03 - Microbes 9 through 13 (gram-negative bacilli) Flashcards

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1
Q

What are the antigens of Gram-negative bacilli?

A

Cell Wall Antigen O

Flagella Antigen H

Capsule Antigen K

Lipid A = Endotoxin

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2
Q

What are the three Gram-negative bacilli that are curved?

A

Vibrio cholerae

Campylobacter jejuni

Helicobacter pylori

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3
Q

Gram-negative bacilli that are curved with most pathogens in the antigenic groups O1 or O139?

A

Vibrio cholerae

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4
Q

Vibrio cholerae is an etiologic agent of?

A

Cholera — enterocolitis syndrome (gastroenteritis)

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5
Q

Transmission and epidemiology of Vibrio cholerae

A

Endemic to areas w/ poor sanitation e.g. tropical Asia (especially India), Africa, parts of S & C America — several hundred thousand cases annually

Usual transmission of epidemic cholera is through ingestion of contaminated water drinking, food preparation, bathing

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6
Q

What is the pathogenesis of cholera?

A

organisms ingested in large numbers

Incubation period – few hours to five days

Non-invasive organisms localize in small intestine

Cholera toxin produced (enterotoxic exotoxin)

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7
Q

What occurs when the Cholera toxin produced (enterotoxic exotoxin)?

A

stimulates hypersecretion of water and chloride

reverses ion transport in gut (alters intestinal permeability)

Causes massive diarrhea – “rice water stools” – up to 16 liters a day — severe dehyrdation

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8
Q

What is the typical mortality of cholera?

A

up to 50% if untreated

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9
Q

What is the treatment and control of cholera?

A

good hygiene / disinfect feces and vomitus contaminated items

oral replacement of fluid w/ electrolytes

IV of balanced multi-electrolytes

ABX - TETRACYCLINE and other broad spectrum (typically for severely compromised patients)

(No effective immunization)

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10
Q

key takeaways for Tx of cholera?

A

ABX - TETRACYCLINE and other broad spectrum

No effective immunization

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11
Q

Lab Dx of cholera?

A

special request for culture needed in US due to rarity and need for special media (alkaline and selective)

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12
Q

If you have a microbe that requires a selective and alkaline media for culture which is it most likely?

A

cholera vibrio

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13
Q

Which microbe is an etiologic agent of a gastroenteritis due to the ingestion of contaminated shellfish (especially oysters)— a common cause of GE in Asian coastal regions, lower freq in US

A

Vibrio parahemolyticus

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14
Q

Which microbe is found in warm, coastal seawater and is an etiologic agent of infrequent, acute infection?

A

Vibrio vulnificus

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15
Q

Acute gastroenteritis and septicemia due to ingestion of raw or undercooked seafood, particularly raw oysters (very high fatility rate about 50%)

Severe cellulitis due to seawater contaminating a break in the skin – causes severe skin / tissue infection with hemorrhagic bullae and necrotizing fasciitis (high fatality rate about 15%)

A

Vibrio vulnificus

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16
Q

What are the normal etiologic agents of virbrio vulnificus?

A

Acute gastroenteritis and septicemia due to ingestion of raw or undercooked seafood, particularly raw oysters (very high fatility rate about 50%)

Severe cellulitis due to seawater contaminating a break in the skin – causes severe skin / tissue infection with hemorrhagic bullae and necrotizing fasciitis (high fatality rate about 15%)

17
Q

What is the only microbe that has “s” or gull wing shapes as a description of the gram stain?

A

Campylobacter jejuni

18
Q

Describe the gramstain of Campylobacter jejuni:

A

Gram-negative bacillus, thin curved rods, occassionally has “s” or gull wing shapes

19
Q

What is the typical transmission and epidemiology of Campylobacter jejuni? incubation period?

A

ingestion of fecal contaminated food, especially undercooked CHICKEN or contamination of other foods from uncooked chicken, raw milk (from cattle feces), and non-chlorinated water

Incubation period: 2-5 days, symptoms resolve in 3-6 days

20
Q

pathogenicity of Campylobacter jejuni makes it #1 or 2 in N. America (similar to salmonella)…. what are some signs and symptoms?

A

Ulceration of intestinal mucosal epithelium causing diarrhea (infrequently bloody stools), abdominal pain, nausea, vomiting, (infrequent fever)

21
Q

What are the virulence factors of Campylobacter jejuni?

A

Grows in human bile
Flagella promote chemotaxis to colonize the intestine
Adhesive molecules promote attachment
Production of Cytolethal Distending Toxin (CDT) - AB-type toxin that has DNase activity (directly damages DNA)

SOME ARE ABX RESISTANT

22
Q

Treatment and control of Campylobacter jejuni?

A

Generally no ABX, only rehydration and electrolyte replacement

23
Q

Lab Dx of Campylobacter jejuni:

A

Selective culture media w/ ABX

Microaerophile

Incubation of primary isolation media at 42 deg C permits differentiation from species who can grow only at 37 deg C

24
Q

What is the gram stain of Helicobacter pylori?

A

Curved gram-negative bacillus

25
Q

Helicobacter pylori is an etiologic agent of what?

A

peptic ulcers – causes chronic inflammatory lesions of the gastric mucus layer

26
Q

Diagnostic testing for Helicobacter pylori?

A

Breath test to detect UREASE production (only UREASE mentioned in list)

Endoscopy and biopsy – microaerophilic environment & special growth media; DNA probe

27
Q

What is the only microaerophilic microbe?

A

Campylobacter jejuni… BUT H. pylori ALSO requires amicroaerphilic environment for growth on special media

28
Q

UREASE breath test +

A

Helicobacter pylori