PLAB Pharmacology > Anti-Microbials > Flashcards

Anti-Microbials Flashcards

(131 cards)

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1
Q

Penicillin G, V–form and type of antibiotic

A
  • Penicillin G–IV and IM form
  • Penicillin V–oral form
    • prototype beta lactam antibiotics
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2
Q

penicillin G, V–mechanism

A
  • D-Ala-D-Ala structural analog
  • bind penicillin binding proteins (transpeptidases)
  • block transpeptidase cross linking of peptidoglycan in cell wall
  • activate autolytic enzymes
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3
Q

penicillin G, V–use

A
  • mostly used for gram + organisms–S. pneumoniae, S. pyogenes, Actinomyces
  • also used for gram - organisms–mainly N. meningitidis
  • also used for spirochetes–T. pallidum
  • bactericidal for gram + cocci, gram + rods, gram - cocci, and spirochetes
  • penicillinase sensitive
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4
Q

penicillin G, V–toxicity

A
  • hypersensitivity reactions
  • direct Coombs + hemolytic anemia
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5
Q

penicillin G, V–resistance

A
  • penicillinase in bacteria (a type of beta lactamase) cleaves beta lactam ring
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6
Q

name the penicillinase sensitive penicillins

A
  • amoxicillin
  • ampicillin
  • aminopenicillins
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7
Q

penicillinase sensitive penicillin–mechanism

A
  • same as penicillin
  • wider spectrum
    • “AMinoPenicillins are AMPed up penicillin”
    • penicillinase sensitive
  • also combine with clavulanic acid to protect against destruction by beta lactamase
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8
Q

penicillinase sensitive penicillins–oral bioavailability

A
  • “AmOxicillin has greater Oral bioavailability than ampicillin”
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9
Q

penicillinase sensitive penicillins–use

A
  • extended spectrum penicillin
    • H. influenzae
    • H. pylori
    • E. coli
    • Listeria monocytogenes
    • Proteus mirabilis
    • Salmonella
    • Shigella
    • enterococci
  • coverage:
    • ampicillin amoxicillin HHELPSS kill entercocci
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10
Q

penicillinase sensitive penicillins–toxicity

A
  • hypersensitivity reactions
  • rash
  • pseudomembranous colitis
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11
Q

penicillinase sensitive penicillins–mechanism of resistance

A
  • penicillinase in bacteria (a type of beta lactamase) cleaves beta-lactam ring
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12
Q

name the penicillinase-resistant penicillins

A
  • dicloxacillin
  • nafcillin
  • oxacillin
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13
Q

penicillinase-resistant penicillins–mechanism

A
  • same as penicillin
  • narrow spectrum
    • penicillinase resistant b/c bulky R group blocks access of beta-lactamase to beta-lactam ring
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14
Q

penicillinase-resistant penicillins–use

A
  • S. aureus–except MRSA: resistant b/c of altered penicillin binding protein target site
    • “use naf (nafcillin) for staph”
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15
Q

penicillinase-resistant penicillins–toxicity

A
  • hypersensitivity rxns
  • interstitial nephritis
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16
Q

name the antipseudomonal penicillins

A
  • piperacillin
  • ticarcillin
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17
Q

antipseudomonal penicillins–use

A
  • Pseudomonas spp. and gram - rods
  • susceptible to penicillinase
  • use with beta lactamase inhibitors
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18
Q

antipseudomonal penicillins–toxicity

A
  • hypersensitivity rxns
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19
Q

name the beta lactamase inhibitors

A
  • Clavulanic Acid
  • Sulbactam
  • Tazobactam
    • CAST
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20
Q

what are beta lactamase inhibitors often taken with? Why?

A
  • often added to penicillin to antibiotics
    • to protect the antibiotic from destruction by beta-lactamase (penicillinase)
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21
Q

cephalosporins (gen I-IV)–mechanism

A
  • beta lactam drugs that inhibit cell wall synthesis but are less susceptible to penicillinases
  • bactericidal
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22
Q

what are the organisms not covered by 1st-4th generation cephalosporins? what is the exception?

A
  • LAME
    • Listeria
    • Atypicals–Chlamydia, Mycoplasma
    • MRSA
    • Enterococci
  • exception: ceftaroline–5th generation cephalosporin which covers MRSA
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23
Q

1st gen cephalosporins:

name 2

what organisms do they cover?

A
  • cefazolin
  • cephalexin
  • gram + cocci
  • Proteus mirabilis
  • E. coli
  • Klebsiella pneumoniae
    • ​“PEcK”
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24
Q

why would cefazolin be used prior to surgery?

A
  • to prevent S. aureus wound infections
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25
2nd gen cephalosporins: name 3 what organisms do they cover?
* ce**fa**clor * ce**fox**itin * ce**fur**oxime * "**Fa**ke **fox fur**" * gram + cocci * ***H.** influenzae* * ***E**nterobacter aerogenes* * ***N**eisseria spp.* * ***S**erratia marcesvens* * ***P**roteus mirabilis* * ***E.** coli* * ***K****lebsiella pneumoniae* * *​"***HENS PEcK**"
26
3rd gen cephalosporins: name 3 what organisms do they cover?
* ceftriaxone * meningitis * gonorrhea * disseminated Lyme dz * cefotaxime * ceftazidime * *Pseudomonas* * serious gram - infections resistant to other beta lactams
27
4th gen cephalosporins: name 1 what organisms do they cover?
* cefepime * gram - organisms * with increased activity against *Pseudomonas* and gram + organisms
28
5th gen cephalosporins: name 1 what organisms do they cover?
* ceftaroline * broad gram + and gram - organism coverage, including MRSA * does NOT cover *Pseudomonas*
29
cephalosporins--toxicity
* hypersensitivity rxns * autoimmune hemolytic anemia * disulfiram like rxn * vitamin K deficiency * exhibit cross reactivity with penicillins * inc nephrotoxicity of aminoglycosides
30
cephalosporins--mechanism of resistance
* structural change in penicillin binding proteins--transpeptidases
31
name the carbapenems
* imipenem * meropenem * ertapenem * doripenem * newer carbapenems include ertapenem (limited *Pseudomonas* coverage) and doripenem)
32
imipenem--mechanism
* (carbapenems) * imipenem is broad spectrum, beta lactamase resistant carbapenem
33
what is imipenem always administered with? why?
* cilastatin (inhibitor of renal dehydropeptidase I) to decrease inactivation of drug in renal tubules * with imipenem, "the kill is **lastin**' with ci**lastin**"
34
carbapenems--use
* gram + cocci * gram - rods * anaerobes * wide spectrum but significant side effects limit use to life threatening infections or after other drugs have failed * meropenem--dec risk of seizures and is stable to dehydropeptidase I
35
carbapenems--toxicity
* GI distres * skin rash * CNS toxicity at high plasma levels * seizures
36
name the monobactam
* aztreonam
37
monobactam (aztreonam)--mechanism
* less susceptible to beta lactamases * prevents peptidoglycan cross linking by binding to penicillin-binding protein 3 * synergistic with aminoglycoside * no cross allergenicity with penicillins
38
monobactam (aztreonam)--use
* gram - rods only * no activity against gram + rods or anaerobes * for penicillin allergic patients and those with renal insufficiency who cannot tolerate aminoglycosides
39
monobactams--toxicity
* usually nontoxic * occasional GI upset
40
vancomycin--mechanism
* inhibits cell wall peptidoglycan formation by binding D-ala-D-ala portion of cell wall precursors * bactericidal against most bacteria * bacteriostatic against *C. difficile* * not susceptible to beta lactamases
41
vancomycin--use
* gram + bugs only * serious, multidrug-resistant organisms, including MRSA, *S. epidermidis*, sensitive *Enterococcus* species, *Clostridium difficile* * oral dose for pseudomembranous colitis
42
vancomycin--toxicity
* well tolerated in general but **NOT** trouble free * **N**ephrotoxicity * **O**totoxicity * **T**hrombophlebitis * diffuse flusing--red man syndrome * can largely prevent by pretreatment with antihistamines and slow infusion rate
43
vancomycin--mechanism of resistance
* occurs in bacteria via amino acid modification of **D-ala-D-ala** to D-ala-D-lac * "Pay back **2 D-ala**s (dollars) for **van**dalizing (**van**comycin)"
44
protein synthesis inhibitors--mechanism
* specifically, target smaller bacterial ribosome (70S, made of 30S and 50S subunits), leaving human ribosome (80S) unaffected
45
name the 30S and 50S inhibitors
* **30**S inhibitors * **A** = **A**minoglycosides [bactericidal] * **T** = **T**etracyclines [bacteriostatic] * **50**S inhibitors * **C** = **C**hloramphenicol, **C**lindamycin [bacteriostatic] * **E** = **E**rythromycin (macrolides) [bacteriostatic] * **L** = **L**inezolid [variable] * "Buy **AT 30, CCEL** (sell) at **50**"
46
name the aminoglycosides
* **G**entamicin * **N**eomycin * **A**mikacin * **T**obramycin * **S**treptomycin * "**Mean"** (a**min**oglycoside) **GNATS** ca**NNOT** kill anaerobes"
47
aminoglycosides--mechanism
* bactericidal * irreversible inhibition of initiation complex thru binding of the 30S subunit * can cause misreadin gof mRNA * also block translocation * require O2 for uptake * therefore ineffective against anaerobes
48
aminoglycosides--use
* severe gram - rod infections * synergistic with beta lactam antibiotics * neomycin for bowel surgery
49
aminoglycosides--toxicity
* **N**ephrotoxicity * **N**euromuscular blockage * **O**totoxicity * especially when used with loop diuretics * **T**eratogen * "**Mean**" (aminoglycoside) **GNATS** ca**NNOT** kill anaerobes"
50
aminoglycosides--mechanism of resistance
* bacterial transferase enzymes inactivate the drug by acetylation, phosphorylation, or adenylation
51
name the drug classes that block cell wall synthesis by inhibition of peptidoglycan cross linking?
* penicillinase sensitive penicillins * penicillinase resistant penicillins * antipseudomonals * cephalosporins * carbapenems * monobactams
52
name the drugs that prevent cell wall synthesis by inhibiting peptidoglycan synthesis
* vancomycin * bacitracin
53
name the drugs that block nucleotide synthesis by inhibiting folic acid synthesis (involved in methylation)
* sulfonamides * trimethoprim
54
name the drug that damages DNA via free radicals
* metronidazole
55
name the drug that blocks mRNA synthesis
* rifampin
56
name the drug classes that block DNA gyrase
* fluoroquinolones * quinolone
57
name the drugs that block protein synthesis at the 50S subunit
* chloramphenicol * clindamycin * linezolid * macrolides * streptogramins
58
name the drugs that block protein synthesis at the 30S subunit
* aminoglycosides * tetracyclines
59
name the tetracyclines
* tetracycline * doxycycline * minocycline
60
tetracyclines--mechanism
* bacteriostatic * bind to 30S and prevent attachment of aminoacyl tRNA * limited CNS penetration
61
how is doxycycline eliminated, and in which patients can it be used?
* fecally eliminated * can be used in patients with renal failure
62
what should you avoid when taking tetracyclines, and why?
* milk (Ca2+), antacids (Ca2+ or Mg2+), or iron containing preparations * b/c divalent cations inhibit drugs' absorption in the gut
63
tetracyclines--use
* *Borrelia burgforferi* * *M. pneumoniae* * drugs ability to accumulate intracellularly makes them very effective against *Rickettsia* and *Chlamydia* * used to treat acne
64
tetracyclines--toxicity
* GI distress * discoloration of teeth and inhibition of bone growth in children * photosensitivity
65
what is a contraindication for taking tetracyclines?
* pregnancy
66
tetracyclines--mechanism of resistance
* dec uptake or inc efflux out of bacterial cells by plasmid encoded transport groups
67
chloramphenicol--mechanism
* blocks peptidyltransferase at 50S ribosomal subunit * bacteriostatic
68
chloramphenicol--use
* meningitis (*Haemophilus influenzae, Neisseria meningitidis, Stretococcus pneuomoniae*) and Rocky Mountain Spotted Fever (*RIckettsia rickettsii*) * limited use owing to toxicities but often still used in developing countries b/c of low cost
69
chloramphenicol--toxicity
* anemia--dose dependent * aplastic anemia--dose independent * gray baby syndrome--in premature infants b/c they lack liver UDP glucuronyl transferase
70
chloramphenicol--mechanism of resistance
* plasmid encoded acetyltransferase inactivates the drug
71
clindamycin--mechanism
* blocks peptide transfer (translocation) at 50S ribosomal subunit * bacteriostatic
72
clindamycin--use
* anaerobic infections (ie. *Bacteroides* spp., *Clostridium perfringens*) in aspiration pneumonia, lung abscesses, and oral infections * also effective against invasive group A streptococcal infection
73
clindamycin vs. metronidazole
* clindamycin--treats anaerobic infections _above_ the diaphragm * metronidazole--treats anaerobic infections _below_ the diaphragm
74
name the oxalidinones
* linezolid
75
oxalidinones--mechanism
* inhibit protein synthesis by binding to 50S subunt and preventing formation of the initiation complex
76
oxalidinones--use
* gram + species including MRSA and VRE
77
oxalidinones--toxicity
* bone marrow suppression--especially thrombocytopenia * peripheral neuropathy * serotonin syndrome
78
oxalidinones--mechanism of resistance
* point mutation of ribosomal RNA
79
name the macrolides
* azithromycin * clarithromycin * erythromycin
80
macrolides--mechanism
* inhibit protein synthesis by blocking translocation ("macro**slides**") * bind to the 23S rRNA of the 50S ribosomal subunit * bacteriostatic
81
macrolides--use
* atypical pneumonias--*Mycoplasma, Chlamydia, Legionella* * STIs--*Chlamydia* * gram + cocci--streptococcal infections in patients allergic to penicllin * *B pertussis*
82
macrolides--toxicity
* **MACRO** * gastrointestinal **M**otility issues * **A**rrhythmia caused by prolonged QT interval * acure **C**holestatic hepatitis * **R**ash * e**O**sinophilia * increases serum concentration of theophylline, oral anticoagulants * clarithromycin and erythromycin inhibit cytochrome P-450
83
macrolides--mechanism of resistance
* methylation of 23S rRNA -binding site prevents binding of drug
84
name the sulfonamides
* sulfamethoxazole (SMX) * sulfisoxazole * sulfadiazine
85
sulfonamides--mechanism
* inhibit dihydropteroate synthase, thus inhibiting folate synthesis * bacteriostatic * bacteriocidal when combined with trimethoprim
86
sulfonamides--use
* gram + * gram - * *Nocardia* * *Chlamydia* * SMX for simple UTI
87
sulfonamides--toxicity
* hypersensitivity rxns * hemolysis if G6PD deficient * nephrotoxicity--tubulointerstitial nephritis * photosensitivity * kernicterus in infants * displace other drugs from albumin (ie. warfarin)
88
sulfonamides--mechanism of resistance
* altered enzyme (bacterial dihydropteroate) * decrease uptake * increase PABA synthesis
89
dapsone--mechanism
* similar to sulfonamides * but structurally distinct agent
90
dapsone--use
* leprosy (lepromatous and tuberculoid) * *Pneumocystis jirovecii* prophylaxis
91
dapsone--toxicity
* hemolysis if G6PD deficient
92
trimethoprim--mechanism
* inhibits bacterial dihydrofolate reductase * bacteriostatic
93
trimethoprim--use
* used in combination with sulfonamides (trimethoprim-sulfamethoxazole [TMP-SMX]) * causes sequential block of folate synthesis * combination used for UTIs, *shigella*, *Salmonella, Pneuomocystis* *jirovecii* pneuomonia treatment and prophylaxis, toxoplasmosis prophylaxis
94
trimethoprim--toxicity
* megaloblastic anemia * leukopenia * granulocytopenia * may alleviate with supplemental folinic acid * "**TMP T**reats **M**arrow **P**oorly"
95
name the fluoroquinolones
* ciprofloxacin * norfloxacin * levofloxacin * ofloxacin * moxifloxacin * gemifloxacin * enoxacin
96
fluoroquinolones--mechanism
* inhibit prokaryotic enzymes topoisomerase II (DNA gyrase) and topoisomerase IV * bactericidal * must not be taken with antacids
97
fluoroquinolones--use
* gram - rods of urinary and GI tracts (including *Pseudomonas*) * *Neisseria* * some gram + organisms
98
fluoroquinolones--toxicity
* GI upset * superinfections * skin rashes * headache * dizziness * less commonly, can cause leg cramps and myalgias * may prolong QT interval * may cause tendonitis or tendon rupture in people \> 60 years old and in patients taking prednisone * "fluoroquino**lones** hurt attachments to your **bones**"
99
what are contraindications for fluoroquinolones?
* pregnant women * nursing mothers * children \< 18 yo due to possible damage to cartilage
100
fluoroquinolones--mechanism of resistance
* chromosome encoded mutation in DNA gyrase * plasmid mediated resistance * efflux pumps
101
daptomycin--mechanism
* lipopeptide that disrupts cell membrane of gram + cocci
102
daptomycin--use
* *S. aureus* skin infections (especially MRSA) * bacteremia * endocarditis * VRE
103
why is daptomycin not used for pneumonia?
* daptomycin avidly binds to and is inactivated by surfactant
104
metronidazole--mechanism
* forms toxic free radical metabolites in the bacterial cell that damage DNA bactericidal * antiprotozoal
105
metronidazole--use
* treats: * ***G**iardia* * ***E**ntamoeba* * ***T**richomonas* * ***G**ardnerella vaginalis* * **A**naerobes--*Bacteroides, C. difficile* * used with a proton pump inhibitor and clarithromycin for "triple therapy" against *H. **p**ylori* * *​*"**GET GAP** on the **M**etro with **metro**nidazole"
106
metronidazole--toxicity
* disulfiram-like rxn (severe flushing, tachycardia, hypotension) with alcohol * headache * metallic taste
107
* M. tuberculosis* 1. prophylaxis 2. treatment
1. Isoniazid 2. **R**ifampin, **I**soniazid, **P**yrazinamide, **E**thambutol 1. **RIPE** for treatment
108
* M. avium-intracellulare*​ 1. prophylaxis 2. treatment
1. azithromycin, rifabutin 2. more drug resistant than *M. tuberculosis* 1. azithromycin or clarithromycin + ethambutol 2. can add rifabutin or ciprofloxacin
109
* M. leprae* 1. prophylaxis 2. treatment
1. N/A 2. long term treatment with dapsone and rifampin for tuberculoid form 1. add clofazimine for lepramatous form
110
name the rifamycins
* rifampin * rifabutin
111
rifamycins--mechanism
* inhibit DNA dependent RNA polymerase
112
rifamycins--use
* *Mycobacterium tuberculosis* * delay resistance to dapsone when used for leprosy * used for meningococcal prphylaxis and chemoprophylaxis in contacts of children with *Haemophilus influenzae* type B
113
rifamycins--toxicity
* minor hepatotoxicity * drug reactions--inc cytochrome P-450 * orange body fluids--non hazardous side effect
114
when is rifabutin favored over rifampin and why?
* RIfabutin favored over rifampin in patients with HIV infection due to less cytochrome P-450 stimulation * "**R**if**amp**in **ramp**s up cytochrome P-450, **but** rifa**but**in does not"
115
rifamycins--mechanism of resistance
* mutations reduce drug binding to RNA polymerase * monotherapy rapidly leads to resistance
116
Rifampin: 4 things to remember
* **4 R's** * **​R**NA polymerase inhibitor * **R**amps up microsomal cytochrome P-450 * **R**ed/orange body fluids * **R**apid resistance if used alone
117
name the 4 antimycobacterial drugs
* Rifamycins--rifampin, rifabutin * Isoniazid * Pyrazinamide * Ethambutol * Streptomycin
118
Isoniazid--mechanism
* dec synthesis of mycolic acids * bacterial catalase-peroxidase (encoded by KatG) needed to convert INH to active metabolite
119
Isoniazid--use
* *Mycobacterium tuberculosis* * this is the only agent used as solo prophylaxis against TB * also used as monotherapy for latent TB
120
isoniazid--toxicity
* hepatotoxicity * P-450 inhibition * drug induced SLE * vitamin B6 deficiency--peripheral neuropathy, sideroblastic anemia * **INH I**njures **N**eurons and **H**epatocytes
121
what should be administered with isoniazid?
* puridoxine (vitamin B6)
122
isoniazid--mechanism of resistance
* mutations leading to underexpression of KatG
123
pyrazinamide--mechanism
* mechanism uncertain * prodrug that is converted to the active compound pyrazinoic acid * works best at acidic pH (ie. in host phagolysosomes)
124
pyrazinamide--use
* *Mycobacterium tuberculosis*
125
pyrazinamide--toxicity
* hyperuricemia * hepatotoxicity
126
ethambutol--mechanism
* dec carbohydrate polymerization of mycobacterium cell wall by blocking arabinocyltransferase
127
ethambutol--use
* *Mycobacterium tuberculosis*
128
ethambutol--toxicity
* **optic** neuropathy (red-green color blindness) * pronouce "**eye**thambutol"
129
streptomycin--mechanism
* interferes with 30S component of ribosome
130
streptomycin--use
* *Mycobacterium tuberculosis* (2nd line)
131
streptomycin--toxicity
* tinnitus * vertigo * nephrotoxicity
PLAB Pharmacology
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