Flashcards in Antimicrobial Resistance and Susceptibility Deck (43):
Which is the most important superbug associated with hospitals?
Carbapenem- resistant K. pneumoniae
Which of the following are most common in hospitals and the community, including livestock and companion animals?
a. Methicillin-resistant S. aureus (MRSA)
b. ESBL-producing E. coli
c. Multidrug resistant S. pneumoniae
d. A and C
e. A and B
f. B and C
e. A and B
True/ False. Antibiotic therapy is only recommended for invasive infections.
Which drugs have a resistance to Salmonella?
Cephalosporins or fluoroquinolones
Which drugs have a resistance to Campylobacter?
Macrolides or fluoroquinolones
True/ False. MDR (multi drug resistant) bacteria are usually resistant to all drugs except cephalosporins.
False. They are resistant to cephalosporins
Which of the following are beta-lactam resistant?
d. All the above
d. All the above
What does MRSA stand for?
Methicillin Resistant Staphylococcus Aureus
True/False. MRSA and MRSP have the lowest affinity to penicillins and cephalosporins.
Which of the following MRSA is associated with livestock?
What does MRSP stand for?
Methicillin Resistant Staphylococcus Pseudintermedius
True/False. Approximately 70% of MRSP cases are skin and wound postsurgical infections acquired in the clinic.
What does ESBL stand for?
Extended Spectrum Beta Lactamase
What is ESBL?
It is an enzyme hydrolyzing/inactivating most Beta lactams produced by gram-negative bacteria
What is the only beta lactam ESBL does not hydrolyze/inactivate?
True ESBLs are susceptible to B- lactamase inhibitors such as _____.
What are the three main ESBL classes?
Which is the most common type of ESBL in animals?
A false ESBL (resistant to Beta-lactamase inhibitors) is widespread in small animals and limited to poultry
Which ESBL type can be transferred horizontally from E.coli livestock to E.coli in humans?
How do bacteria acquire resistance?
Horizontal gene transfer by transformation, transduction, and conjugation
What is transduction?
A transfer mediated by phage delivery
True/False. Antimicrobial resistance is a qualitative property.
False. Its a quantitative property
What are the two dilution methods for AST?
Broth dilution tests
Agar dilution tests
What are the two agar diffusion methods for AST?
Disk/tablet diffusion test (semi-quantitative)
Gradient diffusion E test (quantitative)
___ is the lowest concentration that inhibits completely growth of the test strain.
MIC (minimum inhibitory concentration)
What is MBC (Minimum bactericidal concentration)
The lowest concentration that kills the test strain
True/False. Diffusion method has a high reproducibility and robustness, whereas dilution method has a medium reproducibility and robustness.
False. Diffusion method has a MEDIUM reproducibility and robustness, whereas dilution method has a HIGH reproducibility and robustness.
Is the dilution method more expensive or cheaper than the diffusion method?
More expensive than diffusion
True/False. Standardization and quality control are required for reproducibility of AST.
How is quality control done?
-Reference strains of different species are routinely included in the testing (every day, or every week)
-MIC of the reference strain has to fall within a given range
-If not within a range the test will not be valid and should be repeated
What is the incubation period for the AST laboratory test?
35 Degrees C for 16-20 hours
What is a breakpoint?
A drug-specific value to interpret the results of susceptibility testing and determine if an antibacterial is potentially useful in the treatment of a bacterial infection.
A strain is defined as ___ by a level of antimicrobial activity associated with a high likelihood of therapeutic success.
A strain is defined as ___ by a level of antimicrobial activity associated with a high likelihood of therapeutic failure.
What is the standard range of a susceptible MIC? Resistant MIC?
less than or equal to 4 = susceptible
greater than or equal to 32 = resistant
What data is needed for setting breakpoints?
1. MIC distribution to determine MIC value that separates the WT population from resistant populations
2. PD/PK index
3. Clinical and bacteriological outcome data from clinical trials
When is a strain defined as wild type (WT) for a species?
By the absence of any acquired resistance genes and/or mutations increasing the MIC of the antimicrobial agent
If a strain is ___ for AST, it is inhibited at blood concentrations achieved by standard dosage of the drug.
Clinical efficacy is possible if the strain infects body sites where the drug concentrates or if the dosage can be increased compared to standard dosage.
Resistant for AST
The strain is NOT inhibited at blood concentrations achieved by standard dosage of the drug.
What are the two drugs used for detection of MRSA/MRSP?