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

What letter represents the cell wall (somatic) antigen?

Answer 3

O

Question 4

What antigen letter is always present?

Answer 4

O

Question 5

What letter represents the flagellar antigen?

Answer 5

H

Question 6

What letters represent the capsular antigen?

Answer 6

K or Vi

Question 7

What antigen will mask the cell wall (somatic) antigen in the serological typing of Salmonella?

Answer 7

The capsular antigen, K or Vi, will mask the cell wall (somatic) antigen, O

Question 8

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

Answer 8

yellow with black center

Question 9

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

Answer 9

orange with black center

Question 10

What media can produce a positive result with just growth on the medium, not requiring color change?

Answer 10

citrate, KCN, malonate

Question 11

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

Answer 11

phenylpyruvic acid

Question 12

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

Answer 12

indole

Question 13

What are the color changes observed in a positive decarboxylase test?

Answer 13

purple to yellow to purple

Question 14

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

Answer 14

acid production from a carbohydrate

Question 15

What does A/A mean on TSI?

Answer 15

glucose fermentation in the butt and lactose and/or sucrose in the slant

Question 16

What does K/A mean on TSI?

Answer 16

ferments glucose in the butt only

Question 17

What does K/K mean on TSI?

Answer 17

nonfermentor

Question 18

What is the principle of the nitrate test?

Answer 18

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

Question 19

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

Answer 19

does not reduce nitrates

Question 20

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

Answer 20

ONPG

Question 21

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

Answer 21

ammonia is liberated raising the pH causing the phenol red indicator to turn the medium fuchsia

Question 22

What sugar is fermented by all coliforms that is not fermented by most enteric pathogens?

Answer 22

lactose

Question 23

What organisms is indole positive, citrate negative, and dry pink on MacConkey?

Answer 23

E. coli

Question 24

What organisms is the most common cause of an UTI?

Answer 24

E. coli

Question 25

What is the principle of the VP test?

Answer 25

some bacteria have the ability to produce acetylmethyl carbinol (acetoin) from glucose

Question 26

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

Answer 26

motility, Klebsiella is nonmotile

Question 27

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

Answer 27

sugar fermenations

Question 28

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

Answer 28

indole, pneumoniae is negative

Question 29

What is the causative agent of bronchial pneumonia?

Answer 29

Klebsiella pneumoniae

Question 30

What is Klebsiella pneumoniae's typical colonial morphology?

Answer 30

large, mucoid, pink, stringy colonies on Mac

Question 31

Other than motility, what test can be used to differentiate Klebsiella from Enterobacter?

Answer 31

Urea

Question 32

Which test is useful in distinguishing Citrobacter and Proteus from Salmonella?

Answer 32

Lysine decarboxylase

Question 33

How can Citrobacter freundii be differentiated from Citrobacter diversus?

Answer 33

Indole (diversus is positive) and H2S (diversus is negative)

Question 34

Which species is chromogenic, resistant to antibiotics, associated with UTI, nosocomial infections, and wound infections?

Answer 34

Serratia marcesens

Question 35

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

Answer 35

Proteus

Question 36

How can Proteus mirabilis and Proteus vulgaris be differentiated?

Answer 36

Indole (vulgaris is positive) and ornithine (vulgaris is negative)

Question 37

How do members of the genera Proteus and Providencia appear on LIA?

Answer 37

red slant

Question 38

Which three genera among the Enterobacteriaceae are phenylalanine positive?

Answer 38

Morganella, Providencia, and Proteus

Question 39

How can Morganella morganii be differentiated from Proteus species?

Answer 39

Morganella margin does not produce H2S or swarm

Question 40

What are the distinguishing characteristics of Yersinea pestis?

Answer 40

It is coccobacillary, encapsulated, and shows bipolar staining

Question 41

What species of Enterobacteriaceae is non-motile at 37C but motile at 25C?

Answer 41

Yersinia enterocolitica

Question 42

Which genera give the following reactions on TSI: K/A and H2S positive?

Answer 42

Salmonella (significant pathogen), Edwarsiella , and Proteus

Question 43

What is the Kauffman-White schema?

Answer 43

Describes the almost 2,000 serotypes of the genera Salmonellae

Question 44

What are the typical biochemical reactions of Salmonella typhi?

Answer 44

TSI: K/A H2S (weakly positive)

Question 45

What are the reactions of Shigella on TSI?

Answer 45

K/A no gas and no H2S

Question 46

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

Answer 46

Salmonella cholerae-suis

Question 47

What organisms will be missed if a stool sample is left to sit too long?

Answer 47

Shigella

Question 48

Which serological group of Shigella is most frequently isolated in the US?

Answer 48

Group D Shigella sonnei

Question 49

Which of the rapid ID methods for the Enterobacteriaceae has the advantage of being the easiest to set up and produces reliable results in 4 hours?

Answer 49

Micro-ID

Question 50

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

Answer 50

Infants and toddlers, children under 10

Question 51

What food is a frequent source of contamination with Salmonella?

Answer 51

chicken

Question 52

Which body fluid should be tested in cases of carriers of Salmonella typhi?

Answer 52

Bile

Question 53

Why do severe cases of Shigella dysenteriae produce mental confusion?

Answer 53

it produces a neurotoxin

Question 54

What is the vector for the transmission of plague?

Answer 54

rat flea

Question 55

What type of plague is the most contagious?

Answer 55

Pneumonic plague

Question 56

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

Answer 56

Selective Mac agar containing 1% D-sorbitol instead of lactose, which should grow clear

Question 57

In the classification of the Enterobacteriaceae, what is a tribe?

Answer 57

Group of biochemically similar genera

Question 58

What are the IMViC tests?

Answer 58

Indole Motility VP Citrate

Question 59

What would the results of IMViC for E. coli

Answer 59

+ + = =

Question 60

What is the 'nickname' for Klebsiella pneumoniae?

Answer 60

Friedlander's Bacillus

Question 61

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

Answer 61

Alkalescens dispar

Question 62

What is true food poisoning?

Answer 62

Staphylococcus produces true food poisoning due to an exotoxin in 1-4 hours

Question 63

What is a food infection?

Answer 63

Salmonella produces; have to ingest large amounts of viable organisms and takes longer