03a: Antibacterial Agents Flashcards by Nuna H

List the four sites of antibiotic action.

Cell wall synthesis
Protein synthesis
Nucleic acid synthesis
Folic acid synthesis

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List the classes of antibiotics that target cell wall synthesis. Star the beta lactams

Penicillins*
Vancomycin
Beta-Lactamase Inhibitors
Cephalosporins*
Carbapenems*

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Penicillin is (bactericidal/bacteriostatic) and (time/conc)-dependent.

Bactericidal; time-dependent

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Mechanism of action of beta lactams is (stim/inhib) of (X), followed by bacterial cell (Y).

Inhibition;
X = PBPs (cross link peptide chains of peptidoglycan)
Y = lysis (via osmotic P or autolysins)

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Natural penicillins, such as (X), primarily target gram (pos/neg) (aerobes/anaerobes) and is treatment of choice for which situations/infections?

X = penicillin G
Gram-pos aerobes (strep);

Strep (GAS pharyngitis)
Syphilis

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Extended spectrum penicillins differ from natural penicillins in that they have greater:

access/ability to penetrate through O.M. of gram negatives

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Aminopenicillins, such as (X), have coverage similar to penicillin G with (more/less) coverage for:

X = ampicillin; more

Enterococcus
Listeria
Enterobacteriaceae

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T/F: Aminopenicillins have very broad range of coverage for gram positives.

False

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T/F: Penicillinase-resistant penicillins have very broad range of coverage for gram positives.

True

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Drug of choice for endocarditis prophylaxis (i.e. via enterococcus).

Aminopenicillins (ex: ampicillin)

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T/F: Most penicillins must be given by IV or IM to achieve adequate levels.

True (degraded by gastric acid)

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T/F: Penicillins distribute well into most tissues, particularly bone/CSF.

False - less so in bone/CSF, though CSF levels are 5-20% of serum levels

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Penicillins are mainly excreted (changed/unchanged) via which route?

Unchanged;

Renal (rapid)

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Most common adverse effect of penicillins.

Hypersensitivity (3-10%), though anaphylaxis is rare

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T/F: There may be cross-reactivity between penicillins and cephalosporins, but not other beta-lactams.

False - can be cross-reactivity between any of those

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Beta-Lactamase Inhibitor example.

Clavulanic acid

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Cephalosporins have which mechanism of action?

They’re beta-lactams! Similar to penicillins (inhibit PBPs)

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(X) is a first-generation cephalosporin that acts primarily on which type of bacteria?

X = cefazolin

Gram-positive aerobes (ex: strep, MSSA)

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(X) is a second-generation cephalosporin that acts primarily on which type of bacteria? (Y) is also a second-gen drug, but with additional activity against (Z).

X = cefuroxime
Gram-pos (mainly Strep, less Staph) and Gram-neg aerobes;
Y = cefoxitin
Z = gram-neg anaerobes

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Which cephalosporin would you likely use to treat respiratory infections and community acquired pneumonia?

Cefuroxime (second generation)

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(X) is a third-generation cephalosporin that acts primarily on which type of bacteria?

X = ceftriaxone
Gram pos (mainly Strep, less Staph) and gram neg aerobes (less than fourth gen)

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Which cephalosporin would you likely use to treat strep pneumo and gram negative infections?

Gen 3 (ceftriaxone)

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Which cephalosporin would you likely use to treat hospital-acquired Pseudomonas?

Gen 4 (cefepime)

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T/F: Gen 4 cephalosporins have no gram-positive acitivty.

False - similar to Gen 1 activity

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T/F: Cephalosporins have no activity against anaerobes.

False - Cefoxitin(a gen 2) does against gram-neg anaerobes

Aside from (X), the pharmacokinetics of cephalosporins are similar to (Y) drugs.

``` X = ceftriaxone (longer half-life and biliary excretion) Y = penicillins ```

T/F: Cephalosporins have adverse effects/toxicity overall similar to penicillins.

True

Carbapenems have which mechanism of action?

They're beta-lactams! Similar to penicillins (inhibit PBPs)

Carbapenems: (X) is combined with (Y) to prevent:

``` X = imipenem Y = cilastatin ``` Imipenem brakdown to nephrotoxic product

List the three mechanisms that pathogens use for antimicrobial resistance.

1. Efflux of drug 2. Alteration of drug 3. Degradation of drug

(X) are broad-spectrum agents, generally reserved for documented resistance activity. These agents work on gram (pos/neg) (aerobes/anaerobes).

X = carbapenems | Gram pos and neg aerobes and anaerobes

Most common adverse effect of carbapenems are:

GI disturbances

T/F: Vancomycin is a beta-lactam that's bactericidal and time-dependent.

Partly false - it's a glycopeptide (not beta-lactam)

Spectrum of vancomycin is gram (pos/neg) (aerobes/anaerobes).

Gram pos aerobes and anaerobes (including MRSA)

Vancomycin primarily used for which two scenarios?

1. MRSA | 2. Pt with anaphylaxis to beta-lactams

"Red man syndrome" can be seen with infusion of (X) drug too rapidly.

X = vancomycin

List the classes of antibiotics that target protein synthesis.

1. Aminoglycosides 2. Tetracyclines 3. Macrolides 4. Clindamycin

Aminoglycosides, such as (X), have which mechanism of action?

X = gentamicin Bind (irreversibly) to 30S ribosome (causing misreading)

Gentamicin activity is (bactericidal/bacteriostatic) and (time/conc)-dependent. Its spectrum of activity mainly includes gram (pos/neg) (aerobes/anaerobes).

Bactericidal; Conc-dependent Gram neg (and limited gram pos) aerobes

Distribution of gentamicin is primarily into which body compartment?

Extracellular (highly polar); no CNS penetration

Adverse effects of gentamicin.

1. Nephrotoxicity (reversible) | 2. Ototoxicity (auditory/vestibular; irreversible)

Tetracyclines, such as (X), have which mechanism of action?

X = doxycycline Bind (reversibly) to 30S ribosome (causing misreading)

Doxycycline activity is (bactericidal/bacteriostatic) and (time/conc)-dependent.

Bacteriostatic; | Time-dependent

Gentamicin works (intra/extra)-cellularly. It is transported via which mechanisms?

Intracellularly (on 30S ribosome) 1. Porin channels (passive) 2. Active transport (oxygen dependent)

Gentamicin is less effective in (aerobic/anaerobic) and (acidic/basic) conditions. Why?

Anaerobic, acidic; Decreased transport (which is oxygen-dependent)

(X) drugs are often used in combo with others (in sick, high-risk patients), while waiting for tests to ID illness.

X = Gentamicin (aminoglycosides)

For optimal bactericidal effects, Gentamicin must have Cmax: MIC ratio of:

10:1 (conc-dependent)

Doxycycline has generally broad spectrum of gram (pos/neg) coverage, but (resistance/adverse effects) pose issues.

Both (pos and neg aerobes and anaerobes); | Both acquired resistance and adverse effects are problematic

Oral absorption of doxycyline is (fair/poor) and it distributes into (most/only select) tissues. How is it eliminated?

Fair (but decreased by simultaneous ingestion of certain minerals); Most; Undergoes glucoronidation, then excreted in urine and bile

Doxycycline is contraindcated in which patient population? Why?

Children under 8 due to photosensitivity (rash) and tooth/bone discoloration

Doxycycline most common adverse effect.

GI disturbances

Macrolides, such as (X), have which mechanism of action?

X = azithromycin Reversibly bind 50S ribosome

Azithromycin is (bactericidal/bacteriostatic) and (time/conc)-dependent. Its coverage is similar to that of (X) drug, but with less gram (Y) coverage.

Depends on dose and organism; Time-dependent X = penicillins Y = anaerobic

T/F: Azithromycin has activity against T. pallidum and chlamydia.

False - only chlamydia

T/F: Azithromycin has activity against H. flu and Legionella.

True

T/F: Azithromycin is used in resp tract infections, such as against mycoplasma.

True

Oral absorption of azithromycin is (fair/poor) and it distributes into (most/only select) tissues. How is it eliminated?

Fair (some food interactions; Most (except CSF); Metabolized by liver; excreted in bile and urine

Clindamycin has which mechanism of action?

Binds 50S ribosome and inhibits protein synthesis

Clindamycin is (bactericidal/bacteriostatic) and covers (broad/narrow) range of gram (pos/neg) bacteria.

Bacteriostatic; | Broad (gram pos aerobes and anaerobes)

Clindamycin has (fair/poor) oral absorption and distributes into (most/only select) tissues. It's excreted (changed/unchanged) in (bile/urine).

Fair; Most (except CSF); Changed (inactivated metabolites); Bile and urine

Most common adverse effect of Clindamycin.

GI tolerability

List the two antibacterial drug classes that act as Nucleic Acid structure inhibitors.

1. Quinolones | 2. Metronidazole

Generation (1/2/3/4) of quinolones are no longer used.

Gen 1

Anaerobic activity is seen in gen (1/2/3/4) quinolones.

Gen 4

Quinolones have (fair/poor) oral absorption and distributes into (most/only select) tissues. It's excreted (changed/unchanged) in (bile/urine).

Fair; Most; Unchanged in urine

The major "hole" in cephalosporin coverage is (X) bacterial species.

X = ENTEROCOCCUS

Monobactam drugs, such as (X), have similar mechanism to (Y) drugs but with gram (pos/neg) spectrum only.

X = aztreonam Y = penicillins Only gram-neg

T/F: Patient with penicillin allergy can be given aztreonam.

True - it's a monobactam

For (X) class of drugs, think DRUG INTERACTIONS.

X = macrolides

(X) class of drugs covers atypical bacteria in their spectrum.

X = macrolides

Linezolid is (bactericidal/bacteriostatic) and has which mechanism of action?

Bacteriostatic; | Binds 50S ribisome

Linezolid has mainly gram (pos/neg) spectrum of activity. In clinical practice, it's primarily used against which bacteria?

Gram positive aerobes; MRSA and VRE infections

Levofloxacin is part of (X) drug class. It's (bactericidal/bacteriostatic) and (time/conc)-dependent.

X = quinolones Bactericidal; Conc-dependent

(X) drugs are considered the "last line of defense" in the community setting.

X = quinolones

Levofloxacin mechanism of action.

Inhibits topoisomerases (enzymes that maintain DNA supercoiling)

T/F: Quinolone oral bioavailability is equal to IV bioavailability.

Essentially true! Excellent oral absorption

T/F: Quinolones prove ineffective in hospital-acquired infections.

False - cover pseudomonas and atypicals

Metronidazole is in (X) class of drugs. It's (bactericidal/bacteriostatic) and (time/conc)-dependent. What's the mechanism?

X = nitroimidazole Bactericidal; conc-dep Enters cell and is reduced to cytotoxic product

Spectrum of metronidazole is:

ANAEROBES

Gold standard drug for anaerobic infections, especially gram-neg.

Metronidazole (used for "below diaphragm" anaerobes)

Above diaphragm: typically gram (pos/neg) anaerobes. And below diaphragm?

Gram-pos above; gram-neg below

Gold standard #2 drug for anaerobic infections, especially gram-pos.

Clindamycin (used for "above diaphragm" anaerobes)

"Metallic" taste is side effect of which drug?

Metronidazole

03a: Antibacterial Agents Flashcards

(83 cards)