Antimicrobial Drugs (BE # 4) Flashcards

Question

Bacitracin

Answer 1

Bacteria - Bacillus subtilis MOA - inhibits synthesis of glycan strands in peptidoglycan molecule, so wall structure is compromised & can no longer withstand turgor pressure. They lyse Only used topically; part of triple antibiotic ointment

Answer 2

Bacteria - Actinomycetes MOA - binds to glycan strands to prevent protein cross-linking (doesn't bind to enzyme like beta lactam antibiotics). Cell wall is compromised, can't withstand turgor pressure, it lyses Used against G(+) bacteria Traditionally, "drug of last resort" against MRSA & entercocci

Answer 3

Bacteria - Bacillus poymyxa MOA - disrupts cell membrane; act as detergents; attach to LPS's and phospholiipids in outer membrane & plasma membrane; membranes are disrupted & get leaky. Not very selectively toxic since eukaryotes have plasma membrane, too. Only used topically; usually in triple antibiotic ointment Effective agains G(-) because of outer membrane

Answer 4

Nalidixi acid - uti's traveler's diarrhea (E. coli) Ciprofloxacin Hydrochloride (Cipro) - anthrax Levofloxacin (Levaquin) - bronchitis, pneumonia, chlamydia, gonorrhea, skin infections, uti MOA - inhibition of DNA replication; targets enzyme that unwinds DNA prior to replication

Answer 5

Flagyl MOA - inhibition of DNA replication; taken up into DNA, forming unstable molecules. Only occurs when drug is reduced in anaerobic bacteria Sleelctive toxicity: only affects anaerobic bacteria, not human cells, which are aerobic, or aerobic bacteria effective against Clostridium difficile, protistan infections

Answer 6

Rifampin Bacteria - Actinomycete MOA - inhibits transcription; targets the enzyme, RNA polymerase, involve in transcription Selective toxicity: prokaryotic RNA polymerase is different than eukaryotic RNA polymerase, so won't affect humans

Answer 7

Bacteria - Actinomycetes MOA - target the large or small subunit of the prokaryotic ribosome, interfering with some step in translation. Selective toxicity - there's a difference between prokaryotic & eukaryotic ribosomes. The ration of RNA proteins is different in prokaryotes & eukaryotes.

Answer 8

Bacteria - Actinomycetes * Widest spectrum of activity of any antibiotic * Most common antibiotic added to animal feed * Can cause mild to severe toxic effects MOA - target the large or small subunit of the prokaryotic ribosome, interfering with some step in translation. Selective toxicity - there's a difference between prokaryotic & eukaryotic ribosomes. The ration of RNA proteins is different in prokaryotes & eukaryotes. Used to treat Lyme disease, can, uti's

Answer 9

origninally obtained from Streptmyces bacteria, but now fully synthesized in lab * cheap & easy to manufacture - easy to get in Mexico * toxic to bone marrow * last drug of choice in US * used to treat bacterial meningitis * can cross blood brain barrier, so used to treat brain abscesses MOA - target the large or small subunit of the prokaryotic ribosome, interfering with some step in translation. Selective toxicity - there's a difference between prokaryotic & eukaryotic ribosomes. The ration of RNA proteins is different in prokaryotes & eukaryotes.

Answer 10

bacteria - Actinomycetes * Bacteristatic against most G(+) * valuable in treating infections caused by penicillin resistant orgs or those allergic Erythromycin is considered one of the least toxic of commonly used antibiotics MOA - target the large or small subunit of the prokaryotic ribosome, interfering with some step in translation. Selective toxicity - there's a difference between prokaryotic & eukaryotic ribosomes. The ration of RNA proteins is different in prokaryotes & eukaryotes.

Answer 11

semisynthetic * common side effect is Clostridium difficile - associate diarrhea (CLASSICALLY LINKED TO CLINDAMYCIN USE) MOA - inhibition of translation; target the large or small subunit of the prokaryotic ribosome, interfering with some step in translation. Selective toxicity - there's a difference between prokaryotic & eukaryotic ribosomes. The ration of RNA proteins is different in prokaryotes & eukaryotes.

Answer 12

Molecular mimicry - drug mimics the normal molecule, which inhibits a reaction in some way First & only effective antibacterial available before penicillin MOA - sulfa drug is very similar in structure to the compound PABA, so binds to the enzyme so that PABA can't. Many bacteria require PABA to make folic acid (Vit B) which they use to synthesize nucleic acids & other compounds. When sulfa drug binds to the enzyme, bacterium can't make folic acid. Selective toxicity: animals obtain folic acid from diets, so don't have the enzymes to make it themselves so are unaffected by the drug.

Answer 13

Another antibiotic, clavulanic acid, is added to amoxicillin. Clavulanic acid binds to beta lactamases & prevents them from inactivating the amoxicillin. broad-spectrum

Answer 14

a drug mimics the normal molecule, inhibiting a chemical reaction in some way.

Answer 15

They are caused by antibiotic use. Antibiotics kill off normal flora bacteria, changing the environment & making the patient more susceptible to other infections.

Answer 16

``` yeast infection (Candida albicans) Clostridium difficile (diarrhea) ```

Answer 17

take probiotics to restore natural flora fecal bacteriotherapy (fecal transplant)

Answer 18

innate / natural ability of a bacterial species to resist the activity of an antibiotic through its inherent structure or function. Ex. some beta lactam antibiotics have no effect on G(-) bacterial cell walls because they are too large to fit through porins in the outer membrane

Answer 19

mutations - during reproduction genetic transfer (gene swapping) - resistant genes found on R plasmids can be transferred to another through conjugation through pili, transduction (viral vector) or transformation.

Answer 20

if a mutant is resistant to a drug, it will survive, but the nonresistant ones will die. After a few generations, most of the survivors will be resistant to the drug.

Answer 21

resistance to 2 or more antibiotics via a common mechanism. Ex. penicillin contains beta lactam rings. Bacteria with the enzyme beta lactamase will break the rings. These bacteria are also resistant to some cephalosporins (they have beta lactam rings, too).

Answer 22

Determines microbial sensitivities to antibiotics. - Bacteria is spread evenly on agar plate. - Filter paper disks are saturated with drug & placed on plate 1. zones of inhibition - clear areas around bacteria 2. bacteria are sensitive to drug - if there's a clear area around disk (use it!) 3. bacteria are intermediate - small zone w/ or w/o mutants (don't use!) 4. resistant - no zone (don't use!)

Answer 23

They are eukaryotes like us, so there are fewer differences between cells. It's more difficult to follow the principle of selective toxicity).

Answer 24

Bacteriostatic antibiotics inhibit bacteria so the immune system can get rid of them. AIDS patients are immunocompromised, so would not have the ability to fit them off.

Answer 25

Many anti-fungals target egrosterol in the plasma membrane, which creates pore in it & causes leakage & death. Our plasma membrane cholesterol has a slightly different structure, so is unaffected.

Answer 26

produced by Streptomyces * binds to ergosterols, creating pores in membranes * used for treatment of systemic fungal diseases * used topically for Candida infections * toxic to kidneys

Answer 27

an Azole * inhibits ergosterol synthesis * used for treatment of athlete's food, jock itch, ringworm, nail infections * less toxic

Answer 28

* inhibits ergosterol synthesis * taken systemically for nail fungus * hepatoxic (liver) class action lawsuits

Answer 29

* blocks mirotubule assembly (proteins involved in mitosis) * binds to keratin in skin * used to treat tine capitis (ringworm) of hair, nails

Answer 30

an Azole * inhibits ergosterol synthesis * OTC used for treatment of vaginal yeast infections * less toxic

Answer 31

an Azole * inhibits ergosterol synthesis * often given as a single oral dose for treatment of vaginal Candida infections

Answer 32

1. maintain high levels of antibiotics long enough to kill pathogens and mutants 2. administer 2 antibiotics together (Augmentin) 3. Restrict antibiotic use to essential use only 4. Take all of antibiotic 5. Culture so you know exactly what is causing infection

Answer 33

Antiviral drug MOA - nucleosides are precursors to nucleotides (nucleoside = nitrogenous base + sugar). The analog drugs are similar in structure to nucleosides. They take the place of natural nucleosides, blocking the completion of a viral DNA chain. Selective toxicity - Viruses incorporate these "fakes" more rapidly than do cells.

Answer 34

Antiviral - Nucleoside Analog treat herpes simplex & herpes zoster (chicken pox/shingles)

Answer 35

Antiviral - Nucleoside Analog treatment of herpes zoster (chicken pox/shingles) & herpes simplex infections

Answer 36

Antiviral - Nucleoside Analog * treats respiratory syncytial virus (RSV). * In combo with interferons, shows some efficacy against Hep. C

Answer 37

MOA - HIV is RNA so must first go thru reverse transcription to make DNA from its RNA. AZT inhibits reverse transcriptase, the enzyme that makes DNA from viral mRNA. Viral replication is then stopped. Selective toxicity - Humans don't have this enzyme since our cells make mRNA from DNA in regular transcription (don't do reverse transcription).

Answer 38

MOA - work by blocking the function of the viral neuraminidase protein; virus cannot release from cell after budding from host. treats influenza

Answer 39

MOA - not fully understood; appears to inhibit the uncoating of the virus.

Answer 40

MOA - not fully understood; appears to inhibit fusion of enveloped herpes virus to human cells OTC treatment of oral Herpes Simplex Virus