Antimicrobials Flashcards
Bactrim is a combination of what two drugs?
Sulfonamides and Trimethoprim
Fluoroquinolones mechanism of action?
it inhibits the DNA synthesis, messes with the bacterial DNA
What are the 2 big problems for Macrolides?
narrow spectrum, poor GI intolerance
Televancin has the same coverage as what?
Vancomycin- it is a copy cat
The amount of time that the area of the curve (AUC) of the antibiotic remains above the MIC. Used in pharmacodynamic models to express if an antimicrobial would be effective against a certain pathogen.
AUC/MIC ratio
What type of therapy is designed to be initiated as soon as an infection is presumed, usually upon presentation with symptoms of an infection and physical evidence of an infection?
Empiric therapy- this is used the most and you will have to be correct in the beginning otherwise outcome are bad
Inhibitors of folate synthesis are what?
metabolic inhibitors
What is the drug of choice for tick infections?
Doxycycline
The highest concentration of a drug is the peak, the lowest concentration of a drug is trough. What are these important in?
the dosing cycle
What is the drug of choice for Group A Streptococcus?
Penicillin
The lowest concentration of agent required to sterilize the medium or to kill 99.9% of the bacterial count after in-vitro placement
MBC- minimum bactericidal concentration
The mechanism of action for tetracyclines is to inhibit bacterial _______ by reversibly bind to __________.
protein synthesis, reversibly binding to the 30s ribosomal subunit
- the 30s ribosomal subunit has the mechanism of action for inhibiting protein synthesis
- bacteriostatic
What should you ask your patient when considering Metronidazole?
alcohol use
The inhibition or destruction of the infecting organism without damage to the host cells (kill the bad, save the good)
selective toxicity
What is special about ceftazidime?
it is the only drug in the 3rd generation cephalosporin that covers pseudomonas
What does Metronidazole cover?
anaerobes- bacteroides and C. difficile
What is the only beta-lactamase antibiotic that covers MRSA?
Ceftaroline
Adverse drug reaction for aminoglycosides?
Nephrotoxicity- acute tubular necrosis
What has an antipseudomonal beta-lactam and a beta-lactamase inhibitor added to it? Only reason to use it?
Piperacillin/Tazobactam
the antipseudomonal beta-lactam is in the piperacillin
Use because we suspect pseudomonas
broadest Penicillin
What is important to know about the mechanism of action for Vancomycin?
it destroys the cell wall
- inhibits bacterial cell wall synthesis at a different site than Beta-Lactams
- inhibits synthesis and assembly of second stage of peptidoglycan polymers
- binds to D-alanine-D-alanine portion of cell wall precursors
- bactericidal (except for Enterococcus)
Mechanism of action for Macrolides?
inhibits protein synthesis, 50s ribosomal subunit
What is limited to very severe infections and is resistant to a lot of things? The binding to the 30s is 5x higher than in tetracyclines and is therefore more ____.
Tigercycline, potent
What is the dosing of Vancomycin based on?
primarily renal excretion, must know the patient’s kidney function
The persistent effect of an antimicrobial agent on microbial growth following brief exposure of the microorganisms to the antimicrobial agent
PAE- postantibiotic effect
Beta-lactams and glycopeptides are what?
cell wall synthesis inhibitors
What increased the spectrum of Penicillin a little bit and added coverage for enterococcus?
Aminopenicillins
You can use _____ for MSSA but you must use Vancomycin for _____.
beta-lactam for MSSA, must use Vancomycin for MRSA
Dalbavancin is similar to Oritavancin (copy cats of Vancomycin). What is different about Dalbavancin?
1500mg one time or 1000mg dose followed by 500mg dose 1 week later
Certain bacteria make and secrete Beta-lactamases, what are they?
gram negatives and staphlococci
Main use for 4th generation cephalosporin?
gram-negatives, especially pseudomonas
What generation has the best activity against gram-positive aerobes?
first generation cephalosporins
If a pt comes in for surgery without an active infection and you want to prevent an infection by giving Abx, what type of therapy is it?
prophylactic
Drugs which irreversibly destroy the ability of a microorganism to replicate, these drugs kill the bacteria without outside assistance from immune system
Bactericidal
Linezolid is a weak ________ oxidase inhibitor. You can’t give this with _________.
monoamine
antidepressants- because it can increase the risk of serotonin syndrome
If a patient has a fever, serious painful abdominal cramping, very nasty smelling diarrhea, especially after taking Clindamycin, consider what disease?
C. difficile
What is not covered by Carbapenems?
MRSA
Ertapenem (one of the Carbapenems) does not cover Pseudomonas
Vancomycin only covers _____ and the main reason to use this drug is _____.
gram-positives, main reason to use this drug is S. aureus
While Vancomycin is given BID or TID, this drug is only given QD. This is what separates this drug from Vancomycin and perhaps the reason for being created.
Televancin
What is the go-to drug for gram-negative aerobes and is definitely used for Enterococcus for synergy?
Aminoglycosides
Extent of bacterial killing depends on the time the active drug concentration remains above the MIC.
concentration-independent (time-dependent) killing
The rate and extent of bactericidal action increase with increasing drug concentration. Better killing as the concentration increases.
concentration-dependent killing
What is special about Oritavancin? (a copy cat of Vancomycin)
a one time 1200mg dose that has an elimination 1/2 life of 245 hours
Drugs which reversibly impair replicating ability of microorganisms, need the innate immune system to eradicate microorganisms
Bacteriostatic
Beta-lactams bind to the _______ which is responsible for the assembly, maintenance and regulation of peptidoglycan metabolism. This leads to _____ of cell due to osmotic instability or autolysis.
PBP, death
What works on the cell wall, is really old, and isn’t used much?
Colistin
You can’t use Daptomycin for what disease?
PNA- this drug is inactivated by the surfactant in the lungs (exam question)
What should you avoid in children because it will cause discoloration of teeth? Unless of course it is a life threatening situation.
Tetracycline
-kid has tick bite and they might die if you don’t give them this drug, give it to them
What do folate synthesis inhibitors do?
inhibit folate synthesis, mess with folic acid
There are five general mechanisms which antimicrobials exhibit to exert their action on bacteria. What are they?
- inhibition of cell wall synthesis
- direct damage to the outer membrane of the bacteria
- modification of nucleic acid/DNA synthesis
- modify protein synthesis (at the ribosome)
- modification of the energy metabolism within the cytoplasm (at the folate cycle)
What is the oral option for MRSA?
Sulfamethoxazole/Trimethoprim
What are the most broad spectrum antibiotics that we have right now?
Carbapenems- only IV form
Penicillins, Cephalosporins, Carbapenems, and Monobactams are all _______ which are _________ that all have the same _________.
Beta-lactams, cell wall synthesis inhibitors, mechanism of action
What are enzymes released by the bacteria that go out and inactivate the beta-lactam Abx?
beta-lactamases
What is Red-Man Syndrome?
if you run the infusion of Vancomycin too fast the pt and suddenly turn red, this is resolved when the infusion is stopped
You must use IV form of Vancomycin for _______ and the capsule form for _____.
- IV form- systemic infections
- Capsule- C. difficile
- this drug is so large it cannot cross the GI tract
If a pt comes into the ER with PNA and you start them on 2 ABx for community acquired PNA, but you don’t know what bacteria is causing it, what type of therapy is it?
empiric (EXAM)
Spectrum for Macrolides
good for atypical bacteria, does not cover viruses
Tetracyclines, macrolides/ketolides, aminoglycosides, chloramphenicol, quinupristin/dalfopristin, clindamycin, linezolid, and glycylcycline are what?
protein synthesis inhibitors
What are 3 things to know about Aztreonam?
only covers gram-negative, it covers Pseudomonas, you can safely use this in patients that have an allergy to penicillin
You can’t use this in patients who have poor renal function.
SMX/TMP
What is it called when you go from a broad spectrum Abx to a narrow spectrum Abx once you know what is causing the infection?
deescalation
When you know what bacteria is causing a disease and you treat accordingly, what type of therapy is it?
definitive/targeted antimicrobial therapy
What is the main use for Penicillin?
Streptococcus, most other things are resistant
Penicillin is considered narrow even though it is braod
What generation has good anaerobic coverage with Cefoxitin (the only one below the diaphragm)?
second generation cephalosporins
-others are above the diaphragm and have good aerobe coverage (mainly respiratory)
What kills the bacteria outright?
a. Bactericidal
b. Bacteriostatic
a. bactericidal
Bacteriostatic prevents the replication of the bacteria, once the bacteria lives out it cycle, it will die
What is FQ good for?
gram positive, great for community acquired PNA (S. pneumoniae)
What are the Tetracyclines?
doxycycline, minocycline (used for acne treatment), and tetracycline
Any antibiotic can cause diarrhea, but Clindamycin is one of the main things you worry about for what disease?
C. difficile
Skin disorders caused by SMX/TMP
rash, urticaria, epidermal necrolysis, Steven’s-Johnson
What does Levofloxacin?
pseudomonas and strep pneumo
Don’t drink milk or take tums with this medication because it won’t get absorbed.
Tetracycline
What are we going to use Linezolid for?
we suspect MRSA
Mechanism of action for aminoglycosides.
bactericidal and concentration dependent- once daily, big dose which decreases the nephrotoxicity
The lowest concentration of an antimicrobial agent required to prevent visible growth of a microorganism after incubation in artifical liquid media
MIC- minimum inhibitory concentration
What is very good for gram-positives, can be used for MRSA, covers S. aureus, and covers anaerobes? (very important to know this)
Clindamycin
What is the adverse drug reaction of Macrolides that is important to know?
QTc prolongation
-for azithromycin it increases the risk for sudden cardiac death (black box warning)
seems very important to know
What are the protein synthesis inhibitors?
tetracyclines, glycylcycline, macrolides/ketolides, aminoglycosides, chloramhenicol, quinupristin/dalfopristin, clindamycin, linezolid
This class of drugs is only used for gram-negatives, only IV form, only in the hospital and is used for severe infections.
Aminoglycosides
Tetracyclines cover what type of aerobes? Especially _______. And it covers _______ bacteria because it does not work on the cell wall.
gram-positives are covered, especially S. aureus (MSSA, MRSA), covers atypical bacteria
Fluoroquinolones are what?
nucleic acid synthesis inhibitors
What is rare with monotherapy and more common when administered with other nephrotoxic agents?
nephrotoxicity/ototoxicity for Vancomycin
