Anti-microbial General Principles Flashcards
Which type typically attack the cell wall- bacteriocidal or bacteriostatic?
Bacteriocidal attack the cell wall to kill the organism
Bacteriostatic stop growth, work on proteins and ribosomal subunits
What is the minimum inhibitory concentration (MIC)?
Lowest concentration of ABX required to prevent growth
Can you compare the potency different ABX based on their MIC for a given organism?
No
What is minimum bactericidal concentration (MBC)?
Lowest concentration required to kill bacteria
MIC or MBC: Reported on the culture and sensitivity report?
MIC
What is concentration-dependent killing?
Want to get a high peak concentration and then allow concentration to drift down over time. Examples aminoglycosides and fluoroquinolones
What is time-dependent killing?
Want the MIC to be longer period of time. Trough values are typically important for ABX the are time dependent killing.
Example is beta lactams, monobactams, macrolides
Is post-antibiotic effect demonstrated in all antimicrobials?
Yes; demonstrated in virtually all antimicrobials
What is Post-antibiotic effect (PAE)?
ABX continue to suppress the growth of bacteria even after the ABX is no longer detectable
PAE decreased or increased in acidic environments?
Decreased in acidic (infected) media
T/F: Post-antibiotic effect is especially present in concentration dependent ABX?
True
What four things contribute to antimicrobial resistance?
- Overuse for inappropriate indications
- Broad Spectrum
- Poor infection control
- Inappropriate dose or duration
T/F: All gram positive bacteria have intrinsic resistance to vancomycin?
False, all gram negative bacteria
Intrinsic or Acquired resistance definition: reflects a genetic alteration in the bacteria that renders a once effective antimicrobial ineffective?
Acquired
What are the four mechanisms through which acquired resistance is achieved?
- Decreased permeability (Stops the ABX from entering the organism)
- Increased efflux pumps (form pumps to “kick out” ABX)
- Inactivation (ex. beta lactamase)
- Modification of antimicrobial target
T/F
The more board the spectrum, the greater chance of resistance
True
T/F
Continuous infusion has been shown to be more effective than intermittent boluses
FALSE
has not been shown
Should 2 ABX with different MOA be used?
Yes to inhibit emergence of resistant strains of an organism. Creates synergistic effect
Ex. beta lactam and aminoglycoside (BL breaks down bacterial cell wall and allows easier entry for aminoglycoside)
Treatment of an established infection with an effective therapy of ABX agents is based upon what three things?
- Delivery of a concentration of drug to the site of infection
- Concentration sufficient to kill or inhibit growth of the offending organism
- Sufficient period of time to eradicate the infection
What 5 clinical situations is bactericidal therapy considered necessary for clinical cure?
- CV infection (particularly endocarditis or prosthetic valves)
- Meningitis and cerebral abscess.
- Severe neutropenia
- Osteomyelitis
- Tx of prosthesis or vascular access related infections w/o removing the device
Vascular access devices typically grow what type of bacteria?
Gram Positive
Lung infections typically grow what type of bacteria?
Gram Negative
What is an antibiogram?
A chart demonstrating the resistance patterns in your specific hospital/facility/region and compares bacterial strains and how susceptible they are to each ABX available
What are examples of impaired host defense?
- Anatomical (ulceration)
- Neutropenia
- Aspleenia
- Malignancy
- HIV
- Immunosuppresant therapy
How are the pharmacokinetics of pregnant patients changed?
Increased volume of distribution and increased GFR