enteropathogenic bacterial infections

Question 0

escherichia coli (most strains are commensal in intestines), aggressive when in sterile sites (urinary tract, meninges, peritoneum) 
what are the 4 strains of E. coli?

Answer 0

common cause of DIARRHEA and UTI
-UTI: RF: structural /fnc abn of urinary tract, sexually active women…Sx: urinary urgency, dysuria (burning), WBC in urine. if asc –> pyelonephritis (flank pain, fever, inc WBC). if chronic –> inflm infiltrate of PMNs and mononuclear cells. if chronic in renal –> chronic pyelonephritis and renal failure
-usually resident flora of perineum and periurethral areas (fecal contamination).
if IC: pna, sepsis (e coli in blood–> endotoxin released–> macrophages release TNF –> septic shock)
newborn (+ group B strep - both in vagina): MENINGITIS, SEPSIS

1. enterotoxigenic
2. enteropathogenic
3. enterohemorrhage (HUS)
4. enteroinvasive

Question 1

6 enteropathogenic bacterial infections

Answer 1

1. E. coli
2. salmonella
3. shigellosis
4. cholera
5. campylobacter jejuni
6. yersinia

Question 2

enterotoxigenic E. coli

Answer 2

• major cause of DIARRHEA in poor tropical areas (TRAVELER’S DIARRHEA - no PMNs/RBCs)
• contaminated water and food, attaches to intestinal mucosa and release enterotoxins and cause secretory dysfunc

Question 3

enteropathogenic E. coli

Answer 3

-major cause of DIARRHEA in poor tropical areas (esp INFANTS AND CHILDREN) through contaminated water/food.
-deforms microvilli of intestinal epithelial cells
SX: diarrhea, vomiting, fever, malaise

Question 4

enterohemorrhagic E. coli

Answer 4

-contaminated meat/milk
-toxin adheres to colonic mucosa (similar to SHIGAtoxin), destroys epithelial cells
-causes HUS –> WBC, RBC in DIARRHEA, ANEMIA, RENAL FAILURE
SX: bloody diarrhea, crampy abd pain, low grade fever

Question 5

enteroinvasive E. coli

Answer 5

food borne dysentery (same as shigella), invades and destroys distal ileum and colon mucosal cells –> inflm and eroded
SX: abd pain, fever, tenesmus, bloody diarrhea
TX: Abs

Question 6

salmonella (major cause of mortality in less developed countries)

Answer 6

gram - rods: causes SALMONELLA ENTEROCOLITIS, TYPHOID FEVER.
SALMONELLA ENTEROCOLITIS = salmonella food poisoning. by food (incl infected animals) with nontyphoidal salmonella strain.
-spread by oral fecal route.
SX: 12-48hrs after eating (vs staph -6hrs), vomit, cramping abd pain, fever.
TX: supportive

Question 7

typhoid fever (uncommon in US)

Answer 7

caused by salmonella typhi, in which humans are the only reservoir

• spread from infected pts/carriers (older women with gallstones/biliary scarring w. colonization) thru contaminated water and food, esp DAIRY, SHELLFISH
• infection usually overlying PEYER’S PATCHES in ileum (x in macrophages –> bursts –> INF PERITONITIS => TYPHOID NODULES (macrophages with ingested bacteria, WBC, RBC)
• macrophages (TNF, IL-1) –> FEVER, malaise, wasting

Untx: incub 10-14d, active invasion/bacteremia, fastigium (hepatomegaly, splenomegaly), lysis, convalescence

TX: Ab, supportive, 20% untx die usually from 2ary inf (pna)

Question 8

shigellosis

Answer 8

• shigellosis boyddi, flexneri, sonnei, dysenteriae (most virulent)
• SHIGA TOXIN: 60s (-|protein), distal colon edematous, acutely inflm, eroded, ulcers, pseudomembrane (PMN, fibrin, necrotic epithelium)
• oral fecal, poor hygiene and sanitation areas

SX: blood, mucoid stools, crampy abd pain, dz 3-8d, shorter w. ab

Question 9

cholera (aerobic, curved gram -rod)

Answer 9

• Vibrio cholera exotoxin causes SEVERE DIARRHEAL DZ caused by contamination with human feces (shellfish, H2O).
• exotoxin has 2 subunits, A+B. B attaches and A enters cell to inc cAMP (Adenyly cyclase) –> MASSIVE NA, H20 SECRETION INTO SI lumen. begins w. loose stool –> severe watery diarrhea (RICE H2O)
• SHOCK and DEATH WITHIN 24HR if not replenished.

Question 10

Campylobacter jejuni (gram - rod, similar to vibrios)
- in developed countries

Answer 10

-causes traveler’s diarrhea in DEVELOPED countries
-contaminated food(raw milk, poultry, meat)/H2O, also spread by oral-fecal contact
-superficial enterocolitis: ulceration –> patchy inflm exudates(pseudomembranes).
SX: >10STOOLS/DAY, WATER/BLOODY STOOLS, may cause ACUTE ULCERATIVE COLITIS, assoc with GULLIAN-BARRE

Question 11

yersinia

Answer 11

-caused by yesinia entercolitica (contaminated meat), y. pseudotuberculosis (feces of domestic animals). both gram - coccoid or rod shaped
-enterocolitica: ulceration and necrosis of peyers patches–>LN
SX: fever, BLOODY DIARRHEA, abd pain (RLQ –> confused w. appendicitis), arthralgia, arthritis, erythema nodosum are complications
-pseudotubculosis: ileal mucosa –> LN (ileal-cecal) –> abscesses and granulomas in LN, spleen, liver