Enterobacteriaceae Flashcards
Pathogenesis:
E. coli is widely recognized as the most common cause of UTIs in humans
Uropathogenic E. coli (UPEC)
Virulence factors of Escherichia coli
PILI
CYTOLYSIN
AEROBACTIN
adhere to epithelial cells and not be washed out with urine flow.
PILI
kill immune cells and inhibit phagocytosis and chemotaxis
CYTOLYSIN
allow bacterial cells to chelate iron
AEROBACTIN
5 MAJOR CATEGORIES in Gastrointestinal Pathogens of Escherichia coli
I. Enterotoxigenic Escherichia coli (ETEC)
II. Enteroinvasive Escherichia coli (EIEC)
III. Enteropathogenic Escherichia coli (EPEC)
IV. Enterohemorrhagic Escherichia coli (EHEC)
V. Enteroadherent Escherichia coli, which includes:
a. diffusely adherent Escherichia coli (DAEC)
b. enteroaggregative Escherichia coli (EAEC).
ENTEROADHERENT E. coli infections:
Diarrheal syndromes (absence of WBCs and RBCs) & UTI
types of ENTEROADHERENT E. coli:
Associated with both UTI and GIT infections
DAEC (Diffusely Adherent E. coli)
types of ENTEROADHERENT E. coli:
Causes cystitis in children and acute pyelonephritis in pregnant women
DAEC (Diffusely Adherent E. coli)
types of ENTEROADHERENT E. coli:
Causes diarrhea by adhering to the surface of intestinal mucosa
EAEC (Enteroaggregative E. coli)
types of ENTEROADHERENT E. coli:
Adheres to HEp2 cells, packed in a “stacked-brick” pattern
EAEC (Enteroaggregative E. coli)
ENTEROTOXIGENIC E. coli infection:
Traveler’s diarrhea a.k.a Montezuma’s revenge or La Tourista
Colonization of ENTEROTOXIGENIC E. coli
Proximal small intestines
Infective dose of ENTEROTOXIGENIC E. coli
10^6 to 10^10
ENTEROTOXIGENIC E. coli Produces two (2) toxins:
Heat-labile Toxin (LT)
Heat-stable Toxin (ST)
ENTEROTOXIGENIC E. coli toxins:
Similar to choleragen toxin from Vibrio cholera
Heat-labile Toxin (LT)
ENTEROTOXIGENIC E. coli toxins:
Activates adenylate cyclase causing hypersecretion of both electrolytes and fluids into the intestinal lumen leading to water diarrhea
Heat-labile Toxin (LT)
ENTEROTOXIGENIC E. coli toxins:
Stimulates guanylate cyclase which leads to hypersecretion of electrolytes and water into the intestinal lumen
Heat-stable Toxin (ST)
ENTEROINVASIVE E. coli infection:
Dysentery-like/Shigella-like Infection;
Water diarrhea with WBCs
Infective dose of ENTEROINVASIVE E. coli
> 10^6
(E. coli)
Pathogenesis:
Produces dysentery with direct penetration, invasion and destruction of the intestinal mucosa
EIEC: ENTEROINVASIVE E. coli
Infection of EPEC: ENTEROPATHOGENIC E. coli
Infantile Diarrhea
(Escherichia coli)
Stool typically contains large amount of mucus but apparent blood is not
present
EPEC: ENTEROPATHOGENIC E. coli
(Escherichia coli)
Lacked the toxins of ETEC and lacks the invasiveness of EIEC
EPEC: ENTEROPATHOGENIC E. coli
Pathogenesis of EPEC: ENTEROPATHOGENIC E. coli
Adhesive property – attach to the borders of the intestinal cells
EHEC: ENTEROHEMORRHAGIC E. coli is also known as:
Verotoxic E. coli (VTEC) / STEC
Infection of EHEC: ENTEROHEMORRHAGIC E. coli
Hemorrhagic colitis,
HUS,
Bloody diarrhea without WBC
(Escherichia coli)
Associated with ingestion of poorly cooked meats
EHEC: ENTEROHEMORRHAGIC E. coli
Virulence Factors of EHEC
Verotoxin I
Verotoxin II
Virulence Factors of EHEC:
Identical to Shiga toxin produced by S. dysenteriae
Verotoxin I
Virulence Factors of EHEC:
Can be neutralized by antibodies to Shiga toxin
Verotoxin I
Virulence Factors of EHEC:
Biologically similar but immunologically different from Shiga toxin and Verotoxin I