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STEP 1 Pharm > Antibacterials > Flashcards

Antibacterials Flashcards

1
Q

Penicillin mechanism and usage

A

Bind to PBPs (aka transpeptidases) and block peptidoglycan cross linking in the cell wall of bacteria.

Used for gram positives and N.meningitides and T. pallidum.

Bactericidal

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2
Q

Ampicillin, amoxiillin mechanism

A

Aminopenicillins bind to PBP and prevent cross linking of peptidoglycans. Also penicillinase sensitive.

Combine with clavulanic acid to protect against beta lactamases.

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3
Q

Aminopenicillin usage

A

Extended spectrum penicillin, includes haemophilus, e.coli, listeria, proteus, salmonella, shigella.

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4
Q

Aminopenicillin toxicity

A

hypersensitivity reactions, rash, pseudomembranous colitis.

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5
Q

Oxacillin, nafcillin, dicloxacillin mechanism and usage

Side effect?

A

Blocks transpeptidases (PBP) from cross linking peptidoglycans on cell wall. These are penicillinase resistant because of a bulky R group.

Used for S.aureus.

Cause interstitial nephritis!!!!!

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6
Q

Ticarcillin,piperacillin mechanism/usage.

A

Block PBP and cross linking of peptidoglycans. Used for pseudomonas and other gram negative rods. Best combined with beta lactamase inhibitors.

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7
Q

Beta lactamase inhibitors

A

Clavulanic acid, sulbactam, tazobactam.

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8
Q

How do cephalosporins work?

A

Beta lactam drugs that are less sensitive to penicillinases. Don’t cover listeria, mycoplasma, chlamydia, MRSA, or enterococci

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9
Q

First generation cephs

A

Cefazolin, cephalexin – used for gram + proteus, e.coli, klebsiella

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10
Q

Second generation cephs

A

Cefoxitin, cefuroxine, cefaclor. Used for Haemophilis, enterobacter, neisseria, proteus, e.coli, klebsiella, serratia.

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11
Q

Third generation cephs

A

Ceftriaxone, cefotaxime, cefazidime

Used for serious gram negatives (meningitis, gonorrhea, pseudomonas)

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12
Q

Fourth generation cephs

A

Cefepime (good activity against pseudomonas and gram positives)

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13
Q

Fifth generation cephs

A

Ceftaroline. Broad gram positive coverage, but DOES NOT cover pseudomas.

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14
Q

Side effects of cephalosporins

A

HSR’s. Vitamin K deficiency. Increases the nephrotoxicity of aminoglycosides.

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15
Q

Aztreonam mechanism and usage

A

Monobactam drug, resistant to beta lactamases. Binds to PBP3. Synergistic with aminoglycosides.

Used for gram negative rods only. No activity aginast gram positives or anaerobes.

Also used for people allergic to penicillin who can’t tolerate aminoglycosides due to renal insufficiency

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16
Q

Carbapenems (imipenem, carbapenem, ertapenem, meropenem) mechanism and usage

A

Broad sprectrum betalactamase resistant drugs.

Used for gram positive cocci, gram negative rods, anaerobes.
Lots of SE that include GI upset and seizures

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17
Q

Why are carbapenems (imipenem) administered with another drug? What is that drug?

A

Administered with cilastatin that inhibits the dihydropeptidase in renal tubules. This increases its activity.

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18
Q

Toxicity of carbapenems

A

GI upset, seizures, skin rash.

Meropenem has better profile

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19
Q

Vancomycin

A

Inhibits cell wall peptidoglycan formation by binding to the D-Ala-D-ala portion of cell wall precursors.

Used for only serious gram positive reactions

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20
Q

Toxicity of vancomycin

A

Usually trouble free, but occasionally not. Nephotoxic, ototoxic, thrombophlebitis.

Can cause red man syndrome

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21
Q

Protein synthesis inhibitors

A

Inhibit components of the 30S and 50S subunits of the 70S bacterial ribosomal complex. Human ribosome 80S is unaffected.

Include Aminoglycosides, Tetracyclines (30S)

Chloramphenicol, clindamycin
Erythromycin (macrolides)
Linezolid
(50S)

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22
Q

Aminoglycosides (Gentamycin, neomycin, amikacin, tobramycin, streptomycin). Anything prohibitive about them?

A

Bactericidal, inhibit the formation of the initiation complex and cause misreading of RNA. REQUIRE O2 FOR UPTAKE, so cannot kill anaerobes.

Used for severe gram negative infections like francisella or pseudomonas. Synergistic with beta lactams

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23
Q

Toxicity of aminoglycosides

A

Nephotoxicity (especially with cephalosporins), ototoxicity (especially with loop diuretics), neuromuscular blockade.

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24
Q

How are aminoglycosides inactivated?

A

bacteria can acetylate, or phosphorylate, or adenylate.

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25
Q

Tetracyclines (tetracycline, doxycycline, minocycline)

A

Bacteriostatic, bind to the 30S subunit and prevent attachment of aminoacyl-tRNA. Limited CNS penetration.

Doxycycline is fecally eliminated, so can be used in renal patients.

26
Q

What shouldn’t patients on tetracyclines take?

A

Milk, antacids (ca or mg), or iron containing stuff.

Divalent cations prevent absorption of drug.

27
Q

Usage of tetracyclines

A

Borrelia, mycoplasma, accumulates intraceullularly so very effective against rickettsia/chlamydia too.

used to treat acne

28
Q

Tetracyclines toxicity

A

GI distress, discoloration of teeth and inhibition of bone growth in children, photosensitivity.

29
Q

Tetracycline resistance?

A

Due to decreased uptake or greater efflux out of bacterial cells by plasmid encoded pumps.

30
Q

Macrolides

A

Include Azithromycin, clarithromycin, erythromycin.

31
Q

Macrolides mechanism and usage

A

Include Azithromycin, clarithromycin, erythromycin. Bind to 23S of 50S subunit and block translocation (macroslides).

Use for atypical pneumonias, STDs, and gram positive cocci (strep infections in penicillin allergic patients)

32
Q

Macrolides toxicity

A

Gastrointestinal motility issues, arrythmia (long QT), cholestatic hepatitis, rash, eosinophilia.

Increases serum concentration of theophylline, oral anticoagulants

33
Q

Macrolides reistance?

A

Bacteria can methylate the 23S binding site of 50S.

34
Q

Chloramphenicol mechanism and usage

A

Blocks peptidyltransferase at 50S subunit. Bacteriostatic.

Used for meningitis, ricketssiae, strep pneumo.

Limited usage because of toxicities, but low cost so used in developing countries.

35
Q

Chloramphenicol toxicity

A

Anemia, aplastic anemia, GRAY BABY SYNDROME (because they lack UDP-glucuronyl transferase and can’t metabolize the drug) .

36
Q

Chloramphenicol resistance

A

Plasmid encoded acetyl-transferase inactivates the drug

37
Q

Clindamycin

A

Blocks peptide transfer (translocation) at 50S. Blocks the slide.

Used for anaerobes in aspiration pneumonia, lung abscesses, oral infections. Can be effective against GAS.

Anaerobes above the diaphragm, metronidazole treats anaerobes below the diaphragm.

38
Q

Clindamycin toxicity

A

C. Diff, fever, diarrhea.

39
Q

Sulfonamides

A

Sulfamethoxizole, sulfisoxizole, sulfadizine.

Inhibit folate synthesis. PABA antietabolites inhibit dihydropteroate synthase.

Prevent bacterial synthesis of RNA/DNA/protein.

Used for gram positives, gram negatives, NOCARDIA, chlamydia.

Simple utis

40
Q

Sulfonamide toxicity

A

Hypersensitivity, hemolytic anemia if G6PD deficient. Nephrotoxic, kernicterus in infants.

41
Q

Trimethoprim

A

Inhibits bacterial dihydrofolate reductase. Used in combination with sulfonamides to have 2 steps of blocking folate synthesis.

Used for UTIs, shigella, salmonella, PCP!!!!!!

42
Q

Trimethoprim toxicity

A

Megaloblastic anemia, leukopenia, granulocytopenia. May alleviate with folinic acid. TMP (treats marrow poorly)

43
Q

Fluoroquinolones

A

Ciprofloxacin, norfloxacin, etc…

Inhibits DNA gyrase (topoisomerase II) and topoisomerase IV. Can’t take with antiacids.

44
Q

Fluroquinolones toxicity

A

GI upset, superinfections, rashes, dizzziness.

Can cause TENDONITIS, TENDON RUPTURE, CRAMPS, MYALGIAS. Fluoroquinolones hurt attachments to your bones

Don’t give to pregnant women, nursing mothers, or children under 18 because of cartilage damage.

45
Q

Fluoroquinolones resistance

A

Chromosome-encoded mutation in DNA gyrase, plasmid mediated resistance, and efflux pumps

46
Q

Metronidazole mechanism and usage

A

Forms free radical toxic metabolites in the bacterial cell that damage DNA. Bactericidal and anti-protozoal.

Treats anaerobic infections below the diaphragm. Giardia, entamoeba, trichomonas, gardnerella. Used with a ppi and clarithromycin for triple therapy against H.Pylori.

47
Q

Metronidazole toxicity?

A

Disulfiram-like reaction with alcohol. Severe flushing, tachycardia, hypotension with alcohol. Headache, metallic taste

48
Q

Prophylaxis for tuberculosis?

A

Isoniazid

RIPE for treatment

49
Q

Prophylaxis for MAC

A

Azithromycin,rifabutin

treat with azithromycin and ethambutol.

50
Q

Prophylaxis for leprosy?

A

None, but treat with rifampin, dapsone, clofazamine for lepromatous form.

51
Q

Isoniazid

A

Decreases synthesis of mycolic acids. Must be activatived by a bacterial catalase-peroxidase (encoded by KatG). Used for TB.

52
Q

Isoniazid toxicity

A

B6 deficiency, neurotoxicity, hepatotoxicity.

Injures neurons and hepatocytes (INH)

53
Q

Rifamycins mechanism.

A

Rifampin, rifabutin

Inhibits DNA-dependent RNA polyermase.

used for MTB, delays resistance to dapsone when used in M leprae. Can by used for meningoprophylaxis and haemophilus prophylaxis.

54
Q

Toxicity of rifamycins

A

Minor hepatotoxicity. Induces cyp450. Orange body fluids.

55
Q

Pyrazinamide

A

Mechanism uncertain. May acidify intracellular environment, especially in phagolysosomes.

used for MTB

56
Q

Pyrazinamide toxicity

A

Hyperuricemia

57
Q

Ethambutol

A

Decreases carbohydrate polymerization of mycobacterium cell wall by blocking arabinosyltransferase

58
Q

Ethambutol toxicity

A

causes optic neuropathy and red-green color blindness.

59
Q

Prophylaxis for CD4

A

TMP SMZ for PCP

60
Q

Prophylaxis for CD4

A

TMPSMZ for PCP and Toxoplasmosis

Can used aerosolized pentamidine for patients who can’t tolerate TMPSMZ

61
Q

Prophylaxis for CD4

A

Azithromycin for MAC

STEP 1 Pharm (17 decks)

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