Microbiology

Question 1

What kind of bacteria does the MacConkey agar stain for?

Answer 1

Gram negative

Question 2

What is the purpose of the Hektoen enteric agar?

Answer 2

Differentiate salmonella and Shigella

Question 3

What does mycoplasma require in order to grow?

Answer 3

Needs cholesterol, purines, and pyrimidines because it has a weak membrane

Cholesterol helps to stabilize the cell membrane

Question 4

Which bacteria need cysteine to grow?

Answer 4

Francisella
Brucella
Legionella
Pastuerella

Question 5

Which organisms commonly form biofilms?

Answer 5

Staph epidermis
Strep mutans
Pseudomonas

Question 6

In which phase of bacterial growth do antibiotics work the best in?

Answer 6

The log phase: phase of rapid replication

Question 7

Which stain can recognize capsules?

Answer 7

India Ink- doesnt always work

Question 8

What is the toxin of Strep pyogenes? How does she work

Answer 8

M protein: binds to complement and doesnt allow it to work properly (C3b)

Question 9

What is the toxin of Staph Aureus and how does it work?

Answer 9

Toxin A: binds to the Fc portion of IgG so that it doesnt get targeted

Question 10

__________ can change its pili and outer membrane proteins as a way of tricking the cell and avoiding destruction (antigenic variation)

Answer 10

Niesseria Gonorrhea

Question 11

What are two viruses that are WELL KNOWN for antigenic variation

Answer 11

Influenza

HIV

Question 12

_________ survives by inhibiting phagosome-lysosome fusion

Answer 12

M tuberculosis

Question 13

_________ survives inside the cell by escaping the phagosome before the phagosome lysosomal fusion

Answer 13

Listeria

Question 14

What is LPS? Is it found on gram negative or gram positive bacteria?

Answer 14

LPS is found on gram negative bacteria; it consists of O antigen, a core, and a Lipid A molecule

Lipid A is the toxin and binds to phagocytes; released at the death of the cell

Question 15

What are the bacteria that are encapsulated? At least the larger bacteria?

Answer 15

Strep pneumo 
Klebsiella 
H flu 
Pseudomonas Aeruginosa 
N. meningitidis 
Cryptococcus neoformans 

Some Killers Have Pretty Nice Capsules

Question 16

________ is the primary virulence factor in gram negative septic shock

Answer 16

LPS

Question 17

What is the mode of action of the diphtheria toxin?

Answer 17

ADP ribosyl transferase inactivates eEF2 which inhibits eukaryotic cell protein synthesis

Targets the heart, nerves, and epithelium

Question 18

What is the toxin of pseudomonas aeruginosa?

Answer 18

Exotoxin A: ADP ribosyl transferase inactivates eEF2 which inhibits eukaryotic cell protein synthesis

Question 19

Which two bacteria have toxins that interfere with the 60S ribosomal subunit?

Answer 19

Shigella toxin and Verotoxin (EHEC)

Question 20

Which toxin blocks the release of GABA as an inhibitory transmitter to ACH, causing a spastic paralysis?

Answer 20

Tetanus toxin

Question 21

Which toxin blocks the release of ACh leading to a flaccid paralysis?

Answer 21

Botullinum toxin

Question 22

In what two infections is a cAMP cascade induced?

Answer 22

Enterotoxigenic E coli

Vibrio cholerae

Question 23

When cAMP is increased in the intestines what happens?

Answer 23

Water follows leading to profuse watery diarrhea

Question 24

What are the components of the anthrax toxin?

Answer 24

EF= edema factor
LF=lethal factor
PA=protective antigen

Question 25

What two toxin affect the Gi protein?

Answer 25

Bacillus anthracis

Bordetella pertussis

Question 26

Alpha toxin of Clostridium perfringens uses __________ to damage cell membranes and myonecrosis?

Answer 26

Lecithinase

Question 27

A 27 year old male comes into the ED with a fever and malaise. He reports a hx of IV drug use. Chest exam reveals a new murmur. Where would this organism be found in a healthy person as a part of normal flora?

Answer 27

Staph aureus infective endocarditis

Lives in the nose and skin

Question 28

A number of people become ill following a picnic with GI infection. Most of the patients had symptoms appear within 2-6 hours of eating the food. Sx included diarrhea, vomiting, and abdominal pain. If the food were laid on an agar, what shape would you expect any bacteria to be?

Answer 28

Gram postive cocci in clusters

Question 29

What are the spreading factors of strep pyogenes?

Answer 29

Streptokinase: breaks down the fibrin clots which allows for the bacteria to travel throughout the body

Streptococcal DNAse: liquifies pus

Hyaluronidase: hydrolyzes ground substance of connective tissue

Question 30

A 2 day old infant in the NICU develops a fever, respiratory distress, high white count with high neutrophil count. Per medical history, the mother was in labor for 2 days secondary to anesthesia allergy and inability to operate via Csection. What is the most likely causative organism?

Answer 30

Baby has sepsis

Caused by group B strep

Question 31

Name that bacteria 
Alpha hemolytic 
Optochin sensitive 
Lancet shaped bacteria 
Lysed by bile

Answer 31

Strep pneumo

Question 32

A 16 yo male presents to the ED following a car accident. The patient did not have his seatbelt on and was thrown from the vehicle. He undergoes a STAT splenectomy secondary to a splenic laceration. When he is in recovery, the parents are asking what they need to know regarding the patients new condition- what do you tell them?

Answer 32

That he is at risk for encapsulated bacterial infections

Question 33

_________ is the most common cause of adult pneumonia

Answer 33

Strep pneumo