Microbiology - Antimicrobial Agents & Susceptibility Tests

Front 1

Definition of: Antimicrobial Agent

Back 1

A type of chemotherapeutic agent used for teatment of infectious diseases.

Front 2

Definition of: Antibiotic
-In low concentrations it?

Back 2

Chemical substance produced by a microorganism.
-Inhibits growth of other microorganisms.

Front 3

Criteria for antibiotic to be used clinically? (5)

Back 3

-Selective toxicity
-Non Allergenic
-Soluble in body fluids
-Penetration of infected tissue
-Not readily develop resistance

Front 4

Definition of: Broad Spectrum

Back 4

Affects wide variety of microorgs. (Gram Pos, Gram Neg, Enterobacteriacae)

Front 5

Definition of: Narrow Spectrum

Back 5

Affects small group of microorgs. (Gram Pos OR Gram Neg)

Front 6

Definition of: Bactericidal

Back 6

KILLS the bacteria.

Front 7

Definition of: Bacteriostatic

Back 7

PREVENTS the bacteria from multiplying.

Front 8

Modes of Action of Antimicrobial Agents? (5)
*(Insane Cyclists Pedal Down Crazy Obstacles)*

Back 8

Inhibitors of:
-Cell wall synthesis
-Protein Synthesis
-DNA & RNA Synthesis
-Cell Membrane function
-Other metabolic processes

Front 9

Process of: Cell Wall Synthesis

Back 9

Beta-lactam antibiotics combine with penicillin binding proteins in bacterial cell wall. Cross links not formed - cell wall weakens - ruptures - bacterial cell death.

Front 10

Beta-Lactam Antibiotics TWO Major Groups:

Back 10

Penicillins, Cephalosporins

Front 11

Penicillin G's other name:

Back 11

Benzylpenicillin

Front 12

Natural Penicillins
Mode of Action:

Back 12

Cell wall inhibitors
Bactericidal

Front 13

Natural Penicillins
Spectrum:

Back 13

Narrow Gram Pos, few gram negs (Haemph, Neisseria)

Front 14

Natural Penicillins
Bacterial Resistance:

Back 14

Beta-lactamase susceptible

Front 15

Natural Penicillins
Clnical Use:

Back 15

Pen G- acid, labile (not orally)
Pen V- acid, stable
Combo with others

Front 16

Natural Penicillins
Class Concept:

Back 16

Yes

Front 17

Natural Penicillins
Examples:

Back 17

Pen G
Pen V

Front 18

B-Lactamase Resistant Penicillins
Mode of Action:

Back 18

Cell wall inhibitors
Bactericidal

Front 19

B-Lactamase Resistant Penicillins
Spectrum:

Back 19

Narrow - gram pos, staph infections

Front 20

B-Lactamase Resistant Penicillins
Bacterial Resistance:

Back 20

NOT inactivated by beta lactamase, resistance by altered peniccilin binding proteins

Front 21

B-Lactamase Resistant Penicillins
Clinical Use: (3)

Back 21

Orally, intramuscularly, or intravenous

Front 22

B-Lactamase Resistant Penicillins
Class Concept:

Back 22

Yes

Front 23

B-Lactamase Resistant Penicillins
Examples:
(Oxs Clobber Double Men)

Back 23

-Oxacillin
-Cloxacillin
-Dicloxacillin
-Methicillin

Front 24

Expanded Spectrum Penicillins
Mode of Action:

Back 24

Cell wall inhibitors
Bactericidal

Front 25

Expanded Spectrum Penicillins
Spectrum:

Back 25

Broad

Front 26

Expanded Spectrum Penicillins
Bacterial Resistance:

Back 26

Beta-lactamase susceptible

Front 27

Expanded Spectrum Penicillins
Clinical Use:
(___________ has better _________ properties than ________.)

Back 27

Amoxicillin had better absoprtion properties than Ampicillin.

Front 28

Expanded Spectrum Penicillins
Examples:
(Am)

Back 28

Amoxicillin
Ampicillin

Front 29

Expanded Spectrum Penicillins
Class Concept:

Back 29

Yes

Front 30

Anti-pseudomonal Penicillins
Mode of action:

Back 30

Cell wall inhibitors
Bactericidal

Front 31

Anti-pseudomonal Penicillins
Spectrum:

Back 31

Broad

Front 32

Anti-pseudomonal Penicillins
Bacterial Resistance:
(Inactivated by? Stable from?)

Back 32

Inactivated by staph beta lactamase
Stable against gram neg beta lactamase

Front 33

Anti-pseudomonal Penicillins
Clinical Use: (4pnts)

Back 33

$$, Used for: highly resistant bacteria, synergy with aminoglycosides, combo

Front 34

Anti-pseudomonal Penicillins
Class Concept:

Back 34

No

Front 35

Anti-pseudomonal Penicillins
Examples:
(CARlos smokes DOPE from his PIPE to get LOw, which is bad(Anti))

Back 35

CARboxy penicillins
CARbenicillin
tiCARcillin
ureiDOPEnicillins
azLOcillin
mezLOcillin
PIPEracillin

Front 36

Beta-Lactamase Inhibitors
Mode of Action:

Back 36

Inhibit beta-lactamase enzymes

Front 37

Beta-Lactamase Inhibitors
Spectrum:

Back 37

Broad

Front 38

Beta-Lactamase Inhibitors
Bacterial Resistance:
(What are inactivated by this?)

Back 38

NO
Beta lactamases inactivated

Front 39

Beta-Lactamase Inhibitors
Clinical Use:
(In combo with?)

Back 39

In combination with beta lactam antibiotics

Front 40

Beta-Lactamase Inhibitors
Class concept:

Back 40

No

Front 41

Beta-Lactamase Inhibitors
Examples:
(Clav, Sulb, Taz - CST)

Back 41

Clavulanic Acid (Amox-Clav, Ticar-Clav)
Sulbactam (Amp-sulbactam)
Tazobactam

Front 42

Cephalosporins 1st Gen
Mode of Action:

Back 42

Cell wall inhibitors
Bactericidal

Front 43

Cephalosporins 1st Gen
Spectrum:

Back 43

Broad

Front 44

Cephalosporins 1st Gen
Bacterial Resistance:

Back 44

Beta Lactamase susceptible

Front 45

Cephalosporins 1st Gen
Clinical Use:
(Mostly? Some? On? $$?)

Back 45

Mostly Gram Pos
Some gram neg, organisms
$$ than penicillins

Front 46

Cephalosporins 1st Gen
Class Concept:

Back 46

Yes

Front 47

Cephalosporins 1st Gen
Examples: (3)

Back 47

Cephalothin
Cefazolin
Cephalexin

Front 48

Cephalosporins 2nd Gen
Mode of Action:

Back 48

Cell wall inhibitors
Bactericidal

Front 49

Cephalosporins 2nd Gen
Spectrum:
(Decreased against?)

Back 49

Broad, decreased against gram pos

Front 50

Cephalosporins 2nd Gen
Bacterial Resistance:

Back 50

Beta lactamase susceptible

Front 51

Cephalosporins 2nd Gen
Clinical Use:
(More? Not?)

Back 51

More gram neg
NOT Pseudo

Front 52

Cephalosporins 2nd Gen
Class Concept:

Back 52

No

Front 53

Cephalosporins 2nd Gen
Examples:

Back 53

Cefaclor
Cefamandole
Cefuroxime
Cefoxitin

Front 54

Cephalosporins 3rd Gen
Mode of Action:

Back 54

Cell Wall Inhibitors
Bactericidal

Front 55

Cephalosporins 3rd Gen
Spectrum:
(Good for? (2))

Back 55

Broad
Good for Enterobacteriacee and Pseudomonas

Front 56

Cephalosporins 3rd Gen
Bacterial Resistance:

Back 56

Beta Lactamase Susceptible

Front 57

Cephalosporins 3rd Gen
Clinical Use:

Back 57

Enterobacteriacee and Pseudomonas

Front 58

Cephalosporins 3rd Gen
Class Concept:

Back 58

No

Front 59

Cephalosporins 3rd Gen
Examples:
(CefT)

Back 59

Cefixime
Cefotaxime
Ceftazidime
Ceftriaxone

Front 60

Cephalosporins 4th Gen
Mode of Action:

Back 60

Cell wall inhibitors
Bactericidal

Front 61

Cephalosporins 4th Gen
Spectrum:

Back 61

Broad

Front 62

Cephalosporins 4th Gen
Bacterial Resistance:

Back 62

Beta lactamase suseptible

Front 63

Cephalosporins 4th Gen
Clinica Use:

Back 63

More Gram Pos and Gram Neg

Front 64

Cephalosporins 4th Gen
Class Concept:

Back 64

No

Front 65

Cephalosporins 4th Gen
Examples:
(CeF-P)

Back 65

Cefipime (Cefepime)
Cefpirome

Front 66

Cephalosporins Similarites:
(Mode of Action, Spectrum, Bacterial Resistance)

Back 66

MOA: Cell wall inhibitors, bactericidal
SPEC: Broad (General)
BR: Beta lactamase susceptible

Front 67

Aztronam
Mode of Action:

Back 67

Cell wall inhibitors
Bactericidal

Front 68

Aztronam
Spectrum:

Back 68

Narrow, gram neg

Front 69

Aztronam
Clinical Use:

Back 69

Used for resistant gram negs
Old magic bullet

Front 70

Aztronam
Examples:
(Az)

Back 70

Aztreonam

Front 71

What is the antimicrobial agent thats a Carbapenem?

Back 71

Imipenem

Front 72

Imipenem
Mode of Action:

Back 72

Cell Wall Inhibitors - penicillin binding proteins
Bactericidal

Front 73

Imipenem
Spectrum:

Back 73

Broad

Front 74

Imipenem
Bacterial Resistance:

Back 74

Most beta lactamases
MRSA and VRE

Front 75

Imipenem
Clinical Use:
(Nickname?)

Back 75

Anaerobes and most gram neg rods
Widest spectrum
"Magic Bullet"

Front 76

Imipenem
Examples:

Back 76

Imepenem

Front 77

What is known as the Magic Bullet because it has the widest spectrum?

Back 77

Imipenem

Front 78

What is the antimicrobial agent thats a Glycopeptides?

Back 78

Vancomycin

Front 79

Vancomycin
Mode of Action:

Back 79

Cell wall inhibitor
Bactericidal

Front 80

Vancomycin
Spectrum:

Back 80

Narrow gram pos

Front 81

Vancomycin
Bacterial Resistance:

Back 81

VRE

Front 82

Vancomycin
Clinical Use: (2)
(Toxic effects?)

Back 82

MRSA treatment
C.Diff
Toxic Side Effects: hearing loss

Front 83

Vancomycin
Examples:

Back 83

Teicoplanin

Front 84

Are all cell wall inhibitor antimicrobials bactericidal?

Back 84

Yes

Front 85

What are the antimicrobials that inhibit cell wall synthesis?

Back 85

The penicillins, Four generations of cephalosporins, Aztronam, Imipenem, Vancomycin

Front 86

What is the most common site of action in Protein Synthesis Inhibition?

Back 86

Where tRNA brings the amino acids into place in the ribosomes.

Front 87

What are the four antimicrobials that Inhibit Protein Synthesis?

Back 87

-macrolide group
-chloramphenicol
-tetracyclines
-aminoglycosides

Front 88

What antimicrobial is in the macrolide group?

Back 88

Erthyromycin

Front 89

Erythromycin
Mode of Action:

Back 89

Inhibits protein synthesis
- binds to ribosomal subunits
Bacteriostatic UNLESS high concentration

Front 90

Erythromycin
Spectrum:

Back 90

Narrow, gram pos and neg
NOT entero

Front 91

Erythromycin
Clinical Use: (5)
(To large for?)

Back 91

Penicillin allergies
Strep throat (S.pyogenes)
Mycoplasma, Legionella, Chlamydia
-Too large for blood-brain border

Front 92

Erythromycin
Examples:

Back 92

Clindamycin

Front 93

What is clindamycin, why is it special, and what is it used for?

Back 93

An antimicrobial that has better absorption and penetration properties.
Used for: Anaerobic infections, pseudomembranous colitis

Front 94

Chloramphenicol
Mode of action:

Back 94

Inhibits protein synthesis - ribosomes
Bacteriostatic

Front 95

Chloramphenicol
Spectrum:

Back 95

Broad

Front 96

Chloramphenicol
Clinical Use:
(Toxic Effects?)

Back 96

TOXIC Effects: Gray syndrome, aplastic anemia, bone marrow depression
-used for typhoi and meningitis

Front 97

Tetracyclines
Mode of Action:

Back 97

Inhibits protein synthesis - tRNA
Bacteriostatic

Front 98

Tetracyclines
Spectrum:

Back 98

Broad

Front 99

Tetracyclines
Clinical Use:
(Interferes with?)

Back 99

Chlymadia, mycoplasma, rickettsial infections, acne
Binds Ca and Mg ions
Intereferes with: bone formation and birth control pills

Front 100

Tetracyclines
Examples: (4)

Back 100

Terramycin
Aureomycin
Doxycycline
Minocycline

Front 101

Aminoglycosides
Mode of Action:

Back 101

Inhibits protein synthesis - ribosomes
Bactericidal

Front 102

Aminoglycosides
Spectrum:

Back 102

Broad

Front 103

Aminoglycosides
Clinical Use:
(Not for? Synergy with? What needs to mimic what? Toxic to?)

Back 103

- NOT FOR: anaerobic infections, no CNS penetrations
-Synergy with: beta lactams (anti-pseudomonal penicillins)
-Ca and Mg ions need to mimic tissue levels
-Toxic to: kidneys and CNS, hearing loss

Front 104

Aminoglycosides
Examples:
(KGTANS) (cin)

Back 104

Kanamycin
Gentamicin
Tobramycin
Amikacin
Netilmicin
Spectinomycin

Front 105

What are the antimicrobials that inhibit DNA and RNA synthesis?
(NMF)

Back 105

Nalidixic Acid
Metronidazole
Fluoroquinolones

Front 106

What class of antibiotics do fluoroquinolones come from?

Back 106

Quinolones

Front 107

Fluoroquinolones
Mode of Action:

Back 107

Bind DNA gyrase enzymes
Bactericidal

Front 108

Fluoroquinolones
Spectrum:

Back 108

Broad

Front 109

Fluoroquinolones
Clinical Use:

Back 109

Gram pos and negs, enterobactericeae, cartilage and skeletal damage

Front 110

Fluoroquinolones
Examples:

Back 110

Ciprofloxacin
Norfloxacin

Front 111

Naladixic Acid
Mode of Action:

Back 111

Inhibits DNA synthesis
Bactericidal

Front 112

Naladixic Acid
Spectrum:

Back 112

Broad

Front 113

Naladixic Acid
Clinical Use:

Back 113

Urinary uses

Front 114

Metronidazole
Mode of Action:

Back 114

Inhibits DNA synthesis
Bactericidal

Front 115

Metronidazle
Spectrum:

Back 115

Narrow

Front 116

Metronidazle
Clinical uses:

Back 116

Anaerobic infections, Trichomonas vaginalis, giardia

Front 117

What are the antimicrobials that Inhibit cell membrane function? (1)

Back 117

Polymyxins

Front 118

Polymyxins
Mode of Action:

Back 118

Cell Membrane
Bactericidal

Front 119

Polymyxins
Spectrum:

Back 119

Narrow gram neg

Front 120

Polymyxins
Clinical Use:
(Toxicity? Whats used in media?)

Back 120

Pseudomonas
Toxicity: kidneys and nerves
Colistin used in media

Front 121

Polymyxins
Examples:
(BE Oint)

Back 121

Colistin (Polymxyin E)
Polymyxin B
Polysporin ointment

Front 122

What are the antimicrobials that Inhibit other metabolic processes? (3)

Back 122

Sulfonamides
Trimethoprim
Nitrofurantoin (Nitrofurans)

Front 123

Sulfonamides
Mode of Action:

Back 123

Competitive inhibition of PABA folic acid pathway
Bacteriostatic

Front 124

Sulfonamides
Spectrum:

Back 124

Broad

Front 125

Sulfonamides
Bacterial Resistance:
(When?)

Back 125

Resistance forms during treatment

Front 126

Sulfonamides
Clinical Use:
($$, Synergy with?)

Back 126

Inexpensive
Urinary drugs
Synergy with: Trimethoprim, Cotrimoxazole, Sulfamethoxazole, SXT (Trimeth-sulfa)

Front 127

Sulfonamides
Examples: (2)

Back 127

Sulfa drugs
Sulfonamides

Front 128

Trimethoprim
Mode of Action:

Back 128

Competitive inhibition of PABA folic acid pathway
Bacteriostatic

Front 129

Trimethoprim
Spectrum:

Back 129

Broad

Front 130

Trimethoprim
Clinical Use:
(Synergy with?)

Back 130

Urinary drug
Synergy with Sulfas: SXT

Front 131

Trimethoprim
Examples:

Back 131

SXT (bactrum, septra)

Front 132

What antimicrobial is part of the class: Nitrofurans? (1)

Back 132

Nitrofurantoin

Front 133

Nitrofurantoin
Mode of Action:

Back 133

Damages DNA, Enzyme in protein translation
Bacteristatic at low conc
Bactericidal at high conc

Front 134

Nitrofurantoin
Spectrum:

Back 134

Broad

Front 135

Nitrofurantoin
Clinical Use:
(Color?)

Back 135

Bright yellow compound
Urinary drug

Front 136

What is the overall objective of a clinical microbiology laboratory?

Back 136

Find out: What organism is causing, and what antimicrobial would best kill or control it

Front 137

Definition of: Sensitive

Back 137

killed by

Front 138

Definition of: Resistant

Back 138

NOT killed by

Front 139

When do you NOT need to do a sensitivty test?

Back 139

When the organism is universally susceptible

Front 140

Questions a physician must apply in order to choose right agent? (4)

Back 140

Antimicrobial effective at the pH site?
Penetrate?
Toxic to host tissue?
Cost effective?

Front 141

Three Convential Methods of antimicrobial susceptibility testing?

Back 141

-Broth dilution
-Agar Dilution
-Disc Diffusion(WHAT WE DO)

Front 142

What is a Standardized Bacterial Inoculum used for?

Back 142

To improve accuracy of test results

Front 143

Colony Selection depends on?

Back 143

-NOT mixed cultures
-3-10 colonies sampled
-taken from primary plate

Front 144

Growth phase of inoculum?

Back 144

-in log growth phase for 18-24hrs
-colonies inoculated to a broth and incubated for 4hrs

Front 145

Standardizing inoculum?
(How to make it match?)

Back 145

-must match 0.5 McFarland standard
-sterile saline or broth added to broth until it matches standard

Front 146

What should a 0.5 McFarland standard be at?
(What does CFU stand for?)

Back 146

1.5 x 10 to the 8 CFU/mL
CFU- colony forming unit

Front 147

What is the growth medium used in susceptibility testing?

Back 147

Mueller Hinton (MH) broth or agar

Front 148

Final pH of Agar?

Back 148

7.2 - 7.4

Front 149

In agar, what two ions should be at what concentration for testing?

Back 149

Ca and Mg, correct concentration (equal to tissues)

Front 150

Thymidine concentration interferes with results of?

Back 150

Sulfonamides and trimethoprim

Front 151

What are the two apaptations of broth dilution susceptibility tests?

Back 151

Macro Method and Micro Method

Front 152

What is Macro method?
How do you know the lowest concentration to inhibit growth?

Back 152

manual method, reference method, diluted in a series of doubling dilutions in test tubes
-lowest concentration that inhibits growth is the one with nothing in it

Front 153

Antimicrobials label name must include? (3)

Back 153

-generic name
-assay potency
-expiration date

Front 154

SI Units =

Back 154

mg/L

Front 155

Microgram x 1000 =

Back 155

milligrams

Front 156

mL x 1000 =

Back 156

liters

Front 157

Dilutions stock standard is?

Back 157

1000 mg/L

Front 158

To calculate dilutions? (Equation)

Back 158

V1C1=V2C2

Front 159

Micro method is?

Back 159

Fully automated method, used frequently

Front 160

Definitino of MIC?

Back 160

Minimal Inhibitory Concentration - lowest conc of antimicrobial in mg/L that prevents invitro growth or organism

Front 161

When reading: Growth control is okay when?

Back 161

It shows growth

Front 162

What two fluids are obtained for antimicrobial testing?

Back 162

Urine and blood

Front 163

Antimicrobial effectiveness is in check for in vivo when:

Back 163

it is two to four times higher then the in vitro MIC

Front 164

Definition of: MBC

Back 164

Minimal bactericidal concentration - lowest conc of antimicrobial in mg/L resulting in more then 99.9% killing in vitro

Front 165

MBC only determined for:

Back 165

bactericidal antimicrobials
(MIC done first)

Front 166

Microdilution Broth Susceptibility Tests:

Back 166

-plastic plates with molded microtube wells to hold dilutions of antimicrobials
- plates kept frozen
- appropiate for gram pos and gram neg and urinary isolates

Front 167

Is a standard innoculation used in these plates?

Back 167

Yes, thawed before and plates inoculated with a small volume of bacterial suspension.

Front 168

Reading of plates:
(Incubated at/how long?)
(Sterility Well)
(Growth Control)

Back 168

-incubated overnight at 35degrees first!
-sterility well - contains growth medium, not innoculated
-growth control - NO antimicrobial, should show growth

Front 169

Resistant strains could flag possible, They are: (3)

Back 169

MRSA, VRE, ESBLs

Front 170

Can be done automatically through a:

Back 170

Vitek

Front 171

Agar Dilution Susceptibility Tests:
(Agar)
(Inoculum)

Back 171

-similar to broth
-Mueller Hinton Agar
-standardized

Front 172

Process for Agar Test: (3)

Back 172

-inoculated with standard
-incubated overnight
-inspected growth

Front 173

Growth indicates:

Back 173

Resistance

Front 174

NO Growth indicates:

Back 174

Susceptibility

Front 175

Disc Diffusion Susceptibility Test (KIRBY BAUER) :

Back 175

-standardized innoculum spread over entire plate
-antibiotic discs placed
-incubation (antimicrob diffuses into agar, forms circular zone around disc)

Front 176

Reading of Disc Test:

Back 176

-colonies DONT form where sufficient antimicrobial is
- measure size of zone to read

Front 177

Definition of: Zone of Inhibition

Back 177

-area around antimicrobial disc where no growth is seen

Front 178

Resistance on Disc test shown as:

Back 178

-full growth up to disc

Front 179

Falsely Larger Zone due to: (1)

Back 179

-thin agar

Front 180

Falsely Smaller Zone due to: (2)

Back 180

-thick agar
-stiff agar

Front 181

Definition of: Critical Point

Back 181

Lowest concentration of antimicrobial around disc inhibiting growth

Front 182

Interpretation:
S-
R-
I-

Back 182

S-Susceptible (19mm and over)
R-Resistant (15mm and over)
I-Intermediate (16-18mm)

Front 183

Disc Test Procedure: (8)

Back 183

Select 4-5 isolated colonies of same type.
Transfer to tube containing 4-5ml of broth.
Adjust turbidity to match McFarland Standards.
15mins - inoculate agar plate.
Dry for 3-5mins.
15mins - 35degree incubator.
16-24 hours, measure.
Interpret.

Front 184

More CFU/ml : (too heavy)
Less CFU/ml : (too light)

Back 184

- smaller zone sizes (falsely resistant)
- larger zone sizes (falsely sensistive)

Front 185

Agar: (depth)

Back 185

- 4mm
-thinner -larger zones
-thicker -smaller zones

Front 186

Larger zone means:

Back 186

Sensitive

Front 187

Smaller zone means:

Back 187

Resistant

Front 188

Will surface moisture affect it?

Back 188

Yes, some

Front 189

Direction for streaking plates:

Back 189

all three directions and outside

Front 190

Application of Discs:

Back 190

-placed within 15mins of streaking
- pressed firmly against agar with forceps
- NOT into media
- plates incubated for 15mins (35degrees, ambient air, 16-24hrs)

Front 191

If colony WITHIN main zone of inhibition:

Back 191

check for purity, if pure they are are resistant colonies

Front 192

What swarms into zone after being formed? Should we be worried?

Back 192

Proetus species (gram neg), ignore them and measure normally

Front 193

If inner ring of colonies within zone:

Back 193

-measure inner zone

Front 194

Definition of: Susceptible

Back 194

- (sensitive)
- organism is suseptible to action of that antimicrobial

Front 195

Definition of: Resistant

Back 195

- organism is resistant to action of the antimicrobial

Front 196

Definition of: Intermediate

Back 196

- used when hard to test, otherwise would go with susceptible one

Front 197

What do we record when completely susceptible?

Back 197

-SUSCEPTIBLE
NOT zero

Front 198

Bacteria must be ______, _____, _____ in order to use the Kirby Bauer test.

Back 198

-fast growers
-nonfastidious
-grow in ambient air

Front 199

Quality Control are used to:

Back 199

- check the accuracy of susceptiblity testing

Front 200

QC Done when:

Back 200

-new discs or antimicrobial panels are received (may be daily, monthly, weekly)

Front 201

Organisms used for QC: (3)

Back 201

-Staph aureus
- E.Coli
- Pseudomonas aeruginosa

Front 202

Storage of antimicrobial discs:

Back 202

- 20degrees or colder, moisture free
-working supply at 4degrees
-warmed to room temp before use

Front 203

Too test for MRSA:

Back 203

-add sodium chloride to broth and agar to enhance growth
-incubate between 30-35
-use oxacillin screen test
-any growth=resistance

Front 204

Too test for S.Pneumoniae

Back 204

-use direct method for innoculum
-agar enriched with blood
-oxacillin disc added
-zones od 20mm or more=susceptibility to penicillin
-smaller zones=resistance?

Front 205

What is: The Episilometer Test (E-test)

Back 205

-plastic strip with a predefined antimicrobial agent concentration immobilized on one side

Front 206

Procedure of E-Test:

Back 206

-strip placed on surface of agar
-incubate plate
-intersection of growth ellipse with strip gradient indicates MIC of agent for that organism

Front 207

Results of E-Test:

Back 207

-LOW MIC= sensitive
-HIGH MIC= resistant