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Gastroenterology > Gastro Micro > Flashcards

Gastro Micro Flashcards

1
Q

 Slender, curved Gram- rods
 Motile with polar flagella
 Microaerophilic (can only be grown under very low oxygen tension)

A

H pylori

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2
Q

virulence in H pylori
holes in cells?
Type III SS?
Re-arranges cytoskeleton?

A

 VacA – vacuolating cytotoxin – holes in cells  cell death
 PAI (pathogenicity associated island – different G+C content) encoding Type III secretion system
 Cag – rearranges cytoskeleton

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3
Q

Most common bacterial GI infection in developed countries
low infection dose
animal reservoir
spiral, G- rods, microaerophilic

A

Camplybacter jejuni

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4
Q

Can lead to Guillian-Barre syndrome

A

Camplybacter

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5
Q

Diarrhea w/ C jejuni?

A

watery that progresses to blood/pus and lasts about 3-7 days

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6
Q

 Curved, Gram- rods
 Motile, polar flagellum
 Oxidase positive
 Commonly found in saltwater, disease in warm months

A

Vibrio

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7
Q

Lives in organisms in the water
O1 and O139 outbreaks (200+ serotypes)
rice-water stools
high infectious dose to survive stomach pH

A

Vibrio cholera

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8
Q

 Free-living in sea water
 Seafood-associated food poisoning
 Most common foodborne illness in Japan
 Gulf and Pacific Coasts of US, warm months
 Watery diarrhea often with abdominal cramps nausea, vomiting, low-grade fever, 24 hrs after exposure
 Self-limiting, rare treatment needed

A

vibrio parhaemolyticus

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9
Q

 Free-living in sea water
 Consumption of raw oysters or wound infection (cellulitis)
 Vomiting, diarrhea, abdominal cramps

A

vibrio vulnifus

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10
Q 
	Gram negative coccobacillus
	Antiphagocytic capsule
	Major component of the human GI tract
	Opportunistic pathogen
	Most common anaerobic infection
A

Bacteroides fragilis

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11
Q 
	Gram negative coccobacillus
	Antiphagocytic capsule
	GI tract, nasopharyngeal and vaginal flora
	Opportunistic pathogen, abscesses
	Pulmonary
	Periodontal
A

Prevotella melaninogenica

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12
Q

 Large, “boxcar” Gram+ rods
 Found in soil and intestines of humans and animals
 Most human infections from spores in soil or food
 Gas gangrene and cellulitis
 Food poisoning

A

Clostridium perfringens

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13
Q

 Spore contamination of wounds
 Tetanospasmin (tetanus toxin) is an AB neurotoxin
 Enters at neuromuscular junction and is transported by motor neurons to ganglia
 Incubation time depends on distance of wound from CNS
 Cuts a V-snare

A

C tetani

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14
Q

 Consumption of contaminated food
 Infants: ingesting spores from carpets
 Infection of wounds with spores
 AB toxins

A

C botulinum

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15
Q

 Most common diarrheal disease associated with antibiotic use (creates niche)
 Endogenous or hospital spores are source
 Toxins A and B work synergistically to produce disease (2 separate toxins)
 A: enterotoxin&raquo_space; diarrhea
 B: cytotoxin&raquo_space; inflammation

A

C diff

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16
Q 
E coli: 
Lactose? 
Glucose? 
Oxidase? 
Nitrates? 
Motile?
A 
Lactose? - ferment 
Glucose? - ferment
Oxidase? -neg
Nitrates? to nitrites
Motile? yep
17
Q

Shiga toxin, HUS
O157:H7
cow reservoir - bad meat industry practices!!!

A

EHEC

18
Q

Leading bacterial cause of diarrhea worldwide
Non-inflammatory, high volume ~ cholera
LT~ binds to GM1 gangliosides on cell surface; cholera toxin (activates adenylyl cyclase  chloride efflux)
ST ~cGMP, activates PKA which regulates CFTR, may also decrease sodium reabsorption
Adhesins – fimbriae, species specific

A

ETEC

19
Q 
very similar to Shigella
	Lac-
	Non-motile
	Dysentery similar to shigellosis
	Infectious dose much higher
	Low incidence in US
	Children under 5 yo in developing countries
A

EIEC

20
Q

Infantile diarrhea in developing countries
No toxins
Apical adhesion, moderate invasion, flattens villi
EPEC adherence factor – EAF
EPEC – attached by pili, injects a receptor for other bacteria to produce a pedestal for other colonization (change the locks to fit your own keys) - attachment & effacement
 Profuse, watery infant diarrhea in developing countries
 Clustered microcolonies in small intestine that degenerate with loss of brush border and microvilli
 Pedestal formation via LEE, but no Stx, ST or LT
 Attachment and effacing (A/E) lesion

A

EPEC

21
Q

Gram-, Lac-, Glu+, produce H2S
 Symptoms begin 20-72 hrs post consumption of improperly cooked food
 Nausea, vomiting, followed by or concomitant with abdominal cramps and diarrhea lasting 3-4 days
 Fever in half of patients
 Diarrhea ranges from loose stools to dysentery
 Antibiotics usually not necessary

A

Salmonella

22
Q

Gram-, Lac-, Glu+
Invade M cells, survive in macrophages
 Vi capsule antigen inhibits neutrophil uptake
 Spread to mesenteric lymph nodes and RES in macrophages
 Subsequent spread to blood
 Sepsis can occur
 Perforations of GI tract at necrotic Peyer’s patches can lead to severe hemorrhage
 Insidious, rising fever with headache, abdominal pain
 Slow pulse, mental confusion
 Diarrhea late if at all
 Death possible by ruptured spleen or intestine
 Chronic infection of gall bladder possible
 Culture from blood (or feces)
 DOC: ceftriaxone
 Oral vaccine for travelers to endemic areas (70%)

A

S typhi

23
Q 
	Epidemics in Central and South America
	1000X Stx compared to other species
	HUS
	High fatality rate (20%)
	Gram-, non-motile rod
	Lac-, Glu+, no gas, no H S
	Leukocytes prominent in stool samples
	Acute inflammatory colitis and bloody diarrhea– dysentery like EIEC
	S. sonnei often less bloody, more watery
	Very low infectious dose: 10-100 cfu
	Entry into M cells in gut
	Escape from phagocytic vesicle
	Extension to neighboring enterocytes
	Rarely leaves GI tract
A

Shigella

24
Q

 Gram- coccobacilli with bipolar staining
 Primarily animal pathogens
 Human outbreaks linked to consumption of milk, pork in US
 Gastroenteritis
 Relatively rare
 Abdominal pains can mimic appendicitis – “pseudoappendicitis”
 Usually self-limiting
Siderophilic (more common in people w/ hemochromatosis) repliacates in terminal ilieum, can cuase reactive arthritis

A

Yersinia enterocolitica

25
Q

Single most important cause of diarrheal disease of infants & children world-wide
Non-enveloped, dsRNA 2-3 concentric icosahedral particles: double shelled virion – very stable (fomites)
Potential for antigenic shift: segmented genome, dsRNA
mRNAs are capped, but not polyadenylated
lytic
1-4 day incubation

A

Rotavirus

26
Q

Non-enveloped, (+) strand RNA viruses
– Total estimated cases of food-borne illness in U.S: ~38,600,000/yr
– Noroviruses responsible for ~23 million of total (~60%)
• Symptoms include:
– Nausea, vomiting, fever, followed by “watery diarrhea”
– No blood or leukocytes in stool
– Vomiting more prominent with norovirus infections
1 day incubation

A

Norovirus

27
Q

Agent for Hand Foot Mouth Disease

A

Coxsackivirus A16

28
Q

HAV Family

A

Picornaviridae
ET
ssRNA+

29
Q

HBV Family

A

Hepadnaviridae
PT
dsDNA (cannot be cured)
*transferred to infant during birth not in utero
*Dane particles - 20nm particles that can titrate antibody response

30
Q

HBV markers
a vaccinee?

a resolved acute infection?

a low risk carrier?

a high risk carrier?

Will see high levels of HBe antigen w/o much antibody response

A

HBV markers
a vaccinee? –antiHBs (only component in vaccine)

a resolved acute infection? (anti-surface antigen antiHBs, anti-HBc – if antibody to core is present, they had a natural infection) IgM anti-HBc (acute/ recent infection)

a low risk carrier? Will be able to see surface antigen but not surface antibody, will see HBe in low risk and antiHBe

a high risk carrier? Will see high levels of HBe antigen w/o much antibody response

31
Q

HCV family

A

Flaviridae, ssRNA
85% chronic
genotype determines prognosis

32
Q

HDV

A

Delta Virus
ssDNA
co-infection w/ HBV required

33
Q

HEV family

A

Calciviridae
ssRNA+ nonenveloped
1/5 fatal in pregnant women

Gastroenterology (5 decks)

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