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Clinical Bacteriology > (M) Lec 6.2: Antimicrobial Susceptibility Testing > Flashcards

(M) Lec 6.2: Antimicrobial Susceptibility Testing Flashcards

1
Q

What are the three different antimicrobial agents?

A
  1. Antibacterial agents
  2. Antiviral agents
  3. Antifungal agents
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2
Q

This antimicrobial agent is destructive to and inhibits bacteria.

A

Antibacterial agents

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3
Q

This antimicrobial agent weakens and inhibits viruses.

A

Antiviral agents

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4
Q

This antimicrobial agent inhibits fungi.

A

Antifungal agents

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5
Q

What are the two categories of antimicrobial agents?

A
  1. Bacteriocidal agents
  2. Bacteriostatic agents
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6
Q

This type of antimicrobial agent kills the microbes (eg. penicillins, cephalosporins, and vancomycin)

A

Bacterocidal agents

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7
Q

This type of antimicrobial agent inhibits the growth (eg. tetracycline, sulfonamides, erythromycin)

A

Bacteriostatic agents

Clue: Static, meaning walang growth

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8
Q

T or F: Categories may overlap which depends on the dosage, route of administration, and site of infection.

A

T

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9
Q

Categories may overlap depending on what three factors?

A
  1. Dosage
  2. Route of administration
  3. Site of infection
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10
Q

This type of antibiotic has limited spectrum like penicillin G for gram positive organisms.

A

Narrow-spectrum antibiotics

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11
Q

This type of antibiotic has a wide spectrum against both gram positive and gram negative like tetracycline.

A

Broad-spectrum antibiotics

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12
Q

Which type of spectrum inhibits and destructs the normal flora of the patient and is a secondary infection or superinfection?

A

Broad-spectrum antibiotics

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13
Q

What are the things to consider in the selection of the antimicrobial agent?

A
  1. Effect to the organism
  2. Toxicity level to the host and to normal flora
  3. Pharmacological activities and allergic reactions
  4. Host’s immune system, medical considerations, and organ functions
  5. Solubility
  6. Age of the patient, site of infection, and route of administration
  7. Toxic to fetus and crosses the placenta or BBB
  8. Cost effectiveness
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14
Q

What are the four categories/types of antibiotics?

A
  1. Cell wall inhibiting
  2. Altering bacterial cell membranes
  3. Inhibits protein synthesis
  4. Inhibits folic acid synthesis
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15
Q

Cell Wall Inhibiting Antibiotics

This type of antibiotic contains the B lactam ring.

A

Beta lactam antibiotics

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16
Q

Cell Wall Inhibiting Antibiotics

Nucleotide intermediates accumulate in the cell wall = ?

A

Inhibition of cell wall synthesis

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17
Q

Cell Wall Inhibiting Antibiotics

Penicillin G and V are formed from?

A

Mold Penicillum notatum

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18
Q

Cell Wall Synthesis Antibiotics

What is the spectrum of synthetic aminopenicillins, ampicillin, amoxicillin, and bacampicillin?

A

Gram positive other than Staphylococcus (resistant)

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19
Q

Altering Bacterial Cell Membranes Antibiotics

This antibiotic binds to the outer surface of the cell membrane and alter phospholipids.

A

Bacitracin antibiotics

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20
Q

Altering Bacterial Cell Membranes Antibiotics

Source of bacitracin antibiotics?

A

Bacillus licheniformis

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21
Q

Altering Bacterial Cell Membranes Antibiotics

What is the spectrum of bacitracin antibiotics?

A

Gram positive including Staphylococcus and some gram negative

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22
Q

Altering Bacterial Cell Membranes Antibiotics

What is the spectrum of Polymyxins B and E (Colistin)?

A

Gram negative

Used as topical agents for burns and wound infections

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23
Q

Inhibits Protein Synthesis Antibiotics

These antibiotics interfere with protein synthesis.

A
  1. Aminoglycosides
  2. Erythromycin
  3. Chloramphenicol

Aminoglycosides: Streptomycin, Tobramycin, and Gentamycin

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24
Q

Inhibits Protein Synthesis Antibiotics

Source of Streptomycin?

A

Streptomyces griseus

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25
# Inhibits Protein Synthesis Antibiotics What is the spectrum for Streptomycin?
Combination for Tb and B lactam enterococcus
26
# Inhibits Protein Synthesis Antibiotics Source of Gentamycin?
Micromonospora purpurea
27
# Inhibits Protein Synthesis Antibiotics What is the spectrum for Gentamycin?
Generally, gram negative bacilli
28
# Inhibits Protein Synthesis Antibiotics Source of Tobramycin?
Streptomyces fradiae
29
# Inhibits Protein Synthesis Antibiotics What is the spectrum for Tobramycin?
Recommended in showing resistance to Gentamycin
30
# Inhibits Protein Synthesis Antibiotics What is the spectrum for Erythromycin?
Gram positive, S. pyogenes, S. pneumoniae (Penicillin-resistant), M. pneumoniae, Legionella, Neisseria, and Haemophilus
31
# Inhibits Protein Synthesis Antibiotics What is the spectrum for Chloroamphenicol?
Gram positive and gram negative
32
What are the five types of antibiotics that inhibit folic acid synthesis?
1. Sulfonamides 2. Quinolones 3. Nitrofurantoin 4. Rifampin 5. Metronidazole
33
# Inhibits Folic Acid Synthesis Antibiotics Competitive inhibition of folic acid synthesis
Sulfonamides
34
# Inhibits Folic Acid Synthesis Antibiotics (Sulfonamides) Used primarily for acute UTI
Sulfamethoxazole
35
# Inhibits Folic Acid Synthesis Antibiotics (Sulfonamides) Inhibits enzyme dihydrofolate reductase
Trimethoprim
36
# Inhibits Folic Acid Synthesis Antibiotics (Sulfonamides) Treatment of chronic UTI and Enterobacteriaceae infection
Trimethoprim-sulfamethoxazole
37
# Inhibits Folic Acid Synthesis Antibiotics Inhibition of DNA gyrase activity which interferes with synthesis of DNA
Quinolones
38
# Inhibits Folic Acid Synthesis Antibiotics (Quinolones) Treats UTI
Nalidixic Acid
39
# Inhibits Folic Acid Synthesis Antibiotics (Quinolones) Has a broader spectrum and is used as a treatment for UTI and invasive ear infection
Fluoroquinolones (Ciprofloxacin)
40
# Inhibits Folic Acid Synthesis Antibiotics (Quinolones) Most effective to UTI (excreted and concentrated)
Norfloxacin
41
# Inhibits Folic Acid Synthesis Antibiotics Inhibition of bacterial enzymes or protein synthesis
Nitrofurantoin
42
# Inhibits Folic Acid Synthesis Antibiotics Inhibition of DNA-dependent RNA polymerase
Rifampin
43
# Inhibits Folic Acid Synthesis Antibiotics Used in the treatment of Tb and prophylaxis for N. meningitidis
Rifampin
44
# Inhibits Folic Acid Synthesis Antibiotics Cause altered DNA synthesis resulting to bacteriocidal effect
Metronidazole
45
# Inhibits Folic Acid Synthesis Antibiotics Activated under anaerobic conditions and treats Gardnerella vaginosis and pseudomembranous colitis from C. difficile
Metronidazole
46
# Antimycobacterial Agents Inhibits DNA-dependent RNA polymerase
Rifampin
47
# Antimycobacterial Agents Inteferes in formation of mycolic acid
Isoniazid (INH)
48
# Antimycobacterial Agents Bacteriocidal
Pyrazinamide (PZA)
49
# Antimycobacterial Agents Bacteriostatic and inhibits mycolic acid
Ethambutol
50
# Antimycobacterial Agents Aminoglycoside that is generally used as a second line drug
Streptomycin
51
# Antifungal Agents Attacks sterols in fungal cell wall (ergosterols)
Amphotericin B
52
# Antifungal Agents Prevents sterol synthesis affecting cell membrane
Imidazole
53
# Antifungal Agents Dermatophytic, yeast, and superficial fungal infection
Clotrimazole
54
# Antifungal Agents Binds to ergosterol in fungal cell membrane
Nystatin
55
The preferred laboratory method for susceptibility testing
Kirby-Bauer Disk Diffusion Test
56
What makes up Kirby-Bauer Disk Diffusion Test?
Standardized suspension + bacteria + MHA + paper disk
57
Lack of growth = zone of inhibition *(diameter is measured)*
Clear Zone
58
# Manner of Reporting Appears to be effective
Susceptible (sensitive)
59
# Manners of Reporting Appears to be ineffective
Resistant
60
# Manners of Reporting In between
Intermediate
61
What is the principle of the laboratory method for susceptibility testing?
Inverse linear relationship between the diameter of the zone of inhibited growth around the antibiotic disk and the algorithm of the minimal inhibitory concentration (MIC) of the organism
62
T or F: There is a directly proportional linear relationship between the diameter of the zone of inhibited growth around the antibiotic disk and the algorithm of the MIC of the organism.
F ## Footnote Inverse linear relationship
63
Lowest concentration of antibiotic that inhibits in vitro bacterial growth
Minimal Inhibitory Concentration (MIC)
64
* Calcium and Magnesium: activity of aminoglycosides x P. aeruginosa * Activity of the tetracycline against all bacteria * Calcium and Magnesium lead to activity against these agents
Mueller Hinton Agar (MHA)
65
What is the pH for Kirby-Bauer?
7.2 to 7.4
66
What is the depth for Kirby-Bauer?
4 mm
67
Density of the inoculum
0.5 McFarland standard
68
Too light inoculum or older culture
False susceptible
69
Too heavy inoculum
False resistant
70
T or F: Night colonies take less than 24 hours.
T
71
Thicker zone of inhibition leads to?
False resistant
72
Thinner zone of inhibition leads to?
False susceptible
73
Incubation for AST?
35 deg. Celsius +/- 2 deg. Celsius for 16 to 18 hours
74
T or F: Higher temperature leads to larger zone of inhibition.
F ## Footnote Low temperature
75
T or F: You can stack more than five plates for AST.
F ## Footnote You cannot since the center may not reach the correct temperature.
76
This is needed for fastidious organisms only.
Increased CO2

Clinical Bacteriology (33 decks)

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