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Microbiology > exam 2 > Flashcards

exam 2 Flashcards

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Biology 101 flashcards
1
Q

what sugar is fermented by ALL of the family enterobacteriaceae?

A

glucose

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2
Q

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

A

peritrichous

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3
Q

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

A

O

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4
Q

The flagellar antigen?

A

H

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5
Q

The capsular antigen?

A

K or Vi

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6
Q

which of the above antigens may mask the cell wall antigen in the serological typing of salmonella?

A

K or Vi

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7
Q

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

A

yellow with black center

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8
Q

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

A

orange colonies with black center

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9
Q

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

A

citrate
KCM
malenate

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10
Q

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

A 
phenyl pyruivc acid 
phenylalanine deaminase (enzyme)
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11
Q

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

A

indol

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12
Q

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

A

starts purple because all ferment glucose so they turn yellow but if glucose runs out they utilize amino acids it turns back to purple
positive test - purple - yellow - purple
negative test - purple to yellow

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13
Q

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

A

carbohydrate fermentation that produces acid

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14
Q

interpret the following reactions observed on TSI : A/A K/A AND K/K

A

A/A: lactose &or sucrose fermenters / glucose fermenter
K/A: nonlactose &or nonsucrose fermenter/ glucose fermenter
K/K : nonfermenter
*if it cannot ferment lactose or sucrose it will utilize peptones to change the top the different colors

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15
Q

what is the principle of the nitrate test?

A

the reduction of nitrates (NO3) to nitrites (NO2) and may progress to liberation of NO2

test 1 examines for nitrites
if none test 2 is performed looking for residual nitrates

then if still none you add zinc dust
stays clear +

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16
Q

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

A

negative test result

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17
Q

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

A

ONPG

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18
Q

what endpoint is produced in a positive urea test that produces the alkaline retain of the indicator?

A

ammonia

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19
Q

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)

A

lactose

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20
Q

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

A

E. Coli

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21
Q

what organism is most common cause of a UTI

A

E. Coli

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22
Q

what is the principle of the VP test?

A 
inoculate .2 ml MR-VP broth with no more than one colony
incubate for 4-6 hours
add 3 drops alpha-naphthol 
then 2 drops KOH
then wait five minutes for color change
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23
Q

what is the best single test to use to differentiate enterobacter and klebsiella?

A

motility

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24
Q

how can certain strains of Hafnia alvei be differentiated from enterobacter aerogenes?

A

sugar fermentation

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25
Q

what single test is best use to differentiate klebsiella oxytoca from kelbsiella pneumonia

A

indol

26
Q

what is the causative agent for bronchial pneumonia?

A

klebsiella pneumoniae

27
Q

what is its typical colonial morphology?

A

large, mucoid, pink, stringy, on mac

encapsulated

28
Q

what is another test that can differentiate klebsiella pneumoniae from enterobacter?

A

urea

29
Q

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?

A

LDC citrobactor and proteus are =

salmonella is +

30
Q

how can citrobactor freundii be differentiated from citrobacter diversus?

A

freundii produces gas I= / ODC =/

diversus no gas / I+/ ODC +

31
Q

which species is:

  • chromogenic
  • resistant to antibiotics
  • associated with UTI , hospital acquired infections,
  • wound infections from outdoorsy people
A

serratia marcesens

32
Q

which genus is characterized by “swimming” motility that is best observed on chocolate and sheep blood agar

A

proteus

33
Q

how can proteus mirablis and proteus vulgarism be differentiated?

A

indol

34
Q

how do members of the genera proteus and providence appear on lysine iron agar

A

red over yellow

35
Q

which three genera among the enterobacteriaceae are phylalanine positive?

A

proteus, providencia, morganella

36
Q

how can morganella morganii be differentiated from proteus sp.?

A

it doesn’t swarm or produce H2S

37
Q

what are the distinguishing characteristics of Yersinae pestis?

A

“safety pin” gram stain

coccobacillary and encapsulated

38
Q

what species of enterobacteriaceae is non-motile at 37 C but motile at 25C

A

yersinea enterocolitica

39
Q

which genera give the following reactions on the TSI ; K/A and H2S positive

A

salmonella, edwarsiella, proteus

40
Q

which genera out of salmonella, edwarsiella, and proteus is pathogenic?

A

salmonella

41
Q

what is the kauffman-white schema?

A

name given to all serological types of salmonella that helps with ID

42
Q

what are the typical biochemical reactions of salmonella typhi?

A

K/A weakly positive H2S

43
Q

what are the reactions of shigella sp. on TSI

A

K/A no H2S or gas

44
Q

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

A

sallmonella cholera-suis

45
Q

why should stool specimens be planted on laboratory media as soon as possible?

A

shigella

46
Q

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

A

shigella sonnei, GROUP D

47
Q

which of the rapid identification methods for the enterobacteriaceae discussed in the lecture has at the advantage of being the easiest to setup and producing reliable results in 3-4 hours?

A

micro ID

48
Q

what age group shows the most cases of gastroenteritis due to E. Coli?

A

young children, babies, toddlers

49
Q

what food is frequent source of contamination with salmonella?

A

chicken

50
Q

which body fluids should be tested in cases of carriers of salmonella typhi?

A

bile

51
Q

why do severe cases of shigella dysenteriae produce mental confusion?

A

because of the neurotoxin produced

52
Q

what its he vector for the transmission of plague?

A

rat fleas

53
Q

what type of plague is most contagious?

A

pneumonic plague

54
Q

what test is used int eh laboratory to differentiate E. Coli 0157:H7 from normal strains of E. Coli?

A

selective MAC containing 1% D-sorbitol rather than lactose 0157:H7 strains are sorbitol = and will be colorless

55
Q

in the classification of the tenterobacteriaceae what is a tribe?

A

group of biochemically similar genera

56
Q

what are the IMViC tests?

A

I - indol
M- methyl red
Vi- voges proskaure
C- citrate

57
Q

what would the be the test results from IMViC tests for E. Coli?

A

indol +
MR +
VP =
C =

58
Q

what is the nickname for the klebsiella pneumoniae

A

friedlanders bacillus

59
Q

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

A

alkalescense dispar

60
Q

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

A

staphylococcus- food poisoning but onset is after only a few hours because you have ingested performed toxins
salmonella - food infection you are ingesting the viable organisms which take 48 hours to feel effects

Microbiology (6 decks)

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