Lec 9 rad240 pathology
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Transcript of Lec 9 rad240 pathology
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Lec 9rad240 pathology
G I T Pathology continuation
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OSMOTIC DIARRHEA• Disaccharidase deficiencies• Bowel preps• Antacids, e.g., MgSO4
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EXUDATIVE DIARRHEA• BACTERIAL DAMAGE to GI MUCOSA• IBD• TYPHLITIS (immunosuppression
colitis)
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MALABSORPTION DIARRHEA
• INTRALUMINAL• MUCOSAL CELL SURFACE• MUCOSAL CELL FUNCTION• LYMPHATIC OBSTRUCTION• REDUCED FUNCTIONING BOWEL
SURFACE AREA
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MOTILITY DIARRHEA• DECREASED TRANSIT TIME–Reduced gut length–Neural, hyperthyroid, diabetic–Carcinoid syndrome
• INCREASED TRANSIT TIME–Diverticula–Blind loops–Bacterial overgrowth
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INFECTIOUS enterocolitis• VIRAL
–Rotavirus (69%), Calciviruses, Norwalk-like, Sapporo-like, Enteric adenoviruses, Astroviruses
• BACTERIAL– E. coli, Salmonella, Shigella, Campylobacter, Yersinia, Vibrio,
Clostridium difficile, Clostridium perfringens, TB– Bacterial “overgrowth”
• PARASITIC– Ascaris, Strongyloides, Necator, Enterobius, Tricuris– Diphyllobothrium, Taenia, Hymenolepsis– Amebiasis (Entamoeba histolytica)– Giardia
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VIRAL enterocolitis
• Rotavirus most common, by far– Selectively infects and destroys mature
enterocytes in the small intestine–Crypts spared
• Most have a 3-5 day course• Person to person, food, water
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BACTERIAL enterocolitis• Ingestion of bacterial toxins– Staph– Vibrio– Clostridium
• Ingestion of bacteria which produce toxins– Montezuma’s revenge (traveller’s diarrhea), E.coli
• Infection by enteroinvasive bacteria– Enteroinvasive E. coli (EIEC)– Shigella– Clostridium difficile
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E. coli• Toxin, invasion, many subtypes• Food, water, person-to-person• Usually watery, some hemorrhagic• INFANTS often, in epidemics
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SALMONELLAFood, not hemorrhagic
SHIGELLA(person-to-person, invasive, i.e.,
often hemorrhagic)
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CAMPLYOBACTER• Toxins, Invasion
• Food spread
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YERSINIA (enterocolitica)
• Food• Invasion• LYMPHOID REACTION
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VIBRIO cholerae
• Water, fish, person-to-person• Cholera epidemics• NO invasion (watery)• ENTEROTOXIN
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CLOSTRIDIUM DIFFICILE
• CYTOTOXIN (lab test readily available)• NOSOCOMIAL• PSEUDOMEMBRANOUS (ANTIBIOTIC
ASSOCIATED) COLITIS
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BACTERIAL OVERGROWTH SYNDROME
• One of the main reasons why “normal” gut flora is NOT usually pathogenic, is because, they are constantly cleared by a NORMAL transit time.
• BLIND LOOPS• DIVERTICULA• OBSTRUCTION• Bowel PARALYSIS
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PARASITES
• NEMATODES (ROUNDWORMS)– Ascaris, Strongyloides, Hookworms (Necator &
Anklyostoma), Enterobius, Trichuris
• CESTODES (TAPEWORMS)– FISH (DIPHYLLOBOTHRIUM latum)– PORK (TAENIA solium)– DWARF (HYMENOLEPSIS nana)
• PROTOZOANS: AMOEBA (ENTAMOEBA histolytica), Giardia lamblia
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ENTAMOEBA HISTOLYTICA
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GIARDIA LAMBLIA
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MISC. COLITIS (OTHER)• NECROTIZING ENTEROCOLITIS (neonate) (Cause unclear)
• COLLAGENOUS (Cause unclear)• LYMPHOCYTIC (Cause unclear)• AIDS• GVHD after BMT, as in stomach• DRUGS (NSAIDS, etc., etc., etc.)• RADIATION, CHEMO• NEUTROPENIC (TYPHLITIS), (cecal, caecitis)• “DIVERSION” (like overgrowth)• “SOLITARY” RECTAL ULCER (anterior, motor dysfunction)