Antibiotics: Principles of Antimicrobial Pharmacology Flashcards
Chemotherapy
Use of drugs to kill or suppress growth of invasive microbial or host neoplastic cells
Antibiotic
Substance produced by microbes that has ability to harm or inhibit growth of other microbes
Selective toxicity
Ability of drug to injure target cells without injury to host
Minimum inhibitory concentration (MIC)
Lowest conc. needed to prevent visible bacteria growth
Minimum bacterial concentration (MBC)
Lowest conc. needed to reduce number of viable bacteria
Selective toxicity is achieved by exploiting ____ between pathogen and host cells
Differences
Antibiotics are ligands that bind reversibly/irreversibly to molecular targets of bacterial cells
Reversibly
Bacteriostatic
Suppresses cell proliferation but doesn’t cause cell death
Bactericidal
Causes cell death
Bactericidal drugs are preferred for which infections?
Endocarditis
Meningitis
Osteomyelitis
Post-antibiotic effect
Delay in bacterial growth after removal of antibiotic
3 categories of activity of antibiotics
Time-dependent
Peak concentration-dependent
AUC- dependent
Time-dependent antibiotics require continuous drug exposure or high drug concentrations?
Continuous drug exposure
Peak concentration-dependent antibiotics need more/less frequent dosing schedules
Less frequent
____ is the determining factor of infection clearance for AUC-dependent antibiotics
Total cumulative dose over time
Innate antibiotic resistance
Antibiotic was never active against a certain bacteria
Acquired antibiotic resistance
Loss of formerly active antibiotic by vertical or horizontal (plasmid-mediated) transfer
Ways bacteria can acquire resistance to an antibiotic
Inactivation
Decreased uptake or increased efflux
Reduced binding affinity
Bypass/overcome blockade of target metabolic pathway
Consequences of antibiotic resistance.
Failure to clear infection
Increased risk of secondary infections (kills normal protective flora)
If 2 antibiotics are effective for treatment, choose the newer/older one to avoid resistance developing
Older
Most antibiotics are ___ so they have poor ____ bioavailability
Hydrophilic, oral
Tissues that are hard to penetrate by antibiotics and may require direct administration
Bone
Eye
Pulmonary epithelium
Abscessed tissue
Biofilms
Route preferred for rapid onset, critically ill patients
IV
Lab test that can help determine optimal antibiotic duration of treatment
Procalcitonin
Drug levels in ___ correlate with antibiotic efficacy in injected tissues
Blood
Hydrophilic drugs can cross the BBB more easily if the CNS is ___
Inflamed
Obese patients may require dosing based on ___ weight due to poor distribution of hydrophilic drugs in adipose tissue
Ideal
Antibiotic classes that decrease kidney functions
Aminoglycosides
Beta lactams
Sulfonamides
Glyco/lipo peptides
Antibiotics classes that decrease liver function
Lincosamides
Macrolides
Tetracyclines
Nitroimidazoles
You need to ___ the dose of some antibiotics in patients with kidney or liver disease
Reduce (or choose a different antibiotic)
Indications for combination therapy
Mixed organisms
Unknown etiology/organism
Drug synergy
Prevention of resistance in TB and H pylori infections
When to give prophylactic antibiotics
Major surgeries
Bacterial endocarditis
Opportunistic infections in immunocompromised pts
Exposure to STI
Antibiotics contraindicated in pregnancy and lactation
- Aminoglycosides – ototoxicity and nephrotoxicity
- Tetracyclines – bone growth suppression, tooth staining
- Sulfonamides – kernicterus in nursing infants
- Folate antagonists – maternal folic acid deficiency causing
developmental (neural tube) defects - Fluoroquinolones – toxic to developing cartilage
Gram positive bacteria have a thin/thick cell wall
Thick
Gram negative bacteria have a thin/thick cell wall
Thin
Gram + or - bacteria are easier to treat
Gram + (diffuse easily across thick cell wall to get to targets on plasma membranes)
Hydrophilic/lipophilic drugs cross plasma membrane easier
Lipophilic
Small hydrophilic drugs can cross outer membrane of gram negative bacteria through ___ transport through ____
Passive; porins
Bacterial that are neither gram neg or pos. (Atypical bacteria)
Chlamydia
Mycoplasma
Rickettsia
Legionella
