Antimicrobials Flashcards
penicillin G, penicillin V
narrow-spectrum B-lactams
simple penicillin
penicillin V is orally active - used to treat oropharyngeal infections
Mechanism for B-lactam cell wall inhibitors
looks like Dala-Dala, binds PBPs (transpepsidases), blocks peptidoglycan cross-linking
Adverse affects of B-lactam cell wall inhibitors
allergic reactions, including anaphylaxis, rashes, nephritis
adverse effects of carbapenems
increases risk of seizure
extended spectrum penicillins
amoxicillin
static
concentration that inhibits growth is much less than concentration that kills
cidal
concentration that inhibits growth is similar to concentration that kills
examples of tidal drug classes
B-lactams, ahminoglycosides, fluoroguinolones, metronidazole, vancomycin, streptogramins, daptomycin
examples of static drug classes
clindamycin, macrolides, tetracyclines, sulfonamides, trimethoprim
superinfection
disruption of flora by antimicrobial allows single microorganism to overgrow and cause pathology - highest risk is with broad-spectrum antibiotics
mechanism of B-lactams
inhibit bacterial cell wall synthesis
B-lactamases
catalyze hydrolysis of B-lactam ring of B-lactam antibiotics causing inactivation.
formation by pathogens creates resistance
B-lactamase inhibitors
clavulanic acid, sulbactam, tazobactam
used in combination with penicillins to prevent their inactivation
naficillin
very narrow spectrum lactamase resistant penicillin
piperacillin
anti-pseudomonal B-lactam
used w/ penicillinase inhibitors
cefazolin, cephalexin
1st generation cephalsporins
B-lactams
cephalexin is orally active
cefuroxime
B-lactam
2nd generation cephalosporin
orally active
extended gram (-) coverage
ceftriaxone
B-lactam
3rd generation cephalosporin
increased activity against gram (-) organisms resistant to other B-lactam drugs - used for serious infections
can penetrate the BBB
cefepime
B-lactam
4th generation cephalosporin
more active against pseudomonas
ceftaroline
B-lactam
5th generation cephalosporin
active against MRSA
meropenem
B-lactam
carbapenem
low susceptibility to B-lactamases
adverse effects: increased seizure risk
aztreonam
B-lactam
monobactam
active only against gram (-) bacteria
vancomycin: mechanism, adverse effects, uses, mode of resistance
non-B-lactam cell wall inhibitor
mechanism: binds Dala/Dala and blocks transglycosylation and elongation of the peptidoglycan chain
adverse effects: red man syndrome
uses: MRSA, C.Diff
resistance: via altered peptidoglycan - Dala-Dlac
chloramphenicol
macrolide
adverse effects: bone marrow depression, aplastic anemia
uses: severe salmonella, Tx of pneumococcal and miningococcal meningitis and B-lactam sensitive people, also topical abx
azithromycin
macrolide
adverse effects: GI upset, prolonged QT
clindamycin
macrolide
adverse effects: associated with C.diff
MRSA active
linezolid
protein synthesis inhibitor - oxazolidinone
mechanism: binds to a unique site located on the 23S ribosomal RNA of the 50S ribosomal subunit
adverse effects: bone marrow supression, serotonin syndrome in pts using SSRIs
uses: should be reserved for treatment of infections caused by multidrug-resistant gram-positive bacteria
gentamicin
protein synthesis inhibitor - aminoglycoside
mechanism: binds to 30S subunit irreversibly
adverse effects: nephro-oto-neuro toxicity
doxycycline
protein synthesis inhibitor - binds to 30S subunit reversibly
adverse effects: incorporated into teeth/bones, photosensitivity.
doxy and tigecycline MRSA active, doxy Tx for malaria
sulfamethoxazole
folate pathway inhibitor - antimetabolite of PABA that acts as competitive inhibitor or substrate for dihydropteroate synthase in folic acid synthesis.
adverse effects: hypersensitivity reactions.
active against MRSA
used with trimethoprim
sulfamethoxazole
folate pathway inhibitor - antimetabolite of PABA that acts as competitive inhibitor or substrate for dihydropteroate synthase in folic acid synthesis.
adverse effects: hypersensitivity reactions (including Stevens-Johnson syndrome, but rare).
active against MRSA
used with trimethoprim
ciprofloxacin
topo inhibitor - fluoroquinolone.
mechanism: interfere with bacterial DNA synthesis by inhibiting topoisomerase II (DNA gyrase)
adverse effects: tendonitis, tendon rupture, peripheral neuropathy, CNS effects, porolonged QT.
moxi, levo, gemi more active on S. pneumoniae than cipro.
daptomycin
membrane disruptor
mechanism: inserts itself into membranes and causes leakage of small ions/molecules.
adverse effects: myopathy
inactivated by pulmonary surfactants, MRSA active
metronidazole
mechanism: forms cytotoxic products that interfere with bacterial nucleic acid synthesis.
adverse effects: headache, peripheral neuropathy, alcohol sensitivity
uses: anaerobies, antiprotozoal, giardia
TB drugs
rifampin, isoniazid, pyrazinamide, ethambutol
