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Flashcards in Antibiotics Deck (105)
1

Penicillin forms

G = IV, IM
V = oral

2

Mechanism of penicillin

bind penicillin-binding proteins (transpeptidases)
block transpeptidase cross-linking of peptidoglycan in cell wall
activates autolytic enzymes

3

Use of penicillin

Mostly used for gram positive organisms (S. aureus - MSSA; Group A strep, Group B strep, Actinomyces)

Some gram negative cocci - N. meningitidis)
Spirochetes (T. pallidum)

Bactericidal for gram-positive cocci, gram-positive rods, gram-negative cocci, and spirochetes that are penicillinase sensitive

4

Toxicity of penicillin

hypersensitivity reactions, hemolytic anemia

5

Resistance to penicillin

penicillinase in bacteria (a type of beta-lactamse) cleaves beta-lactam ring

6

Mechanism of amoxicillin/ampicillin

same as penicillin; wider spectrum; penicillinase sensitive
can combine with clavulanic acid to protect against destruction by beta-lactamase

amoxicillin (more oral bioavailability)

Mech: bind penicillin-binding proteins (transpeptidases)
block transpeptidase cross-linking of peptidoglycan in cell wall
activates autolytic enzymes

7

Use of amoxicillin/ampicillin

Extended-spectrum penicillin (gram-positive cocci, gram-negative cocci, gram-positive rods, spirochetes)

PLUS
H. influenzae, H. pylori, E. coli. Listeria, Proteus, Salmonella, Shigella, enterococci

HHELPSS kill enterococci

8

Toxicity of amoxicillin/ampicillin

Hypersensitivity reactions; rash; pseudomembranous colitis

9

Resistance to amoxicillin/ampicillin

penicillinase in bacteria (a type of beta-lactamase) cleaves beta-lactam ring

10

Name the penicillinase-resistant penicillins

dicloxacillin, nafcillin, oxacillin

11

Mechanism of dicloxacillin/nafcillin/oxacillin

same as penicillin: bind penicillin-binding proteins (transpeptidases); block transpeptidase cross-linking of peptidoglycan in cell wall; activates autolytic enzymes

narrow spectrum
penicillinase resistant because bulky R group blocks access of beta-lactamase to beta-lactam ring

12

Use of dicloxacillin/nafcillin/oxacillin

S. aureus (MSSA only)

MRSA is still resistant to these because of altered penicillin binding protein target site

13

Toxicity of dicloxacillin/nafcillin/oxacillin

Hypersensitivity rxn; interstitial nephritis

14

Name the antipseudomonal penicillins

Piperacillin and ticarcillin

15

Mechanism of piperacillin/ticarcillin

same as penicillin: bind penicillin-binding proteins (transpeptidases); block transpeptidase cross-linking of peptidoglycan in cell wall; activates autolytic enzymes

extended spectrum

16

Use of piperacillin/ticarcillin

pseudomonas spp. and gram-negative rods

susceptible to penicillinase; use with beta-lactamase inhibitors

17

Toxicity of piperacillin/ticarcillin

hypersensitivity rxn

18

Name the beta-lactamase inhibitors

Clavulanic acid, sulbactam, tazobactam

add to penicillin antibiotics to protect the antibiotic from destruction by beta-lactamase (penicillinase)

CAST

Amox/Clav
Amp/Sul
Pip/Tazo

19

Mechanism of the cephalosporins

beta-lactam drugs that inhibit cell wall synthesis but are less susceptible to penicillinases

bactericidal

20

Organisms that are NOT covered by cephalosporins

LAME: listeria, atypicals (chlamydia, mycoplasma), MRSA and enterococci

Exception: ceftaroline covers MRSA

21

Name the first generation cephalosporins

cefazolin, cephalexin

22

Use of the first generation cephalosporins

gram-positive cocci; Proteus, E. coli, Klebsiella (PEcK)

cefazolin used prior to surgery to prevent S. aureus wound infections

23

Name the second generation cephalosporins

cefoxitin, cefaclor, cefuroxime

24

Use of the second generation cephalosporins

gram-positive cocci; H. influenzae, Enterobacter, Neisseria species, Proteus, E. coli, Klebsiella, Serratia (HEN PEcKS)

25

Name the third generation cephalosporins

ceftriaxone, cefotaxime, ceftazidime

26

Use of the third generation cephalosporins

serious gram-negative infections resistant to other beta-lactamse

27

Use of ceftriaxone specifically

Neisseria meningitis, gonorrhea; alpha hemolytic streps, disseminated lymes disease

28

Use of ceftazidime specifically

pseudomonas

29

Name the fourth generation cephalosporins

cefepime

30

Use of fourth generation cephalosporins

gram-negative organisms, with increased activity against pseudomonas and gram-positive organisms

31

Name the fifth generation cephalosporins

ceftaroline

32

Use of the fifth generation cephalosporins

broad gram-positive and gram-negative organism coverage, including MRSA; does NOT cover pseudomonas

33

Toxicity of the cephalosporins

hypersensitivity reactions, autoimmune hemolytic anemia, disulfiram-like reaction, vitamin K deficiency

Exhibit cross-reactivity with penicillins

increased nephrotoxicity with aminoglycosides

34

Resistance to cephalosporins

structural changes in penicillin-binding proteins (transpeptidases)

35

Name the carbapenems

imipenem, meropenem, ertapenem, doripenem

36

Mechanism of imipenem

broad-spectrum, beta-lactamase-resistant carbapenem

37

What is imipenem administered with?

also with cilastatin (inhibitor of renal dehydropeptidase I) to decrease inactivation of drug in renal tubules

38

Which are the newer carbapenems?

Ertapenem (limited pseudomonas coverage)
Doripenem

39

Use of the carbapenems

gram-positive cocci, gram-negative rods, and anaerobes

wide spectrum, use in LIFE-THREATENING infections after other drugs have failed

40

Toxicity of the carbapenems

GI distress, skin rash, and CNS toxicity (seizures) at high plasma levels

41

Specific about meropenem

has a decreased risk of seizures and is stable to dehydropeptidase I

42

Name the monobactams

aztreonam

43

Mechanism of aztreonam

less susceptible to beta-lactamases
prevents peptidoglycan cross-linking by binding to penicillin-binding protein 3
synergistic with aminoglycosides
NO cross-allergenicity with penicillins

44

Use of aztreonam

gram-negative rods ONLY

use in penicillin-allergic pts and those with renal insufficiency who cannot tolerate aminoglycosides

45

Toxicity of aztreonam

usually nontoxic; occasional GI upset

46

Mechanism of vancomycin

inhibits cell wall peptidoglycan formation by binding to D-ala D-ala portion of cell wall precursors

bactericidal
not susceptible to beta-lactamases

47

Use of vancomycin

gram-positive bugs ONLY
use in serious, multi-drug resistant organisms, including MRSA, S. epidermidis, sensitive Enterococcus species and C. difficile (oral only for pseudomembranous colitis)

48

Toxicity of vancomycin

well tolerated in general but NOT trouble free - Nephrotoxicity, Ototoxicity, Thrombophlebitis

diffuse flushing - RED MAN SYNDROME

49

Prevent Red Man Syndrome

occurs because of too fast infusion of vancomycin

prevent with antihistamines and SLOW infusion rate

50

Resistant to vancomycin

occurs in bacteria via amino acid modification of the D-ala D-ala motif to D-lac D-lac

see this in enterococcus species (VRE)

51

Name the 30S inhibitors

aminoglycosides (bactericidal)
tetracyclines (bacteriostatic)

52

Name the 50S inhibitors

chloramphenicol, clindamycin (bacteriostatic)
erythromycin (macrolides) (bacteriostatic)
linezolid (variable)

53

Name the aminoglycosides

Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin

54

Mechanism of aminoglycosides

bactericidal
irreversible inhibition of initiation complex through binding of the 30S subunit
can cause misreading of the mRNA
blocks translocation
requires O2 for uptake (therefore ineffective against anaerobes)

55

Use of aminoglycosides

severe gram-negative rod infections
synergistic with beta-lactam antibiotics

56

Specific use of neomycin

neomycin for bowel surgery

57

Toxicity of aminoglycosides

Nephrotoxicity, Neuromuscular blockade, Ototoxicity (esp when used with loop diuretics)

Teratogen

58

Resistance to aminoglycosides

bacterial transferase enzymes inactivate the drug by acetylation, phosphorylation or adenylation

59

Name the tetracyclines

tetracycline, doxycycline, minocycline

60

Mechanism of tetracyclines

bacteriostatic; limited CNS penetration

binds to 30S and prevent attachment of aminoacyl-tRNA

61

Specific pharmacokinetic property of doxycycline

it is eliminated fecally and thus can be used in patients with renal failure

62

Interaction of tetracycline and what?

Divalent cations

Tetracyclines should not be taken with milk (Ca2+), antacids (Ca2+ or Mg2+) or iron-containing preparations because divalent cations inhibit drugs absorption in the gut

63

Use of tetracyclines

Borrelia burgdorferi (lymes), M. pneumoniae

drug can accumulate intracellularly so good against Rickettsia and Chlamydia

also used to treat acne

64

Toxicity of tetracyclines

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

contraindicated in PREGNANCY

65

Resistance to tetracyclines

decreased uptake or increased efflux out of bacterial cells by plasmid-encoded transport pumps

66

Mechanism of chloramphenicol

blocks peptidyltransferase at 50S ribosomal subunit

bacteriostatic

67

Use of chloramphenicol

Meningitis (H. influenzae, Neisseria meningitidis, S. pneumoniae)
Rocky Mountain Spotted Fever (Rickettsia rickettsii)

limited use owing to toxicities, used in developing countries because cheap

68

Toxicity of chloramphenicol

Anemia (dose dependent), aplastic anemia (dose independent), gray baby syndrome (in premature infants because they lack the liver UDP-glucoronyl transferase)

69

Resistance to chloamphenicol

plasmid-encoded acetyltransferase inactivates the drug

70

Mechanism of clindamycin

blocks peptide transfer (translocation) at 50S ribosomal subunit
bacteriostatic

71

Use of clindamycin

ABOVE THE DIAPHRAGM ANAEROBES
anaerobic infections (e.g. Bacteroides, Clostridium perfringens) in aspiration pneumonia, lung abscesses, and oral infections

also effective against invasive group A strep infections

72

Toxicity of clindamycin

pseudomembranous colitis (C. diff overgrowth), fever, diarrhea

73

Name the oxazolidinones

linezolid

74

Mechanism of linezolid

inhibit protein synthesis by binding to 50S subunit and preventing formation of the initiation complex

75

Use of linezolid

gram-positive species including MRSA and VRE

76

Toxicity of linezolid

bone marrow suppression (esp. thrombocytopenia), peripheral neuropathy, serotonin syndrome

77

Resistance to linezolid

point mutation of ribosomal RNA

78

Image of the site of action of the protein synthesis/ribosomal subunit inhibitors

insert image

79

Name the macrolides

azithromycin, clarithromycin, erythromycin

80

Mechanism of macrolides

inhibit protein synthesis by blocking translocation
bind to the 23S rRNA of the 50S ribosomal subunit
bacteriostatic

81

Use of macrolides

atypical pneumonia (Mycoplasma, chlamydia, legionella), STIs (chlamydia), gram-positive cocci (strep. pneumo/strep viridans esp in pts allergic to penicillins), and B. pertussis

82

Toxicity of macrolides

MACRO: gi Motility issues, Arrhythmia caused by prolonged QT interval, acute Cholestatic hepatitis, Rash, eOsinophilia

increases serum concentration of theophyllines, oral anticoagulants

clarithromycin and erythromycin inhibit cytochrome p450

83

Resistance to macrolides

Methylation of 23S rRNA-binding site prevents binding of drug

84

Mechanism of trimethoprim

inhibits bacterial dihydrofolate reductase
bacteriostatic

85

Use of trimethoprim

used in combination with sulfonamides (TMP-SMX), causing sequential block of folate synthesis

Combination used for UTIs, shigella, salmonella, pneumocystis jirovecii pneumonia treatment and prophylaxis, toxoplasmosis prophylaxis

86

Toxicity of trimethoprim

Megaloblastic anemia, leukopenia, granulocytopenia (may alleviate with supplemental folinic acid)

TMP Treats Marrow Poorly

87

Name the sulfonamides

sulfamethoxazole (SMX), sulfisoxazole, sulfadiazine

88

Mechanism of sulfonamides

inhibit folate synthesis
para-aminobenzoic acid (PABA) antimetabolites inhibit dihydropteroate synthase
bacteriostatic (bactericidal when with TMP)

89

What is a closely related drug to sulfonamides and what is it used to treat?

Dapsone and it also inhibits folate synthesis

used for lepromatous leprosy

90

Use of sulfonamides

gram-positives, gram-negatives, Nocardia, chlamydia

Triple sulfas or SMX for simple UTI

91

Toxicity of sulfonamides

hypersensitivity reactions, hemolysis if G6PD deficient, nephrotoxicity (tubulointerstitial nephritis), photosensitivity, kernicterus in infants, displace other drugs from albumin (e.g. warfarin)

92

Resistant to sulfonamides

altered enzyme (bacterial dihydropteroate synthase), decreased uptake or increased PABA synthesis

93

Name the fluoroquinolones

ciprofloxacin, norfloxacin, levofloxacin, ofloxacin, moxifloxacin, gemifloxacin, enoxacin

94

Mechanism of fluoroquinolones

inhibit prokaryotic enzymes topoisomerase II (DNA gyrase) and topoisomerase IV
bactericidal
must NOT be taken with antacids

95

Use of fluoroquinolones

gram-negative rods of urinary and GI tracts (including pseudomonas), Neisseria, some gram-positive organisms

96

Toxicity of fluoroquinolones

GI upset, superinfections, skin rashes, headache, dizziness

less common: leg cramps and myalgias

may prolong QT interval
may cause tendonitis or tendon rupture in people >60 years old and in patients taking prednisone

97

Contraindications to fluoroquinolone use

pregnant women, nursing mothers, and children

98

Resistance to fluoroquinolones

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

99

Mechanism of daptomycin

lipopeptide that disrupts cell membrane of gram-positive cocci

100

Use of daptomycin

S. aureus skin infections (especially MRSA), bacteremia, endocarditis, VRE

101

Do not use daptomycin in?

pneumonia because avidly binds to and is inactivated by surfactant

102

Toxicity of daptomycin

myopathy and rhabdomyolysis

103

Mechanism of metronidazole

Forms toxic free radical metabolites in the bacterial cell that damage DNA

bactericidal, antiprotozoal

104

Use of metronidazole

BELOW THE DIAPHRAGM ANAEROBES

treats Giardia, Entamoeba, Trichomonas, Gardnerella vaginalis, Anaerobes (Bacteroides, C. difficile)

used with PPIs and clarithromycin for "triple therapy" against H. Pylori

GET GAP on the metro

105

Toxicity of metronidazole

disulfiram-like reaction (severe flushing, tachycardia, hypotension) with alcohol; headache, metallic taste