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Microbiology > Drugs > Flashcards

Drugs Flashcards

1
Q

Strategies toward development of new antibiotics

A
  1. Combat bacterial resistance mechanisms: develop inhibitors of drug inactivating proteins and efflux transporters, develop drug analogs that are resistant to drug-inactivating proteins
  2. ID new targets for chemotherapy for chemotherapy
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2
Q

Aminoglycosides

A

Antibiotics that inhibit protein synthesis

Includes streptomycin, tobramycin, gentamicin, amikacin, neomycin, kanamycin

Targets 30S ribosomal subunit to irreversibly interfere with protein synthesis by either blocking initiation, blocking ribosomal translocation, or causing mistranslation

Post-antibiotic effect

Bactericidal against many aerobic gram negative bacteria

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3
Q

Streptomycin

A

Aminoglycoside

Used as second-line treatment for TB (in combo with other agents to inhibit resistance)

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4
Q

Tobramycin

A

Most clinically used aminoglycoside

Used for severe infections caused by aerobic Gram- bacteria that are resistant to other drugs

Often used in combo with beta-lactam antibiotics because synergystic

More expensive than gentamycin

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5
Q

Gentamicin

A

Most clinically used aminoglycoside

Used for severe infections caused by aerobic Gram- bacteria that are resistant to other drugs

Often used in combo with beta-lactam antibiotics because synergystic

More cheaper than tobramycin

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6
Q

Amikacin

A

Aminoglycosides

Only really used in cases of resistance to tobramycin and gentamicin (there are many bacterially-produced enzymes that cause inactivate tobramycin and genamicin)

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7
Q

Neomycin

A

Aminoglycoside

Restricted to topical use only because very toxic (neosporin)

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8
Q

Kanamycin

A

Aminoglycoside

Restricted to topical use only because very toxic

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9
Q

Adverse Effects from Aminoglycosides

A

Reversible nephrotoxicity

Irreversible ototoxicity (auditory damage and/or vestibular damage)
Auditory damage include tinnitus, high frequency hearing loss
Vestibular damage includes vertigo and ataxia

More likely to occur with use of aminoglycosides longer than 5 days

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10
Q

Tetracyclines

A

Inhibit protein synthesis

By blocking 30s ribosomal subunit, inhibit peptide elongation

Bacteriostatic for many aerobic Gram+ and -, including rickettsiae, chlamydiae, and mycoplasmas

Used for rickettsial infections (RMSF, typhus, and Q fever), STIs (chlamydia, urethritis, cervicitis, and epididymititis), respiratory tract infections (pneumonia), Lyme’, anthrax, malaria, and skin/soft tissue infections

Absorption is impaired by food and multivalent cations (Ca2+, Mg2+, Fe2+, and Al3+) cause chelation

Includes tetracycline, oxytetracycline, demeclocycline, minocycline, doxycycline, and tigecycline (first two have VERY short half life)

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11
Q

Adverse Effects from Tetracyclines

A

GI problems (nausea, vommitting, diarrhea)

Tooth discoloration and deformity, especially in children

Photosensitization (easily sunburn)

Hepatoxicity during pregnancy

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12
Q

Doxycycline

A

Tetracycline used for treatment and prevention of malaria, anthrax, and treatment of Lyme

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13
Q

Tigercycline

A

An IV tetracycline with a long half life used for treatment of community acquired pneumonia, intra-abdominal, skin and soft tissue infections cause by MDR bacteria (MRSA, VRE, etc)

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14
Q

Macrolides

A

Inhibit protein synthesis

Bind to the 50S subunit to inhibit ribosomal translocation

Bacteriostatic against aerobic Gram+ and some Gram- bacteria

Used for community acquired pneumonia, bronchitis, otitis media, strep throat, chlamydia, diptheria, pertussiss

Erythromycin, carithromycin, azithromycin, and telithromycin

Can cause GI problems and hepatotoxicity

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15
Q

Azithromycin

A

Macrolide with long half life

Aka Z-Pak

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16
Q

Lincosamide

A

Inhibits protein synthesis

Binds to 50S subunit and interferes with protein synthesis by blocking ribosomal translocation

Bacteriostatic ONLY against aerobic and anaerobic Gram+ bacteria

Used for soft tissue and skin infections

Can cause diarrhea, pseudomembranous colitis caused by C. dif, and skin rash

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17
Q

Adverse effects from macrolides

A

Hepatotoxicity-through hypersensitivity reaction

GI Effects-stimulate gut motility-anorexia, nausea, vomiting, and diarrhea accompanying oral administration

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18
Q

Strepogramins

A

Protein synthesis inhibitors

Bind to 50S ribosomal subunit to inhibit ribosomal translocation

For VRE and MSSA (not MRSA)

Used against Gram+ bacteria

Quinupristin and dalfopristin

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19
Q

Oxazolidinone

A

Protein synthesis inhibitors

Bind to 50S to inhibit initiation step of protein synthesis

Used against aerobic and anaerobic Gram+

Used for treatment of infections caused by MDR gram+ bacteria (MRSA, VRE, and penicillin resistant streptococci)

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20
Q

Sulfonamides

A

Inhibit DNA synthesis (anti-folate)

Competitive antagonist of dihydropteroate synthase needed for purine synthesis; act as PABA analogs

Bacteriostatic when used as single agent; bactericidal when used with tripmethoprim (which inhibits DNA synthesis further downstream)

Sulfisoxazole, sulfamethoxazole, and sulfasalazine

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21
Q

Sulfisoxazole

A

Sulfonimide (antifolate DNA synthesis inhibitor)

Used for UTIs

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22
Q

Sulfamethoxazole

A

Sulfonimide (antifolate DNA synthesis inhibitor)

Used for UTIs

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23
Q

Sulfasalazine

A

Sulfonamide (anti-folate DNA synthesis inhibitor)

Used for ulcerative colitis, enteritis, and other IBD
Has anti-inflammatory properties

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24
Q

Adverse effects of sulfonamides

A

Hypersensitivity/allergic reactions-fever, rash,

Most serious=crystalluria, hematuria, or obstruction

25
Q

TMP-SMX

A

Combination of trimethoprim and sulfamethoxazole

Both are anti-folates that, when used together, are bactericidal

Used for UTIs, pneumonia, Shigellosis, Salmonella, prostatitis, and acute bronchitis

Treatment less than 5 days can cause allergic reaction
Treatment longer than 5 days can cause megaloblastic anemia and leukopenia

26
Q

Trimethoprim

A

Inhibits DNA synthesis

Blocks DHFR needed to make purines

27
Q

Fluroquinolone

A

Inhibit DNA synthesis

Inhibit DNA gyrase and topoisomerase

Bactericidal against Gram- and Gram+

Used for UTIs, diarrhea caused by Shigella or Salmonella or E. Coli, soft tissue and bone and joint infections, intra-abdominal infections, respiratory tract infections

Levofloxacin, gemifloxacin, and moxifloxacin effective for respiratory tract infections

Cipro used for anthrax (caused by Gram+)

Ciprofloxacin, lomefloxacin, levofloxacin, ofloxain, gemifloxacin, moxifloxacin

28
Q

Beta-Lactam Antibiotics

A

Antibiotic that targets cell wall

Inhibit cross linking of peptidoglycan units by mimicking D-Ala-D-Ala to bind to Ser-enzyme

Without cell wall, bacteria bursts

Combined with beta-lactamase inhibitors

4 types, but all share core ring: penicillin, cephalosporin, monobactam, and carbepenems

29
Q

Beta-lactamase

Action and drug names

A

Gram- response to beta-lactam antibiotics

Clavulanic acid
Avibactam-broad spectrum inhibitor

Act like transpeptidases, but use water to hydrolyze serine-lactam linkage to irreversibly inactivate beta-lactams and allow for peptidoglycan cross linking

Two types: serine and metallo

30
Q

Penicillin

Details and drug names

A

Beta-lactam antibiotic

Use with probenecid to increase half life (prevent excretion)

Oral, IV, or IM administration

Common: pencillin G
Antistaphlycoccal pencillin: oxacillin, cloxacillin, dicloxacillin
Extended spectrum: amoxicillin

Resistance=MRSA

31
Q

Penicillin G

A

Beta-lactam antibiotic, Common penicillin

Acid labile, beta-lactamase susceptible

Gram+, and Gram- cocci

32
Q

Anti-staphylococcal Penicillins

A

Beta-lactam antibiotic

Includes oxacillin, cloxacillin, and dicloxacillin

Acid stable, beta-lactamase resistant

not suitable for enterococci, anaerobes, and Gram- cocci and rods

33
Q

Amoxicillin

A

Beta-lactam antibiotic, extended spectrum penicillin

Acid stable, beta-lactamase sensitive

Greater activity against Gram- because able to penetrate outer membrane

With clavulanate=augmentin

34
Q

Cephalosporins

A

Beta-lactam antibiotic

Greater spectrum because increased resistance to beta-lactamases

5 generations

35
Q

Cefazolin

A

First generation cephalosporin

Best for Gram+

Given for surgery prophylaxis

36
Q

Cefamandole

A

Second generation cephalosporin

Gram + and -
No allergic cross reactivity with penicillin

37
Q

Ceftazidime

A

Third generation cephalosporin

Extend Gram- at expense of Gram+

Can cross BBB

38
Q

Cefepime

A

Fourth generation cephalosporin

Broad spectrum

Penetrates BBB

39
Q

Ceftaroline

A

Fifth generation cephalosporin

Used for MRSA because has high affinity for transpeptidase found in MRSA

40
Q

Monobactams

A

Beta-lactam antibiotic

Active ONLY against Gram-rods

Given by IV and excreted rapidly

Resistant to beta-lactamases

No cross reactivity with pencillin

41
Q

Aztreonam

A

Beta-lactam antibiotic, Monobactam

Only active against Gram- rods

42
Q

Carbapenems

A

Beta-lactam antibiotic, Imipenem

Broad spectrum

Cilastatin used to block excretion.

Resistant to serine bet-lactamases, but NOT metallo beta-lactamases

Cross BBB

Cross reactivity with penicillin allergies

43
Q

Imipenem

A

Beta lactam antibiotic, carbapenem

Broad spectrum and can cross BBB

44
Q

Vancomycin

A

Glycopeptide; Non-beta lactam cell wall inhibitor

For Gram+ bacteria, especially staphylococci
Too big to affect Gram-

Binds tightly to D-Ala-D-Ala to block transglycosylase and transpeptidase action

Used for MRSA and methicillin-resistant endocarditis or sepsis

Resistance: bacteria switches from D-Ala-D-Ala to D-Ala-D-Lactate, which decreases Vancomycin affinity by 1000x

Requires IV administration

45
Q

Dalbavancin

A

Glycopeptide non-beta lactam antibiotic

Derivative of Vancomycin, but only need two doses

46
Q

Oritavancin

A

Glycopeptide non-beta lactam antibiotic

Derivative of Vancomycin, but only need one dose

47
Q

Daptomycin

A

Lipopeptide non-beta lactam antibiotic

Drills pores in inner membrane of Gram+ that allow K+ loss WITHOUT cell rupture

48
Q

Polymyxins

A

A lipopeptide non-beta lactam antibiotic

Binds to a liposaccharide only on outer membrane of GRAM- bacteria and makes perforation leading to permeability of the inner and outer cell membrane

Used topically; in neosporin

49
Q

Fosfomycin

A

Antibiotic inhibitor of peptidoglycan precursors

Inhibits MurA, which is needed to catalyze the first committed step (NAG-UDP –> NAM-UDP)

Used for Gram+ and-

Commonly used for UTIs

50
Q

Bacitracin

A

Antibiotic inhibitor of peptidoglycan precursors

Inhibits dephosphorylation of lipid carrier of peptidoglycan subunits

Active only against Gram+

Only used topically

51
Q

D-Cycloserine

A

Antibiotic inhibitor of peptidoglycan precursors

D-Ala analog so inhibits enyzmes needed to convert Ala–>D-Ala (racemase) and glue D-Ala subunits together (D-alanine ligase)

Used in combination with other antibiotics as a second line drug to treat TB, but otherwise toxic

52
Q

First line TB drugs

A

Rifampin
Isoniazid
Pyrazinamide
Ethambutol

53
Q

Features of Second-line TB drugs

A

Given for MDR-TB

Less effective than first line drugs with significant side effects

Expensive

54
Q

Isoniazid

A

First line treatment for TB; targets mycolic acid biosynthesis at FAS-II

Bactericidal against both extracellular and intramacrophage mycobacteria

Taken orally

High probability of resistance, so used with other drugs

Pro-drug activated by bacterial enzyme KatG

Side effects: hepatitis and peripheral neuropathy (because competitive inhibitor of vitamin B6)

Supplement administration with B6

Metabolism varies by genetics; drug inactivated by acetylation

55
Q

Rifampin

A

First line treatment for TB

Inhibits bacterial transcription elongation by inhibiting RNA from interacting with RNApol

Bactericidal

Administer orally

Side effects: flu-like symptoms; increases P450 members including CYP3A which increases elimination of other drugs
Harmless red or purple urine

56
Q

Rifabutin

Rifapentine

A

Derivative of rifampin used as first line treatment for TB

Have higher potency, longer half life, and less CYP interference

57
Q

Pyrazinamide

A

First line treatment for TB that inhibits protein synthesis

Bactericidal; pro-drug activated by PZase

Oral

Inhibits trans-translation so there is a defect in rescue of stalled ribosome and depletion of available ribosomes for protein synthesis

Works synergistically with rifampin

Rapid emergence of resistance

58
Q

Ethambutol

A

First line treatment for TB

Inhibits incorporation of arabinose in cell wall; cell wall is too weak

Oral

Side effects: optic neuritis and red green color blindness

High probability of resistance

Microbiology (10 decks)

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