export_gi bacteria ii

Question 1

MacConkey agar tests for?

Answer 1

Lactose fermentation

Question 2

MacConkey results are red indicates?

Answer 2

Lactose fermentation POSITIVE

E. coli, some others

Question 3

MacConkey results are white indicates?

Answer 3

Lactose fermentation NEGATIVE

Salmonella, Shigella, and others

Question 4

Indole test tests for?

Answer 4

Indole production

Question 5

Indole test results red indicates?

Answer 5

Indole production POSITIVE

E. coli, Vibrio spp., and others

Question 6

Indole test results in no color change indicates?

Answer 6

Indole production NEGATIVE

Salmonella

Question 7

Hydrogen sulfite test used to differentiate?

Answer 7

Salmonella from Shigella

Question 8

H2S production test for Salmonella

Answer 8

Results in a black precipitate, indicating H2S production

Question 9

H2S production test for Shigella

Answer 9

No precipitate formed, indicating no production of H2S

Question 10

Enteropathogenic E. coli (EPEC) features and disease

Answer 10

Gram-negative, facultative anaerobe, moderately invasive

Causes watery diarrhea, pediatric cases are big

Question 11

EPEC pathogenesis

Answer 11

BfpA
Type III secretion system

NO toxins

Question 12

BfpA

Answer 12

“Bundle-forming pilus”

Adhesins

Question 13

Type III secretion system

Answer 13

Injection of bacterial protein
For EPEC, this protein is called Tir (receptor for another protein called intimin)

F actin polymerization occurs, which results in increased efflux of water

Question 14

EPEC diagnosis and treatment

Answer 14

Culture and biochemical tests
MacConkey positive

Indole positive

PCR

Supportive therapy

Question 15

Enterotoxigenic E. coli (ETEC) features and disease

Answer 15

Gram-negative, facultative anaerobe, non-invasive

“Travelers diarrhea” - watery diarrhea from contaminated water and ice

Question 16

ETEC pathogenesis

Answer 16

Fimbriae (pili)
LT toxin

ST toxin

Question 17

Fimbriae

Answer 17

Adherence to epithelial cells

associated w/ ETEC

Question 18

LT toxin

Answer 18

Heat liable toxin
AB toxin

Increases cAMP, resulting in water efflux

Plasmid-encoded

Question 19

ST toxin

Answer 19

Heat stable toxin
Non-AB toxin, does NOT enter cell

Increases cGMP

Plasmid-encoded

Question 20

ETEC diagnosis and treatment

Answer 20

DNA probes to detect LT and ST encoding genes

Supportive therapy

Question 21

Salmonella spp. two types

Answer 21

S. typhi

Non-typhoidal Salmonella

Question 22

Non-typhoidal Salmonella

Answer 22

S. cholerasuis
S. enteritidis

S. typhimurium

Question 23

S. typhi features

Answer 23

Gram-negative rods, motile, facultative anaerobes, intracellular pathogen

Question 24

S. typhi transmission and resistance

Answer 24

Oral-fecal route

Acid tolerant

Question 25

Incubation for S. typhi

Answer 25

~13 days

Question 26

Progression of S. typhi

Answer 26

``` Fever with headache, with increasing fever for 3 days Typhoid fever (longer than ~4 weeks) ``` GI symptoms Re-infection (shedding of S. typhi in stool)

Question 27

S. typhi pathogenesis

Answer 27

Adherence to M cells

Question 28

M cells

Answer 28

Found in the small intestine Sample and present intestinal contents to immune cells Associated with Peyer's patches

Question 29

S. typhi adherence to M cells and dissemination

Answer 29

Type III secretion system Invade vacuoles of M cells and escapes into cytosol Can then invade macrophage and escape into lymphatics, resulting in bacteremia

Question 30

Diagnosis and treatment of S. typhi

Answer 30

Culture of stool samples | Antibiotics based on susceptibility profile

Question 31

Prevention of S. typhi

Answer 31

Avoid potential sources of infection | Vaccinations for travelers - Ty21A and ViCPS

Question 32

Nontyphoidal Salmonella features

Answer 32

Gram-negative rods, facultative anaerobe, motile/flagellated (H Ag), intracellular pathogens

Question 33

Incubation period for nontyphoidal Salmonella

Answer 33

6-48 hours post-ingestion

Question 34

Symptoms of nontyphoidal Salmonella

Answer 34

Nausea, vomiting, abdominal cramps, watery diarrhea with or without blood, sometimes fever, ranges from loose stool to severe dysentery-like diarrhea

Question 35

Nontyphoidal Salmonella pathogenesis

Answer 35

Same as typhoidal, up to macrophage infiltration; two options - Rapid killing of the macrophage, resulting in massive inflammation response that confines the infection to intestines OR (immunocompromised patients) systemic dissemintation, bacteremia, focal infections

Question 36

Diagnose nontyphoidal Salmonella

Answer 36

Serology (anti-Vi Ag Ab) Culture from blood and stool MacConkeys negative Production of H2S

Question 37

Treatment for nontyphoidal Salmonella

Answer 37

Confined to intestines - replace electrolytes, antibiotics NOT recommended Systemic - antibiotics, based on resistance profile

Question 38

Campylobacter jejuni features and disease

Answer 38

Gram-negative curved rod, microaerophilic, invasive | Ulceration/acute enteritis, watery diarrhea, sepsis, Sequelae (Guillain-Barre syndrome)

Question 39

Incubation time for Campylobacter jejuni

Answer 39

2-11 days

Question 40

Pathogenesis of Campylobacter jejuni

Answer 40

Similar to Salmonella, but not much is known

Question 41

Diagnosis and treatment of Campylobacter jejuni

Answer 41

Culture | Supportive therapy, or antibiotics (invasive disease only, based on susceptibility profile)

Question 42

Transmission of Samonella typhi vs. non-typhoidal

Answer 42

fecal--oral transmission typhi--humans are only reservoir non-tyhphoidal--human and animal reservoirs