Acute infectious diarrheal disease
´Ù¾çÇÑ ÀÓ»óÀû Áõ»óÀÌ ÀÖÀ¸¸ç virus, bacteria, parasite¸¦ Æ÷ÇÔÇÑ ´Ù¾çÇÑ °¨¿°ÀÎÀÚµéÀÌ
°ü¿©ÇÑ´Ù.
1. Pathogenic mechanism
1) inoculum size
Salmonella, Vibrio cholera : 105-108°³
Shigella, Giardia lamblia, Entamoeba : 10-100°³ Á¤µµ·Îµµ infectionÀ» ÀÏÀ¸Å²´Ù.
* transmission
Shigella, Entamoeba, Giardia : person to person
Salmonella : food
2) Adherence
±ÕµéÀº º´À» ÀÏÀ¸Å°±â À§ÇØ Á¤»ó À§Á¡¸·¿¡ ºÎÂøÇØ¾ß Çϴµ¥ À̶§ normal flora¿Í °æÀïÇϸç
Áõ½ÄÇÑ´Ù. ¼¼±ÕÀº Àå³»¼¼Æ÷¿¡ ºÎÂøÇÏ´Â specific cell-surface proteinÀ» ºÐºñÇÑ´Ù.
¿¹> V. cholera : specific surface adhesin(toxin-coregulated pilus, ´Ù¸¥ accessory
colonization factors)À¸·Î ¼ÒÀå¼¼Æ÷ÀÇ brush border¿¡ ºÎÂøÇÑ´Ù.
ETEC : adherence protein(colonization factor Ag) ºÐºñ
EPEC, EHEC : Àå³» Á¤¸·¼¼Æ÷ÀÇ brush border¿¡ ºÎÂøÇÏ´Â virulence determinant»ý»ê
3) toxin production
¨ç enterotoxin : secretory mxÀ» ÅëÇÏ¿© watery diarrheaÀ¯¹ß
* prototype : cholera toxin
(A subunit : toxinÀÇ enzymatic activity, B subunit : enterocyte surface receptor¿¡
°áÇÕ)
ETEC : heat-labile enterotoxin(LT)»ý»ê-> secretory diarrheaÀ¯¹ß
¨è cytotoxin : mucosal cellÆÄ±«
-> inflammatory diarrhea, bloody diarrhea(dysenteryÀ¯¹ß)
S. dysentery(shiga toxin), V. parahemolyticus, C. difficile, EHEC(O157:H7)(shiga-like
toxin)
¨é neurotoxin : CNS, PNS¿¡ ÀÛ¿ë
Staphylococcal, Bacillus cereus toxin -> CNS¿¡ ÀÛ¿ëÇÏ¿© vomitingÀ¯¹ß
¨ê exotoxin : Shigella dysenteriae type 1 -> exotoxin»ý»ê -> enterotoxin, cytotoxic
activity
4) Invasion
Shigella, EIEC -> mucosal epithelial cell invasion
-> intraepithelial multiplication
subsequent spread to adjacent cell
Salmonella : bowel mucosa invasionÇÏÁö¸¸ enterocyte¸¦ ÆÄ±«Çϰųª dysentery¸¦
ÀÏÀ¸Å°Áö ¾Ê´Â´Ù.
S. typhi, Y. enterocolitica -> intestinal mucosa penetration
-> Peyer's patch, lymph node¿¡¼ Áõ½Ä
-> Ç÷¾×À» Ÿ°í ÆÛÁü
-> enteric fever, headahce, relative bradycardia, abd pain, splenomegaly,
leucopenia
2. Host defenses
1) Normal flora : 99%ÀÌ»óÀÌ anaerobic bacteria
acidic pH, volatile fatty acid»ý¼ºÇÏ¿© colonizationÀ» ¸øÇϵµ·Ï ÇÑ´Ù.
2) Gastric acid : acidic pH of stomach = important barrier
gastric surgeryÈÄ Salmonella, shigella, G. lamblia, ¸¹Àº helminthsµîÀÇ °¨¿°ÀÌ
Áõ°¡ÇÑ´Ù.
antacid, H2 blocker·Î neuralization -> enteric colonization risk¡è
rotavirus : acidity¿¡µµ »ýÁ¸
3) intestinal motility : major mx
4) immunity : cell-mediated immunity, humoral immunity ¸ðµÎ Áß¿ä
3. Lab
pathogenic E. coli : routine culture·Î normal fecal¿Í ±¸º°¡¿
LT, STÀÇ special test : ´ëºÎºÐÀÇ lab¿¡¼ À¯¿ë¡¿
cholera : TCBS agar
salmonella & shigella : MacConkey's agar
Tab 128-1 Acute diarrhea¸¦ ÀÏÀ¸Å°´Â pathogen
1) Noninflammatory(Enterotoxin) - proximal small bowel
- watery diarrhea
- stool WBC(-)
V. cholerae, ETEC, C. perfringens, Bacillus cereus, S. aureus
Aeromonas hydrophila, Plesiomona shigellosis, Rotavirusµî,
Giardia lamblia, Cryptosporidium
2) Inflammatory(Invasion or cytotoxin) - colon or distal small bowel
- dysentery or inflammatory diarrhea
- stool neutrophil(+)
Shigella, Salmonella, C. jejuni, EHEC, EIEC, Y. enterocolitica,
V. parahemolyticus, C. difficile, E. histolytica
3) Penetrating - distal small bowel
- enteric fever
- stool monocyte(+)
S. typhi, Y. enterocolitica
Tab 128-2 Bacterial food poisoning
1-6 hr incubation : S. aureus, B. cereus
8-16hr : C. perfringens, B. cererus
> 16hr : V. cholerae, ETEC, Salmonella, Shigella, V. parahemolyticus