Exam 2

Question 1

What sugar is fermented by ALL members of the family Enterobacteriaceae?

Answer 1

glucose

Question 2

What arrangement of flagella is characteristic of motile members of this family?

Answer 2

peritrichous

Question 3

letter is used to represent the cell wall (somatic) antigen?

Answer 3

O

Question 4

letter used to represent the flagellar antigen

Answer 4

H

Question 5

letter used to represent the capsular antigen

Answer 5

Vi and K

Question 6

Which antigens may mask the cell wall antigen in the serological typing of Salmonella?

Answer 6

K or Vi

Question 7

How would an organism that ferments lactose and produces H2S appear on XLD and HE

Answer 7

yellow with black center on XLD

orange with black center on HE

Question 8

Name several media in which a positive result can be growth in the medium, even if there is no accompanying color change.

Answer 8

citrate, kcn, malinate

Question 9

What is the end product in the test for the enzyme phenylalanine deaminase?

Answer 9

phenyl pyruvic acid

Question 10

Which test utilizes Kovac’s reagent to test for the enzyme tryptophanase?

Answer 10

indole

Question 11

What are the color changes observed in a positive decarboxylase test, starting with the initial, uninoculated color?

Answer 11

Purple to yellow to purple

Question 12

pH indicator is generally used to detect what type of reaction by enteric organisms?

Answer 12

carbohydrate fermentation

Question 13

the following reactions observed on TSI: A/A, K/A, and K/K.

Answer 13

a/a glucose, lactose or sucrose
k/a ferments glucose only
k/k non fermentor

Question 14

What is the principle of the nitrate test?

Answer 14

the reduction of nitrates leads to the formation of nitrites. may progress to liberation of nitrogen.

Question 15

What does the development of a pink color only after the addition of Zn dust indicate?

Answer 15

negative

Question 16

What biochemical test is especially useful for the detection of a late lactose fermenting organism?

Answer 16

ONPG

Question 17

What endpoint is produced in a positive urease test that produces the alkaline reaction of the indicator?

Answer 17

ammonia

Question 18

what sugar is fermented by the coliforms (normal intestinal flora like E. coli or Enterobacter) that is NOT fermented by most enteric pathogens (like Salmonella and Shigella)?

Answer 18

lactose

Question 19

What organism is indole positive, citrate negative, dry pink on MacConkey, and produces a green, metallic sheen on EMB?

Answer 19

E. coli

Question 20

What organism is the most common cause of a UTI?

Answer 20

e coli

Question 21

What is the principle of the VP test?

Answer 21

organism produced a particular end product acetylmethylcarbinol

Question 22

What is the best single test to use to differentiate Enterobacter and Klebsiella?

Answer 22

motility

Question 23

How can certain strains of Hafnia alvei be differentiated from Enterobacter aerogenes?

Answer 23

sugar fermentation

Question 24

What single test is best to use to differentiate Klebsiella oxytoca from Klebsiella pneumoniae?

Answer 24

indole

Question 25

What is the causative agent of bronchial pneumonia? | What is its typical colonial morphology?

Answer 25

* klebsiella pneumonia * encapsulated, large mucoid, stringy and pink * ureas

Question 26

what test other than motility can be used to differentiate from most Enterobacter?

Answer 26

ureas

Question 27

Which test is particularly useful in distinguishing Citrobacter and Proteus, both of which are H2S positive coliforms, from Salmonella, which is an H2S positive pathogen?

Answer 27

lysine

Question 28

How can Citrobacter freundii be differentiated from Citrobacter diversus?

Answer 28

H2S neg

Question 29

Which species is chromogenic (produces a pigment), is very resistant to antibiotics, and is associated with UTI, hospital-acquired infections, and with wound infections in people who spend a lot of time outdoors in the woods?

Answer 29

serratia

Question 30

which genus is characterized by "swarming" motility that is best observed on chocolate sheep blood agar?

Answer 30

proteus

Question 31

how can proteus mirablis and proteus vulgaris be differentiated?

Answer 31

mirabilis=indole negative | vulgaris=indole positive

Question 32

how do member of the genera proteus and providencia appear on lysine iron agar (LIA)?

Answer 32

give a red slant

Question 33

which three genera among the enterobcteriaceae are phenylalanine positive?

Answer 33

proteus providencia morganella

Question 34

how can morganella morganii be differentiated from proteus sp.?

Answer 34

does not swarm or produce H2S

Question 35

what are the distinguishing characteristics of yersinea pestis?

Answer 35

coccibacilli encapsulated shows bipolar staining(safety pin)

Question 36

what speices of enterobacteriaceae is non-motile at 37 degrees C but motile at 25 degrees C?

Answer 36

yersinea enterocolitica

Question 37

Which genera give the following reactions on TSI: *acid butt *alkaline slant *H2S positive which one of them is a significant pathogen?

Answer 37

Salmonella, edwardsiella, proteus | *Slamonella

Question 38

what is the kauffman white schema?

Answer 38

name given to all serological types of Salmonella

Question 39

what are the typical biochemical reactions of salmonella typhi?

Answer 39

k/a weakly positive H2S

Question 40

what are the reaction of shigella sp. on TSI?

Answer 40

k/a no H2S and no gas

Question 41

which species of Salmonella is most frequently recovered from the septicemic type of salmonella infection?

Answer 41

salmonella cholerae-suis

Question 42

why should stool samples be planted on laboratory media as soon as possible? (what organism could be missed)

Answer 42

shigella

Question 43

which serological group of shigella is most frequently isolated in the US?

Answer 43

shigella sonnei (groupd)

Question 44

Which of the rapid identification methods for the Enterobacteriaceae discussed in lecture has the advantage of being the easiest to set up and of producing reliable results in 3 1/2 to 4 hours?

Answer 44

micro ID

Question 45

What age group shows the most cases of gastroenteritis due to E. coli?

Answer 45

infants and toddlers

Question 46

What food is a frequent source of contamination with Slamonella

Answer 46

chicken

Question 47

which body fluids should be tested in cases of carriers of Salmonella?

Answer 47

bile

Question 48

Why do severe cases of shigella dysenteriae produce mental confusion?

Answer 48

It produces a neurotoxin

Question 49

what is the vector for the transmission of plague?

Answer 49

rat fleas

Question 50

what type of plague is most contagious?

Answer 50

pnumonic plague

Question 51

What test is used in the lab to differentiate E. coli 0157:H7 from normal stains of E. coli?

Answer 51

Mackonkey with d-sorbitol | 0157 are sorbitol negative and colorless on Macconkey

Question 52

in the classification of the Enterobacteriaceae what is the tribe?

Answer 52

in between a family and the genus

Question 53

what are the IMViC tests? | results for E coli?

Answer 53

I=indole + M=methyl red + Vi=voges proskant (vp) - C=citrate -

Question 54

what is the nickname for klebsiella pneumoniae?

Answer 54

Friedlander’s bacillus

Question 55

what non-pathogenic organism is so similar to Shigella biochemically that it is included in the serological typing of Shigella isolates?

Answer 55

alkalescens dispar

Question 56

what is the difference between a true food poisoning and food infection?

Answer 56

Staphylococcus, which produces a true food poisoning due to an exotoxin already in the food, 1-4 hours, Salmonella produces a food infection organism has to have time to for the toxins to be produced in the body.