Unit 3: K43a.Intro To ABX Flashcards
What kind of cells comprise humans?
Eukaryotes
What kind of cells comprise bacteria?
Prokaryotes
Where can one find the genetic material in bacteria?
In the nucleoid, a tangle of genetic material
TRUE or FALSE: bacteria have a nucleus
False
Eukaryote or prokaryote: parasites
Eukaryote
Eukaryote or prokaryote: fungi
Eukaryote
Eukaryote or prokaryote: viruses
Prokaryote
Eukaryote or prokaryote: bacteria
Prokaryote
Why does it matter if a microbe is a eukaryote or prokaryote?
We need to know if the antimicrobial used can also damage human cells
After gram staining, what color are
- GRAM + cells?
- GRAM - cells?
- Purple
2. Pink
What is the peptidoglycan later, and what difference does it make in gram + vs gram - bacteria?
Peptidoglycan is a layer surrounding a bacterium. In gram +, it is THICK. In gram -, it is THIN. The peptidoglycan holds the color for the gram stain.
What is the difference between AEROBIC and ANAEROBIC bacteria?
Aerobic bacteria need oxygen.
Anaerobic bacteria do not need oxygen.
What are the names for anaerobic bacteria that
- can use oxygen
- will die if exposed to oxygen?
- Facultative anaerobes
2. Obligate anaerobes
Aerobic bacteria are further classified into what?
Glucose fermenters vs non glucose fermenters
What is a fastidious organism?
Only grows in particular things
Think: the friend you invite to dinner but will only eat certain foods in certain places
Explain MIC
Minimum Inhibitory Concentration: lowest concentration needed to inhibit growth of bacteria
Define MBC
Minimum Bactericidal Concentration: lowest concentration of an antibiotic that will kill bacteria
Bacteriostatic vs Bactericidal
Bacteriostatic: prevents bacterial growth
Bactericidal: kills bacteria by attacking the cell wall
Reason to give bacteriostatic antibiotics…
Does not kill. Just inhibits. Decreases bacterial load so person’s immune system can eliminate infection.
RISK: organism can regrow when medication stopped
Reasons to give bactericical antibiotics…
Attacks cell wall to kill bacteria. Given for serious situations:
—severe/dangerous infections: endocarditis, meningitis, osteomyelitis
—infection in an immunocompromised patient
Bactericidal meds can be _____ dependent or _____ dependent. Need to know this because…
Concentration
Time
Affects how they are dosed
What does the MIC mean for time-dependent dosing?
Therapeutic effect only happens when the concentration is above MIC. When the concentration drops below MIC, it is time for another dose.
Name some classic time-dependent Bactericidal antibiotics
Beta-Lactams
Tetracyclines
Linezolid
Name some classic concentration dependent antibiotics
vancomycin
Aminoglycosides
Gentamicin
Gentamicin toxicities:
Nephrotocicity
Ototoxicity
What does the MIC mean for concentration-dependent dosing?
Cmax/MIC (aminoglycosides)
OR
AUC/MIC (vancomycin)
**administering large doses on an intermittent basis will maximize effect
Define NARROW SPECTRUM
Treats a very specific or a few specific bacteria. Doesn’t kill other bacteria unnecessarily.
Define BROAD SPECTRUM
Works for a large variety of bacteria prior to identification of specific organism (e.g. sepsis protocol)
Define EXTENDED SPECTRUM
A child medication that is chemically modified from the narrow spectrum parent. New child med is effective against more bacteria than the parent med.
Major risk of broad spectrum antibiotics
Superinfection
Criteria for ABX selection
— C and S results (takes a few days)
— Host status (allergies, age, pregnancy, site of infection, etc)
— drug factors (pharmacokinetics, cost, toxicity, resistance)
Definitive antibiotic treatment
We know exactly what we’re treating
Empiric ABX treatment
Using an antibiotic that is effective for organism that typically causes that specific infection (e.g. nitrofurantoin for uncomplicated UTI)
Prophylactic ABX treatment
To prevent infection
i.e. valacyclovir daily to prevent HSV outbreak
Mechanisms of microbe resistance
— decreased bacterial cell permeability (unable to enter bacteria)
— enzymatic modifications (e.g. bacteria make enzymes that destroy antibiotic)
— alterations on target site
— active efflux: bacterial cell pumps antibiotic back out of cell
ESKAPE pathogens: explain why they’re a concern and name them
High resistance. Limited treatment options.
Enterococcus faecium Staphylococcus aureus Klebsiella pneumoniae Acinetobacter baumannii Pseudomonas aeruginosa Enterobacter species
1 duty in prescribing antibiotics
Prevent resistance
How to prescribe the prevent resistance
Limit antibiotic use
Avoid using antibiotics for colonization
Adding most narrow spectrum agent that you can
Use correct dose
Use correct duration of therapy (shortest possible)
MBC:MIC > 4
Bacteriostatic
MBC:MIC <= 4
Bactericidal
Bacteriostatic or Bactericidal?
Tetracyclines
Bacteriostatic
Bacteriostatic or Bactericidal?
Beta Lactams
Bacteriostatic
Bacteriostatic or Bactericidal?
Vancomycin
Bactericidal
Bacteriostatic or Bactericidal?
Sulfonamides
Bacteriostatic
