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36 Cards in this Set
- Front
- Back
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ETEC ***know***
FEATURE Pathogenic mechanism Primary site Mucosal pathology Epidemiology Fever Stools Type Blood WBCs transmission |
enterotoxigenic i. coli
Enterotoxin LT and/or ST Small intestine Intact, hyperemia Traveler's diarrhea, Childhood diarrhea Absent Copius, watery Absent Absent contaminated food and water |
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EIEC
Pathogenic mechanism Primary site Mucosal pathology Epidemiology Fever Stools Type Blood WBCs |
-interoinvasive e. coli
Invades enterocytes Large intestine Necrosis, ulceration inflammation Sporadic, uncommon Common Scanty, purulent Common Prominent |
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EHEC
Pathogenic mechanism Primary site Mucosal pathology Epidemiology Fever Stools Type Blood WBCs |
etnterohemorrhagic
Shigalike cytotoxin Large intestine Effacement of microvilli, cell death Hemorrhagic colitis, HUS Absent Copius, bloody Prominent Absent |
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EPEC
Pathogenic mechanism Primary site Mucosal pathology Epidemiology Fever Stools Type Blood WBCs |
enteropathogenic e. coli
Adherence to enterocytes Small Intestine Effacement Of Rnicrovilli Infantile, Childhood diarrhea Common Copius, watery Absent Minimal |
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EAEC
Pathogenic mechanism Primary site Mucosal pathology Epidemiology Fever Stools Type Blood WBCs |
enteroaggregative e. coli
? ? ? Occasional Watery Absent Absent |
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exotoxins vs. endotoxins and enterotoxins
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exotoxins; released by all gram + except for listeria which produces endotoxins, and some -. exotoxin is released from cells
endotoxin is shed from cell membranes -endotoxin is only released from gram - except for listeria, a gram +. enterotoxins are exotoxins that act on GI |
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Shigella
-Bacteriology -Closely related to -Shigella are divided into four species (groups) based on -4 groups |
1. E. coli biochemically, antigenically
2. Non-motile 3. Do not ferment lactose 4. differences in Oantigens and some biochemical reactions -a. Shigella dysenteriae (A) b . Shigellaflexneri (B) c. Shigella boydii (C) d . Shigella sonnei ( |
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Epidemiology
-Shigellae are highly host adapted -Important factors in transmission: -effectivity rate -Secondary attack rates -Shigellosis in the U.S. affects what population -where is it transmitted -what type of shigella? |
1. NEVER a commensal in the human intestinal tract
2. to humans 3. feces, fingers, food, and flies (four F's) 4. High infectivity rate: < 200 organisms cause infection 5. are high: 20-60% 6. pediatric disease affecting children less than 10 yrs. of age a. Associated with daycare centers b. Typically caused by S.sonnei (D) |
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Worldwide epidemics of what type of shigella are associated with high mortality
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S.dysenteriae type 1 (Shiga bacillus) are associated with high mortality
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Pathogenesis
-1 . Fundamental event in pathogenesis: -Invasion is a 3-step process, explain. -4 other actions to proliferate in cell -invasion beyond what is unusual |
-invasion of colonic mucosa
-a. Entry -- parasite directed endocytosis of M cells 1) genes (invasion plasmid antigens, Ipa) encoding for adherence and entry are found on a large 220-kb plasmid 2) shigellae adhere selectively to M cells; enter the basolateral aspect of colonic epithelial cells 3) shigellae cause death of macrophages by activating normal programmed cell death (apoptosis) b. Escape from phagocytic vacuole c. Actinpolymerization d. Propulsion through cytoplasm by actin "tails" c. Passage into adjacent cells through finger-like projections; invasion beyond lamina propria is unusual (no further than mucosal layer) |
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Shiga toxin
-can cause |
Not essential for invasion
b. Contributes to severity of disease c. Can cause hemolytic-uremic syndrome |
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D. Clinical aspects
-Dysentery syndrome - classic 4 symptoms |
a. Abdominal cramps
b. Tenesmus - painful straining to pass stools c. Fever d. Bloody, mucoid stools |
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clinical aspects
S.sonni diarrhea in the U.S. Stool microscopy reveals |
a. Fever
b. Systemic symptoms c. Watery diarrhea 3. -large numbers of fecal leukocytes |
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tx
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1. Disease is usually self-limiting
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prevention
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1. Sewage disposal
2. Water chloh nation 3. Insect control - flies are important vectors 4. Good individual sanitary practices - hand-washing 5. Proper food preparation 6. Vaccines are under investigation |
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Salmonella
Bacteriology -ferments lactose -produces what -used to isolate from stool -used to confirm tests -talk about variance |
Non-lactose fermenters
2. Produce hydrogen sulfides from sulfur-containing amino acids 3. Selective media is used to isolate salmonellae from stools 4. Panels of biochemical tests are used to confirm infection 5. 1500 distinct variants exist based on antigenic analysis of O/K/H antigens |
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Disease Syndromes
-pathogens found in infection related to |
-Gastroenteritis
humans, livestock, mammals, reptiles, birds and insects -Infection related to improper food handling |
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most common vehicles of infection
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Poultry products including eggs, 75% comes from veggies
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Peak incidence
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- summer/fall
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2 major types of disease
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S. typhimurium, S. enterifzdis
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Highest attack rates: Outbreaks occur in
____have been associated with infections |
7) children <5, adults >70
8) nursing homes, hospitals, mental institutions a) Exotic pet turtles, reptiles |
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Pathogenesis
-Major pathogenic mechanism |
invasion
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Sequence of events
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a) Adherence to the brush border of intestinal cells causes membrane "ruffles"
b) Bateria are internalized by pinocytosis c) Bacteria enter lamina propia - endure host inflammatory response |
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Clinical Manifestations
Symptoms begin -symptoms -diarrhea process -fever -infecting dose |
-24 to 48 hours following ingestion of contaminated food or water
2) Nausea, vomiting, cramping, diarrhea - "food poisoning" 3) Diarrhea persists 3 to 4 days, resolves spontaneously 4) Fever is present in 50% of patients 5) infecting dose >10 5 bacilli |
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Treatment
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Fluids and electrolyte replacement
2) Antibiotics not typically used in healthy adults 3) Antibiotics are recommended for groups of patients at risk for bacterernia a) Newborn infants b) Patients X50 yrs of age c) Patients with lymphoproliferative disorders d) Patients with anatomic cardiovascular disease e) Patients with bone or joint disease f) Patients with transplants g) Patients with AIDS |
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Typhoid Fever (enteric fever)
-Epidemiology |
1) Worldwide cause of morbidity and mortality
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Pathogenesis
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1) S. typhi enter and kill M cells
2) Organisms invade macrophages, multiply 3) Organisms spread to the reticuloendothelial system and reach the blood stream |
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. Clinical Manifestations
-Enteric fever is a -Incubation period Characterized by what symptoms -GI, fever/heart, liver |
multiorgan-system. infection
2) - 14 days 3) fever, relative bradycardia, headache a) Faint rash occurs with early fever (rose spots) b) Fever persists for weeks 4) Constipation is more common than diarrhea 5) Bacteremia may lead to infection at other sites 6) Intestinal perforation may occur 7) Infection in biliary tree leads to chronic cami er state |
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Diagnosis
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Early - positive blood cultures
2) Later - positive stool, urine cultures |
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Bacteremia common in who and by what.
-infection of what might occur? |
. Bacteremia during gastroenteritis is common in the very young, very old and immunocompromised
b. Invasion of the blood stream may occur in the setting of either gastroentenitis or as a part of the entenic fever syndrome c. Infection of a pre-existing structural abnormality (such as skeletal lesions, cardiovascular lesions) may occur |
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Asymptornatic Carrier State
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Defined as persistence of salmonellae in the stool or urine for periods of a year or longer
b. Biliary tree, abnormal urinary tract may be Iocations where organisms are harbored c. Food handlers who are caniers are reservoirs for epidemics d. Antibiotic treatment variably successful in eradication |
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Yersinia
Bacteriology |
Coccobacilli which demonstrate bipolar staining
2. Some strains grow better at temperatures below 37*C 3. |
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-Species of major clinical significance
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a. Y. pestis -plague (will be discussed in Zoonoses lecture)
b. Y. enterocolitica c. Y. pseudotuberculosis |
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Pathogenesis
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1. Enteropathogenie Yersinia invade M cells of Peyer's patches
2. Sequence of events: ingestion --- > invasion of M cells of Peyer's patches --- > proliferation in lymph nodes --- > small intestinal inflammation and ulceration |
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Clinical manifestations of Yersinia infections
Y enterocolitica |
a. Enterocolitis
1) Fever 2) Diarrhea 3) Abdominal pain b. Acute mesenteric lymphadenitis c. Terminal ileitis d. Septicemia |
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Yersiniapseudotuberculosis
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Acute mesenteric lymphadenitis
1) Fever 2) Pain 3) Nfimics acute appendicitis 4) Diagnosis is made by isolation of organisms from lymph nodes, less commonly from blood |
