Enteropathogenic Bacterial Infections Flashcards
Escherichia coli
Gram (-), most strains intestinal commensals
UTIs and Diarrhea
Major opportunistic infection- Pneumonia & sepsis.
New Borns- meningitis & sepsis
Strains that cause diarrhea have specialized virulence properties (plasmid borne)
Enterotoxigenic E. Coli
Major cause of diarrhea in poor tropical diarrhea “travelers diarrhea”- actute self limited
Watery and lacking neutrophils & RBCs
Contaminated water and food
Enterotoxins cause secretory dynsfunction of the small bowel.
Enteropathogenic E. coli
Contaminated food & water
Adheres to & deforms microvilli of intestinal epithelial cells.
Diarrhea, vomitting
Enterohemorrhagic E. coli
Contaminated milk or meat
Adheres to colonic mucosa- bloody diarrhea
Enterotoxin
Enteroinvasice E. coli
Food borne dysentery * similar to shigella
Invades & destroys mucosal cells of the distal ileum & colon
Bloody diarrhea
Uropathogenic E. coli
Most common in sexually active women.
From resident flora-reflecting fecal contamination of these regions
Specialized adherance factors- Gal-Gal on pili, enable them to bind residues on the uroepithelium
Pneumonia (enteric bacteria)
E. Coli, Klebsiella, Serratia, Enterobacter
Gram (-)
*Opportunistic
Normally gram + flora of the oral cavity inhibits the colonization by adhering to fibronectin, but chronically ill persons produce salivary protease that degrades fibronectin
Proliferation of aspirated organisms in terminal airways
Gram (-) Sepsis
E. coli, Pseudomonas, Klebsiella, Enterobacter
*Opportunistic
Inability to eliminate low-level bacteremia.
Septic shock caused by presence of TNF due to bacterial endotoxin (LPS)
Neonatal Meningitis & Sepsis
E. Coli, Group B Strep
Colonize vagina–> colonize GI of newborn
Salmonella enterocolitis
Acute Self-limiting diarrhea
Food contaminated w/ non-typhoidal Salmonella (meat, poultry eggs, dairy products)
Fecal-Oral
Invades enterocytes in the distal small bowel and colon.
Toxins that injure intestinal cells
Salmonella typhi
Typhoid Fever- acute systemic illness
*Humans are only natural reservoir. Fecal-oral
Dairy and shellfish
Invades small bowel mucosa. Engulfed by macrophages, inhibit respiratory burst, multiply w/in
Infected macrophges stimulated TNF, IL-1 production.
Degeneration of brush border
Heptaomegaly, splenomegaly
Shigella
S. boydii, S. dysenteriae, S. flexneri. S. sonneri
Shigellosis-necortizing infection of the distal small bowel & colon. Fecal-Oral (cannot survive well outside of stool)
Gram (-) rods
S. dysenteriae is the most virulent
Self-limiting- presents w/ bloody mucoid stool
Proliferates rapidly in cytoplasm of enterocytes of small bowel, Endocytosis is essential for virulence, virulence factor is encoded by a plasmid.
Produce potent exotoxin: Shiga toxin-inhibits protein synthsis, water diarrhea
Formation of a pseudomembran
*bacteremia is uncommon
Vibrio cholera
Cholera- profuse watery diarrhea flecked w/ mucous
Gram (-) rod
contaminated food & water, sellfish (US)
Does not invade the mucosa
Exotoxin- cholera toxin–> secretion of Na+/water from the small bowel
Infection confers long-term protection from recurrent illness.
Vibrio parahaemolyticus
Non-cholera- acute gastroenteritis
Gram (-) Bacillus
Seafood
Campylobacter jejuni
*most common cause of bacterial diarrhea- Traveler’s diarrhea (blood & mucous)
Acute, self-limited, inflammatory
Gram (-) rod
Contaminated food, water, fecal-oral
Survive gastric acidity, multiply in alkaline upper small bowel.
*Associated w/ Gullain-Barre syndrome
