Infectious Agents (Igboin)

Question 1

What is a biofilm?

Answer 1

Multicellular community of bacteria on a surface, encased in exopolymer

Question 2

Does bacteria attach directly to a surface?

Answer 2

No. Attach to conditioning layer (salivary proteins, fibrin, etc.)

Question 3

What causes the initial irreversible absorption of bacteria unto biofilms?

Answer 3

Adhesions

Question 4

How do other molecules build on to the primary colonizers?

Answer 4

Co-aggregation: adhesion molecule and receptor

Question 5

What are the three basic needs of a biofilm?

Answer 5

1. Physical: adherence
2. Nutritional
3. Respiratory: anaerobes and facultative anaerobes

Question 6

What is the difference between reversible and irreversible binding in biofilms?

Answer 6

Irreversible: adhesins and receptors

Reversible: smaller forces

Question 7

What makes up the majority of a biofilm?

Answer 7

Spider web of extracellular polymers (75-95%)

Question 8

What shape do the micro colonies make?

Answer 8

Mushroom

Question 9

What are the two methods of releasing bacteria from the biofilm?

Answer 9

Active: enzyme
Passive: fluid flow and collision

Question 10

What are the advantages for a microbe of living in a biofilm?

Answer 10

1. Protection
2. Rapid genetic sharing
3. Lots of nutrients

Question 11

What is quorum sensing? What is its purpose?

Answer 11

Cell-cell communication in bacteria where they monitor each other’s density

Purpose: synchronize behaviors such as biofilm formation

Question 12

What is the difference between gram-and gram+ quorum sensing?

Answer 12

Gram-: 2 main components (autoinducer LuxI, receptor LuxR)

Gram+: 3 main components (oligopeptide, receptor, response regulator)

Question 13

T/F: In quorum sensing, a higher cell population density will upregulate transcription.

Answer 13

TRUE

Question 14

What is special about LuxS/AI-2 quorum sensing?

Answer 14

Proposed interspecies communication

Question 15

What are the three classes of signaling molecules?

Answer 15

1. AHL
2. Oligopeptides
3. AI-2

Question 16

How can you block biofilm formation?

Answer 16

Block quorum sensing

Question 17

What are some characteristics of bacteroides?

Answer 17

1. Gram -
2. Strict anaerobes
3. Complex carbs

Question 18

How do bacteroides withstand short exposure to O2?

Answer 18

Superoxide dismutase and catalase

Question 19

What typically results from a intra-abdominal infection?

Answer 19

Biphasic diseases

B. Fragilis

Question 20

Why is B. Frag the most predominant bacteria in PC abscesses?

Answer 20

1. Phagocyte resistant

2. Oxygen tolerant

Question 21

T/F: Abdominal abscesses allow for bacteria to enter the blood causing possible sepsis/shock.

Answer 21

TRUE

Question 22

How are abscesses diagnosed?

Answer 22

CAT scan and cultures

Question 23

How are abscesses treated?

Answer 23

Surgery and antibiotics

Question 24

What is sepsis?

Answer 24

Systemic illness with multiple organ malfunction and hemodynamic derangement

Question 25

How is sepsis treated?

Answer 25

1. High O2 2. IV fluids 3. vasopressors 4. Antibiotics

Question 26

How is syphilis diagnosed?

Answer 26

Detect antibodies against the bacterium

Question 27

How do you treat syphilis?

Answer 27

Penicillin

Question 28

What are some general characteristics of treponemes?

Answer 28

1. Helical shape 2. Corkscrew movement 3. Periplasmic flagella

Question 29

Describe primary syphilis?

Answer 29

Syphilitic chancre formed and will heal spontaneously

Question 30

What is part of secondary syphilis?

Answer 30

Patient develops rash due to systemic spread of bacteria Can result in latent syphilis

Question 31

What is associated with tertiary syphilis?

Answer 31

Development of lesions attacking various tissues in the body GUMMAS

Question 32

What causes lyme disease?

Answer 32

B. Burgdorferi

Question 33

How does B. Burgdorferi (lyme disease) enter the human?

Answer 33

Via the salivary glands of deer tick

Question 34

How does b. Burgdorferi spread?

Answer 34

Human plasmin

Question 35

What are the three stages of lyme disease?

Answer 35

1. Localized skin infection 2. Disseminated infection in CNS (IL-1 and TNFalpha) 3. Months to years later: arthritis

Question 36

How is lyme disease detected and treated?

Answer 36

Detected: antibodies Treatment: NO penicillin, doxycycline or amoxicillin