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Infectious Disease > Antibacterial Chemotherapy > Flashcards

Antibacterial Chemotherapy Flashcards

1
Q
  • very selective toxicity, bactericidal in growing, proliferating cells
  • primarily used for gram (+)
  • mechanism of action: covalent binding to transpeptidases/PBPs, inhibition of transpeptidase reaction, activation of murein hydrolases
A

penicillins

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2
Q

absorption of penicillins?

A

oral-though many are acid sensitive

parenteral- IV or IM

depot- benzathina penicillin G

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3
Q

distribution of penicillins?

A

good to most tissues and fluids, exlcusing pleural/pericardial/synovial

poor penetration to eye, prostate, CNS (except in meningitis)

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4
Q

excretion of penicillins?

A

-tubular through organic acid secretory system, blocked by probenecid

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5
Q

penicillins have __________ cell killing, where ______ above MBC relates to efficacy

A

time dependent

time

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6
Q

penicillins primaryily used against gram positives?

A

Pen G and Pen V

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7
Q

anti staph penicillins?

A

nafcillin, methicillin, isoxazolyl pencillins (ox-, clox-)

beta lactamase resistant

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8
Q

extended spectrum penicillins with increased gram (-) activity?

A

ampicillin, amoxacillin, ticarcillin, piperacillin, mezlocilli

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9
Q

anti pseudomonal penicillins effective against proteus and pesudomonas?

A

ticarcillin, piperacillin, mezlocillin

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10
Q

problem with anti pseudomonal penicillins?

A

rapid emergence of resistance with pseudomonas, so use in combo with aminoglycosides or fluoroquinolones

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11
Q

adverse effects of penicillins?

A
  • ampicillin rash, self limiting
  • hypersensitivity reaction: rapid onset, not dependent on therapeutic dose
  • seizures in high doses
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12
Q

resistance to penicillins due to?

A
  • inaccessible PBPs: gram negatives, MRSA
  • Beta lactamase resistant: plasmid mediated, use beta lactamase resistant penicillins (nafcillin, oxacillin, cloxacillin)
  • co administer beta lactamase inhibitor (clavulanic acid, sulbactam, tazobactam)
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13
Q
  • structure and function similar to penicillins
  • less sensitive to beta lactamases
  • broader spectrum of activity
  • poor oral absorption
  • renal toxicity
  • secondary ICWS
A

cephalosporins

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14
Q
  • generally greater gram (-) activity
  • 2nd generation less gram (+) activity
  • less beta lactamase sensitivity
  • cephalosporine resistant (especially 4th generation-cefepime)
  • less toxic to patient, better distribution to CNS
A

cephalosporins

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15
Q

cefazolin and cephalexin (oral) are ______ generation cephalopsporins with _______ spectrum

A

1st generation

narrow

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16
Q

cefuroxime (oral), cefotetan, cefaclor (oral) are _______ generation cephalopsorins with _________ spectrum

A

second generation

intermediate

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17
Q

cefotaxime, ceftriaxone, ceftazidime, cefdopoxime (oral) are _______ generation cephalosporins with ________ spectrum

A

3rd generation

broad

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18
Q

cefepime is _______ generation cephalosporin with _________ spectrum

A

4th generation

broad

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19
Q

adverse effects of cephalosporins?

A
  • local irritation from injection
  • renal toxicity-tubular necrosis, interstitial nephritis, may be enhanced by aminoglycosides
  • cefotetan and cefoperazone have disulfiram effect, give with vitamin K b/c bleeding and platelet disorders
  • hypersensitivity - 1% cross reaction with penicillins
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20
Q
  • gram negative activity, virtually inactive against gram (+) or anaerobes
  • becta lactamase resistant
  • crosses blood brain barrier
  • no cross reactivity in penicillin sensitive patients
A

aztreonam (a monobactam)

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21
Q
  • broad spectrum, anaerobes
  • beta lactamase resistant
  • pseudomonas: rapid resistance, use with aminoglycosides
  • IV only
  • crosses BBB
  • inactivated by renal dipeptidase, co administer Cilastatin
  • cross reative with penicillins, incidence low
A

imipenem (carbapenem)

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22
Q
  • inhibits transglycosylation
  • bactericidal for gram positive
  • IV for systemic use (MRSA), oral for C diff
  • IV cleared through kidney- enhances oto and renal toxicity of aminoglycosides
  • red man or redneck syndrome- histamine release
A

vancomycin

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23
Q
  • ICWS, broad spectrum
  • inhibits cytoplasmic step in cell wall precursor synthesis
  • active uptake by G6P
  • oral
  • actively excreted by kidney
  • approved for single dose therapy of UTI
  • synergistic with beta lactams, aminoglycosides, fluoroquinolones
A

fosfomycin

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24
Q
  • markedly nephrotoxic

- topical antibiotic only

A

bacitracin

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25
Q
  • basic peptides, act as detergents
  • active against gram negatives, except proteus and neisseria
  • limited to topical use due to systemic toxicity (esp. renal)
  • salvage therapy for highly resistant acinetobacter, pesudomonas, and enterobacteriae
A

polymixin B and E (colistin) , membrane active drugs

26
Q
  • target is different in pathogen than host

- substantially less selective toxicity than with ICWS

A

inhibitors of protein synthesis (IPS)

27
Q
  • reversible binding to 30S subunit, bacteriostatic, selectivity based on bacterial uptake
  • oral, chelate metal ions so don’t admin with food/milk/antacids
  • well distributed except CNS, concentrates in teeth, bone, liver, bile, kidney
  • cross placenta, excreted in milk
A

tetracyclines

28
Q
  • broad spectrum
  • mycoplasma, chlamydia, rickettsiae
  • Lyme disease
A

tetracyclines

29
Q

adverse effects of tetracyclines?

A
  • GI irritation
  • superinfections-pseudomonas, proteus, clostridia, candida
  • impaired liver function
  • photosensitization
  • calcium chelation: deposit in teeth and bones, discoloration, growth retardation, deformity
30
Q

resistance to tetracyclines?

A
  • decreased uptake due to efflux pumps
  • altered ribosomal proteins or RNA
  • common in pseudomonas, proteus
  • indiscriminate use/overuse
31
Q
  • new generation of tetracyclines, no affected by efflux pump
  • slight increased risk of death
A

tigecycline

32
Q
  • macrolide antibiotics
  • GI absorption but acid labile , enteric coating or esters
  • also IV
  • crosses placenta
  • excreted in bile
  • half life 1-5 hours (except one)
  • bacteriostatic or bacteriocidal depending on dose
A

erythromycin, clarithromycin, azithromycin

33
Q

clinical uses of macrolide antibioitics?

A
  • gram (+), some gram neg and mycobacteria
  • backup for penicillins in pen-sensitive patients
  • azithromycin and clarithromycin broader spectrum
  • mycoplasma pneumonia, legionnaire’s, chlamydia
34
Q

adverse effects of macrolide antibiotics?

A
  • GI
  • microsomal enzyme inhibition- drug/drug interactions, oral anticoags, digoxin, antihistamines
  • hepatotoxicity-esp with erythromycin estolate, cholestatic jaundice
35
Q

resistance to macrolide antibiotics?

A
  • staph resistant, some strep and pneumo
  • altered methylated rRNA, efflux pump, esterase which hydrolyzes erythromycins
  • methylation and efflux pumps
36
Q
  • minimal P450 based interactions

- tissue levels 10-100X plasma levels, 1/2 life 2-4 days

A

macrolide antibiotics

37
Q

clarithromycin and mycobacterium active against _______ in AIDS patients

A

avium intracellulare

38
Q
  • ketolide, semi synthetic macrolide
  • oral
  • metabolized in liver
  • poor substrate for efflux pump
  • once daily dosing
  • respiratory tract infections (CA-pneumonia, bronchitis, sinusitis)
  • inhibits CYP3A4
  • QT prolongation
A

telithromycin

39
Q
  • bactericidal-irreversible inactivation of 30S ribos
  • multiple effects on translation: misreading of mRNA, interfere with initiation, break up polysomes
  • poor oral absorption, given IV
  • no significant host metabolism
  • glomerular filtration, very high concentrations in proximal tubules
  • concentration dependent killing
A

aminoglycosides

40
Q
  • use concentration dependent killing
  • peak serum concentration relates to extent of killing
  • higher peak values result in increased efficacy and decreased development of resistance
A

aminoglycosides, fluoroquinolones

41
Q

clinical uses for aminoglycosides?

A
  • non resistant gram (-) infections (Ecoli, proteus, pseudomones)
  • pseudomonas: gentamicin > tobramycin > amikacin
  • streptomycin and getamicin are older, use older first
42
Q

related to aminoglycosides, used for penicillin resistant gonococci?

A

spectinomycin

43
Q

adverse effects of aminoglycosides?

A
  • nephrotoxicity: high concentrations in renal cortex, usually reversible
  • ototoxicity: loss of vestibular/auditory function, may be reversible
  • neuromuscular blockage: common during surgery, myasthenia gravis
44
Q

resistance to aminoglycosides?

A
  • increased bacterial metabolism through adenylation/acetylation/phosphorylation
  • alteration in bacterial uptake
  • altered ribosomal protein
45
Q
  • reversible inhibitor of protein synthesis: bacteriostatic, broad spectrum
  • pharmacokinetics: CNS levels=serum levels
  • plasmid mediated resistance, slow development
  • adverse effects: GI following fungal superinfection, anemia due to bone marrow suppression, aplastic anemia, usually irreversible and fatal, gray baby syndrome
A

chloramphenicol

46
Q

clinical use of chloramphenicol?

A
  • powerful antibacterial, use limited by toxicity and resistance
  • typhoid fever, rocky mountain spotted fever
47
Q
  • lincosamide- antibiotic, bacteriostatic
  • well absorbed and distributed, except CNS
  • useful against bacteroids fragilis, other anaerobes
  • MRSA, endocarditis prophylaxis
  • GI upset, C diff superinfections, hepatotoxic
A

clindamycin

48
Q
  • peptide macrolactones
  • IV, potent CYP3A4 inhibitor
  • block sites affected by macrolides and clindamycin
  • approved for use against vanco resistance enterococcus faecium, MRSA
  • no cross resistance with other IPS
A

streptogramins (quinupristin, dalfopristin)

49
Q
  • prevents formation of 70S ribosome (unique), no cross resistance with other IPS
  • bactericial against streptococci, bacteriostatic against staph and enterococic
  • primary indication: vancomycin resistant E. faecium (limit to multi drug resistant gram + infections)
  • bone marrow suppression, thrombocyopenia
A

linezolid (oxazolidinone)

50
Q
  • PABA analogs, competitive inhibitor of dihydrofolate synthesis
  • bacteriostatic
  • oral, topical for burns
  • acetylation yields inactive metabolite
  • excreted in urine
A

sulfonamides

51
Q
  • topical for burns
  • opthalmic
  • UTIs
  • ulcerative colities
  • adverse: allergic reactions , Stevens Johnson
  • resistance: overproduction of PABA
A

sulfonamides

52
Q
  • dihydrofolate reductase inhibitors
  • treat UTI, usually combined with sulfonamide
  • used for pneumocystic pneumonia, complicated UTI, many others
  • combo is bactericidal
A

tremethoprim

53
Q

adverse effects of trimethoprim?

A

anti folate effects: megaloblastic anemia, leukopenia, granulocytopenia, treat with folinic acid

54
Q
  • fluoroquinolones: fluorinated analogs of nalidixic acid
  • excreted in kidney, blocked by probenicid
  • DNA gyrase inhibitors
A

ciprofloxacin, levofloxacin, ofloxacin

55
Q

clinical use of fluoroquinolones?

A
  • gram(-) in GI and urogenital tract infections, some gram (+)
  • respiratory, skin, soft tissue infections, esp for multi drug resistant organisms
56
Q

adverse effects of fluoroquinolones? resistance?

A
  • connective tissue disorders

- altered DNA gyrase, decreased permeability, plasmid mediated protection

57
Q
  • oxidative stress
  • 50% active drug excreted in urine
  • treats UTIs, effective at ph < 5.5
  • occasional hemolytic anemia
  • all pesuodomonas, proteus resistant
A

nitrofurantonin

58
Q
  • blocks synthesis of mycolic acids for mycobacterial cells wall, bactericidal in growing cells only
  • TB prophylaxis or chemotherapy
  • hepatotoxic, peripheral and central neuropathy (use pyridoxine B6)
  • resistance: katG in mycobacterium
A

isoniazid (INH)

59
Q
  • inhibits bacterial RNA synthesis
  • inducer of microsomal enzymes, hepatotoxic, orange color to body fluids
  • anti mycobacterial chemo
A

rifampin

60
Q
  • inhibits synthesis of mycobacterial cell wall glycan

- dose dependent optic neuritis, decreased acuity, loss of red green sight

A

ethambutol

61
Q
  • blocks membrane function of mcyobacterium
  • gouty arthritis
  • contraindicated in pregnancy
A

pyrazinamide

62
Q
  • used for M.leprae
  • sulfone, concentrates in skin, muscle, liver, kidney
  • hemolysis, methemoglobinemia common
A

dapsone

Infectious Disease (22 decks)

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