Act 10-11 Flashcards
(25 cards)
What are antimicrobial drugs/agents?
Compounds that kill microorganisms or inhibit the growth of microorganisms.
Define antibiotics.
Natural antimicrobial agents produced by microorganisms.
What are semi-synthetics?
Chemically altered antibiotics.
Define synthetics in the context of antimicrobial agents.
Chemically synthesized in the lab.
Give an example of a synthetic antimicrobial agent.
Sulfa drugs.
Name a microorganism that produces Bacitracin.
Bacillus subtilis.
Which microorganism is associated with the antibiotic Polymyxin?
Paenibacillus polymyxa.
Which Actinomycetes produce Streptomycin?
Streptomyces griseus.
What is the Kirby-Bauer method?
A standardized method used to measure the effectiveness of antimicrobial agents on pathogenic microorganisms.
What type of agar is used in the Kirby-Bauer method?
Mueller-Hinton agar.
What is the pH range for Mueller-Hinton agar?
Between 7.2 and 7.4.
What is the inoculum used in the Kirby-Bauer method?
Broth culture diluted to match a 0.5 McFarland turbidity standard.
What does the 0.5 McFarland standard represent?
Roughly equivalent to 1.5 x 10^8 cells per mL.
True or False: Results from the disk-diffusion method are always adequate for clinical purposes.
False.
What is the purpose of the E test?
To estimate the minimal inhibitory concentration (MIC) of an antibiotic.
What does the zone of inhibition indicate?
The zone around the disk where no growth occurs.
What does it mean if an antimicrobial agent is labeled as ‘Susceptible/Sensitive’?
It may be an appropriate choice for treating the infection caused by the bacterial isolate tested.
What does ‘Intermediate’ indicate in antimicrobial susceptibility testing?
Potential utility of the antimicrobial agent in concentrated body sites or high drug concentrations.
What does ‘Resistant’ mean in the context of antimicrobial susceptibility testing?
The antimicrobial agent may not be effective against the bacterial isolate.
List one mechanism of antibiotic resistance.
- Blocking entry
- Enzymatic destruction/inactivation of drug
- Alteration of the drug’s target site
- Rapid efflux of antibiotics.
How do Gram (-) bacteria exhibit resistance through blocking entry?
Their cell wall restricts absorption of many molecules through openings called porins.
What is the role of beta-lactamase in antibiotic resistance?
It hydrolyzes the beta-lactam ring structure of penicillin.
How does MRSA alter its drug target site?
By modifying the penicillin-binding protein (PBP) on the cell membrane.
What is the significance of inspecting culture after 18-24 hours of incubation?
To ensure sufficient bacterial growth for observation.
