Antibiotics Flashcards by Viet Nguyen

penicillin mechanism

1) bind PBP (transpeptidase)
2) block transpeptidase cross-linking peptidoglycan
3) active autolytic enzymes

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penicllin spectrum

gram positive (s. pneumo. s. pyogenes, actinoymyces), n. meningitidis, T. pallidum.

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penicillin toxicity:

hypersensitivity + hemolytic anemia

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ampicillin / amoxicillin spectrum of use

extended-spectrum penicillin: H. influenzae, E. coli, Listeria mono, Proteus mirabilis, Salmonella, Shigella (HELPSS)

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ampi/amoxicillin toxicity

hypersensitivity, rash, pseudomembranous colitis

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penicillinase-resistant penicillins = oxacillin, nafcillin

bulky R group blocks access of beta-lactamase to b-lactam ring.

used for s. aureus

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nafcillin toxicity

interstitial nephritis

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ticarcillin / piperacillin = antipseudomonals

use WITH b-lactamase inhibitors.

be careful of hypersensitivity

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cephalosporins general mechanism

inhibit cell wall synthesis –> bactericidal

less susceptible to penicillinase.

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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)

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cephalo sfx

1) vit. K deficiency.

2) INCREASED nephrotoxicity of aminoglycosides

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aztreonam mechanism

prevents peptidoglycan cross-linking by binding to PBP 3. synergistic w/ aminoglycosides

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aztreonam spectrum

gram-neg rods: NOT useful for gram+ or anaerobes. useful for those who have penicillin allergies / renal insufficiency w/o aminoglycoside tolerance

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carbapenems mechanism

broad-spectrum. administer w/ cilastin (inhibi renal dehydropeptidase I) to dec. drug inactivation in renal tubules

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carbapenem spectrum

gram-+ cocci, gram- rods, anaerbos. wide spectrum. reserved for life-threatening infections / last resort.

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special carbapenems

meropnem has dec. risk of seizures –> stable against dehydropeptiase I

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carbapenem toxicity

seizures / rash

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vancomycin mechanism

binds D-ala-D-ala part of cell wall precursor. bactericidal that inhibits cell wall peptidoglycan

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vanco clinical use

gram+ (MRSA, c. difficile)

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vanco toxicity

NOT: nephrotoxicity, Ototoxicity, Thrombophelbitis.

diffuse flushing = red man syndrome (infuse slowly & w/ antihistamines)

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aminoglycosides mechanism

inhibition formation of initiation complex –> misreading of mRNA. block translocation.

requires O2 for UPTAKE –> ineffective against ANAEROBES

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clinical use of aminoglycosides

gram-negative rod infections. synergistic w/ b-lactam. neomycin for bowel surgery

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aminoglycosides toxicity

1) nephrotoxicity (when combined w/ cephalosporin)
2) neuromuscular blockade
3) ototoxicity
4) teratogen

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tetracycline mechanism

bacteriostatic: bind to 30S –> prevent aminoacyl-tRNA attachment.

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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)