Micro - Systems (Normal Flora & GI)

Question 1

What is the dominant microorganism in the normal flora of the skin?

Answer 1

S. epidermidis

Question 2

What is the dominant microorganism in the normal flora of the nose? What other major microorganism colonizes the nose?

Answer 2

S. epidermidis; colonized by S. aureus

Question 3

What is the dominant microorganism in the normal flora of the oropharynx?

Answer 3

Viridans group streptococi

Question 4

What is the dominant microorganism in the normal flora of the dental plaque?

Answer 4

S. mutans

Question 5

What are 2 dominant microorganism in the normal flora of the colon? Which is more dominant?

Answer 5

B. fragilis > E. coli

Question 6

What is the dominant microorganism in the normal flora of the vagina? What other 2 microorganisms colonize the vagina?

Answer 6

Lactobacillus, colonized by E. coli and group B strep

Question 7

What kind of flora do neonates delivered by C-section have, and how does this change over time?

Answer 7

Neonates delivered by C-section have no flora but are rapidly colonized after birth

Question 8

Which 2 bugs cause food poisoning that starts quickly and ends quickly?

Answer 8

S. aureus and B. cereus food poisoning starts quickly and ends quickly

Question 9

Name 7 bugs that cause food poisoning.

Answer 9

(1) B. cereus (2) C. botulinum (3) C. perfringens (4) E. coli O157:H7 (5) Salmonella (6) S. aureus (7) V. parahaemolyticus and V. vulnificus

Question 10

What is the source of infection for B. cereus food poisoning?

Answer 10

Reheated rice; Think: “Food poisoning from reheated rice? Be serious!” (B. cereus)

Question 11

What is the source of infection for C. botulinum food poisoning?

Answer 11

Improperly canned foods (sign is bulging cans)

Question 12

What is the source of infection for C. perfringens food poisoning?

Answer 12

Reheated meat dishes

Question 13

What is the source of infection for E. coli O157:H7 food poisoning?

Answer 13

Undercooked meat

Question 14

What is the source of infection for Salmonella food poisoning?

Answer 14

Poultry, meat, and eggs

Question 15

What is the source of infection for S. aureus food poisoning?

Answer 15

Meats, mayonnaise, custard; preformed toxin

Question 16

What is the source of infection for V. parahaemolyticus and V. vulnificus food poisoning?

Answer 16

Contaminated seafood

Question 17

Besides food poisoning, what else can V. vulnificus cause?

Answer 17

V. vulnificus can also cause wound infections from contact with contaminated water or shellfish

Question 18

Name 7 bugs that cause bloody diarrhea.

Answer 18

(1) Campylobacter (2) E. histolytica (3) Enterohemorrhagic E. coli (4) Enteroinvasive E. coli (5) Salmonella (6) Shigella (7) Y. enterocolitica

Question 19

What is the morphology of Campylobacter? In what conditions do they grow?

Answer 19

Comma- or S-shaped organisms; growth at 42 C

Question 20

What kind of organism is E. histolytica? What is the main condition that it causes? What other physical/imaging finding is common?

Answer 20

Protozoan; Amebic dysentery; Liver abscess

Question 21

What is the main strain of Enterohemorrhagic E. coli (EHEC) associated with bloody diarrhea? What condition can EHEC cause? What toxin does it make?

Answer 21

O157:H7; Can cause HUS; Makes Shiga-like toxin

Question 22

How does enteroinvasive E. coli cause bloody diarrhea?

Answer 22

Invades colonic mucosa

Question 23

Does either Salmonella or Shigella ferment lactose?

Answer 23

No, both are lactose (-)

Question 24

Does Salmonella or Shigella have flagella motility?

Answer 24

Salmonella

Question 25

What kind of reservoir does Salmonella have? What are 2 especially common sources of infection?

Answer 25

Has animal reservoir, especially poultry and eggs

Question 26

What kind of infective dose dose shigella have?

Answer 26

Very low ID50 (i.e., median infective dose)

Question 27

What kind of toxin does Shigella produce? What kind of reservoir does it have?

Answer 27

Produces Shiga toxin (human reservoir only)

Question 28

Other than bloody diarrhea, what condition can Shigella cause?

Answer 28

Bacillary dysentery

Question 29

In what setting do Y. enterocolitica outbreaks typically occur?

Answer 29

Day-care outbreaks

Question 30

With what condition is Y. enterocolitica associated?

Answer 30

Pseudoappendicitis

Question 31

Name 6 bugs that cause watery diarrhea.

Answer 31

(1) C. difficile (2) C. perfringens (3) Enterotoxigenic E. coli (4) Protozoa (5) V. cholerae (6) Viruses

Question 32

Other than diarrhea, what condition does C. difficile cause?

Answer 32

Pseudomembranous colitis

Question 33

What kind of diarrhea can C. difficile cause?

Answer 33

Watery diarrhea, Occasionally bloody diarrhea

Question 34

What causes C. difficile?

Answer 34

Caused by antibiotics

Question 35

Besides watery diarrhea, what other major symptom/condition does C. perfringens also cause?

Answer 35

Also causes gas gangrene

Question 36

What organism is associated with Traveler’s diarrhea?

Answer 36

Enterotoxigenic E. coli

Question 37

What kind of toxins does Enterotoxigenic E. coli produce?

Answer 37

Produces heat-labile (LT) and heat-stable (ST) toxins

Question 38

What are the 2 protozoa that can cause watery diarrhea? Which targets the immunocompromised?

Answer 38

(1) Giardia (2) Cryptosporidium (in immunocompromised)

Question 39

What is the morphology of V. cholerae?

Answer 39

Comma-shaped organisms

Question 40

Describe the diarrhea caused by V. cholerae.

Answer 40

Rice-water diarrhea

Question 41

What is often a source of V. cholerae?

Answer 41

Often from infected seafood

Question 42

What are 2 viruses that cause watery diarrhea?

Answer 42

(1) Rotavirus (2) Norovirus