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Step 1 Flash Cards > Antibacterials > Flashcards

Antibacterials Flashcards

1
Q

Penicillin mechanism

A

G - IV, V - oral

  • bind penicillin-binding proteins (transpeptidases)
  • block transpeptidase cross-linking of peptidoglycan
  • activate autolytic enzymes
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2
Q

penicillin clinical use

A
  • usually used for gram +ves, bactericidal for gram positive cocci and rods, gram negative coci, and spirochetes
  • S. pneumo, S. pyogenes, Actinomyces, N. meningitidis, T. pallidum
  • “STAN’S” favorite drug is penicillin
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3
Q

penicillin toxicity and resistance

A
  • tox: hypersensitivity reactions, hemolytic anemia

- resistance: penicillinase in bacteria cleaves B lactam ring

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4
Q

ampicillin, amoxicillin mechanism

A
  • same as penicillin, wider spectrum, also combined with clav to protect against b-lactamase
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5
Q

amp/amox clinical use

A
  • extended spectrum penicillin - H flu, E coli, listeria, proteus, salmonella, shigella, enterococci
  • HELPSS kill enterococci
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6
Q

amp/amox tox and resistance

A
  • tox: hypersensitivity reactions, rash, pseudomembranous colitis
  • resistance: penicillinase in bacteria cleaves B lactam ring
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7
Q

oxacillin, nafcillin, dicloxacillin mechanism

A
  • same as penicillin, narrow spectrum because of bulky R group blocking access to B lactam ring
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8
Q

oxacillin, nafcillin, dicloxacillin clinical use and tox

A
  • s. aureus (not MRSA), skin/soft tissue infections

- tox: hypersensitivity reactions, interstitial nephritis

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9
Q

ticarcillin, piperacillin mechanism, clinical use and tox

A
  • same mechanism as penicillin, extended spectrum
  • used against psuedomonas and GNR, use with B lactamase inhibitors, susceptible to penicillinase
  • tox: HS reactions
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10
Q

B lactamase inhibitors

A
  • CAST: clavulanic acid, sublactam, tazobactam

- added to penicillins to protect from destruction by B lactamase (penicillinase)

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11
Q

cephalosporin mechanism of action

A
  • B lactams that inhibit cell wall synthesis, but are less susceptible to penicillinases
  • bind to PBPs irreversibly, bactericidal
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12
Q

1st gen cephalosporins clinical use

A
  • cephalexin, cefazolin

- PEcK - proteus, E coli, Klebsiella

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13
Q

2nd gen cephalosporin clinical use

A
  • cefoxitin, cefaclor, cefuroxime

- HEN PEcKs - H flu, Enterobacter, Neisseria, proteus, E coli, Klebs, Serratia

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14
Q

3rd gen cephalosporin clinical use

A
  • ceftriaxone, cefotaxime, ceftazidime
  • serious gram negative infections
  • ceftriaxone –> meningitis and gonorrhea
  • ceftazidime –> pseudomonas
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15
Q

4th gen cephalosporin clinical use

A
  • cefepime

- increased activity against pseudomonas and gram positives

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16
Q

5th gen cephalosporin clinical use

A

-ceftaroline - broad GN and GP coverage, including MRSA but not psuedo

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17
Q

cephalosporin tox

A
  • HS reactions, Vit K deficiency, low cross-reactivity with penicillins, increased nephrotoxicity of aminoglycosides
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18
Q

aztreonam mechanism and tox

A
  • a monobactam, resistant to B lactamases
  • prevents peptidoglycan cross-linking by binding to PBP3
  • synergistic with aminoglycosides
  • no cross-allergenicity with penicillins
  • usually non-tox, some GI upset
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19
Q

aztreonam clinical use

A

GNR only, no activity against gram + or anaerobes

- for pen allergic patients with renal insufficiency who cannot tolerate aminoglycosides

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20
Q

carbapenems mechanism

A
  • broad spectrum beta lactamase resistant
  • imipenem always given with cilastatin (inhibitor of renal dehydropeptidase I) to decrease inactivation of the drug in the renal tubules
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21
Q

carbapenems clinical use and tox

A
  • gram + cocci, GNRs, and anaerobes
  • life-threatening infections
  • tox: GI distress, skin rash, seizures (dec risk with meropenem)
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22
Q

Vancomycin mechanism

A
  • inhibits cell wall peptidoglycan formation by binding D-ala D-ala portion of cell wall precursors
  • bactericidal
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23
Q

vanc tox and mech of resistance

A
  • NOT trouble free
  • nephrotoxic, ototoxic, thrombophlebitis
  • red man syndrome
  • bacteria change D-ala D-ala to D-ala D-lac to become resistant
24
Q

vanc clinical use

A
  • gram positive only

- MRSA, enterococci and C. diff

25
Q

protein synthesis inhibitors

A

buy AT 30, CCEL at 50

  • 30s inhibitors: aminoglycosides (cidal), tetracyclines (static)
  • 50s inhibitors: chloramphenicol, clinda, erythromycin, linezolid (all static, linezolid is variable)
26
Q

aminoglycosides (names)

A

gentamycin, neomycin, amikacin, tobramycin, streptomycin

- “Mean” (amino…) GNATS caNNOT kill anaerobes

27
Q

aminoglycosides mechanism

A

bactericidal

  • inhibit formation of initiation complex and cause misreading of mRNA
  • also block translocation
  • require O2 for uptake, therefore ineffective against anaerobes
28
Q

aminoglycosides clinical use

A

severe GNR infections

  • synergistic with beta lactams
  • neomycin for bowel surgery
29
Q

aminoglycosides toxicity

A

caNNOT kill anaerobes

- nephrotoxic, neuromuscular blockade, ototoxic, teratogen

30
Q

aminoglycosides mechanism of resistance

A
  • bacterial transferase enzymes inactivate the drug by acetylation, phosphorylation, or adenylation
31
Q

tetracyclines names and mechanism

A
  • tetracycline, doxycycline, minocycline
  • bacteriostatic, bind to 30s and prevent attachment of aminoacyl-tRNA
  • limited CNS penetration
  • doxy is fecally eliminated and can be used in patients with renal failure
  • dont take with milk or antacids or iron because divalent cations prevent absorption
32
Q

tetracyclines clinical use

A
  • borrelia burgdorferi, M. pneumoniae
  • ability to accumulate intracellularly makes it good against rickettsia and chlamydia
  • also used to treat acne
33
Q

tetracyclines tox and resistance

A
  • tox: GI distress, discoloration of teeth and inhibition of bone growth in kids, photosensitivity
  • contraindicated in preggos
  • resistance: decreased uptake or increased efflux though plasmid-encoded transport pumps
34
Q

macrolides mechanism and clinical use

A
  • azithro, clarithro and erythromycin
  • inhibit protein synthesis by blocking translocation: bind to the 23S rRNA of the 50S
  • used in atypical pneumonia, STDs and g+ cocci
35
Q

macrolides toxicity and resistance

A
  • tox: MACRO – GI Motility issues, Arrhythmia (prolonged QT), acute Cholestatic hepatitis, Rash, eOsinophilia
  • increases serum concentration of theophyllines, oral anticoagulants
  • resistance: methylation of 23S rRNA-binding site preventing binding of the drug
36
Q

chloramphenicol mechanism and clinical use

A
  • blocks peptidyltransferase at 50S ribosomal subunit, bacteriostatic
  • used in meningitis and RMSF
37
Q

chloramphenicol tox and resistance

A
  • tox: anemia, aplastic anemia, gray baby syndrome,

- resist: plasmid-encoded acetyltransferase inactivates the drug

38
Q

clindamycin mechanism, clinical use and tox

A

blocks peptide transfer (translocation) at 50S

  • anaerobic infection in asp pneumo, lung anscesses and oral infections
  • also good for GAS
  • treats anaerobes above the diaphragm, metronidazole treats below the diaphragm
  • C diff, fever, diarrhea
39
Q

sulfonamides mechanism and clinical use

A
  • SMX, sulfisoxazole, sulfadiazine
  • inhibits folate synthesis, PABA antimetabolites inhibit dihydropteroate synthase, bacteriostatic
  • used for gram +, gram -ve, nocardia, chlamydia, UTI
40
Q

sulfonamides tox and resistance

A
  • HS reactions, hemolysis in G6PD, nephrotoxic, photosensitivity, kernicterus in infants, displace other drugs from albumin
  • resist: altered enzyme, decreased uptake or increased PABA synthesis
41
Q

trimethoprim mechanism and tox

A
  • inhibits bacterial dihydrofolate reductase

- tox: megaloblastic anemia, leukopenia, granulocytopenia (may alleviate with supplemental folic acid)

42
Q

trimethoprim clinical use

A
  • used in combo with SMX, causing sequential block of folate synthesis
  • UTI, shigella, salmonella, PCP and toxo prophylaxis
43
Q

fluoroquinolones (-oxacins) mechanism and use

A
  • inhibit DNA gyrase (topoisomerase II) and topo IV, bactericidal, must not be taken with antacids
  • used in GNR infections of GI and urinary tracts, neisseria, some g+
44
Q

fluoroquinolone tox and resist

A
  • tox: GI upset, superinfections, skin rashes, headache, dizziness
  • less commonly tendonitis, tendon rupture, leg cramps and myalgias
  • no preggos, nursing mothers and kids < 18 due to cartilage damage
  • may prolong QT
  • resist: chromosome-encoded mutation in DNA gyrase, plasmid-mediated resistance, efflux pumps
45
Q

metronidazole mechanism and tox

A
  • forms free radical toxic metabolites in the bacterial cell that damage DNA
  • bactericidal, antiprotozoal
  • tox: disulfram-like reaction (flushing, tachy, hypotension) with alcohol, headache, metalic taste
46
Q

metronidazole clinical use

A

GET GAP on the metro

- giardia, entamoeba, trichomonas, gardnerella vaginalis, anaerobes, h Pylori

47
Q

MAC treatment

A
  • azithro or clarithro + ethambutol, can add rifabutin or cipro
48
Q

leprae treatment

A

long term treatment with dapsone and rifampin for TB form

add clofazimine for lepromatous form

49
Q

HIV prophylaxis

A

< 200 - TMP/SMX for PCP
< 100 - TMP/SMX for PCP and toxo
< 50 - azithro for MAC

50
Q

MRSA treatment

A

vanco, dapto, linezolid, tigecycline, ceftaroline

51
Q

VRE treatment

A

linezolid and streptogramins

52
Q

INH mechanism, use and tox

A
  • decreased sythesis of mycolic acids, catalase needed to convert INH to active metabolite
  • only solo prophylaxis for TB
  • tox: INH Injures Neurons and Hepatocytes
  • B6 can prevent neurotox
53
Q

Rifamycins mech, use, tox

A
  • inhibit DNA-dep RNA polymerase
  • used for TB, delays resistance to dapsone for leprosy
  • only indication for monotherapy is meningococcal prophylaxis
  • can also be used for HiB prophylaxis in contacts
  • tox: minor hepatotox and inc 450, orange body fluids (rifabutin> rifampin in HIV b/c less p450 stim)
54
Q

pyrazinamide mech, use, tox

A
  • uncertain mechanism, effective at acidic pH
  • used for TB
  • tox: hyperyuricemia, hepatotox
55
Q

ethambutol mech, use, tox

A
  • mech: decreased polymerization of mycobacterium cell wall by blocking arabinosyltransferase
  • used in TB
  • tox: optic neuropathy (R/G color blindness)

Step 1 Flash Cards (36 decks)

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