Intro to Antibiotics Flashcards
What is a broad spectrum antibiotic?
It is active against gram positive AND gram negative bacteria and it increases resistance.
What is a narrow spectrum antibiotic?
It is active against gram positive OR gram negative.
What does bactericidal mean?
- Kills bacteria
- Reasonably achievable tissue concentration that is greater than the minimum bactericidal concentration (MBC.)
What does bacteriostatic mean?
- Stops growth or replication of bacteria
- Reasonably achievable tissue concentration that is greater than the minimal inhibitory concentration (MIC.)
What do you need for a bacteriostatic drug to work?
You need a competent immune system.
What does MIC stand for?
Minimal Inhibitory Concentration
What does MBC stand for?
Minimum Bactericidal Concentration
When are time-dependant antibiotics most effective?
When the level of drug remains above a certain cut-off for a significant portion of the day.
T > MIC is greater than _____% of the dose interval?
40 - 50%
When are concentration-dependant antibiotics most effective?
When a high leave of the drug is reached, often above an absolute cut-off. Does not need to be maintained for any specific amount of time.
What does PAE stand for?
Post - Antibiotic Effect
Concentration-dependant drugs have a ______ that causes continued organism suppression even after drug levels drop.
Post - Antibiotic Effect
Cmax / MIC > ______?
8-12
What is the “third - category” of dose - dependent drugs?
Some drugs have efficacy correlated with total body exposure to the drug (estimated by the AUC.)
AUC / MIC > 125
What does AUC stand for?
Area Under the Curve
What are the MOA of x-dependent drugs? (4)
- Inhibition of cell wall synthesis
- Disruption of cell membranes
- Inhibition of protein synthesis
- Inhibition of DNA synthesis / function
Generally, drugs that inhibit the cell wall are low toxicity drugs. What drug is an exception?
Bacitracin. It is extremely nephrotoxic so it is only used topically.
What are some B - lactam antibiotics?
Penicillins, Cephalosporins, Carbapenems and Monobactams, B - lactamase inhibitors.
T/F: Drugs that inhibit cell wall synthesis require actively dividing bacteria and can be antagonized by antibiotics that inhibit protein synthesis.
True
What is one category of drug that can be used to cause disruption of cell membranes?
Polymyxins
Drugs that cause disruption of cell membranes are toxic, do not depend on bacterial replication and are rapidly _____ drugs.
Bactericidal
T/F: Drugs that are used to inhibit protein synthesis all have the same level of toxicity.
False. Toxicity varies between drugs.
Drugs that inhibit protein synthesis depend on __________ and are mainly bacteriostatic.
Bacterial replication
What are some classes of drugs that inhibit protein synthesis as their MOA?
- Aminoglycosides
- Tetracyclines
- Amphenicols
- Macrolides/Lincosamides
What are some classes of drugs that inhibit protein synthesis as their MOA?
- Sulfonamides
- Fluoroquinolones
- Nitrofurans
- Nitromidazoles
- Rifampin
- Novobiocin
Drugs that are inhibitors of DNA synthesis and function can be ______ if they interfere with mammalian DNA.
Carcinogenic
What class of drug causes nephrotoxicity (renal tubular epithelial cells, collecting ducts, and more distal tubular structures)?
Aminoglycosides
What class of drug causes hepatotoxicity?
Tetracyclines sulfonamides
What classes of drugs cause a neuromuscular blockade?
Aminoglycosides, Polymyxins, and Tetracyclines
What class of drug causes ototoxicity?
Aminoglycosides
Which drugs cause GI upset?
Ampicillin and Clindamycin
Which drugs cause bone marrow toxicity?
Cloramphenicol and Sulfonamide
Which drug is known for it’s hypersensitivity reactions?
Penicillins
What does resistance mean?
Bacterium is not inhibited or killed by concentrations of an antibiotic that would normally do so at concentrations that can be reached in the patient.
** Only use when necessary **
What is extrinsic resistance? (3)
- Drug does not reach the target site.
- Drug is inactivated
- Target is changed
** These mechanisms can affect a single antibiotic or an entire class of drugs. **
What is intrinsic resistance?
Drug will never work against that class of bacteria because it does not possess the target structure (i.e. microbes with no cell wall resistant to penicillin) and does not exist in a favorable environment or antibiotic cannot get to site of action.
What are the two categories of acquired resistance?
- Chromosomal mutation
2. Transferable drug resistance
What is chromosomal mutation?
A form of acquired resistance that potentially occurs with increased sub-therapeutic exposure (non-transferable.)
What is transferable drug resistance?
A form of acquired resistance where the resistant DNA is acquired from another bacterium.
Transferable drug resistance has three different ways to acquire resistance. What are they?
Conjugation: passed from bacteria to bacteria
Transduction: passed from virus to bacteria
Transformation: plasmids are picked up by bacteria
What is Biofilm?
Accumulation of microorganisms in which cells that are frequently embedded within a self-produced matrix of “slime” adhere to each other and/or a surface.
Which bacteria maintains a biofilm?
Pseudomonas
What organisms cause MRSA and MRSP in humans and dogs?
Humans: Staphylococcus aureus
Dogs: Staphylococcus pseudointermedius
T/F: Staph pseudointermedius is a big risk to healthy humans.
False. It only affects humans that are immunocompromised.
What does decolonization mean?
Treating non-clinical carries of a bacteria with antibiotics.
What species can you treat and recover from a bacteria without using decolonization?
Dogs
