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Step 1 Pharm > Anti-Microbials (2) > Flashcards

Anti-Microbials (2) Flashcards

1
Q

What is the MOA of the tetracyclines?

A

Bacteriostatic; bind to 30S and prevent attachment of aminoacyl-tRNA; limited CNS penetration.

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2
Q

What antimicrobial can be used in pts with renal failure because it’s fecally elminated?

A

Doxycycline is fecally eliminated and can be used in patients with renal failure.

bind to 30S and prevent attachment of aminoacyl-tRNA;

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3
Q

Drug used for the following bugs:

Borrelia burgdorferi, M. pneumoniae.

Drugs’ ability to accumulate intracellularly makes them very effective against

Rickettsia and Chlamydia.

A

Tetracyclines: doxycycline

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4
Q

Why can’t we take tetracyclines with milk, antacids or iron containing drugs?

A

. Do not take tetracyclines with milk (Ca2+), antacids (Ca2+ or Mg2+), or iron-containing preparations because divalent cations inhibit drugs’ absorption in the gut.

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5
Q

Young woman comes in with Chlyamydia, you prescribe the drug you SHOULD but what do we need to check first

A

tx Chlymidia with Doxycycline, but it a tetracycline thus teratogenic—make sure she’s not pregnant: see teeth stainig and inhibition of bone growth

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6
Q

Pt comes in with Lymes: Borrellia burgdorferi

What drug do you px and what is the mechanims of resisitance to this?

A

Px tetracycline: like Doxycycilne

resistance: decreaseud uptake or increased efflux out of bacterial cells by plasmid-endoced transport pumps

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7
Q

Drug with serious sides that can be used for the following:

Meningitis (Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae) and Rocky Mountain spotted fever (Rickettsia rickettsii).

A

Chloramphenicol

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8
Q

What serious sides effects are associatd with Chloramphenicol?

A

Anemia (dose dependent), aplastic anemia (dose independent), gray baby syndrome (in premature infants because they lack liver UDP-glucuronyl transferase).

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9
Q

Blocks peptidyltransferase at 50S ribosomal subunit.

Bacteriostatic.

A

Chloramphenicol

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10
Q

Blocks _peptide transfer (translocation) at 50S ribosomal subuni_t.

Bacteriostatic

A

Clindamycin

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11
Q

Used for Anaerobic infections (e.g., Bacteroides spp., Clostridium perfringens) in aspiration pneumonia, lung abscesses, and oral infections.

Also effective against invasive group A streptococcal infection

What’s it’s mechanism?

A

Clindamycin

Blocks peptide transfer (translocation) at 50S ribosomal subunit.

Bacteriostatic.

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12
Q

Inhibit protein synthesis by binding to 50S subunit and preventing formation of the initiation complex.

What serious side effect do we worry about?

A

Linezolid

Bone marrow suppression (especially thrombocytopenia), peripheral neuropathy, serotonin syndrome.

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13
Q

When would we prescribe Linezolid?

What’s it’s side effect profile?

A

Gram-positive species including MRSA and VRE

Bone marrow suppression

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14
Q

What is the mechanism of Macrolides?

What drugs are macrolides?

A

Inhibit protein synthesis by blocking translocation (“macroslides”); bind to the 23S rRNA of the 50S ribosomal subunit. Bacteriostatic

Azithromycin, clarithromycin, erythromycin.

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15
Q

Uses include: Atypical pneumonias (Mycoplasma, Chlamydia, Legionella), STIs (Chlamydia), gram-positive cocci (streptococcal infections in patients allergic to penicillin), and B. pertussis.

A

Macrolides: azithromycin, clarithromycin, erythromycin

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16
Q

What is the side effect profile of macrolides?

A

MACRO:

Gastrointestinal Motility issues,

Arrhythmia caused by prolonged QT interval,

acute Cholestatic hepatitis,

Rash,

eOsinophilia.

17
Q

What specific side effect is seen with clarithromycin and erythromycin?

A

Clarithromycin and erythromycin inhibit cytochrome P-450.

18
Q

What is the mechanism of resistance by bugs to Macrolides?

A

Methylation of 23S rRNA-binding site prevents binding of drug.

19
Q

MOA of Trimethoprim

A

Inhibits bacterial dihydrofolate reductase.

Bacteriostatic.

20
Q

Uses of Trimethoprim

A

Used in combination with sulfonamides (trimethoprim-sulfamethoxazole [TMP- SMX]), causing sequential block of folate synthesis.

Combination used for UTIs, Shigella, Salmonella, Pneumocystis jirovecii pneumonia treatment and prophylaxis, toxoplasmosis prophylaxis.

21
Q

Used for UTIs, Shigella, Salmonella, Pneumocystis jirovecii pneumonia treatment and prophylaxis, toxoplasmosis prophylaxis.

A

Trimpethoprim: blocks dihydrofolate reductase

use with sulfonamide to get sequential blockade of folate synthesis

22
Q

Negative side effects of Trimpethoprim

A

Megaloblastic anemia, leukopenia, granulocytopenia. (May alleviate with supplemental folinic acid). TMP Treats Marrow Poorly.

23
Q

Inhibit folate synthesis. Para-aminobenzoic acid (PABA) antimetabolites inhibit dihydropteroate synthase. Bacteriostatic (bactericidal when combined with trimethoprim).

A

Sulfamethoxazole (SMX), sulfisoxazole, sulfadiazin

24
Q

Uses of Sulfonamides: which inhibit folate synthesis:

(PABA antimetabolite to inhibit dihydropteroate synthase)

A

Gram-positives, gram-negatives, Nocardia, Chlamydia.

Triple sulfas or SMX for simple UTI.

25
Q

Drug that will inhibit dihydropteroate synthase, What is it’s side effect profile?

A

Hypersensitivity reactions, hemolysis if G6PD deficient, nephrotoxicity (tubulointerstitial nephritis), photosensitivity, kernicterus in infants, displace other drugs from albumin (e.g., warfarin).

26
Q

Inhibit prokaryotic enzymes topoisomerase II (DNA gyrase) and topoisomerase IV. Bactericidal.

\Must not be taken with antacids.

A

Fluoroquinolones

Ciprofloxacin, norfloxacin, levofloxacin, ofloxacin, moxifloxacin, gemifloxacin, enoxacin.

27
Q

When do we px floroquinolones?

What is it’s mechanism of action?

A

Gram-negative rods of urinary and GI tracts (including Pseudomonas), Neisseria,

28
Q

Toxicity profile of Floroquinolones

A

GI upset, superinfections, skin rashes, headache, dizziness. Less commonly, can cause leg cramps and myalgias. Contraindicated in pregnant women, nursing mothers, and children < 18 years old due to possible damage to cartilage. Some may prolong QT interval. May cause tendonitis or tendon rupture in people > 60 years old and in patients taking prednisone.

29
Q

Mechanism of Flouroquinoles and mech of resistance by bugs

A

Inhibit prokaryotic enzymes topoisomerase
II (DNA gyrase) and topoisomerase IV. Bactericidal. Must not be taken with antacids.

Chromosome-encoded mutation in DNA gyrase, plasmid-mediated resistance, efflux pumps.

30
Q

Used for S. Aureus skin infections (MRSA) bacteremia and endocardtitis

What’s it’s mechanism of action?

A

Daptomycin

Lipopeptide that disrupts cell membrane of gram-positive cocci.

31
Q

Mechanism of daptomycin and it’s toxicity profile

A

Lipopeptide that disrupts cell membrane of gram-positive cocci.

Myopathy, rhabdomyolysis.

32
Q

Forms toxic free radical metabolites in the bacterial cell that damage DNA.

Bactericidal, antiprotozoal.

A

Metronidazole

33
Q

GET GAP on the Metro with metronidazole! What bugs do we treat with metronidazole?

A

Treats Giardia, Entamoeba, Trichomonas, Gardnerella vaginalis, Anaerobes (Bacteroides, C. difficile).

*Used with a proton pump inhibitor and clarithromycin for “triple therapy” against H. Pylori.

34
Q

Treats anaerobic infection below the diaphragm

vs. this which txs (anaerobic infections above diaphragm).

A

Metronidazole above diaphragm

Clindamycin below the diaphram

35
Q
  1. High risk for endocarditis and undergoing surgical or dental procedures
  2. Exposure to gonorrhea
  3. History of recurrent UTIs
  4. Exposure to meningococcal infection
A
  1. High risk for endocarditis and undergoing surgical or dental procedures: Amoxicillin
  2. Exposure to gonorrhea : Ceftriaxone
  3. History of recurrent UTIs : TMP-SMX
  4. Exposure to meningococcal infection : Ceftriaxone, ciprofloxacin, or rifampin
36
Q
  1. Pregnant woman carrying group B strep
  2. Prevention of gonococcal conjunctivitis in newborn
  3. Prevention of postsurgical infection due to S. aureus
A
  1. Pregnant woman carrying group B strep: Penicillin G
  2. Prevention of gonococcal conjunctivitis in newborn: Ceftriaxone, Ciprofloxacin, Rifampin
  3. Prevention of postsurgical infection due to S. aureus : erythromycin ointment

Step 1 Pharm (15 decks)

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