Micro Flashcards
(51 cards)
Amphotericin B
MOA:
- Binds to ergosterol in fungal cell wall to form holes, changes in membrane permeability lead to cell death.
- Hypo K+ & Mg2+
Use:
- Mucormycosis
- Histoplasmosis
Tox:
- Renal toxicity
- Direct toxin on renal epithelial cells, causing ATN, electrolyte disturbances, RTA
- Hypo K+ causes weakness and arrhythmias
- T-wave flattening, ST seg depression, prominent U-wave, premature atrial and ventricular contractions
- Profound hypo K+ can cause v-tach/v-fib
Rifampin
MOA:
Use:
-Prophylaxis for meningococcal meningitis
Penicillin G, V
MOA:
- Bind penicillin-binding proteins (transpeptidases)
- Block transpeptidase cross-linking of peptidoglycan
- Activate autolytic enzymes
Use:
- G+ organisms (S.pneumoniae, S. pyogenes, Actinomyces)
- N. meningitidis and T. pallidum
- Bactericidal for G+ cocci, G+ rods, G- cocci, and spirochetes
- Penicillinase sensitive
Tox:
-Hypersensitivity rxns, hemolytic anemia
Resistance:
Penicillinase in bacteria ( a type of beta-lactamase) cleaves beta-lactam ring)
Ampicillin
Amoxicillin
(aminopenicillins, penicillinase-sensitive penicillins)
MOA:
- Bind penicillin-binding proteins (transpeptidases)
- Block transpeptidase cross-linking of peptidoglycan
- Wider spectrum than penicillin
- Can combine w/ clavulanic acid to protect against β-lactamase
Use:
- Extended-spectrum penicillin
- H. flu, E. coli, Listeria monocytogenes, Proteus mirabilis, Salmonella, Shigella, enterococci
- *HELPSS kill enterococci**
Tox:
-Hypersensitivity rxn; rash; pseudomembranous colitis
Resistance:
Penicillinase in bacteria ( a type of beta-lactamase) cleaves beta-lactam ring)
Oxacillin
Nafcillin
Dicloxacillin
(Penicillinase-resistant penicillins)
MOA:
- Bind penicillin-binding proteins (transpeptidases)
- Block transpeptidase cross-linking of peptidoglycan
- Narrow spectrum
- Penicillinase resistant b/c bulky R group blocks access of β-lactamase to β-lactam ring
Use:
-S. aureus (except MRSA; resistant b/c of altered penicillin-binding protein target site)
Tox:
-Hypersnsitivity rxns, interstitial nephritis
Ticarcillin
Piperacillin
(antipseudomonals)
MOA:
- Bind penicillin-binding proteins (transpeptidases)
- Block transpeptidase cross-linking of peptidoglycan
- Extended spectrum
Use:
- Pseudomonas spp. & G- rods
- Susceptible to penicillinase
- Use w/ β-lactamase inhibitors
Tox:
-Hypersensitivity rxns
Clavulanic Acid
Sulbactam
Tazobactam
(β-lactamase inhibitors)
- Often added to penicillin antibiotics to protect the antibiotic from destruction by β-lactamase (penicillinase)
- C.A.S.T.
Cephalosporins (generations I, II, III, IV, V)
M.O.A.:
- Bind penicillin-binding proteins (transpeptidases)
- Block transpeptidase cross-linking of peptidoglycan
- Extended spectrum
Use:
- 1st gen. - (cefazolin, cephalexin/Keflex) gram (+) cocci, Proteus mirabilis, E. coli, Klebsiella pneumoniae. Cefazolin used prior to sugery to prevent S. Aureus infxn.
- 2nd gen. -(cefoxitin, cefaclor, cefuroxime) gram(+) cocci, H. flu, Enterobacter aerogenes, Neisseria spp., Protes mirabilis, E. coli, Klebsiella pneumoni ae, Serratia marcescens
- 3rd gen: - (ceftriaxone, cefotaxime, ceftazidime) serious gram (-) infections resistant to β-lactams.
- 4th gen. - (cefepime) increased activity against Pseudomonas and gram-(+) organisms
- 5th gen. - (ceftaroline) broad gram-(+) coverage, including MRSA; does NOT cover Pseudomonas.
Tox: Hypersensitivity reactions, vit. K deficiency, low cross-reactivity with Penicillins. Increases nephrotoxicity of aminoglycosides.
Aztreonam
MOA: A monobactam, resistant to β-lactamases. Prevents peptidoglycan cross=-linking by binding penicillin-binding protein. synergistic with aminoglycosides. No cross- allergenicity with penicillins
Use: gram negative rods. NO activity against gram- (+) or anaerobes. For penicillin-allergic patients and those with renal insufficiency who cannot tolerate aminoglycosides
Toxicity: Usually nontoxic; occasional GI upset
Carbapenems (Imipenem, meropenem, ertapenem, doripenem)
MOA: broad spectrum, β-lactamase-resistant carbapenem. Always administered with cilastatin(inhibitor of renal dehydropeptidase I) to decrease inactivation of drug in renal tubules.
“the kill is lastin’ with cilastatin.”
Use: gram (+) cocci, gram (-) rods, and anaerobes, wide spectrum (very limited use to life-threatening infections or after other drugs have failed). Meropeneem has low risk of seizures and stable to dehydropeptidase I.
Toxicity: GI dsitress, skin rash, and CNS toxicity(seizures) at high plasma levels.
Vancomycin
MOA: Inhibits cell wall peptidoglycan formation by binding D-ala D-ala portion of cell wall precursors. Bactericidal.
MOR: *pay back to 2 Dalas (Dollars) for VANdalizing (vancomycin).
Use: Gram-(+)only- serious, multidrug-resistant org., including /MRSA, enterococci, and C. difficile.
Toxicity: well-tolerated in general- but NOT trouble free. Nephrotoxic, Ototoxic, thrombophlebitis,diffuse flushing- RED MAN SYNDROME (can largely prevent by pretreatment with antihistamines and slow infusion rate).
Protein Synthesis Inhibitors
MOA: Target smaller bacterial ribosome (70S, made of 30S and 50S subunits), leaving human ribosome (80S) unaffected.
Use:
30S Inhibitors
A= Aminoglycosides (bacteriocidal)
T= Tetracyclines (bsacterostatic)
50S inhibitors
C= chloramphenicol, Clindamycin (bacteriostatic)
E= Erythromycin (macrolides) (bacteriostatic)
L= Linezolid (variable)
“Buy A.T. 30 C.C.E.L. (sell) at 50”
Toxicity:
Aminoglycosides (Gentamycin, Neomycin, Amikacin, Tobramycin, Streptomycin) G.N.A.T.S
MOA: Bactericidal, inhibit formation of initiation complex, cause misreading of mRNA. Block translocations. Needs O2 for uptake, so does not work against anaerobes
Mean (amin) G.N.A.T.S. caN.N.O.T kill aneorobes.
Use: severe gram-(_) frod infecti0ons. synergistic with β-lactam antibiotics. Neomycin –> bowel surgery
Toxicity: nephrotoxic, neuromuscular blockade, ototoxicity. teratogen. (N.N.O.T.)
Tetracycline (tetracycline, doxycycline, minocycline)
Bacteriostatic, bind 30s, prevent attachemtn of aminoacyl-tRNA; limited CNS penetration;
Do not take with milk (ca2+), antacids (Ca2+ or Mg2+), or iron-containing preparations b/c divalent cations inhibit its absorption in the gut.
Use: Doxy can be given with renal failure, because fecally eliminated. Borrelia burgdorferi, M. penumoniae, Rickettsia, Chlamydia. Also treats acne.
Toxicity: GI distress, discoloration of teeth and inhibition of bone growth in children, photosensitivity. Contraindicated in pregnancy.
Macrolide (azithromycin, clarithromycin, erythromycin)
MOA: Inhibit protein synthesis by blocking trnaslocation; bind to the 23S rRNA of 50S ribosomal subunit. Bacteriostatic.
Use: Atypical pneumonias (Mycoplasma, Chlamydia, Legionella), STDs (Chlamydia), gram-(+) cocci (strep infxn for ppl allergic to penicillins)
Toxicity: MACRO gastrointerstinal Motility issues, Arrhythmia b/c prolonged QT, acute Cholestatic hepatitis, Rash, eOsinophilia. Increases serum concentration of theophyllines, oral anticoagulants.
Chloramphenicol
MOA: blocks petidyltransferase at 50S ribosomal subunit. bacteriostatic.
Use: Meningitis( H. flu, N. meningitidis, S. pneumoniae), Rocky Mountain spotted fever (Rickettsia rickettsii). Limited use –> toxicities but often still used in developing countries, b/c of low cost
Toxicities: Anemia, aplastic anemia (dose- dependent), gray baby syndrome (in premies, b/c lack liver UdP-glucoronyl transferase)
Cindamycin
MOA: blocks peptide transfer at 50S rib. unit. bacteriostatic
Use: Anaerobic infxns in aspiration pneumonia, lung abscesses, and oral infxns.
Invasive Group A Strep. infxns.
Tox: Pseudomembranous colitis (C. diff overgrowth), fever, diarrhea.
Sulfonamides (Sulfamethoxazole (SMX), sulfisoxazole, sulfadiazine)
MOA: Inhibitt folate synthesis. Para-aminobenzoic acid (PABA) antimetablites inhibit dihydropteroate synthase. Bacteriostatic.
Use: Gram- (+), gram- (-), Nocardia, Chlamydia. triple sulfas or SMX for simple UTI.
Tox: hypersensitivity rxns, hemolysis if G6PD deficient, nephrotoxicity (tubulointerstitial nephritis), photosensitivity, kernicterus in infants, displace other drugs from albumin (e.g., warfarin).
Trimethoprim
MOA: inhibits bacterial dihydrofolate reductase. Bacteriostatic.
Use: Used in combo with SMX= TMP-SMX= bactrim–> sequential blockade of folate synthesis. Combo is for UTI, Shigella, Salmonella, Pneumoncystis jirovecii (tx and prophylaxis), toxoplasmosis prophylasis.
Tox: Megalobalstic anemia, leukopenia, granulocytopenia. TMP: Treat Marrow Poorly.
Fluroquinolones (Ciprofloxacin, norfloxacin, levoxacin, ofloxacin, sparfloxacin, moxifloxacin, gemifloxacin, enoxain, nalidixic acid (a quinolone)
MOA: Inhibit DNA gyrase (topoisomerase II) and topoisomerase IV. Bacteriocidal. Must not be taken with antacids.
Use: Gram (-) rods of urine and GI (including pseudomonas), Neisseria, some gram (+).
Tox: Gi upset, superinfections, skin rashes, headache, dizziness.
less common –> tendonitis,
tendon rupture (ppl >60yr old and ppl taking prednisone), leg cramps, myalgias.
Not for nursing moms, and kids under 18yr due to risk of cartilage damage.
Some prolong QT interval
Metronidazole
MOA: forms free radical toxic metabolites in the bacterial cell that damage DNA. Bactericidal, antiprotozoal.
Use: Treat Giardia, Entamoeba, Trichomonas, Gardnerlla vaginalis, Aneorbes (C. diff, bacteroides).
Tox: Disulfiram-like reaction (severe flushing, tachycardia, hypotension) with alcohol; headache, mettalic taste.
Antimycobacterial drugs (Isoniazid, Azithromycin, rifabutin, N/A)
-M. tuberculosis: prophylaxis=isoniazid. tx: rifampin, isoniazid, pyrazinamide, ethambutol (RIPE for treatment)
- M. avium-intracellulare: prophylaxis=azithromycin, rifabutin
tx: more drugs resistant than M. tuberculosis. Azithromycin or Clarithromycin + Ethambutol. Can add rifabutin or ciprofloxacin. - M. leprae: Prophylaxis=N/A
tx: long-term treatment with dapsone and rifampin for tuberculoid form. Add clofazimine for lepromatous form.
Isoniazid (INH)
MOA: Decrease synthesis of mycolic acids. Bacterial catalase-peroxidase (encoded by katG) needed to convert INH to active metabolite.
Use: Mycobacterium tuberculosis. The only agent used as solo prophylaxis against TB.
Tox: neurotoxicity, hepatotoxicity. Pyridoxine (Vitamin B6) can prevent neurotoxicity, lupus.
INH Injures Neurons and Hepatocytes
Rifamycins (Rifampin, Rifabutin)
MOA: Inhibits DNA-dependent RNA polymerase.
Use: Myobacterium tuberculosis; delays resistance to dapsone when used for leprosy. Used for meningococcal prophylaxis and chemoprophylaxis in contacts of children with H. flu type B.
Tox: minor heptoxicity and drug interactoions (increased P-450); Rifambutin better than rifampin in patients with HIV infection due to less cytochroms P-450 stimulation.
Rifampin’s 4 R’s:
- RNA polymerase
- Ramps up microsomal cytochroms P-450 3. Red/organe body fluids
- Rpaid resistance if used alone
- Rifampin ramps up cytochrome P-450, but rifabutin does not
