Exam 2 Antibiotic Flashcards
Define antimicrobial agent.
Chemical substance produced either by a microorganism or synthetically that can kill or suppress microorganisms.
Define bacteriostatic
Inhibits bacterial growth without killing.
What class of antibiotics inhibit DNA gyrase and topoisomerase
Quinolones; floaxin, ciprofloxacin, enoxacin
What antibiotic interacts with DNA causing loss of helical DNA structure?
Metronidazole
What antibiotic interacts with the RNA polymerase?
Rifampin
Define spectrum of activity in antibiotics.
It targets both gram negative and gram positive bacteria however it also targets normal flora.
Define MIC , minimum inhibitory concentration.
Maximum dilution of product that will inhibit growth of a test microorganism
MBC, minimal bactericidal concentration is defined as?
Greater than or equal to 99.9% reduction of visible colony forming units of a bacterial or fungal suspension suspension
Define breakpoint in ANTIMICROBIAL susceptibility test.
Concentration of antibiotic which defines in vitro whether a species or group of species is susceptible or resistant to an antibiotic/ANTIMICROBIAL.
What are the possible interpretation of antibiotic susceptibility testing and what do they mean?
S - Susceptible: A possible option for treatment for patient. Bacteria does not have any mechanism to overcome the antibiotic.
I - Intermediate: Bacteria is somewhat susceptible and may be an option for treatment if paired up with another kind of antibiotic.
R - Resistant: Bacteria is resistant to antibiotic and not a viable option for treatment
List different kinds of antibiotic classes that inhibit cell wall synthesis
- Beta lactams
- Fosfomycin
- Glycopeptides / lipoglycopeptides
- Monobactam
List different types of beta - lactams.
- Penicillins
- Cephalosporins
- Carbapenems
List different types of Glycopeptides / lipoglycopeptides
- Vancomycin
- Telco plan in
What is a type of monobactam?
Aztreonam
How does fosfomycin work against the bacteria cell wall?
It inhibits the enzyme at the first step of cell wall synthesis
What antibiotic targets the cell membrane?
Polymyxins
What antibiotics target folate synthesis?
Sulfonamides and trimethoprim
What antibiotic targets DNA gyrase?
Quinolones
What antibiotic targets RNA polymerase?
Rifampin
What antibiotics target the 50s subunit?
- Macrolides
- Clindamycin
- Linezolid
- Chloramphenicol
- Streptogramins
What antibiotic targets the 30S subunit?
Tetracyclines and aminoglycosides
List some criteria for an ideal antibiotic.
- Non - toxic; limited side effects
*Able to enter cell
*Specific target
*Sufficient concentration
*Spectrum - Soluble in body fluids; remain active
- Limited development of resistance
What determines the product produced from a beta lactam ring?
Depends on the addition to the beta lactam ring. The product can be penicillin, Cepheus, Carbapenems, or monobactam
Prefix ceph, or suffix cillin, penem denotes what?
A type of beta lactam
What structure is important in penicillin, cephalosporin, and Carbapenems?
The beta - lactam ring. It’s similar (enough) to Acyl-D-alanyl-D-alanine (important in cell wall synthesis) to be taken up by the bacteria.
Glycopeptides and lipoglycopeptides target what kind of bacteria?
Gram positive because they are so large so they cannot affect gram negative bacteria’s outer membrane
Glycopeptides / lipoglycopeptide interfere with cell wall synthesis how?
Forms a hydrogen bond to terminal D - alanyl - D - alanine moiety of NAM / NAG peptides preventing it from being incorporated into the cell wall by PBP.
What are examples of lipoglycopeptides?
Oritavancin, dalbavancin, and telavancin
Vancomycin inhibits cell wall synthesis by binding to…?
D - ala- D - ala terminal of the growing peptide during cell wall synthesis.
What antibiotic is used if the patient has a serious gram positive bacterial infection resistant to beta lactams (or allergic to beta lactam drugs)?
Vancomycin
List situations vancomycin should not to be used in
- Routine surgical prophylaxis
- Empiric therapy (unless evidence of Gram
-positive infection or prevalence of MRSA
is high) - Treatment of a single positive blood
culture - Continued use after susceptibility report
- Eradication of MRSA colonization
How do polymyxin interact with the bacteria’s cell membrane and what is a side effect?
Polymyxin antibiotics act as a detergent to the cell’s membrane shredding it. The down side is neurotoxicity and nephrotoxicity.
How do lipopeptide antibiotics interact with a bacteria’s cell membrane?
Binds to and disrupts gram-positive cell membrane by inserting hydrophobic tail into membrane increasing permeability.
What is colistin mainly used for? What is a side effect of taking colistin?
For multi - drug resistant GNR and its side effect is significant renal toxicity
Daptomycin is effective against what kind of gram positive bacteria?
Cocci especially resistant strains such as MRSA, and VRE, vancomycin resistant entercoccus sp.
Daptomycin is not effective in treating respiratory infection, why?
The lung surfactants bind to the drug inactivating it.
List classes of antibiotics that inhibit protein synthesis
- Aminoglycosides
- Macrolide-lincosamide-
streptogramin (MLS) - Ketolides
- Oxazolidinones
- Chloramphenicol
- Tetracyclines
- Glycylglycines
What are examples of macrolides antibiotic?
Erythromycin, azithromycin, and clarithromycin
When are macrolide antibiotics bacteriocidal? They’re usually bacteriostatic.
If infective dose of bacteria is low and drug concentration is high
What does the MLS antibiotic classes target to inhibit protein synthesis?
23S and 50S ribosomal RNA subunits. Inhibiting the subunits disrupts the translocation that happens to grow peptide chains
Aminoglycosides activity of spectrum is?
Broad spectrum however cannot be taken up by anaerobic bacteria intracellularly. Antibiotic inhibits protein synthesis through inhibition of 30S ribosome subunit.
What is a side effect of aminoglycosides?
Nephrotoxicity, auditory, and vestibular toxicity
Lincosamide target what part of the bacteria to inhibit protein synthesis?
50S ribosomal unit to prevent elongation of the polypetide.
What is a risk associated with lincosamide?
Increased risk of C. diff infection
What is the spectrum of activity for lincosamides?
Gram positive and some anaerobic gram negative bacterias.
What is an example of lincosamide?
Clindamycin
Streptogramin examples are?
Quinupristin and dalfopristin
Dalfopristin inhibits protein synthesis…?
By changing the confirmation of the 50S ribosomal subunit blocking protein synthesis and bacterial growth.
A good antibiotic to pair quinupristin with?
Dalfopristin
Examples of oxazolidinones are?
Linezolid and tedizloid
What do oxazolidnones target to prevent protein synthesis?
Binds to 23S ribosomal RNA of the 50S subunit preventing formation of the functional 70S initiation complex. This prevents bacterial translation and replication.
What kind of bacteria are oxazolidnones effective against?
Gram positive and mycobacteria
Chloramphenicol prevent protein synthesis by…?
Targeting the 50S subunit inhibiting transpeptidation.
Chloramphenicol is effective against
Gram negative and gram positive bacteria
What is a side effect of chloramphenicol antibiotics?
Can cause aplastic anemia
Tetracycline / Doxycycline inhibits protein synthesis how?
Binds to 30S subunit so incoming tRNAs with amino acids cannot bind to ribosome.
Tetracycline / Doxycycline side effects are?
Cutaneous phototoxcity - photoallergic immune reaction and toxicity in the upper GI
Glycylglycines inhibit protein synthesis by…?
REVERSIBLY binding to 30S ribosomal subunit
True or false, glycylglycines are effected by the same resistance mechanisms as tetracycline.
False
Glycylglycines have what kind of side effects
GI side effects
What are the three antibiotics that inhibit DNA & RNA synthesis?
Fluoroquinolones, metronidazole, and rifampin
Fluoroquinolones target and bind to what in the bacteria?
DNA gyrase and topoisomerase
What is a side effect of fluoroquinolones?
Affects tendons causing tendonitis and rupture
Metronidazole targets…?
The helical structure of DNA and disrupts it.
What is require to activate metronidazole?
A reduced environment (anaerobic)
What does rifampin target in the bacteria?
Binds to RNA polymerase
What is the downside of rifampin?
Bacteria can develop spontaneous mutations (insensitive RNAP) and is sometimes used with other drugs.
Sulfonamides works by?
Disrupting the bacterial folic acid pathway by inhibiting dihydropteroate synthase (different than trimethoprim).
What kind of bacteria does sulfonamide are vulnerable to?
Gram positive and negative except P. aeruginosa
Trimethoprim kill bacteria by targeting …?
Dihydrofolate reductase of the folic acid pathway. (Sulfonamides target dihydropteroate synthase).
Sulfonamide side effects are
vomiting, nausea, and hypersensitivity reactions. They are antagonist to warfarin, phenytoin, and oral hypoglycemic agents.
Nitrofurantoin kill bacteria how?
Flavoproteins (nitroreductases) reduce the nitrogen group that turns into reactive intermediates that damages ribosomes and other macromolecules such as DNA, RNA, and proteins.
Nitrofurantoin are good against what kind of bacteria?
Gram positive and gram negative except P. aeruginosa. Its used to treat uncomplicated UTIs
How does lipoglycopeptides work?
- Allows cell wall binding that inhibits cell synthesis.
- Increases permeability and polarize cell membrane potential
