Antibacterial Agents I Flashcards
To choose a good antibiotic, pick the most ________ and least _________.
most effective and specific; toxic
List some of the broad categories of antibacterial drugs.
Anti-cell wall synthesis, bacterial protein inhibitors, folic acid metabolism inhibitors, and bacterial transcription inhibitors
What enzymes are sufficiently different in bacteria to allow for targeting?
DNA gyrase (whereas eukaryotes have topoisomerase), and the 30S and 50S subunits of bacterial rRNA
What are the methods by which bacteria become resistant to drugs?
Expressing efflux pumps (to decrease the intracellular concentration), developing enzymatic degradation (such as beta-lactamase), bypassing the targeted pathway, decreasing entry, or altering the targeted receptor
Bacteriostatic agents ___________, while bactericidal agents ____________.
stop bacterial growth; kill bacteria
Bactericidal drugs are required in ___________.
infections of immune-privileged sites (such as the CNS), immunocompromised patients,
The advantages of oral antibiotics are ___________; the disadvantages are _________.
cost, convenience, and patient acceptance; GI upset, lack of absorption, and not possible in NPO patients
The advantages of IV antibiotic administration are that _________; the disadvantages are ___________.
it is required for some drugs and the bioavailability is more predictable; that it requirement for strict aseptic conditions, it is expensive, and greater provider training is needed
What anatomical site does clindamycin preferentially target?
Bones, so it is good for treatment of osteomyelitis
___________ is a good antibiotic for urinary tract infections, because it gets rapidly excreted in the urine.
Nitrofurantoin
Tetracycline lodges in the _________, where it _______.
gingiva and sebum; is good at targeting oral infections and acne, but has the downside of binding to Ca2++ and discoloring teeth
Again, the important formula for drugs that are renally excreted it __________.
(maintenance dose / dosing intervals) = (steady state serum concentration x clearance)
MD/tau = Cpss x Cl
For hepatically metabolized antibiotics, ______________.
there is no lab indicator of metabolism, so avoid drugs that are hepatically metabolized in patients with liver dysfunction
Bacteroides fragilis is a __________.
Gram-negative rod
Fluoroquinolones target _________.
DNA gyrase
Metronidazole targets ___________.
DNA synthesis, as does nitrofurantoin
Bacteria must _________ folate, while eukaryotes can ___________.
intracellularly synthesize; take it in from the environment
Many antibiotics cannot cross the outer membrane of ____________.
Pseudomonas aeruginosa
Explain the differences between conjugation, transduction, and transformation.
Conjugation is bacterial exchange of plasmids; transduction is bacteriophage-mediated DNA transfer; and transformation is uptake of free DNA from the environment
Give an example of alternative resistant metabolic pathway.
Bacteria overproduce thymine and become resistant
What three drugs/classes of drugs are susceptible to bacteria developing resistance by efflux pumps?
Tetracyclines, fluoroquinolones, and macrolides
The bacteriostatic drugs usually target ________.
metabolic pathways or protein synthesis
The batericidal drugs ____________.
target cell walls, cell membranes, or DNA
Antibiotics that are supposed to be taken on an empty stomach are _________.
susceptible to the acid that is present when we eat food
The antibiotics that readily enter the CSF are __________.
(cephalopods readily try chlorinated soup) cephalosporins (3rd/4th), rifampin, trimethoprim, chloramphenicol, and sulfonamides
The antibiotics that enter the CSF with inflammation are ______________.
Penicillins, vancomycin, ciprofloxacin, and tetracycline
Aminoglycosides are the most toxic to the _________.
inner ears and renal cells
Antibiotics that have a post-antibiotic effect are ____________.
aminoglycosides and fluoroquinolones
Narrow spectrum antibiotics target _________.
either Gram negative or Gram positive
Extended spectrum antibiotics target ___________.
Gram negative and Gram positive
Broad spectrum antibiotics target ___________.
Gram negative, Gram positive, and atypical bacteria
Trimethoprim and sulfonamides are _________.
folic acid synthesis inhibitors
_________ and _________ are evaded by bacteria that develop changes in the 50S ribosome subunit.
Erythromycin and clindamycin
_______ attacks the peptidoglycan side chain.
Vancomycin
DNA gyrase resistance occurs in ___________.
S. aureus and P. aeruginosa (to fluoroquinolone)
Strep pneumoniae becomes resistant to beta-lactams by __________.
modification of drug target
Macrolides get concentrated in the _________.
pulmonary cells
The hepatically metabolized drugs are __________.
DQ CRIMES (doxycycline, quinolones, clindamycin, rifampin, isoniazid, metronidazole, erythromycin-like (i.e., macrolides), and sulfonamides
__________ is a CYP inducer.
Rifampin
These three drugs work best when they are above their MIC for a long time: ________.
macrolides, beta-lactams, and vancomycin
Fluoroquinolones include ________.
levofloxacin
_______ is an aminoglycoside.
Tobramycin
When would you recommend a combination therapy?
For mixed infections (commonly intraabdominal), to prevent the emergence of drug resistant strains (AIDS patients with TB), and to obtain a synergistic effect
