Spring Bugs

Question 1

Lab ID of Mycobacterium Leprae

Answer 1

Gram-positive, bacilli, nonmotile, non-sporeforming, acid-fast, mycolic acid: (mycoside)phenolic glycolipid (PGL-I), high lipid content of cell wall, lipoarabinomannan (LAM), obligate intracellular parasite, strict aerobe

Question 2

Virulence factors of M. Leprae

Answer 2

PGL-I, laminin binding protein, lipoarabinomannan, high lipid content of cell walls

Question 3

Mechanism of phenolic glycolipid I virulence

Answer 3

Binds to the basal lamina of Schwann cells

Question 4

Mechanism of laminin binding protein virulence

Answer 4

Binds to the basal lamina of Schwann cells

Question 5

Mechanism of M. Leprae high lipid content of walls

Answer 5

high lipid content of cell wall made of mycolic acids and LAM -> prevents many pharmacological compounds from crossing bacterial cell membrane into cytosol; CD8+ Tc unable to insert perforin for cell lysis

Question 6

What is the predominant organism that causes dental caries?

Answer 6

Streptococcus mutans

Question 7

Why is streptococcus mutans so prevalent in dental caries?

Answer 7

Metabolizes sucrose more efficiently than other oral bacteria

Question 8

Salmonella Enterica lab ID

Answer 8

gram negative, bacilli, non-spore forming, non-acid fasting, motile, flagella (H antigen), LPS (O antigen), capsule (K antigen), pili, produces H2S when fermenting glucose on Hektoen agar (Black), non-lactose fermenting

Question 9

Transmission of Salmonella Enterica

Answer 9

food preparation practices allowing infecting dose of bacteria by growth in food before ingestion, turtles

Question 10

Identification of Shigella

Answer 10

Gram-negative, Bacilli, Pili, Non-motile, Unencapsulated, Non-lactose fermenting, no flagella, non-sporeforming, non-acid fasting

O-antigen (lipopolysaccharide outer membrane LPS) Serogroup A- Shigella dysenteriae
Serogroup B- Shigella flexneri
Serogroup C- Shigella boydii
Serogroup D- Shigella sonnei

Grows on Hektoen enteric agar- Fermenters of glucose- but does not produce gas in this process (green)

Question 11

What is O antigen?

Answer 11

lipopolysaccharide

Question 12

What is K antigen?

Answer 12

capsule

Question 13

What is H antigen?

Answer 13

Flagella

Question 14

How is shigella acid resistance a virulence factor

Answer 14

able to survive acidic climate of stomach to reach intestines, where it enters and infects host

Question 15

virulence of Invasion plasmid antigens (Ipa)

Answer 15

protein antigens injected by type III secretion system ➡️ induce cytoskeleton reorganization and actin polymerization ➡️ induces engulfment and internalization of Shigella into host cell by endocytosis

Question 16

Virulence of shiga toxin (Stx)

Answer 16

B unit directs binding to a specific glycolipid receptor (Gb3) present on eukaryotic cells ➡️ internalized in an endocytotic vacuole ➡️ Inside the cell, the A subunit crosses the vacuolar membrane in the trans-Golgi network ➡️ exits to the cytoplasm ➡️ enzymatically modifies the ribosome site (28S-RNA of 60S subunit) where amino acyl tRNA binds ➡️ blocking protein synthesis ➡️ leading to cell death

Question 17

Virulence of shiga toxin (Stx)

Answer 17

B unit directs binding to a specific glycolipid receptor (Gb3) present on eukaryotic cells ➡️ internalized in an endocytotic vacuole ➡️ Inside the cell, the A subunit crosses the vacuolar membrane in the trans-Golgi network ➡️ exits to the cytoplasm ➡️ enzymatically modifies the ribosome site (28S-RNA of 60S subunit) where amino acyl tRNA binds ➡️ blocking protein synthesis ➡️ leading to cell death

Question 18

Virulence factors for salmonella enterica

Answer 18

Flagella, pili, Injection (type III) secretion system

Question 19

Virulence of injection (type III) secretion system for salmonella

Answer 19

S. Enterica adheres to cell via pili binding to mannose receptor ➡️ injection (type III) secretion system create a membrane “ruffles” (specialized plasma membrane site of filamentous actin cytoskeleton rearrangements) ➡️ salmonella endocytose and enter cell

Question 20

Identification of clostridium difficile

Answer 20

gram positive, bacilli, spore forming, anaerobic, catalase negative, superoxide dismutase negative

Question 21

Virulence factors for clostridium difficile

Answer 21

toxin A (TcdA) enterotoxin, toxin B (TcdB) a cytotoxin, C. difficile transferase (CDT), spores

Question 22

virulence of c. diff toxin A and toxin B

Answer 22

Toxin A and B glucosylate and inactivate GTPases ➡️ disrupts the signal transduction of G proteins ➡️ rearrange actin filaments ➡️ disrupts intracellular tight junctions ➡️ increase membrane permeability and fluid secretion

Question 23

virulence of c. diff transferase toxin (CDT)

Answer 23

exerts ADP-ribosylation ➡️ inhibit actin polymerization in enterocytes

Question 24

What does the pseudomembrane of C. difficile consist of

Answer 24

inflammatory plaques ➡️ coalesce into pseudomembrane (made of fibrin, leukocytes, and necrotic colonic cells)

Question 25

What kind of helminth is ascaris lumbricoides?

Answer 25

nematode

Question 26

What kind of helminth is diphyllobothrium latum?

Answer 26

cestode

Question 27

What are the five species of plasmodium which infect humans?

Answer 27

``` P. falciparum P. vivax P. ovale P. malariae P. knowlesi (rarely causes disease) ```

Question 29

Lab ID/Characteristics specific to P. falciparum?

Answer 29

1) Infect RBCs of any age 2) Bind to glycophorin A on RBCs 3) Form knobs on RBC surface ➡️ produce high-molecular weight adhesive protein (PfEMP1) ➡️ used to bind to ligands on endothelium 4) large, banana-shaped gametocytes 5) Double chromatin dots 6) May have double infection (>1 parasite per RBC) 7) Maurer dots (RBCs)

Question 30

Lab ID/Characteristics specific to P. ovale?

Answer 30

1) Has dormant stage (hypnozoite) 2) Only invade reticulocytes 3) Enlarged & pale RBCs 4) RBCs are oval and fimbriated (fringed borders) 5) Schuffner dots (RBCs)

Question 30

Lab ID/Characteristics specific to P. vivax?

Answer 30

1) Has dormant stage (hypnozoite) 2) Binds to Duffy antigen on RBCs 3) Only invade reticulocytes 4) Enlarged & pale RBCs 5) Schuffner dots (RBCs)

Question 31

Lab ID/Characteristics specific to P. malariae?

Answer 31

1) only invades senescent cells 2) trophozoites are band-shaped 3) merozoites arranged in rosettes

Question 32

General lab ID/characteristics of plasmodium?

Answer 32

1) Non-motile 2) Gametocytes larger & lack nuclear division compared to asexual stages 3) red nuclear chromatin 4) blue cytoplasm 5) brown/black pigment (hemozoin) with ⬆️ ferroprotoporphyrin IX (breakdown product of hemoglobin)