GI bacteria I Flashcards Preview

Year 1 Microbiology > GI bacteria I > Flashcards

Flashcards in GI bacteria I Deck (39):
1

Which host defenses can trigger expression of bacterial virulence factors?

Mucous, bile

2

What is characteristic of GI distress 1-8 hours after ingestion?

Preformed toxin

3

What is characteristic of GI distress 8-16 hours after ingestion?

Production of toxin after ingestion

4

What is characteristic of GI distress 16+ hours after ingestion?

Adherence, growth, and virulence factor production

5

What pathogens infect with a preformed toxin 1-8 hours after ingestion?

1. Staphylococcus aureus 2. Bacillus cereus (emetic) 3. Clostridium botulinum

6

What pathogens produce toxin 8-16 hours after ingestion?

1. Bacillus cereus (diarrheal) 2. Clostridium perfringens 3. Clostridium botulinum

7

What pathogens adhere, grow, and produce virulence factors 16+ hours after ingestion?

1. Shigella spp. 2. Listeria monocytogenes 3. EHEC 4. EPEC 5. ETEC 6. EIEC 7. Campylobacter spp. 8. Vibrio spp.

8

Is fever associated with bacterial food poisoning?

No

9

What are the four bacterial causes of food poisoning?

1. Staphylococcus aureus 2. Clostridium botulinum 3. Clostridium perfringens 4. Bacillus cereus

10

What are the characteristics of staphylococcus aureus?

1. Gram positive cocci in clusters 2. Non spore forming

11

What is the disease progression of staphylococcos aureus food poisoning?

1. Ingestion of preformed toxin 2. Severe vomiting, diarrhea, constipation and abdominal pain 1-8 hours after ingestion

12

What is the pathogenesis of staphylococcus aureus food poisoning?

Heat stable toxin

13

What are the characteristics of clostridium botulinum?

1. Gram positive rod 2. Spore forming

14

Does staphylococcus aureus produce spores?

No

15

Does clostridium botulinum produce spores?

Yes

16

What is the disease progression of clostridium botulinum food poisoning?

1. Mediated by botulinum toxin 2. Early - vomiting, diarrhea, abdominal pain 1-8 after ingestion 3. Late - flaccid paralysis, progressive muscle weakness and respiratory arrest

17

What is the pathogenesis of clostridium botulinum food poisoning?

1. Ingestion of preformed toxin 2. Large number of spores germinate in intestine and produce toxin 3. Toxin acts at NMJ, blocks Ach release at synapses

18

What are the characteristics of clostridium perfringens?

1. Gram positive rod 2. Spore forming

19

What is the disease progression for clostridium perfringens food poisoning?

1. C. perfringens enterotoxin 2. Diarrhea and abdominal pain 8-16h after ingestion 3. Lasts for 24 hours

20

Does clostridium perfringens produce spores?

Yes

21

What are the characteristics of bacillus cereus?

1. Gram positive 2. Spore forming

22

What is the disease progression for the emetic form of bacillus cereus food poisoning?

1. Vomiting, nausea, abdominal cramps 1-8 hours after ingestion of preformed heat stable enterotoxin 2. Associated with improper storage of cooked rice

23

What is the disease progression for the diarrheal form of bacillus cereus food poisoning?

1. Diarrhea, nausea, abdominal pain 8-16 hours after ingestion of contaminated food 2. Production of heat labile enterotoxin in intestine

24

What are the characteristics of helicobacter pylori?

1. Gram negative curved rod 2. Microaerophilic (5% oxygen)

25

What is the pathogenesis of helicobacter pylori?

1. Penetrates mucosa of stomach, attracted to hemin and urea 2. Produces urease which breaks down urea into NH3 and CO2 to increase pH

26

What is the treatment for H. pylori?

1. Antibiotics 2. Proton pump inhibitor to control acid / further mucosal damage

27

What are the characteristics of listeria monocytogenes?

1. Gram positive short rods sometimes in pairs 2. Facultative anaerobe

28

What are the key survival traits of listeria monocytogenes?

1. Wide growth range (cryophilic) 2. Resistant to high salt concentrations 3. Wide pH range

29

What is the epidemiology of listeria monocytogenes?

1. Contamination common in ready to eat meats 2. High risk of infection in elderly, immunocompromised

30

What is the clinical manifestation of listeria monocytogenes in immunocompromised individuals?

1. Bacteremia 2. Meningitis and encephalitis

31

If a pregnant patient has a fever with no obvious focus, what pathogen should be included in the differential?

Listeria monocytogenes

32

What is the clinical manifestation of neonatal listeria monocytogenes infection?

1. Granulomatosis infantiseptica - pyogenic granulomas distributed over the whole body 2. Early onset in utero - premature birth, abortion3. Late onset - 2-3 weeks after birth

33

What is the pathogenesis of listeria monocytogenes?

1. Adherence via internalin A (IntA) 2. Internalized into a vacuole 3. Acidification of vacuole / phagosome 4. Listeriolysin produced in response to acidification of phagosome

34

How does listeria monocytogenes adhere to the GI tract?

Internalin A

35

What is activated by the acidification of the internalized vacuole in listeria monocytogenes infection?

Listeriolysin

36

What is the role of listeriolysin in listeria monocytogenes infection?

Disrupts vacuole membrane to allow for escape into the cytosol

37

What is the pathogenesis of listeria monocytogenes?

1. Replication in host cell cytosol 2. ActA mediated polymerization to induce motility 3. Disseminated infection to liver, spleen, CNS

38

What is the diagnosis for listeria monocytogenes?

Culture of CSF and blood for 1. Cold enrichment selection 2. Weak B hemolysis on blood agar 3. Motility test

39

What is the treatment for listeria monocytogenes?

Beta lactam or trimethoprim-sulfamethoxazole