L6: Anti-Infective Therapy Flashcards
____: drug used to treat any disease
____: substance that interferes with proliferation of microorganism
____: drug of natural origin (often dirt) that has anti-microbial properties
Chemotherapeutic
Antimicrobial
Antibiotic
True or False: Bacteriocidal antimicrobials inhibit growth while bacteriostatic kills
False
Bacteriocidal = kills
Bacteriostatic = inhibits growth
Which of the following antimicrobials would you give to an immune compromised patient or one with a lethal condition?
A. Bacteriostatic
B. Bacteriocidal
B. Bacteriocidal
True or False: A functioning immune system is required for use of bacteriocidal
False - required for bacteriostatic
What’s the difference between drug resistance and sensitivity?
Resistance: NOT inhibited by clinically achievable drug concentration
Sensitivity: Inhibited by clinically achievable drug concentration
True or False: Anti-microbials tests are all ex-vivo
False - all in vitro
Which tests are used to determine whether abx tx is effective at treating patient infection?
Antimicrobial sensitivity testing
What are the four antimicrobial sensitivity tests?
1) Kirby Bauer - QUALITATIVE
2) Minimum Inhibitory Concentration (MIC)
3) Minimum Bacteriocidal Concentrations (MBC)
4) Antimicrobial Serumcidal Concentrations
To read a Kirby-Bauer plate, measure the _____
zone of inhibition
What are the results of a Kirby-Bauer test?
1) Susceptible
2) Intermediate
3) Resistant
Which test is used to determine the LEAST amount of an antimicrobial agent required to inhibit growth (static or cidal)
Minimum Inhibitory Concentration.
Which test is used to determine the LEAST amount of an antimicrobial agent required to inhibit growth (static or cidal)
A. Kirby Bauer
B. Minimum Inhibitory Concentration (MIC)
C. Minimum Bacteriocidal Concentrations (MBC)
D. Antimicrobial Serumcidal Concentrations
B. Minimum Inhibitory Concentration (MIC)
True or False: Treatment should not exceed the MIC at site of infection
False - treatment SHOULD exceed the MIC at site of infection
How is the growth assesed in the MIC?
A. Plating cell suspensions
B. Turbidity
C. Size
B. Turbidity
In which of the following tests is an antibiotic diluted in broth containing the pt’s isolated in standard amounts and incubated?
A. Kirby Bauer
B. MIC
C. MBC
B. MIC
True or False: MBC test can be adapted to E test or microwell plate
False - MIC can
Which of the following tests is used to identify the MINIMUM amount of an antimicrobial agent required to KILL (bacteriocidal)?
A. Kirby Bauer
B. MIC
C. MBC
C. MBC
True or False: Both Kirby Bauer and MIC can inhibit growth that is either static or cidal
True
True or False: The MIC is always greater than or equal to the MBC. In some cases, levels that are less than or equal to the MBC are needed for efficacy
False
- MIC is always < or equal to MBC
- In some cases, levels greater than or equal to MBC are needed for efficacy
In the case where infection is inaccessible to immune system, the amount of anti-micobial at the site should ____ MBC
exceed
___ is determined by plating cell suspensions from MIC test (an extension of MIC assay)
MBC
Which test is used to identify the minimum concentration of an antimicrobial agent required to kill a patient’s isolate in the patient’s serum?
Antimicrobial Serumcidal Concentration
True or False: Following an Antimicrobial Serumcidal Concentration treatment, patient’s serum is serially diluted with standard amount of their isolate, followed by incubation, to determine if MBC has been achieved
True
Which of the following is NOT a benefit of antibiograms?
A. Cost effective
B. Reserve certain antimicrobials for specific situations
C. Reduce antibiotic-resistance
D. Increase antibiotic-resistance
E. Aid in selection of appropriate antibiotic tx
D. Increase antibiotic-resistance
True or False: Good selective toxicity means that the antimicrobial chemotherapeutic agent has an EXCLUSIVE target in the microbe
True
Do cell membrane active agents have poor or good selective toxicity?
Poor
Do cell wall active agents (exclusive target in microbe) have poor or good selective toxicity?
Good
What features of an abscess lead it to be poorly penetrated by antimicrobials?
Low O2 levels
Low perfusion
Tissue necrosis
True or False: There are excess metabolic targets for antimicrobials in abscess
False - there are fewer
In abscesses, most phagocytes in lesions are dead, meaning new __ and __ can’t reach the site
WBC; antibodies
The presence of which two host metabolites (in abscess) often interfere w/antimicrobials?
Excess folic acid and sulfonamides
When treating an abscess, ____ lose effectiveness at lower pH
Aminoglycosides
What is a major limitation of antimicrobials, specifically for those who are immunocompromised?
immunosuppression
True or False: Superinfections (treat one disease and a new and different disease appears at another site) are commonly seen with use of antibacterials
False - common with antimicrobials
____: Administration of drugs to patient who is not infected, but is still at increased risk of acquiring infections
Chemoprophylaxis
True or False: Prevention of 2 bacterial pneumonia s/p flu or clean surgery that does not breech the mucosa are examples of justified chemoprophylaxis
False - unjustified!
_____: The administration of 2 or more antibiotics in combination
Combinatorial Therapies
A patient has polymicrobic, life-threatening infection and severe neutropenia. They are also
immunocompromised. Are the a good candidate for combination chemotherapy?
Yes
1) Life threatening infection
2) polymicrobial infection
3) severe neutropenia
4) immunocompromised
True or False: Combination chemotherapy is justified if doing so allows you to lower the dose of a toxic drug while also increasing cidal activity
True
____: two or more drugs which, when used in combination, are CIDAL at concentrations lower than that of either component used separately
A. Additive Effect
B. Antagonism
C. Indifference
D. Synergism
D. Synergism
Which two drugs display synergism?
Penicillin
Aminoglycosides
___: can be used to reduce toxicity, but to a lesser extent than synergistic drugs
Additive Effect
___: can be used to reduce toxicity, but to a lesser extent than synergistic drugs
A. Additive Effect
B. Antagonism
C. Indifference
D. Synergism
A. Additive Effect
____: reduction in activity of one or both components of the therapy when both are present
A. Additive Effect
B. Antagonism
C. Indifference
D. Synergism
B. Antagonism
Which two drugs, when used together, exhibit antagonism?
Tetracycline and Penicillin
___: combined action of either drug is the same as with either component alone
A. Synergism
B. Additive Effect
C. Indifference
C. Indifference
What are four mechanisms of drug resistance?
1) Alteration of drug target - modification of target site
2) Prevent access of drug to target
3) Inaction of drug
4) Tolerance
True or False: Efflux pumps are used to prevent access of drug to target
True
True or False: Altered PBP’s can reduce sensitivity to B-lactams while altered DNA Gyrase reduces sensitivity to fluroqunolones. These are just a few examples of alteration of drug target (modification of target site)
True
What is an example of an enzyme made by a microbe to inactivate a drug?
Penicillinase
No change in MIC but MBC increases by a factor of 32. This is an example of ___
tolerance
One mechanism of resistance is tolerance. In tolerance, evasion of killing can occur via: slowing growth rate (___) or depressing production of key enzymes involved in cell wall synthesis (____)
phenotypic
genotypic
