Antibiotics

Front 1

polymyxin B (and ciprofloxacin)

Back 1

selective activity against G- enteric rods, esp against Pseudomonas

Front 2

polymyxin B

Back 2

positively charged polypeptide antibiotic binds first to negatively charged LPS in the outer membrane, then to cytoplasmic membrane phospholipids, causing membrane leakage

Front 3

polymyxin B

Back 3

commonly used as topical agents--systemic use largely supplanted by more effective and less toxic agents

Front 4

polymyxin B

Back 4

affects membrane permeability

Front 5

streptomycin

Back 5

no longer widely used in therapy except in TB

Front 6

streptomycin

Back 6

discovered in deliberate search for antibiotics produced by soil bacteria, extended range of antibiotic therapy to mycobacterium tuberculosis and many gram-negative organisms for which there had not been an effective treatment

Front 7

streptomycin

Back 7

positively charged at physiological pH

Front 8

streptomycin

Back 8

does not penetrate bacteria readily

Front 9

streptomycin

Back 9

some metabolic activity by bacterium needed for antibiotic to enter

Front 10

streptomycin, gentamycin

Back 10

requires aerobic conditions to be effective, inhibited under anaerobic conditions or acid conditions

Front 11

streptomycin

Back 11

bacteriocidal but not lytic

Front 12

streptomycin

Back 12

action on 30S ribosomal subunit, shown by mixing sensitive and resistant subunits in criss-cross experiment and reconstitution of 30S subunits from individual RNA and protein molecules

Front 13

streptomycin

Back 13

at low concentrations binds specifically to 30S ribosomal protein, distorting acceptor site, causing misreading, which causes bad proteins to be made, membrane leakiness, and increase in antibiotic uptake

Front 14

streptomycin

Back 14

molecules enter cell through imperfections in growing membrane

Front 15

streptomycin

Back 15

high concentrations: inhibits formation of initiation complex and peptide bond formation

Front 16

streptomycin

Back 16

resistant mutants readily obtained; mutation occurs before contact with antibiotic, which selects for mutants by providing environment that favors their growth while inhibiting non-resistant bacteria

Front 17

gentamicin

Back 17

interacts with more than one ribosomal protein on 30S subunit, can't obtain resistance in one step

Front 18

gentamicin

Back 18

toxic effects, damaging 8th cranial nerve or renal function

Front 19

tetracycline, doxycycline

Back 19

blocks binding of aminoacyl-RNA to 30S ribosomal subunit

Front 20

tetracycline, doxycycline

Back 20

well-absorbed orally and suited to out-patient treatment when therapy needed over a week or two

Front 21

tetracycline, doxycycline

Back 21

broad spectrum of action, including mycoplasma, rickettsia, chlamydia

Front 22

tetracycline, doxycycline

Back 22

not to be given in pregnancy because of possible adverse effects on fetus--some serious some minor

Front 23

tetracycline, doxycycline

Back 23

up to age of 8, children develop mottled enamel

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tigecycline

Back 24

most potent tetracycline dreivative

Front 25

tigecycline

Back 25

chemical side-chain that makes it refractory to common mechanism of resistance with efflux pump

Front 26

erythromycin, azithromycin

Back 26

blocks chain elongation

Front 27

erythromycin

Back 27

widely used therapeutic agent with spectrum of activity similar to penicillin G but includes mycoplasma and chlamydia

Front 28

azithromycin

Back 28

oral drug related to erythromycin but with higher activity and slightly broader spectrum

Front 29

azithromycin

Back 29

high and sustained tissue concentrations (T 1/2 = 70hr), which increase at site of infection--attributable to uptake by phagocytes which migrate to site

Front 30

chloramphenicol

Back 30

bacteriostatic, though in some bacterial species cessation of growth leads to cidal effect

Front 31

chloramphenicol

Back 31

rarely induces uncommon but sometimes lethal, aplastic anemia

Front 32

chloramphenicol

Back 32

useful against some anaerobes, particularly bowel anaerobes such as B. fragilis

Front 33

chloramphenicol

Back 33

in the U.S., dispensing requires prescription; other countries, sold over thecounter

Front 34

clindamycin

Back 34

derivative of lincomycin

Front 35

clindamycin

Back 35

activity against G+ and moderate activity against anaerobes

Front 36

clindamycin

Back 36

inhibits peptidyl transfer

Front 37

oxazolidinones

Back 37

first new class of anti-ribosomal drugs to be developed in 35 years

Front 38

oxazolidinones

Back 38

highly active against G+ organisms

Front 39

oxazolidinones

Back 39

potential for treating especially VREF, but also potentially MRSA, VRSA, and other multiply resistant bacteria

Front 40

linezolid (Zyvox)

Back 40

prototype of oxazolidinones

Front 41

oxazolidinones

Back 41

excellent pharmacokinetics, equal bioavailability by both oral and intravenous routes and no need for dose adjustment in patients with renal impairment

Front 42

oxazolidinones

Back 42

inhibit tRNA translocation

Front 43

oxazolidinones

Back 43

interacts with 16S RNA and 23S rRNA of the 30S and 50S ribosomal subunits

Front 44

oxazolidinones

Back 44

site of interaction determined by characterizing antibiotic resistant mutants

Front 45

sreptogramins

Back 45

clinical prototype is combination of dalfopristin and quinupristin (synergin)

Front 46

dalfopristin

Back 46

plus quinupristin = Synergin

Front 47

quinupristin

Back 47

plus dalfopristin = Synergin

Front 48

Synergin

Back 48

quinupristin + dalfopristin, 16-fold more active that either alone

Front 49

sreptogramins, oxazolidinones

Back 49

potential for treating MRSA, VREF, and other multiply resistant bacteria

Front 50

mupirocin

Back 50

binds specific tRNA synthetase (isoleucyl-tRNA synthetase) and prevents its function, resulting in no charged Ile-tRNA's available for protein synthesis

Front 51

mupirocin

Back 51

bacteriostatic at low concentrations but bacteriocidal at high concentrations achieved by topical administration, perhaps due to lack of incorporation of isoleucine into protein chains in cell wall

Front 52

mupirocin

Back 52

useful for treatment of MRSA, especially against nasal carrier state

Front 53

mupirocin

Back 53

for topical treatment of impetigo caused by S. aureus or S. pyogenes, weaker against natural surface flora

Front 54

ciprofloxacin, moxifloxacin

Back 54

active vs. G- enteric bacilli, some G+ cocci, and P. aeruginosa

Front 55

ciprofloxacin, moxifloxacin

Back 55

used for UTI, respiratory, and anaerobic infections

Front 56

ciprofloxacin

Back 56

therapeutic treatment of anthrax

Front 57

ciprofloxacin

Back 57

prophylactic when exposure to B. anthracis is potential risk, such as in first responder situation

Front 58

ciprofloxacin, moxifloxacin

Back 58

inhibits DNA gyrase necessary for DNA synthesis. bacteriocidal

Front 59

ciprofloxacin, moxifloxacin

Back 59

resistance emerging rapidly, no longer recommended for treating MRSA

Front 60

ciprofloxacin, moxifloxacin

Back 60

not for pregnant women or children b/c they can damage growing bone

Front 61

metronidazole

Back 61

binds DNA and fragments it

Front 62

metronidazole

Back 62

useful against anaerobic bacteria, especially Bacteriodes species

Front 63

metronidazole

Back 63

used for certain protozoal infections (trichomoniasis and amebiasis)

Front 64

metronidazole

Back 64

action requires anaerobic conditions--antibiotic is reduced and activated by electron transport protein (ferredoxin)

Front 65

rifampin

Back 65

broad spectrum, inhibits transcription by binding to B subunit of bacterial RNA polymerase, inhibiting specific binding to DNA

Front 66

rifampin

Back 66

often used in combination with other antibiotics since resistance develops rapidly when used alone, used with isoniazid or pyrazinamide as major therapies against tuberculosis

Front 67

rifampin

Back 67

efficiently secreted in saliva, so useful as prophylactic against infectious bacteria that enter via nasopharyngeal route

Front 68

rifampin

Back 68

prevents spread of N. menigitidis

Front 69

ethambutol

Back 69

antituberculosis drug; mechanism of action unknown, bacteriostatic against tubercle bacilli

Front 70

pyrazinamide

Back 70

antituberculosis drug; mechanism of action unknown, bacteriocidal drug that requires activity of Mycobacteria amidase to become activated