Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharm Exam #3 > L26 - O'Keefe - Intro to Antibiotics Part 1 > Flashcards

L26 - O'Keefe - Intro to Antibiotics Part 1 Flashcards

1
Q

To diagnose infection, what 4 topics are beneficial to know?

A
  1. site of infection
  2. infecting pathogen
  3. spectrum of activity of antibiotic
  4. host characteristics
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

If you isolate an organism, does that mean that there’s an infection?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are normal flora?

A

Harmless bacteria that are naturally found and suppress growth of pathogenic bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Can normal flora become pathogenic?

A

Yes, if host defenses are impaired or disrupted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define Contamination

A

When a organism is accidentally introduced during collection or processing of a specimen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Give an example of contamination

A

Coag-neg staph in blood of patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define colonization

A

when an organism is present but not invading the host or inducing signs/symptoms of infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Give an example of colonization

A

Psudomonas aeruginosa in patient’s sputum but they aren’t displaying signs of pneumonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define infection

A

pathogen is damaging host tissue and eliciting signs/symptoms of an infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Give an example of infection

A

Strep pneumoniae in sputum of patient who has fever, cough, and shortness of breath

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What bacteria are associated with throat infections?

A

Group A Strep

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What bacteria are associated with infections in urine?

A

E. Coli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What bacteria are associated with skin abscesses?

A

S. aureus (or group a strep)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What bacteria are associated with lung infections?

A

pneumococcus (aka strep pneumoniae)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Define empirical antibiotic therapy

A

when antibiotics are chosen to be given based on preliminary info (before culture results are available)

  • antibiotics chosen have activity against likely pathogens
  • *this is done to try to avoid morbidity/mortality due to a delay in treatment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What preliminary info is used to determine empirical antibiotic therapy?

A

Site of Infection
Likely causative organism
Gram-stain result

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Is normal flora found everywhere in the host?

A

No, some body sites are sterile (see lecture for a list)

18
Q

What is the purpose of susceptibility testing?

A

To see if the proper antibiotic was chosen for empiric therapy

19
Q

What is directed or targeted therapy?

A

When the antibiotic regiment is modified once culture and susceptibility results are available
*antibiotics are selected to treat documented infections (organism and susceptibility are known)

20
Q

Define antimicrobial spectrum of activity. What are the 2 possible spectra?

A

General list of bacteria killed or inhibited by an antibiotic

*established during early clinical/pre-clinical trials and could change with the emergence of resistance

Narrow or Broad spectrum

21
Q

What is Narrow spectrum?

A

antibiotic has activity against a LIMITED group of bacteria

22
Q

Give an example of a narrow spectrum antibiotic used to treat Methacillin resistant bacteria

A

Nafcillin

23
Q

What is broad spectrum?

A

antibiotic with activity against a WIDE variety of bacteria

24
Q

Give an example of a broad spectrum antibiotic class that is used for anaerobes, all gram positive bacteria, etc.

A

Carbapenem

25
Q

What is MIC?

A

Minimum inhibitory concentration

lowest concentration of antibiotic that inhibits visible bacterial growth (ex: in broth culture system where we can see growth in tubes)

26
Q

What is MBC?

A

minimum bactericidal concentration

lowest concentration that kills bacteria
*decreases bacterial inoculum by 99.9% (3 logs)

27
Q

What is the relationship between MIC and MBC?

A

MIC is less than or equal to MBC

*so it takes more antibiotic to kill an organism than to inhibit it’s growth

28
Q

Define susceptibility breakpoint

A

interpretive guidelines by CLSI that categorize antibiotic MIC values as susceptible, intermediate, or resistant (SIR)

29
Q

Why are the interpretive guidelines for SIR different for each antibiotic and bacteria?

A

they are based on PK (achievable serum/tissue conc)
depends on site of infection
depends on antibiotic activity

*thus…MIC values should NOT be compared for diff antibiotics

30
Q

Define Susceptible

A

organism is most likely eradicated with normal doses of antibiotic –> is “sensitive”

31
Q

Define Intermediate

A

treatment MAY b successful using max doses of antibiotic

ex: urine infection where antibiotic gets concentrated in that one region

32
Q

Define Resistant

A

MIC exceeds usual serum concentration of antibiotic, so less than optimal results are expected

33
Q

What are methods that can be used to determine the in-vitro activity of an antibiotic?

A

Quantitative determination of MIC: Broth dilution (macro and micro) and E test

Qualitative: Kirby Bauer Disk Diffusion
(*note: zone diameters are correlated to S and R but you can’t determine the exact MIC)

34
Q

Describe macrodilution (process)

A

2-fold serial dilutions of antibiotic are incubated with standard inoculum of bacteria in test tubes

MIC = 1st tube without visible growth)

35
Q

Is macrodilution used commonly?

A

No because it’s labor and resource intensive

36
Q

What is not typically determined by macrodilution?

A

MBC (if you were to determine it, it would be via growing colonies on agar plates and finding the one where there’s no growth)

37
Q

Describe the microdilution process

A

microtiter plates/cassettes with serial dilutions of several antibiotics are tested simultaneously (1st clear well = mic)

  • is an automated process and the most common!
  • note: size restraints limit # of concentrations that can be tested…MIC may be given as a range
38
Q

How does the Kirby Bauer Disk Diffusion test work?

A

filter paper disks with a known concentration of antibiotic are put on agar plates with a standard conc/log (or lag??) phase growth of bacteria

clear zone around disk is seen where antibiotic was effective in inhibiting bacterial growth

39
Q

How does the E test work?

A

plastic strip containing a gradient of antibiotic concentrations is put on an agar plate that has a standard concentration of bacteria

MIC = where the clear ellipse shaped zone crosses the strip

40
Q

What is PCR used for in relation to bacteria?

A

45 minute result from blood culture gives bacteria identification as well as tests probes for specific antibiotic resistance genes (ex: mecA, KPC, vanA/B)

41
Q

What are susceptibility reports?

A

Gives antibiotic tested, MIC, and SIR for individual bacteria

*are used for antibiotic selection (directed therapy) but are only an INDICATION of antibiotic activity

42
Q

What is a hospital antibiogram?

A

Report with susceptibility data for most common bacteria that are seen in hospitals

*helps guide choices for empiric antibiotic therapy (prior to identification of bacteria)

Pharm Exam #3 (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions