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Bacteriology > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

In broth media how is bacterial growth indicated

A

turbidity

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2
Q

What does enrichment media do

A

has specific nutrients that are needed for fastidious pathogens.

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3
Q

What is XLD agar for

A

selective inhibits non enteric GN bacilli and inhibits GP
and differential for Shigella and Salmonella
phenol red indicator detects acidity from carb fermentations

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4
Q

What can be interpreted if there is growth on an XLD agar that is colorless?
and black? yellow?

A

colorless- no carb fermentation
black-H2S production
yellow-lactose fermenting

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5
Q

What does nutritive media do

A

has nutrients that support non fastidious organism growth

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6
Q

What does selective media do

A

has inhibitory agents that prevent the growth of an organism and allow another to grow

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7
Q

What does differential media do

A

has chemicals or substrates that allow bacteria to be IDed based on their metabolic capabilities

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8
Q

Differential for group D streptococci vs enterococci, and Enterobacteriaceaevs other enteric bacteria and can also be used for differentiation ofListeria monocytogenes

A

Bile esculin agar (BEA)

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9
Q

Cultivation of non-fastidious microorganisms, determination of hemolytic reactions

A

Blood agar (BA)

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10
Q

Bordetella pertussis(small, smooth, pearl-like colonies with a narrow zone of hemolysis); Bordetella parapertussis (brown colonies with a green-black coloration on the reverse side); Bordetella bronchiseptica(brown, medium sized colonies with a rough, pitted surface)

A

Bordet-Gengou agar

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11
Q

Cultivation of fastidious and nonfastidious organisms

A

Brain-heart infusion agar or broth

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12
Q

Contains azide to inhibit gram-negative bacteria, vancomycin to select for resistant gram-positive bacteria, and bile esculin to differentiate enterococci from other vancomycin-resistant bacteria that may grow

A

Bile esculin azide agar with vancomycin

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13
Q

Nutrient agar base with ferric citrate. Hydrolysis of esculin imparts a brown color to medium; sodium deoxycholate inhibits many bacteria.

A

Bile esculin agar (BEA

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14
Q

Enrichment forLegionellaspp.

Supports the growth ofFrancisellaandNocardiaspp.

A

Buffered charcoal–yeast extract agar (BCYE)

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15
Q

Selective forCampylobacterspp.

A

Campy-blood agar

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16
Q

Improved growth of fastidious, obligate, slow-growing anaerobes

A

CDCanaerobe 5% sheep blood agar

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17
Q

Selective medium for isolation ofCampylobacterspp.

A

Cefoperazone, vancomycin, amphotericin (CVA) medium

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18
Q

Selective forYersiniaspp.; may be useful for isolation ofAeromonasspp.

A

Cefsulodin-irgasan-novobiocin (CIN) agar

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19
Q

Cultivation of fastidious microorganisms such asHaemophilusspp.,Brucellaspp., and pathogenicNeisseriaspp.

A

Chocolate agar

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20
Q

Used in the identification ofAcinetobacter,extended-spectrum β-lactamase and carbapenemase producing organisms,E. coli, Listeria monocytogenes, Enterococcusspp.,Pseudomonas aeruginosa, Salmonellaspp., shiga toxin-producingE. coli, E. coliO157-H7, group B streptococcus,Vibriospp.,Yersinia enterocolitica,yeasts, MRSA, and a variety of other organisms

A

Chromogenic media

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21
Q

Selective isolation of gram-positive cocci

A

Columbia colistin-nalidixic acid (CNA) agar

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22
Q

Isolation ofCorynebacterium diphtheriae

A

Cystine-tellurite blood agar

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23
Q

Isolation and differentiation of lactose-fermenting and non–lactose-fermenting e.coli

A

Eosin methylene blue (EMB) agar (Levine)

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24
Q

Differential, selective medium for the isolation and differentiation ofSalmonellaandShigellaspp. from other GN enteric bacilli

A 
Hektoen enteric (HE) agar
XLD agar
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25
Q

Enriched, selective media for the isolation of cultivation ofStreptococcus agalactiae.

A

LIM broth

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26
Q

Isolation and growth ofCorynebacteriumspp.

A

Loeffler medium

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27
Q

Isolation and differentiation of lactose fermenting and non–lactose-fermenting enteric bacilli

A

MacConkey agar

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28
Q

For the selection and differentiation ofE. coliO157:H7 in stool specimens

A

MacConkey sorbitol agar

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29
Q

Selective differentiation of staphylococci

A

Mannitol salt agar

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30
Q

Selective isolation of aerobic gram-positive cocci and bacilli and anaerobic gram-positive cocci. This agar should not be used for observation of hemolytic reactions.

A

Phenylethyl alcohol (PEA) agar with or without blood

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31
Q

Enrichment and selective medium for isolation ofBordetella pertussisandBordetella parapertussis.

A

Regan Lowe

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32
Q

Enrichment and isolation ofSalmonellaspp.

A

Selenite broth

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33
Q

Selective forCampylobacterspp.

A

Skirrow agar

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34
Q

Selective forStreptococcus pyogenesandStreptococcus agalactiae

A

Streptococcal selective agar (SSA)

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35
Q

Selective forN. gonorrhoeaeandN. meningitidis.

Supports the growth ofFrancisellaandBrucellaspp.

A

Thayer-Martin agar (TM) (modified Thayer Martin [MTM])

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36
Q

Supports growth of anaerobes, aerobes, microaerophilic, and fastidious microorganisms

A

Thioglycollate broth

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37
Q

Selective and differential forVibrio choleraeandVibrio parahaemolyticus

A

Thiosulfate citrate–bile salts (TCBS) agar

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38
Q

Selection and enrichment forStreptococcus agalactiaein female genital specimens

A

Todd-Hewitt broth supplemented with antibiotics (LIM)

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39
Q

What interpretation of a TA broth:

generally diffuse evenly growth throughout the broth

A

Facultative anaerobe

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40
Q

What interpretation of a TA broth:

tend to grow toward the surface of the broth

A

strict aerobic bacter

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41
Q

Interpretation of TA broth:

grow at the bottom of the broth

A

strict anaerobic

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42
Q

What type of plate is MAC

A

selective- inhibits GPO and fungi with crystal violet dye

differential- pH indicator that shows lactose fermentation

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43
Q

Explain why salmonella turns black on its agar

A

they do not ferment any carbs but they do produce H2S causing the black color

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44
Q

What type of media is HE agar

A

Selective-inhibits growth of nonpathogenic GNR
selects for salmonella and shigella
Differential-non enteric pathogens show as orange, fermentation causes blue, H2S causes black

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45
Q

What kind of agar is EMB

A

selective- inhibits GP and allows GN
differential-green metallic color for E.coli
dark purple or black for lactose fermentation

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46
Q

Colistin disrupts the cell membranes of GN organisms, and nalidixic aid blocks DNA replication in susceptible organisms

A

Columbia colistin-nalidixic acid (CNA)

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47
Q

What kind of media is blood agar

A

nutritional- blood for hemolytic

differential- beta-hemolysis, partial lysis alpha, nonhemolytic- gamma

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48
Q

What is a catalase test

A

Testing for catalase production, release of water and oxygen causes bubbles +
no bubbles -

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49
Q

What is an oxidase test

A

a drop of tetramethyl-p-phenylenediamine dihydrochloride to a colony
positive- purple
negative- no color change
tests for the presence of oxidase

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50
Q

What is a coagulase test

A

Used to distinguish staph aureus from coagulase negative staph
rabbit plasma, positive if clumping or a clot occurs

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51
Q

What is an indole test

A

looking for bacteria that have enzyme tryptophanase which can degrade tryptophan into indole
positive- pink to red

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52
Q

What is PYR testing

A

looking for enzyme enzyme PYR
ID for gram positive cocci
positive if pink red color

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53
Q

What is a urease test

A

testing if urease is produced
hydrolyzes urea into ammonia, causes pH increase
positive- dark pink color

54
Q

What is a glucose oxidative fermentation test

A

2 tubes are used- yellow if fermentation occurs
if acid in both, it is glucose fermenter and oxidizer
if acid only in open/ aerobic tube, it is a oxidizer
if acid only in mineral oil tube, it is a fermenter
if neither it is a nonutilizer

55
Q

What is an IMViC test

A

Indole- red if positive- looks for indole production from tryptophanase enzyme
Methyl red - red if positive- looks for glucose fermentation
Voges Proskauer- red if positive- looks for acetoin from glucose metabolism
Citrate- blue if positive-looking for use of citrate in metabolism, alkaline pH causes color change

56
Q

What organisms are ++– for IMViC reaction

A

E. Coli

57
Q

What organisms are –++ for IMViC

A

Klebsiella pneumoniae
Enterobacter spp.
Serratia marcescens

58
Q

What organisms are +-++ for the IMViC reactions

A

Klebsiella oxytoca

59
Q

What is TSI test

A

Triple Sugar Iron Agar
phenol red as indicator
ferrous sulfate and sodium thiosulfate as H2S indicator
Slant-has lactose/sucrose- aerobic
Butt-Glucose-anaerobic
must read the slant, butt, black precipitate for H2S positive, cracks in medium mean gas

60
Q

What does K/K for a TSI slant mean

A

no sugars used

alkaline slant, no change in butt

61
Q

What does K/A in TSI agar mean

A

glucose fermented only

alkaline slant and acid butt

62
Q

What does A/A mean in TSI agar

A

acid slant, acid butt

all sugars fermented

63
Q

What does black precipitate in the butt of TSI agar mean? What do bubbles and cracks mean

A

H2S produced

gas produced

64
Q

What does an antimicrobial agent need to successfully inhibit or kill an organism

A

the agent must be in an active form

must have sufficient levels or concentrations at the site of infection

65
Q

What does bactericidal vs bacteriostatic mean

A

static- inhibits growth

icidal- kills the organism

66
Q

What are the common targets of antibiotics

A 
bacterial cell wall synthesis
folate synthesis
DNA replication
RNA transcription
mRNA translation
67
Q

What are the natural mechanisms of resistance that bacteria can have

A
  • lack of affinity for a drug
  • lack of bacterial target
  • inaccessibility
  • efflux pumps that remove drugs
  • ABC transporters
  • enzymes that break down drugs
  • biofilms
68
Q

How do fluroroquinolone antibiotics work?

A

target topoisomerase II and IV, inhibits DNA synthesis

69
Q

What are fluoroquinolones effective against

A

most gram positive and gram negative aerobic and facultative anaerobes
some anaerobic GPRs

70
Q 
What type of drugs are these?
Nalidixic acid 
Ciprofloxacin
Levofloxacin
Gemifloxacin
A

floxacin

fluoroquinolone

71
Q

How do trimethoprim sulfamethoxazole antibiotics work?

A

inhibits DNA synthesis by inhibiting folic acid and B12 production
impacts nucleotide synthesis

72
Q

What organisms are thrimethoprim sulfamethoxazole effective against

A

aerobic and facultative anaerobic gram positive and gram negative

73
Q

What is the drug composition of Trimethoprim sulfamethoxazole?

A

1:5 trimethoprim and sulfamethoxazole

74
Q

How do Rifamycin antibiotics work?

A

inhibits RNA synthesis
targets ddRNA polymerase
impacts RNA transcription, DNA replication and SOS response

75
Q

What organisms are Rifamycins effective against

A

Gram positive, negative and mycobacterium tuberculosis

76
Q

What type of drugs are these
Rifampin
Rifapentine

A

Rif

Rifamycin

77
Q

How do Beta lactam antibiotics work?

A

inhibit cell wall synthesis by targeting and using penicillin binding proteins

  • alters peptidoglycans
  • affects wall synthesis and ROS formation
78
Q

What organisms are B lactams effective against

A

aerobic and anaerobic gram positive and negative organisms

79
Q

What type of drugs are these

-penicillin, ampicillin, oxoacillin

A

Beta lactams
cillin
cef
penem

80
Q

What type of drugs are these

  • cefazolin, cefoxitin, ceftriaxone, cefepime
  • imipenem
A

Beta lactams
cef
penem

81
Q

How do glycopeptide and glycolipopeptide drugs work?

A

inhibit cell wall by targeting peptidoglycan

-decrease cell wall stability

82
Q

What drugs inhibit transglycosylation and transpeptidation?

A

glycopeptides and glycopopeptides

83
Q

What organisms are glycopeptides and glycopopeptides effective against

A

gram positive organisms

84
Q

What types of drugs are these
vancomycin
teiplanin

A

glycopeptides and glycolipopeptides

85
Q

How do lipopeptides work? What organisms are they effective against

A

inhibit cell wall synthesis by targeting membrane

gram positive and gram negative

86
Q

What types of drugs are these?
daptomycin
polymyxin B
What are each of them effective against

A

lipopeptides
dapto- gram positive
poly-gram negative

87
Q

How do aminoglycoside antibiotics work?

A

inhibit protein synthesis by targeting 30S ribosome- tiny subunit

88
Q

What organisms are aminoglycosides effective against?

A

aerobic and facultative gram positive and negative

M. tuberculosis

89
Q 
What type of drugs are these
Gentamicin
Tobramycin
Streptomycin
Kanamycin
A

mycin

aminoglycosides

90
Q

How do tetracyclines antibiotics work?

A

inhibit protein synthesis
inhibit 30S ribosomes
inhibits tRNA binding ribosomes

91
Q

What organisms are tetracyclines effective against

A

aerobic and facultative gram positive and gram negative, maybe tuberculosis

92
Q

What kind of drugs are these
Tetracycline
Doxycycline

A

cycline

tetracyclines

93
Q

How do macrolides work

A

inhibit protein synthesis
target 50S- large subunit
inhibits elongation and translation steps

94
Q

What organisms are macrolides effective against?

A

aerobic and anaerobic gram positive and gram negative

95
Q

What kinds of drugs are these
Azythromcyin
Erythromycin

A

macrolides

ythromycin

96
Q

How do streptogramin antibiotics work

A

inhibit protein synthesis
target 50S-large subunit
stop translation by inhibiting initiation and elongation

97
Q

What organisms are streptogramins effective against

A

aerobic and anaerobic gram positive and gram negative

98
Q

What types of drugs are these
Pristinamycin
Dalfopristin
Quinupristin

A

pristine

streptogramins

99
Q

How do Phenicol antibiotics work?

A

inhibit protein synthesis

-target 50S large

100
Q

What organisms are Phenicols effective against

A

some GPO some GNO

B. fragilis, N. meningitdis, H. influenzae, S. pneumonaie

101
Q

What kind of drug is this

chloramphenicol

A

phenicol

102
Q

What is an additive effect

A

when 2 drugs cause twice the effect

103
Q

What is an indifferent effec

A

when a combination of drugs has no effect

104
Q

What is an antagonistic effect? Name an example

A

when one drug counteracts the other

penicillin and erythromycin

105
Q

What does empiric therapy mean?

A

antibiotics that are administered before blood culture and susceptibility results

106
Q

What is the difference between biological and environmental resistance

A

biologic- observably reduced susceptibility

environmental- resistance due to physical or chemical stimuli in environment

107
Q

What factors could cause environmental resistance

A

pH changes, cation concentration, thymidine content

108
Q

What is intrinsic microorganism mediated resistance

A

resistance from genetics

109
Q

What is acquired resistance

A

resistance that is due to altered cellular physiology and changes in genetic makeup
gene mutation
gene transfer

110
Q

Transduction, transformation and conjugation are all examples of things that can cause what type of resistance?

A

acquired resistance

111
Q

What natural resistance does Klebsiella have to ampicillin

A

have beta lactamase enzymes that destroy ampicillin before it reaches PBP target
inactivation

112
Q

What natural resistance do entercocci have to all cephalosporin antibiotics

A

no penicillin binding protein that can bind to beta lactam agents

113
Q

What do beta lactamase look like in chemical composition

A

like a square with O and N in bottom corners

114
Q

How does beta lactamase cause resistance in gram positive and negative organisms

A

positive- beta lactam cant bind to mutated penicillin binding protein. have beta lactamase enzyme that hydrolyzes beta lactam antibiotic

negative-decreased uptake through porin through porin channels, harder to get in, all other reasons above also

115
Q

In a Kirby Bauer Disk, the ___concentration is closest to the disk

A

highest

116
Q

What affects the zone of inhibition and susceptability breakpoints?

A

thickness of agar
too thick-falsely large zone of inhibition (false resistance)
too thin-falsely low zone of inhibition (false susceptibility)

117
Q

Why are Kirby Bauer disks stored upside down

A

to avoid condensation from interfering with the interpretation of test results. could alter diffusion or give area for bacteria to spread

118
Q

What is the maximum of antibiotic disks that can be placed on a single Mueller Hinton agar plate

A

12 disks in 150mm plate

119
Q

What temperature and for how long can Kirby Bauer disks be stored

A

2-8C for 1 week

bring to room temp before using

120
Q

What type of test is the E test

A

the one with the strip that measures MIC

121
Q

What does the MecA gene cause resistance to?

A

resistance to penicillin, methicillin, nafcillin, cloxacillin and dicloxacillin
encodes for penicillinases- penicillin binding protein
modifies binding site

122
Q

What do MRSA organisms have resistance to

A

oxacillin resistant stap aureus

123
Q

What treatment is used to gauge staph species with MecA gene

A

oxacillin

124
Q

What does the erm gene create resistance for

A

resistance to erythromycin/ macrolide and induces clindamycin
encodes for methylation 23S rRNA

125
Q

What does the msrA gene create resistance for

A

resistance to erythromycin
susceptible to clindamycin
encodes for efflux mechanism that spits antibiotic out

126
Q

What does it mean if the D test has a flattened edge on erythromycin?

A

erm gene

resistant to clyndamycin

127
Q

What does it mean if a D test has resistance to erythromycin only and no flattened edge

A

msrA gene only

not resistant to clindamycin

128
Q

What is the MHT modified Hodge test for?

A

testing for carbapenamase enzyme

gives resistance to all carbapenems

129
Q

What is MBC minimum ___ concentration

A

bactericidal

130
Q

If an antibiotics MBC value is 32+ times higher than the MIC value, this means

A

the organisms could be tolerant to the drug,

drug cannot be used because the high dosage required could be toxic to patient

131
Q

What are macro vs micro broth dilution tests

A

tests in serial dilutions
macro- larger broth volume- impractical
micro-smaller broth volumes

Bacteriology (10 decks)

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