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STEP 1 > Antibiotics > Flashcards

Antibiotics Flashcards

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1
Q

Penicillin forms

A 
G = IV, IM
V = oral
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2
Q

Mechanism of penicillin

A

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

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3
Q

Use of penicillin

A

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

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4
Q

Toxicity of penicillin

A

hypersensitivity reactions, hemolytic anemia

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5
Q

Resistance to penicillin

A

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

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6
Q

Mechanism of amoxicillin/ampicillin

A

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

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7
Q

Use of amoxicillin/ampicillin

A

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

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8
Q

Toxicity of amoxicillin/ampicillin

A

Hypersensitivity reactions; rash; pseudomembranous colitis

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9
Q

Resistance to amoxicillin/ampicillin

A

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

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10
Q

Name the penicillinase-resistant penicillins

A

dicloxacillin, nafcillin, oxacillin

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11
Q

Mechanism of dicloxacillin/nafcillin/oxacillin

A

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

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12
Q

Use of dicloxacillin/nafcillin/oxacillin

A

S. aureus (MSSA only)

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

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13
Q

Toxicity of dicloxacillin/nafcillin/oxacillin

A

Hypersensitivity rxn; interstitial nephritis

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14
Q

Name the antipseudomonal penicillins

A

Piperacillin and ticarcillin

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15
Q

Mechanism of piperacillin/ticarcillin

A

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

extended spectrum

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16
Q

Use of piperacillin/ticarcillin

A

pseudomonas spp. and gram-negative rods

susceptible to penicillinase; use with beta-lactamase inhibitors

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17
Q

Toxicity of piperacillin/ticarcillin

A

hypersensitivity rxn

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18
Q

Name the beta-lactamase inhibitors

A

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

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19
Q

Mechanism of the cephalosporins

A

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

bactericidal

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20
Q

Organisms that are NOT covered by cephalosporins

A

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

Exception: ceftaroline covers MRSA

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21
Q

Name the first generation cephalosporins

A

cefazolin, cephalexin

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22
Q

Use of the first generation cephalosporins

A

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

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

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23
Q

Name the second generation cephalosporins

A

cefoxitin, cefaclor, cefuroxime

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24
Q

Use of the second generation cephalosporins

A

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

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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

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