Flashcards in Antibiotics Deck (83)
If vancomyin is given IV (rapidly), what is the common adverse event syndrome?
"Red man syndrome" with flushing, tachycardia, and hypotension; probably vasodilatory effects
Which class is better for a single, susceptible organism, penicillins or cephalosporins? For a multi-species infection?
In a patient allergic to penicillins, what cephalosporins should be avoided?
1st generation only - remember the PBP 2b vs 2x binding sites
What drugs bind PBP 2b? 2x?
2b: penicillins and 1st gen cephalosporins;
2x: newer cephalosporins, carbapenems, and monobactams
How do first and second generation fluoroquinolones differ?
2nd (levofloxacin) adds anti-bacterial TopoIV activity so has strep pneumo action, unlike 1st gen (cipro) which is gram(-) only
Active TB requires what type of drug regimen? Why? Myco tuberculosis as seen by +PPD only requires what regimen in contrast?
4 drug combination therapy to eliminate resitant clonal remnants; +PPD requires isoniazid only due to lower titers and activity
What should doxycycline NOT be given with?
A metal - di and trivalent cations chelate the drug
What general adverse effect limits use of antimicrobials against targets unique to bacteria?
Allergies (eg against the lactams)
What are the two major resistance mechanisms against vancomycin?
altered cell wall (lactone instead of terminal alanine) and thickened peptidoglycan
Which antimicrobials inhibit the 30S subunit?
aminoglycosides and tetracyclines
What is clindamycin's spectrum of efficacy?
anaerobes (except C dif), and lactam-resistant pneumococci and MRSA
What are the two major resistance mechanisms against lactams?
B-lactamase and altered PBP's
What is the MOA of doxycycline? What organisms are its primary targets?
Block tRNA anticodon-codon binding; intracellular pathogens and lactam-resistant Strep pneumo and MRSA
Clindamycin's lack of efficacy against what organism leads to its major adverse effect?
C dif, causing C dif colitis post-treatment
What lactam antibiotic class has the broadest spectrum?
carbapenem - MRSA is the major resistant species
What drug class is best for gram+ pneumonia with diplococci?
Ceftriaxone (from cephalosporin gen2+) covers the 30% chance of PBP 2b mutated strep pneumo
What antimicrobial targets can be attacked with high doses of drug?
cell walls and their synthesis machinery
What old antibiotic (still used in poorer countries) does Linezolid most resemble? What adverse effect do they share?
What cell membrane toxin antibiotic is nephrotoxic?
What antibiotic is used in infected CF patients? Why?
Colistin; pseudomonas (gram neg) is highly resistant
What are the bacterial cell membrane toxins?
Cyclic lipopeptides and polymixins
What is the probable mechanism of centrilobar hepatitis in TB treatment?
CYP induction by rifampin to degreade isoniazid into a toxic metabolite
What are the major mechanisms of bacterial resistance?
decreased cell permeability to drug, alteration of target site, drug efflux pumps, and enzyme inactivation of drug
What bacterial protein involved in packing DNA is a prime antimicrobial target?
What other antibiotic shares spectrum similarities with macrolides?
Doxycyclines: both are good for intracellular and lactam-resistant gram(+); azithromycin (macrolide) adds H flu to the spectrum
Infection with what virus causes 100% maculopapular eruption in penicillin use?
What is empirical vs definitive antimicrobial selection?
empirical = base on clinical suspicion
definitive = based on culture/labs
What bacteria has ESBL and carbapenemase producing strains? What species does it readily exchange plasmids with?
Enterobacter cloacae; E coli and klebsiella
Which is more important, eradicating TB or allowing a patient to limit care due to horrid side effect profiles?
Eradicating TB (systemic TB is bad and contagious/public health needs)