Antimicrobial Agents I Flashcards by Lindsey Herrera

Bactericidal agents can compensate for pts with _____.

impaired host defenses

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Is it beneficial or toxic for clindamycin to accumulate in bone? Why?

beneficial- treat osteomyelitis

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What is an important consideration for metronidazole?

drug-drug interaction w/ alcohol due to inhibition of aldehyde metabolism

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What are extended spectrum Abx?

effective against gram + AND -

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Name the DQ CRIMES.

D- doxycycline Q- quinolones C- clindamycin R- rifampin I- isoniazis M- metronidazole E- erythromycin-like S- sulfonamides

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What are the 5 major mechanisms of antibacterial resistance to Abx?

altered targets 2. enzymatic destruction 3. alternative resistant metabolic pathway 4. decreased entry 5. increased efflux

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Name 4 drugs that readily enter the CNS.

chloramphenicol 2. sulfonamides 3. cephalosporin (3/4) 4. rifampin- metronidazole

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What is an important consideration for the sulfonamides?

renal crystalluria

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What is an important consideration for isoniazid?

genetic polymorphism of N-acetyl transferase metabolism; potential hepatotoxicity

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What is mutational/chromosomal resistance?

multiple steps/generations; each succeeding generation becomes slightly more resistant

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Name 2 drugs that have selective/toxic accumulations and where.

aminoglycosides- inner ear/brush border 2. tetracyclines- bone and teeth

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What is an important consideration for doxycycline?

not renally eliminated tetracycline

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What drugs should not be used in pregnancy, or with caution? (6)

aminoglycosides 2. metronidazole 3. chloramphenicol 4. tetracyclines 5. fluoroquinolones 6. voriconazole

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Choose: Oral Abx DO/DO NOT cross the placenta.

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What is the post-antibiotic effect?

some Abx, like aminoglycosides and fluoroquinolones, continue to kill or inhibit growth or bacteria for several hours after the conc of drug falls below the MIC

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What is direct Abx toxicity?

affect host cellular processes

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What is transformation?

bacteria picks up free DNA from the environment

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Superinfections are more common in those aged ____ or ____.

under 3yo, over 50yo

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Bactericidal agents are req for treatment of infections that are _____.

not accessible to host immune system responses

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Why are the DQ-CRIMES drugs important?

they have possible drug-drug interactions, genetic polymorphisms, or hepatotoxicity considerations

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What are the cell wall synthesis inhibitors?

Penicillins (-cillin, Clavulanic acid) cephalosporins (Cef-) carbapenems (-penem) vancomycin

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Abx’s may alter the activity of ____ drug metabolizing enzymes, causing indirect toxicity.

CYP450

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Name 4 drugs that have selective/beneficial accumulations and where.

clindamycin- bone 2. macrolides- pulmonary cells 3. tetracyclines- gingival crevicular fluid and sebum 4. nitrofurantoin- urine

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How can resistance be minimized?

only use Abx when need is established; select Abx based on compatibility; use adequate duration and concentration

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\_\_\_\_\_ agent is preferred in severe infections.

Bactericidal

Is it beneficial or toxic for tetracyclines to accumulate in gingival crevicular fluid and sebum? Why?

beneficial- treatment of periodontitis and acne

What is acquired resistance?

selective pressures produce successive generations of organisms with biological traits that minimize drug action

What are the 2 modes of acquired resistance?

1. mutational/chromosomal resistance 2. plasma mediated

\_\_\_\_ agents are req for treatment of infections that are not accessible to host immune system responses.

Bactericidal

What is concentration dependent killing?

some abx kill bacteria faster when given in doses that result in higher plasma concentrations

\_\_\_\_ agents act more quickly and their action is often irreversible.

Bactericidal

What are the broad classifications of antibiotics?

gram + or - cocci; gram + or - rods; gram + or - anaerobes; atypical bacteria

Is it beneficial or toxic for aminoglycoside to accumulate in the inner ear and renal brush border? Why?

toxic- increased tendency for ototoxicity and nephrotoxicity

What determines whether an Abx is bactericidal or bacteriostatic?

mechanism of action/target; conc achieved in vivo; specific microorganism

What are the bacteriostatic mechanisms?

inhibition of protein synthesis (except aminoglycosides); inhibition of intermediary metabolic pathways

Pseudomembranous colitis due to ____ overgrowth can be life-threatening.

Clostridium difficile

What are the inhibitors of DNA function?

fluoroquinolones (-floxacin) nitrofurantoin metronidazole

Bactericidal agent is preferred in ______ infections.

severe

Is it beneficial or toxic for macrolides to accumulate in pulmonary cells? Why?

beneficial- URI treatment

What is an important consideration for clindamycin?

not renally eliminated

\_\_\_\_\_ means the organisms are killed; ____ means organisms are prevented from growing.

Bactericidal; bacteriostatic

What is an important consideration for the quinolones?

ciprofloxacin is renally cleared but is a non-substrate inhibitor of P450

What kind of bacteria has a large reservoir for plasma-mediated transfer?

gram-negative coliform bacteria

What is an important consideration for rifampin?

induces P450, potential hepatotoxicity

What is transduction?

virus injects resistance to bacteria

What kinds of Abx are most likely to cause superinfections?

broad spectrum

Why are disturbances of host microflora/superinfections?

overgrowth of normally suppressed pathogens b/c of broad spectrum Abx

What is natural resistance?

microbes lack a susceptible target for drug action

Name the 6 narrow spectrum Abx.

1. aminoglycosides 2. penicillinase-resistant penicillins 3. clindamycin 4. vancomycin 5. metronidazole 6. penicillin G, V

What are the 3 categories of Abx toxicity?

1. direct 2. indirect 3. disturbances of host microflora/superinfections

What is plasma mediated resistance?

extrachromosomal DNA that can confer immediate resistance

What is conjugation?

plasmid transfer between 2 physically attached bacteria

What are broad spectrum Abx?

effective against gram +, gram -, AND atypical organisms

What are the protein synthesis inhibitors?

macrolides (-mycin) tetracyclines clindamycin chloramphenicol aminoglycosides

Which Abx's are less likely to disturb the host flora?

narrow spectrum

\_\_\_\_ agents can compensate for pts with impaired host defenses.

Bactericidal

Name 4 drugs that enter the CNS with inflammation.

1. penicillin 2. vancomycin 3. ciprofloxacin 4. tetracycline

Bactericidal means\_\_\_\_\_; bacteriostatic means \_\_\_\_\_.

the organisms are killed; organisms are prevented from growing

What is escape?

purines, thymidine, serine, methionine released from purulent infections allows sulfonamide resistance; failure to lyse due to lack of osmotic pressure differences in penicillin resistance

\_\_\_\_\_ due to Clostridium difficile overgrowth can be life-threatening.

Pseudomembranous colitis

Most antibiotics distribute well into tissues outside the CNS, but vary in their ability to cross the \_\_\_\_.

BBB

Name the 6 broad spectrum Abx.

1. macrolides 2. chloramphenicol 3. fluoroquinolones (moxi, gemi) 4. sulfonamides 5. tetracyclines 6. trimethoprim

Name the 4 extended spectrum Abx.

1. aminopenicillins (amox, amp) 2. cephalosporins 3. fluoroquinolones 4. carbapenems

Is it beneficial or toxic for nitrofurantoin to accumulate in urine? Why?

beneficial- treatment of UTIs

What is an important consideration for the erythromycin-like drugs?

drug-drug interactions due to inhibition of P450

What are the bactericidal mechanisms?

inhibition of cell wall synthesis; disruption of cell membrane function; interference with DNA function of synthesis

Is it beneficial or toxic for tetracycline to accumulate in bone and teeth? Why?

toxic- causes abnormal bone growth and brownish tooth discoloration in fetuses and young children

What is indirect Abx toxicity?

allergic rxns and hypersensitivities

Where does direct toxicity typically manifest?

GI tract, liver, kidney, nervous system, blood and blood forming system

Which Abx's require dosage adjustments if renally impaired?

1. penicillin 2. cephalosporins 3. vancomycins 4. aminoglycosides 5 fluoroquinolones

What are narrow spectrum Abx?

effective against EITHER gram + or -