Antibiotics Flashcards
penicillin mechanism
1) bind PBP (transpeptidase)
2) block transpeptidase cross-linking peptidoglycan
3) active autolytic enzymes
penicllin spectrum
gram positive (s. pneumo. s. pyogenes, actinoymyces), n. meningitidis, T. pallidum.
penicillin toxicity:
hypersensitivity + hemolytic anemia
ampicillin / amoxicillin spectrum of use
extended-spectrum penicillin: H. influenzae, E. coli, Listeria mono, Proteus mirabilis, Salmonella, Shigella (HELPSS)
ampi/amoxicillin toxicity
hypersensitivity, rash, pseudomembranous colitis
penicillinase-resistant penicillins = oxacillin, nafcillin
bulky R group blocks access of beta-lactamase to b-lactam ring.
used for s. aureus
nafcillin toxicity
interstitial nephritis
ticarcillin / piperacillin = antipseudomonals
use WITH b-lactamase inhibitors.
be careful of hypersensitivity
cephalosporins general mechanism
inhibit cell wall synthesis –> bactericidal
less susceptible to penicillinase.
cephalo organisms by generation
1) PEK = proteus, Ecoli, Klebsiella
2) HEN PEKS = H. influ, Enterobacter, Neisseria, Protus, Ecoli, Klebsiella, Serratia
3) serious gram-negative infections (resistant to b-lactams):
Ceftriaxone = meningitis / gonorrhea Ceftazidime = pseudomonas
4) Cefepime = incr. activity against pseudomonas + gram-positive
5) ceftaroline = broad spectrum gram-pos & gram-neg –> MRSA! (no pseudomonas)
cephalo sfx
1) vit. K deficiency.
2) INCREASED nephrotoxicity of aminoglycosides
aztreonam mechanism
prevents peptidoglycan cross-linking by binding to PBP 3. synergistic w/ aminoglycosides
aztreonam spectrum
gram-neg rods: NOT useful for gram+ or anaerobes. useful for those who have penicillin allergies / renal insufficiency w/o aminoglycoside tolerance
carbapenems mechanism
broad-spectrum. administer w/ cilastin (inhibi renal dehydropeptidase I) to dec. drug inactivation in renal tubules
carbapenem spectrum
gram-+ cocci, gram- rods, anaerbos. wide spectrum. reserved for life-threatening infections / last resort.
special carbapenems
meropnem has dec. risk of seizures –> stable against dehydropeptiase I
carbapenem toxicity
seizures / rash
vancomycin mechanism
binds D-ala-D-ala part of cell wall precursor. bactericidal that inhibits cell wall peptidoglycan
vanco clinical use
gram+ (MRSA, c. difficile)
vanco toxicity
NOT: nephrotoxicity, Ototoxicity, Thrombophelbitis.
diffuse flushing = red man syndrome (infuse slowly & w/ antihistamines)
aminoglycosides mechanism
inhibition formation of initiation complex –> misreading of mRNA. block translocation.
requires O2 for UPTAKE –> ineffective against ANAEROBES
clinical use of aminoglycosides
gram-negative rod infections. synergistic w/ b-lactam. neomycin for bowel surgery
aminoglycosides toxicity
1) nephrotoxicity (when combined w/ cephalosporin)
2) neuromuscular blockade
3) ototoxicity
4) teratogen
tetracycline mechanism
bacteriostatic: bind to 30S –> prevent aminoacyl-tRNA attachment.
tetracycline contraindications
avoid milk, antacids, iron –> divalent cations –> inhibit gut absorption
tetracycline spectrum
intracellular –> effective against rickettsia / chlamydia. borrelia burgdorferi, m. pneumo
macrolides (azithromycin, clarithromycin, erythromycin) mechanism
inhibit protein synthesis by blocking translocation –> bacteriostatic
macrolide clinical use
atypical pneumos (mycoplasma, chlamydia, legionella), STDs (chlamydia), gram-pos cocci
macrolides toxicity
MACRO: Gi MOtility, Arrythmia due to prolonged QT, Cholestatic hepatitis, Rash, eOsinophilia
INCREASES [theophylline, anticoagulants]
chloramphenicol mechanism of action
bacteriostatic –> blocks peptidyltransferase at 50S
chloramphenicol spectrum
meningitis (h. influ, N. menigiti, Strep pneumo)
Rocky Mountain spotted fever (rickettsia rickettsii)
chloramphenicol toxicity
1) aplastic anemia
2) gray baby syndrome –> lack of UDP-glucuronyl transferase
clindamycin mechanism
blocks peptide translocation –> baceriostatic
clinamycin spectrum
anerobes ABOVE the diaphragm
1) anaerobes of aspiration pneumo: bacteriodes, c. perfringens
2) invasive group A strep
clindamycin toxicity
pseudomembranous colitis, fever, diarrhea
sulfonamide mechanism
inhibit folate synthesis –> bacteriostatic
sulfonamide spectrum of action
gram +, gram -, nocardia, chlamydia,
sulfonamide toxicity
1) nephrotoxicity –> tubuloninterstitial nephritis
2) kernicterus in infants
3) displace drugs from albumin –> warfarin
4) hemolysis if G6PD
5) photosensitivity
trimethoprim mechanism
bacteriostatic –> inhibit dihydrofolate reductase
trimethoprim spectrum
1) sulfonamides –> block folate synthesis
2) combo for UTIs, shigella, salmonella, P. jirovecii. toxoplasmosis prophylaxis
trimethoprim sfx
pancytopenia; TMP: Treats Marrow Poorly.
supplement w/ folinic acid
fluoroquinolones mechanism
bactericidal: inhibit DNA gyrase (topoisomerase II) / topoisomerase IV. avoid in antacids
fluoroquinolone spectrum
gram-neg rods of urinary / GI tracts (pseudomonas), neisseria, gram + organisms
fluoroquinolones toxicity
1) tendonitis / rupture
2) superinfections
3) contraindicated in pregnancy / children –> cartilage damage
4) prolonged QT interval
metronidazole mechanism
free radical toxic metabolites in cell –> damage DNA (bactericidal / antiprotozoal)
metronidazole spectrum
GET GAP (infxn below diaphragm)
1) Giardia
2) Entamoeba
3) Trcichomonas
4) Gardnerella vaginalis
5) Anaerobes (Bacteroides / c. diff)
metronidazole sfx
disulfiram rxn: flushing, tachycardia, hypotension w/ EtoH
m tb treatment
RIPE (rifamin, isoniazid, pyrazinamide, ethambutol)
m tb prophylaxis
isoniazid
m. avium-intracellular prophylaxis
azithromycin, rifabutin
m. avium-intracellular treatment
more drug resistant than tb –>
1) azithromycin / clarithromycin
2) ethambutol
3) rifabutin / cipro
m. leprae
dapsone / rifampin –> tb.
clofazimine for lepromatous form
isoniazid (INH)
dec. synthesis of mycolic acids –> need bacterial catalase-peroxidase to convert INH to active.
isoniazid toxicity
INH = Injures Neurons Hepatocytes
supplement pyridoxine. may induce lupus
rifamycin
1) RNA polymerase inhibitor
2) ramps up cytochrome P450
3) Red body fluids
4) rapid resistance when used alone
5) Rifampin ramps up cytochrome P560 but rifaBUTin does not
pyrazinamie
1) m. tb
2) sfx = hyperuricemia, hepatotoxicity
3) acidify inracellular environment –> active onl in acidic pH of phagolysosomes, where macrophage engulfed TB exists
ethambutol
dec. carbo polymerization of mycobacterium cell wall –> blockage of arabinosyltransferase
ethambutol sfx
optic neuropathy (red-green color blindness)
highly resistant bacteria treatment: MRSA
vanco, dapto, linezolid (caution: serotonin syndrome), tigecycline, ceftraroline
treatment of VRE
1) linezolid / streptogramins (quinupristin/dalfopristin)
