U2.1.3 ANTIBIOTIC RESISTANCE Flashcards

1
Q

Methods of Detecting Antibiotic Resistance

Cephalosporinase Test (Cefinase Test)

A

Chromogenic Beta Lactamase Test

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2
Q

Chromogenic Beta Lactamase Test

(+) color = beta-lactamase producer

A

Pink/red

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3
Q

Chromogenic Beta Lactamase Test

Organisms detected by the test

A

Staph, Haemophilus, Moraxella, Neisseria

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4
Q

Methods of Detecting Antibiotic Resistance

(3) Detection of MRSA/Oxacillin Resistant S. aureus

A
  1. Oxacillin Screen Agar
  2. Cefoxitin Disk (30ug) Screen Test
  3. Chromogenic Agar for MRSA
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5
Q

Methods of Detecting Antibiotic Resistance

recommended for screening of MRSA

A

Cefoxitin Disk (30ug) Screen Test

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6
Q

Methods of Detecting Antibiotic Resistance

colorimetric method used for MRSA colonies

A

Chromogenic Agar for MRSA

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7
Q

Methods of Detecting Antibiotic Resistance

Detection of _____ gene & its products _____

A
  1. mecA
  2. PBP2a
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8
Q

Methods of Detecting Antibiotic Resistance

(2) Methods for Vancomycin Resistance in Staphylococcus

A
  1. Broth Dilution
  2. Agar Screen
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9
Q

Methods for Vancomycin Resistance in Staphylococcus

Broth Dilution is used to detect

A

VRSA; VISA

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10
Q

Methods for Vancomycin Resistance in Staphylococcus

VRSA fi the vancomycin MIC is ___ ug/mL

A

≥16ug/ml

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11
Q

Methods for Vancomycin Resistance in Staphylococcus

BHI with 6ug vancomycin

A

Agar Screen

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12
Q

Methods of Detecting Antibiotic Resistance

(+) for Inducible Clindamycin Resistance

A

D zone

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13
Q

Inducible Clindamycin Resistance

when triggered /activates resistance to clindamycin

A

erm genes

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14
Q

Methods of Detecting Antibiotic Resistance

(2) Method Vancomycin Resistance

A
  1. Enterococci resistance to vancomycin
  2. Vancomycin Screen Agar
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15
Q

Methods of Detecting Antibiotic Resistance : Enterococci resistance to vancomycin

encodes Van-A phenotype

A

vanA gene

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16
Q

Methods of Detecting Antibiotic Resistance : Enterococci resistance to vancomycin

most common phenotypes

A

Van-A and Van-B phenotypes

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17
Q

Methods of Detecting Antibiotic Resistance : Enterococci resistance to vancomycin

6ug vancomycin in BHI agar

A

Vancomycin Screen Agar

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18
Q

Methods of Detecting Antibiotic Resistance

uses MHA with sheep blood; with 1ug/ml oxacillin disk (incubate with CO2)

A

Penicillin Resistance (S. pneumonia)

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19
Q

Methods of Detecting Antibiotic Resistance

Penicillin Resistance
Susceptible if : ____ mm
R o I if : < ____ mm

A

Susceptible if : ≥ 20mm
R o I if : < 20mm

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20
Q

Methods of Detecting Antibiotic Resistance

uses BHI Agar; test inoculum with 120ug/ml gentamycin and 300ug/ml streptomycin disk

A

HLAR (High-Level Aminoglycoside Resistance)

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21
Q

Methods of Detecting Antibiotic Resistance

used for Enterococci

A

HLAR (High-Level Aminoglycoside Resistance)

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22
Q

HLAR (High-Level Aminoglycoside Resistance)

Agar used with gentamycin & streptomycin

A

Remel Agar

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23
Q

HLAR (High-Level Aminoglycoside Resistance)

HLAR in BHI Agar
S if : ____ mm
R if : ____ mm

A

S if : >10 mm
R if : <6 mm

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24
Q

Methods of Detecting Antibiotic Resistance

are enzymes hydrolyzing most penicillins and cephalosporins, including oxyimino-B-lactam compunds but notcephamycins and carbapenems

A

ESBL Extended Spectrum Beta Lactamase

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25
Q

ESBL Extended Spectrum Beta Lactamase

1st seen in

A

E. coli and Klebsiella

26
Q

Methods of Detecting Antibiotic Resistance

plasmid mediated resistance mechanisms; genes (TEM-1; SHV-1 and OXA-1)

A

ESBL Extended Spectrum Beta Lactamase

27
Q

ESBL Extended Spectrum Beta Lactamase

Organisms detected

A

PPM
- K. pneumoniae
- P.mirabilis !!!!
- K. oxytoca
- E.coli
- Morganella !!!!
- Pseudomonas !!!!

28
Q

ESBL Extended Spectrum Beta Lactamase

Remain (S, I or R) to carbapenems, cefoxitin, B-lactamese inhibitors with clavulanic acid (tazobactams and sulbactams)

A

S

29
Q

ESBL Screen

Combination Disk Test involves (2)

A
  1. Test using ceftazidime or cefotaxime alone
  2. Test using ceftazidime or cefotaxime with Clavulanic acid
30
Q

ESBL Screen

(+) for ESBL if ___ mm increase in inhibition zone of cephalosporin with Clavulanic acid versus ceftazidime or
cefotaxime alone

A

≥5mm

31
Q

ESBL Screen

Confirm with MIC: ______ increase in MIC w / clavulanic acid

A

3 fold increase

32
Q

Methods of Detecting Antibiotic Resistance

Carbapenemase Screening (for
the presence of KPC

A

Modified Hodge Test

33
Q

Methods of Detecting Antibiotic Resistance

inhibits B-lactamase resistant
pencillins, clavulanic acid and tazobactam

A

Modified Hodge Test

34
Q

Methods of Detecting Antibiotic Resistance

pattern seen on the presence of inhibition is Modified Hodge Test

A

clover leaf pattern

35
Q

Methods of Detecting Antibiotic Resistance

  • Chromosomal mediated resistance; inducible resistance
  • Acts on 1st to 3rd generation Cephalosporins
A

Cephalosporinase Mediated Resistance

36
Q

Methods of Detecting Antibiotic Resistance

gene detected in Cephalosporinase Mediated Resistance

A

AmpC gene

37
Q

Cephalosporinase Mediated Resistance

______ Test using cefoxitin and cefepime

A

Disk Diffusion Test

38
Q

Other Tests

applicable for aminoglycosides, vancomycin and chloramphenicol

A

Peak and Trough Assays

39
Q

Other Tests

measure of activity of antibiotic in patient’s own serum against the pathogen

A

Serum Bactericidal Test (Schlichter Test)

40
Q

Other Tests

guideline to determine if
patient is receiving effective treatment for a serious infection

A

Serum Bactericidal Test (Schlichter Test)

41
Q

Single step systems with biochemical reactions

A

Multi Test Systems

42
Q

Uses databases or numeric codes for ID

A

Multi Test Systems

43
Q

Multi Test Systems

uses microtubes w/ dehydrated substrates; (API 20E; API Rapid 20E)

A

API

44
Q

Multi Test Systems

one step inoculation; no need for addition of reagent and oil

A

BBL Crystal

45
Q

Multi Test Systems

employs enzyme technology

A

RapID

46
Q

Multi Test Systems

color digital imaging

A

BIOMIC V3

47
Q

Allows analysis of multiple isolates and use biochemical reactions

A

Automated Methods

48
Q

Principles employed in Automated Methods (3)

A
  1. Photometry (Colorimetry)
  2. Nephelometry
  3. Fluorometry
49
Q

Automated Systems

uses redox indicator system

A

BD Phoenix

50
Q

Automated Systems

Uses plastic well microtiter trays with substrates for ID of various organisms

A

Microscan System

51
Q

Automated System

Used to check bacterial growth & color change Microscan System

A

Autoscan reader

52
Q

Automated Systems

fully automated, computer controlled system; colormetric and fluorometric principles

A

Microscan WalkAway

53
Q

Automated Systems

For ID and Susceptibility testing

A

Microscan WalkAway

54
Q

Automated Systems

  • fluorescence for detection of growth and enzyme activity
  • use of dried substrates
  • Results read in Sensititre Autoreader
A

TREK

55
Q

Automated Systems

  • fully automated
  • “hands off”
  • can hold up to 100 panels
  • Fluorometric and Colorimetric Detection
A

BD Phoenix M50

56
Q

Automated Systems

  • growth based technology
  • uses reagent cards
A

VITEK2

57
Q

Automated Systems

  • chromogenic substrates
  • measures changes in absorbance, turbidity
A

VITEK2

58
Q

Rapid method for ID and determining Susceptibility/ Resistance to Antibiotics

A

MALDI-TOF: Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry

59
Q

A colony is fished out and place
on the _______ Target Plate, _______ acid is added to enhance or improve the mass spectrum

A

MALDI Spot Target Plate; Formic Acid

60
Q

2 concepts applied in MALDO-TOF

A
  1. Ionization : laser to sample
  2. Time & Flight vaporized molecule to detector