 S. dysenteriae Ingestion Infectivity dose – 10 S. dysenteriae Colonic mucosal penetration - taken up by M cells in Peyer’s patches Colonic mucosal penetration - taken up by M cells in Peyer’s patches Enclosed in a phagosome by endocytosis Cell multiplication in the cytoplasm Shigella lyses the phagocytic vacuole

9. Pathogenesis – 1 st stage Cell multiplication in the cytoplasm Release of Shiga toxins (consist of one A subunit and 5 B subunits) Release of Shiga toxins (consist of one A subunit and 5 B subunits) Enterotoxic Cytotoxic - Inhibits protein synthesis - cell destruction Cytotoxic - Inhibits protein synthesis - cell destruction Neurotoxic Blocks water and electrolyte absorption Blocks water and electrolyte absorption Ulceration and Intestinal hemorrhage Ulceration and Intestinal hemorrhage Blood and fecal Leukocytes in stool Blood and fecal Leukocytes in stool Inflammatory response - Pyrogenic cytokines (IL-1, IL-6, TNF, IFN) Inflammatory response - Pyrogenic cytokines (IL-1, IL-6, TNF, IFN) Fever and Abdominal cramps Fever and Abdominal cramps Watery diarrhea  dehydration Watery diarrhea  dehydration

10. Pathogenesis – 2 nd stage Invasion of the neighboring cells Increasing severity of Shiga-toxin effects Mucosal abscesses

11. Diagnostic Tests Specimens fresh stool mucus flecks rectal swab – culture

12. Stool Exam GROSS blood-tinged plugs of mucus in the stool MICROSCOPIC fecal leukocytes, few RBCs, and slender gram negative rods

13. Stool Culture CULTURE EMB & MacConkey – colorless colonies Salmonella-Shigella agar – colorless colonies w/o black centers Hektoen enteric agar – green colonies without black centers

14. Stool Culture MediumNonfermenter (Shigella) Fermenters (E.coli) Eosin Methylene BlueColorlessIridescent sheen Mac ConkeyColorlessRed Xylose-lysine deoxycholate RedYellow Hektoen entericGreen, blue-greenYellow-orange Thiosulfate citrate bile salts sucrose colorlessyellow Blood agarNo hemolysishemolysis

15. Biochemical Tests ShigellaE.coli IndoleDifferential reaction+ Methyl red++ Voges-Proskauer-- Citrate (Simmons)-- H2S (TSI)-- Urease-- Phenylalanine deaminase-- Lysine decarboxylase-+/- Arginine dihydrolase--/+ Ornithine decarboxylaseDifferential reaction Motility-+/- Acid produced from lactose-+

16. Slide Agglutination by Specific Shigella Antisera Reaction DysenteriaFlexneriBoydiiSonnei Fermentation of: Lactose Mannitol ---- -+-+ -+-+ +-+- ODC---+ ONPG---+

17. Diagnostic Procedures SEROLOGY - not used for diagnosis - unless taken 10 days apart (serial determination) - (+) result: rise in titer of agglutinating antibodies

18. Diagnostic Procedures POLYMERASE CHAIN REACTION (PCR) ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA) –for epidemiologic studies of enteroinvasive infections –not for routine use

19. Management The key components of shigellosis treatment are –Give effective antibiotic –Replacement of fluid losses –Nutritional support –Follow up

20. Antibiotic Treatment Central in treatment of Shigellosis Hastens recovery, shortens the duration of excretion of pathogen in stool and possibly prevents complications First line: Ciprofloxacin –highly active and clinically effective when given by mouth, –concern about their safety in young children: cartilage damage –Ampicillin, Cotrimoxazole, Nalidixic Acid Indian J Med Res 120, November 2004, pp 454-462 Harrison’s principles of internal medicine, 17 th ed. http://rehydrate.org/dd/su44.htm

21. Replacement of fluid losses Increase fluid intake If dehydration occurs, oral rehydration solution (ORS) is recommended Indian J Med Res 120, November 2004, pp 454-462 Harrison’s principles of internal medicine, 17th ed.

22. Nutritional Support Continued Feeding –prevent hypoglycaemia and weight loss –Foods rich in potassium, such as bananas, are recommended. –One extra meal should be given to the child every day for at least two weeks after the diarrhea stops. http://rehydrate.org/dd/su44.htm

23. Follow up Follow up is important to determine whether patients have responded to treatment. Ask the mother to bring her child back within 48 hour. http://rehydrate.org/dd/su44.htm

24. Prevention Hand washing provision of safe water supply and adequate sanitation facilities maintenance of good personal hygiene and food safety.