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41 Cards in this Set

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polymixin B: selective activity against gram negative enteric rods (especially Pseudomonas); has a positively charged polypeptide that binds to neg. LPS in OM, then to CM phospholipids and causes membrane leakage
inhibitor of protein synthesis; used in treatment of TB; its discovery extended range to many gram-negative organisms; its positively charged at phy. pH and some metabolic activity is needed for streptomycin to enter; under anaerobic or acidic conditions (urine) action is inhibited; bacteriocidal
action of streptomycin
action is on 30S ribosomal subunit; few molecules: misreading; higher con: formation of the initiation complex is bad
inhibit 30S ribosomal function; bacteriocidal; aminoglycoside
gentamicin...all inhibit 30S subunit and are bacteriocidal; interact with more than one ribosomal subunit (resistance harder to get); have toxic effects, damaging 8th cranial nerve or renal function; require aerobic conditions to be effective
tetracycline and doxycycline
tetracyclines (cont)
widely used; block binding of aminoacyl-RNA of 30S ribosomal subunit; bacteriostatic; well absorbed orally; broad spectrum (mycoplasma, rickettsia, and chlamydia); do NOT give in pregnancy and children under 8 get mottled enamel (broad spectrum may be a problem: destroy natural flora in GI tract)
potent tetracycline derivative; contains chemical side chain that makes it refractory to a common mechanism of tetracycline resistance that involves an efflux pump;
inhibitors of 50S ribosomal function; macrolide; blocks chain elongation; bacteriostatic; very widely used; activity similar to penicillin but includes mycoplasma and chlamydia
new oral drugs related to erythromycin but with higher activity and slightly broader spectrum; give high and sustained tissue concentrations
blocks polypeptide chain elongation; bacteriostatic; although in H. influenza cessation of growth leads to -cidal effect; can induce aplastic anemia; not widely used
use of Chloramphenicol
useful against some anaerobes, particularly bowel anaerobes such as B. fragilis; can cause aplastic anemia and therefore not widely used, only restricted to infections in which it is vital for therapy
derivative of lincomycin; activity against gram positive and moderate activity against anaerobes; bacteriostatic; inhibits peptidyl transfer
bacteriostatic; highly active against gram positive bacteria; potential treatment for VREF and also MRSA, VRSA and other multiply resistant bacteria; probably work by inhibiting tRNA translocation; interacs with 16S RNA and the 23S rRNA of the 30S and 50S ribosomal subunits
prototype of oxazolidinone; oral and IV routes; no need for dose adjustments iwth renal impairment;
new class; binds to 50S subunit; bacteriostatic
dalfopristin and quinupristin; clinical prototype of sreptogramins; potential for treating MRSA, VREF, and other multiply resistant bacteria
antibiotic that binds a specific tRNA synthetase (isoleucyl-tRNA synthetase); bacteriostatic at low concentrations but bacteriocidal at high concentrations; useful to treat MRSA (nasal carrier state)
inhibitors of DNA replication; inhibits enzyme DNA gyrase; bacteriocidal; most common ones are fluoroquinolones, ciprofloxacin, and moxifloxacin
quinolones (action against)
active vs. gram negative enteric bacilli; some gram positive cocci and P. aeruginosa; used for variety of infections...UTI, respiratory, and even anaerobic
therapeutic treatment of anthrax, and even as a prophylactic when exposure to B. anthracis is a potential risk...
metronidazole; anaerobic drug; activated form of drug binds DNA and fragments it; useful against anaerobic bacteria; bacteriocidal; used for certain protozoal infections (trichomoniasis and amebiasis); action requires anaerobic conditions
inhibitor of RNA synthesis; broad spectrum; bacteriocidal; inhibits transcription by binding to the B subunit of bacterial RNA polymerase, inhibiting specific binding to DNA...often used in combo with other antibiotics (sinse resistance develops fast)
Rifampin used in combo with what?
isoniazid or pyrazinamide; major therapies against TB
Where is Rifampin secreted?
saliva; makes it very useful as a prophylactic against infectious bacteria that enter via the nasopharyngeal route; notable for preventing spread of N. menigitidis
important anti-TB; bacteriostatic against tubercle bacilli
important anti-TB; mech unknown; bacteriocidal drug that requires activity of the Mycobacteria amidase to become activated
Erythromycin inactivation
by erythromycin esterase hydrolyzes lactone ring;
altered membrane permeability...outer membrane
OM porins decreased expression; B-lactams, nalidixic acid, chloramphenicol
altered membrane permeability...inner membrane
inner membrane trasporters altered...aminoglycosides, rare since usually deleterious regarding PMF...
alter S12 of 30S subunit
streptomycin resistance; these mutations are the most common mech. for Em resistance and Sm resistance; don't occur so much for gentamicin, tobramycin, amikacin...all of which have multiple ribosomal targets
alteration of cell wall precursor targets
impt. for vancomycin and teichoplanin resistance; inducible genes that encodes an enzyme related to D-ala-D-ligases;
Alteration of target enzymes
altered PBPs - lower affinity of change in amount; methicillin resistance is associated with altered affinity to PBP's; also common in pen. resistance in Neisseria, H. influenzae, and P. aeruginosa
Polyene compounds
antifungal; amphotericin B and nystatin; bind to sterols in cell membranes; affinity is better towards ergosterol; poorly absorbed from GI tract
amphotericin B
antifungal; affect membrane permeability; used systemically, but toxic; fungicidal
antifungal; affects membrane permeability; too toxic for systemic use; used topically and for oral fungal infections using the "swish and swallow" technique; not absorbed in GI tract and therefore does not lead to toxicity; fungistatic
systemic antifungal agents; inhibitors of cell membrane synthesis; useful for treatment of oral candidiasis (thrush)...impt. in AIDS patients
Fluconazole and Ketoconazole
azoles; can be given orally, but hepatotoxicity occurs in a smallll amount of patients; major activity is inhibition of ergosterol synthesis, principally by inhibition of cytochrome P450 14a demethylase; fungistatic
an echinocandin; inhibitor or cell wall synthesis; inhibitors of glucan synthesis; fungicidal
antimetabolite against fungus; replaces uracil with 5-flurouracil in fungal RNA; also inhibits thymidylate synthetase via 5-fluorodeoxy-uridine monophosphate; interferes with fungal DNA synthesis; can be either fungicidal or static, depending on fungal isolate
fungal resistance
NO acquired resistance mechanisms that inactivate the drugs have thus far been discovered...normal efflux pumps that have increased levels of expression represent a common mech. as does alteration in targets of the drugs