Non-Enteric GI Pathogens Flashcards
A gram-negative bacillus isolated from a stool specimen produces clear colonies on MacConkey agar and yellow colonies on thiosulfate citrate bile salt sucrose medium. The isolate is subcultured to a sheep blood agar plate with an O/129 disk. The isolate is sensitive to O/129 and is oxidase-positive. You should suspect:
a. Vibrio parahaemolyticus
b. Vibrio cholerae
c. Plesiomonas
d. Aeromonas
b. Vibrio cholerae
(green colonies on MAC: V. parahaemolyticus)
Which of the following Vibrio spp. would you expect to be most likely isolated from a blood culture?
a. V. cholerae
b. V. parahaemolyticus
c. V. vulnificus
d. V. alginolyticus
V. vulnificus
Which of the following genera is typically microaerophilic?
a. Helicobacter
b. Aeromonas
c. Plesiomonas
d. Vibrio
Helicobacter
Campylobacter jejuni is most noted for causing:
a. Wounds
b. Septicemia
c. Gastric ulcers
d. Gastroenteritis
Gastroenteritis
Which of the following is a risk factor for acquiring V. alginolyticus infection?
a. Farming
b. Hunting
c. Fishing or swimming in ocean water
d. Drinking unpasteurized milk
Fishing or swimming in ocean water
An oxidase-positive, indole-positive, β-hemolytic, gram-negative bacillus resistant to O/129, cannot grow in 6% NaCl broth, and is a non–lactose fermenter on MacConkey agar is isolated from an adult stool culture. You should suspect:
a. Aeromonas hydrophila
b. Aeromonas caviae
c. Plesiomonas shigelloides
d. Vibrio parahaemolyticus
Aeromonas hydrophila
Darting motility is a characteristic of:
a. Aeromonas
b. Campylobacter
c. V. cholerae O1
d. V. cholerae non-O1
Campylobacter
Which of the following tests is most helpful in differentiating C. jejuni from the other Campylobacter spp.?
a. Nitrate reduction
b. Urease activity
c. Hippurate hydrolysis
d. Susceptibility to nalidixic acid
Hippurate hydrolysis
What nonculture methods are used to diagnosis Helicobacter
pylori infections?
-urea breath test
The most commonly used nonculture method for the diagnosis of H. pylori is the noninvasive 1C- or 1C-labeled urea breath test. The patient receives an oral dose of labeled urea.
Urease activity by H. pylori results in the formation of radioactive-labeled COz, which is absorbed into the bloodstream and then exhaled. Other nonculture methods include microscopic examination of stained gastric tissue and direct collection
When attempting to recover enteric Campylobacter spp., which
1.specimen,
2. media, and
3. incubation conditions should be used?
- and rectal swabs; stool samples are preferred.
- CAMPY-BAP (Brucella agar-based medium, with 10% sheep red blood cells and a combination of antimicrobials.)
- Charcoal cefoperazone deoxycholate agar is an alternative.
Vibrio Species
- Vibrio cholerae
- Vibrio parahaemolyticus
- Vibrio vulnificus
Vibrio spp. motility
shooting star motility
Kanagawa toxin (phenomenon) is associated with?
V. parahaemolyticus
3 serotypes of V. cholerae O1
Inaba
Ogawa
Hikojima
V. cholerae O1 serotypes
antigentic determinant A & C
Inaba
V. cholerae O1 serotypes
antigenic determinant A & B
Ogawa
V. cholerae O1 serotypes
expresses both Inaba and Ogawa antigens
Hikojima
Side note:
Vibrio spp.
Is halophilic (salt-loving): requires 1% NaCl in the growth media (BAP, MAC, and biochemical tests media)
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enrichment broth for vibrio?
Alkaline peptone water broth
pH 8.6
Campylobacter…if culture will be delayed, transport the spx in ___?
- This medium has demonstrated its effectiveness in recovery of various microorganisms like Vibrio parahaemolyticus and species of Salmonella, Shigella and Yersinia.
Cary-Blair transport medium
-Cary Blair Transport Medium is used for transportation and preservation of clinical specimens, primarily faecal
and rectal samples.
Side note:
V. vulnificus and Non-O1 V. cholerae have acidic polysaccharides
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Enterotoxin that induces chloride ion secretion (watery diarrhea); produces beta hemolysis on BAP using human blood
Kanagawa hemolysin/ Thermostable direct hemolysin (TDH)
Vibrio spp. with Cytolysins, PROTEASES, Collagenase, Lysine degradation enzymes
V. vulnificus
causative agent
disease begins at 2-3 days after exposure, followed by abrupt onset of “rice-watery” stool diarrhea and vomiting
Vibrio cholerae O1 and O139
causative agent
-wound infection may also occur from exposure to contaminated seawater
- gastroenteritis, cholera-like illness
- disease begins at 5-72 hours after exposure with explosive watery diarrhea
Vibrio parahaemolyticus
sudden onset of fever and chills, vomiting, diarrhea and abdominal pain, secondary skin lesions and tissue necrosis are often present
causative agent
Vibrio vulnificus
Campylobacter spp. common isolates
jejuni
coli
fetus
upsaliensis
Campylobacter spp.
original isolates recovered from the feces of dogs at an animal clinic in Uppsala, Sweden
Campylobacter upsaliensis
Campylobacter O2 requirement:
Microaerophilic (5-7% O2 & 5-10% CO2)
Campylobacter Incubation temp and time:
42° C for 48 hours or longer
causes
Gastroenteritis
Guillain-Barré syndrome
reactive arthritis
Campylobacter jejuni
Campylobacter spp. isolated from
1.dogs and
2 cats.
- causes Gastroenteritis, extraintestinal infections, Guillain-Barré syndrom
C. upsaliensis
-campylobacter spp. |
-from Cattle, sheep
-causes vascular infections (e.g., septicemia,septic thrombophlebitis, endocarditis), meningoencephalitis, gastroenteritis
C. fetus
3 common Helicobacter isolates
Helicobacter pylori
Helicobacter cinaedi
Helicobacter fennelliae
causes peptic ulcer
Helicobacter pylori
-homosexual (the organism was first isolated from homosexuals with gastroenteritis)
Helicobacter cinaedi
amed after C. Fennell, who first isolated the organism
Helicobacter fennelliae
Stain for Helicobacter
ematoxylin or Modified Giemsa
Selective medium for Helicobacter
(SBC)
Skirrow’s agar
Butzler’s agar
Campy agar
(supplemented with blood,
hemin, or charcoal)
Helicobacter motility
corkscrew
Side note:
Helicobacter is
-Urease (+)
-Catalase (+)
-Oxidase (+)
Triple positive
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the medium of choice to isolate and differentiate the Vibrio spp. This medium distinguishes sucrose-fermenting strains from non–sucrose-fermenting strains.
TCBS agar
(Thiosulfate–citrate–bile salts–sucrose agar)
two biotypes of V. cholerae O1
classical
el tor
1 agent of cholera pandemic (biotype)
classical
selective media for vibrio spp.
Thiosulfate Bile Salt Sucrose (TCBS)
Side note
V. cholerae and V. parahaemolyticus have 2 chromosomes
V. vulnificus and Non-O1 V. cholerae have acidic polysaccharides
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Side note:
Accessory cholera enterotoxin (ACE) -Increases intestinal fluid secretion
Zonula occludens toxins (ZOT) - Increases intestinal permeability
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Modifies cell surface to increase GM1 binding sites for cholera toxin (virulence factor)
-clue is GM1 binding sites….
Neuraminidase
Recommended stain for Helicobacter spp.
Warthin-Starry Silver Stain
(silver staining for spiral bacter)
sea-gull appearance
campylobater spp.
Selective media for Campylobacter with antibiotic at 42C
- Skirrow’s agar
- Campy’s agar
- Butzler’s agar
(Optimum temperature
is 42C – to inhibit the growth of other fecal species)
