1 Introduction and basic bacteriology

Question 1

What is Purpura Fulminans?

Answer 1

Small capillary clots due to intra vascular coagulation, leading to tiny spots of necrosis all over the body. Simultaneously, bleeds occur all over the place because clotting factors are used up by all the tiny clots.

Question 2

Which organisms are the major causes of Purpura Fulminans?

Answer 2

Neisseria meningitidis, Streptococcus pyogenes, Staphylococcus aureus

Question 3

Which spherical bacterium is named for its golden color?

Answer 3

Staphylococcus aureus

Question 4

What treatment is used to neutralize superantigen exotoxins, and why is it so rarely used?

Answer 4

intravenous immunoglobulin; it is rarely used in part because it is so expensive ($30K)

Question 5

What is drotrecogin-alpha, and what is it used to treat?

Answer 5

activated Protein C; it is used to slow clotting to prevent purpura

Question 6

What illness can develop when a patient has a respiratory viral infection complicated by Staph aureus?

Answer 6

Post-influenza TSS

Question 7

Which bacterium is the most significant cause of serious infections and deaths due to infections in the United States?

Answer 7

Staphylococcus aureus

Question 8

Which bacteria constitute the top two causes of bloodstream infections?

Answer 8

1) Staphylococcus epidermidis 2) Staphylococcus aureus

Question 9

Which bacterium is the number 1 cause of osteomyelitis?

Answer 9

Staphylococcus aureus

Question 10

T or F: Staph aureus is the number 1 cause of pneumonia.

Answer 10

F; it is the number 2 cause of pneumonia

Question 11

Thucydides Syndrome is now recognized as what illness?

Answer 11

post-influenza Staph TSS

Question 12

How many americans die yearly due to seasonal influenza?

Answer 12

3K to 50K

Question 13

Which two proteins are essential in influenza virus for infecting (i.e. entering and exiting) a host cell?

Answer 13

Hemagglutinin and Neuraminidase

Question 14

Which protein allows entry of the influenza virus into an epithelial cell, and what does it bind to on the host cell to initiate this process?

Answer 14

Hemagglutinin binds to sialic acid residues on epithelial cells to allow entry of the virus

Question 15

What needs to occur in order to activate hemagglutinin?

Answer 15

a serine protease needs to cleave the HA and expose the sialic acid binding site on HA

Question 16

Which protein is required in order for influenza virus to exit a host cell?

Answer 16

neuraminidase

Question 17

Which viral protein is the target of Tamiflu?

Answer 17

Neuraminidase

Question 18

How does Staph aureus help to activate influenza HA?

Answer 18

Staph aureus produces a large amount of serine proteases that can cleave and activate HA

Question 19

T or F: TSST-1+ S. Aureus produces lower levels of proteases

Answer 19

F, it produces exceptionally high levels

Question 20

T or F: Influenza virus can be activated by Human serine proteases

Answer 20

T

Question 21

Summarize the pathogenesis of post influenza TSS.

Answer 21

1) Human is co-colonized by influenza A virus and TSST-1+ Staphylococcus aureus
2) S. aureus serine proteases activate the viral HA, and the virus
infects respiratory epithelial cells
3) Virus damages epithelium, allowing for secondary S.
aureus infection and TSST-1 production
4) Post-influenza TSS develops in virally
immunocompromised, susceptible humans

Question 22

What is a pathogen?

Answer 22

A microbe that causes illness

Question 23

What is a primary pathogen?

Answer 23

A microbe that typically causes illness whenever present in the host

Question 24

What is an opportunistic pathogen?

Answer 24

Often normal flora microbe that causes illness when the host is immune compromised

Question 25

What are normal flora, also known collectively as the microbiome?

Answer 25

Microbes that usually live on the skin and mucous membranes without causing illness

Question 26

What is virulence factor?

Answer 26

The strength of the microbe in disease causation, and the factors that give them that strength

Question 27

What are bacilli, and what are some examples?

Answer 27

rod-shaped bacteria; examples include Bacillus cereus [G+], Clostridium tetani [G+], and Escherichia coli [G-]

Question 28

What are some of the sub types of bacilli?

Answer 28

regular rods, fusiform (with tapered ends) and filamentous (thread-like)

Question 29

What are cocci, and what are some examples?

Answer 29

spherical bacteria; examples include Staphylococcus aureus [G+], Streptococcus pyogenes [G+], Streptococcus pneumoniae [G+], and Neisseria meningitidis [G-]

Question 30

What are the major groups of bacteria determined by shape?

Answer 30

bacilli, cocci, coccobacilli, spirilli, spirochetes

Question 31

What are spirilli, and what is an example?

Answer 31

curved bacteria; an example is Vibrio cholerae [G-]

Question 32

What are spirochetes, and what is an example?

Answer 32

long spiral-shaped bacteria; an example is Treponema pallidum

Question 33

Summarize the gram staining process.

Answer 33

1) Stain bacteria for 1 minute with crystal violet and then 2 minutes with Gram’s iodine
2) Decolorize with ethanol
3) Counterstain 30 seconds with safranin

Question 34

T or F: Both crystal violet and safranin are acidic dyes that bind to peptidoglygan carbohydrates.

Answer 34

F; Both crystal violet and safranin are BASIC dyes that bind to Nucleic Acids

Question 35

What color do Gram-positive bacteria stain? Gram-negative?

Answer 35

Gram-positive bacteria stain purple, and Gram-negative stain pink

Question 36

What technique is used to visualize spirochetes?

Answer 36

Darkfield microscopy

Question 37

T or F: Silver stain is used to visualize Legionella pneumophila

Answer 37

T

Question 38

Summarize the acid fast coloring technique.

Answer 38

1) stain with hot carbol fuschin (red)

2) counterstain other bacteria with methylene blue

Question 39

Which organisms is acid fast stain used to visualize, and why is this technique necessary?

Answer 39

mycobacteria and actinomycetes

Question 40

What are the typical dimensions of prokaryotic organisms?

Answer 40

1 micrometer in diameter by a few micrometers long

Question 41

What type of ribosomes do most prokaryotes use, and why is this information clinically significant?

Answer 41

70s ribosomes, frequent target of antibiotics.

Question 42

Describe the typical prokaryotic chromosome.

Answer 42

Circular haploid chromosome, 1-10 megabases in size, contains a few thousand genes