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CMBM Exam 4 > Penicillins/Cephalosporins/Quinolones/Sulfonamides > Flashcards

Penicillins/Cephalosporins/Quinolones/Sulfonamides Flashcards

1
Q

Penicillins/Cephalosporins MOA

A
  • Bind/inhibit PBP’s (penicillin-binding-proteins)

*bacterial transpeptidase enzymes required for new bacterial cell wall synthesis (i.e. peptidoglycan cross-linking)

  • Bacterialcidal

*defective cell walls cause osmotic swelling/release of autolytic enzymes and bacterial lysis

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2
Q

Penicillins/Cephalosporins Resistance

A
  • Beta-lactamase (most common)

*bacterial enzymes that break open/inactivate B-lactam ring (penicillinases, cephalosporinases)

  • Modification of target penicillin binding proteins (PBPs)
  • Impaired penetration of drug to target PBPs
  • Presence of bacterial efflux pump
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3
Q

Probenecid

A
  • Use of Probenecid increases bioavailability (i.e., blood levels) of all penicillins; inhibits tubular secretion of B-lactam antibiotics
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4
Q

Pencillins- antimicrobial spectrum- narrow spectrum

A
  • Penicillin G

*sodium or potassium salt, IM, IV

  • Penicillin V

*potassium, PO

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5
Q

Penicillin V

A
  • 1st gen penicillin
  • Only one of first gen that is orally available
  • Only used for minor infections
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6
Q

Penicillin G Spectrum

A
  • Considered narrow spectrum drug
  • Stapn (non-R); Strep species (ear/throat/sinus pneumonia), Spirochetes (i.e., Treponema pallidum (syphilis), Borrelia burgdoferi (Lyme disease)
  • Serious enterococcal infections w/aminoglycosides
  • Pen G not resistant to B-lactamases
  • Difficulty penetrating gram (-) rods
  • Cross-reactivity to other pens regarding the allergic reactions
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7
Q

Antistaphylococcal penicillins

A
  • Nafcillin

*IM, IV

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8
Q

Nafcillin use

A
  • Indicated only for resistant staphylococcal (i.e., gram (+) cocci) infections; i.e. B-lactamase-producers
  • MRSA is resistant
  • Serious staph infections combined w/aminoglycosides
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9
Q

Aminopenicillins

A
  • Ampicillin (PO, IM, IV)
  • Amoxicillin (PO)
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10
Q

Aminopenicillins use

A
  • 2nd generation penicillins
  • Advantage of reliable oral bioavailability vs pen G
  • Gram (+) spectrum similar to PEN G plus activity against Streptococcus faecalis (enterococcus)
  • Not effective against gram (-) Proteus vulgaris, Pseudomonas aeurginosa, Serratia, Gonococci
  • Common gram (-) rods: E. coli, P. mirabilis, H. influenzae, Salmonella/Shigella, anaerobes
  • Not resistant to B-lactamases
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11
Q

Antipseudomonal 3rd Gen

A
  • Ticarcillin (IM,IV)
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12
Q

Ticarcillin use

A
  • Antipseudomonal (3rd gen. penicillin)
  • Main indication: Gram (-) P. vulgaris, P. aeruginosa (often in combo w/ an aminoglycoside)
  • Not resistant to B-lactamase
  • Poor oral bioavailability
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13
Q

Antipseudomonal 4th Gen.

A
  • Piperacillin (IM, IV)
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14
Q

Piperacillin use

A
  • Antipseudomonal (4th gen penicllin)
  • Broad spectrum antibacterial activity
  • Spectrum similar to 3rd gen w/greater ptoency/effectiveness against more gm (-)
  • Reserved for super-serious infections

*often used w/an aminoglycoside (e.g. Streptomycin) for serious infections w/enterococci (e.g. endocarditis)

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15
Q

Beta-Lactamase inhibitors

A
  • Suicide molecules: bind/inhibit lactamase enzymes (e.g., clavulanic acid, sulbactam, tazobactum)
  • Diff inhibitors combined w/extended spectrum penicillins (e.g., piperacillin-tazobactum)
  • Basic antibacterial spectrum usually the same or slightly increased, hopefull the inhibitor ties up the lactamase so that the antibiotic is not inactivated
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16
Q

Imipenem-cilastatin

A
  • Carbapenems; MOA similar to Pens
  • IV
  • Broad spectrum: gm (+), gm (-), and anaerobes
  • Cross-reactivity w/Pen allergic rxn
  • Demonstrates good resistance to beta-lactamases

- Used only parenterally

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17
Q

Aztreonam (Azactam)

A
  • Monobactam
  • MOA similar to pens
  • IV
  • High affinity for PBP of gm (-); poor affinity for PBPs of gm (+) or anaerobes
  • No cross-reactivity w/Pen allergic rxn.
  • Demonstrates good resistance to beta lactamases

- Used only parenterally

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18
Q

Vancomycin use

A
  • Glycopeptide that inhibits transglycosylase (cell wall synthesis)
  • Bactericidal for gm (+) bacteria (e.g. MRSA)
  • Renal elimination
  • No cross-reactivity w/Pen allergic rxn.

- Demonstrates good resistance to beta-lactamases

- Used only parenterally

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19
Q

Penicillin Clinical Indications

A
  • Otitis media (ear infection)
  • Sinusitis (sinus infection)
  • Pharyngitis (throat infection)
  • Lower respiratory infections
  • UTI’s
  • Systemic infections
20
Q

Cephalosporins Characteristics

A
  • Beta-lactam antibiotics w/larger B-lactam ring structure; more resistant to B-lactamases; often effective in penicilin-R infections

- Cross-allergenicity w/Pens; about 5-10%

- Effective against staphylococcal infections and typhoid fever

21
Q

Cephalosporin Gen characteristics

A
  • From 1st (cefazolin) to 4th (Cefepime)
  • Gradual decrease in gm (+) coverage
  • Increase in gm (-) coverage
  • Increse in CNS penetration (3/4th)
  • Increase in resistance to inactivation by B-lactamases
22
Q

Cephalosporin Pharmacokinetics

A
  • Excretion: mostly unchanged in urine; exception cefoperazone and ceftriaxone w/ increased amounts via liver/biliary/GI
  • Probenacid slows/blocks tubular secretion
23
Q

1st Gen Cephalosporin Spectrum

A
  • Cefazolin

*Preferred use for surgical prophylaxis; has long t1/2 than other

  • Gm (-) similar to 2nd gen pens- not effective against gm (-) Proteus vulgaris, Pseudomonas aeruginosa, Serratia, Gonococci
24
Q

2nd Gen Cephalosporin Spectrum

A
  • Cefoxitin

*effective against Bacteriodes fragilis and most anaerobs

  • Main feature: increase gm (-) activity including against beta-lactamase-producing H. influenzae or K. pneumoniae and penicillin-resistant pneumococci
  • Not active against P. aeruginosa
25
3rd Gen Cephalosporin Spectrum
- Usually less gm (+) activity than 1 and 2 gen., however, used in **gm (+) meningitis** (e.g. pneumonococci) due to **good lipid solubility to penetrate CNS** - **Ceftriaxone** \***drug of choice for resistant gonorrhea (N. gonorrhoeae)** \*sing IM dose for uncomplicated cases and meningits - **Cefixime** can be used orally in place of Ceftriaxone
26
4th Gen Cephalosporin
**- Cefepime**
27
Cephalosporin Clinical Indications
- Alternative to Pens in beta-lactamse-producing bacteri - Otitis, sinusitis, lower respiratory tract infections - Surgical prophylaxis (e.g., **Cefazolin**) - Meningitis, resistant gonorrhea 3rd gen (e.g., **Ceftriaxone**) \*common gram (-) infections
28
Quinolones/Fluoroquinolones MOA
- Bactericidal- inhibits bacterial DNA gyrase
29
Quinolones/1st Gen.
- Nalidixic acid and Cinoxacin - Limited usage - Resistance develops rapidly to these drugs within a few days (usually **mutation of DNA gyrase binding**)
30
Fluoroquinolones/ 2nd Gen.
- Addition of **fluoride** and side rings significantly extends gm (-) spectrum adds some gm (+) acivity but unreliable - **Ciprofloxacin** \*PO, IV - **Ofloxacin** \*PO, IV
31
Fluoroquinolones 2nd Gen. Pharmakokinetics
- Low CNS levels - Good PO, but interference by **antacid formulations w/ Al, Mg, Zn, Ca may result in 50% decrease. This is also true of most fluoroquinolones** **-** Mixed excretion: urine/GI, unchanged and metabolized; all reach effective conc. in urine/GI and accumulate in renal failure **except moxifloxacin (biliary excretion)** **- Ciprofloxacin** inhibits CYP-450 drug metabolizing enzymes, may increase t1/2 of other drugs
32
Fluoroquinolones 2nd Gen. Spectrum
- Broad gram (-): most Klebsiella, Enterobacteriaceae, **Psuedomonas (Cipro most active/potent)**
33
Fluoroquinolones Clinical Uses
- Wide use: skin/soft tissue, bone/joint, UTI/GI (**Travelers diarrhea**), respiratory, otitis media; advantage of PO in serious gm (-) infections, e.g., Pseudomonas; use for prophylaxis in neutropenic patients (e.g. **Ofloxacin**) - Not indicated for CNS/meningitis due to low penetration
34
Fluoroquinolones 3rd Gen.
- Increase PO absorptin, inc Vd, tissue conc \> serum conc. - Longer t1/2, may allow once/day dosing - **Levofloxacin, t1/2 - 7hr** - **Moxifloxacin, t1/2 - 10hr** - Better gm (+) coverage- can be used as an alternative for ear infections (otitis media) and upper respiratory infections- NOT as effective as Cipro for gm (-)
35
Fluoroquinolones 3rd. Gen Spectrum
- Increased **gm (+), esp. for streptococci**; gm (-) similiar to Cipro; however Cipro generally considered most active against gm (-)
36
Fluoroquinolone Adverse Effects
- Skin: rash, allergy, **photosensitivity** (2 types): photoallergic (uncommon) and phototoxicity, highest incidence w/lomefloxacin, other less - Nephrotoxicity- **crystaluria may occur in alkaline urine** **- Joint swelling, tendonitis, tendon rupture** **\*contraindicated: pregnancy/nursing/children**
37
Sulfonamides MOA
- **Inhibit dihydropteroate synthase**, enzyme catalyzing conversion PABA to folic acid required for DNA synthesis \*inhibiting the generation of Dihydrofolic acid - **No cross-reactivity w/Pen allergic rxns.**
38
Sulfonamide Spectrum
- **Gm (-): E. coli, P. mirababilis for uncomplicated UTI's; this is main indication for systemic use of sulfonamides adm. alone**
39
Sulfonamide Pharmacokinetics
- Good PO bioavailability - Excretion: mainly urinary, both metabolites and unchanged (**acidic urine decreased solubility and cause crystalline drug deposits**; alkaline urine favors solubility and excretion
40
Sulfonamides Clinical Indications
- **Systemic use: sulfisoxazole and sulfamethoxazole**, primarily for UTIs - **Local use: sulfasalazine**, bowel lumen (ulcerative colitis) - **Topical use: sulfacetamide** (opthalmic infections)
41
Sulfonamides Adverse Effects
- **Alergy; rash** - **Hemolytic anemia** - CNS; **newborn at risk to dev. Kernicterus (yellow pigment in basal ganglia due to bilirubin)** - Renal; nephrotoxicity/**crystalluria in acidic urine**
42
Trimethoprim/Sulfamethoxazole Characteristics
- Resistance develops quickly when either drug is used alone
43
Trimethoprim/Sulfamethoxazole Spectrum
- **Gm (-) activity is main indication and includes most gm (-) bacteria and Enterobacteriaceae, not Pseudomonas** **-** Indications**: UTIs**, **GI, respiratory infections (doc for Pneumocystis jiroveci)**, prostatitis/vaginitis, otitis media
44
Trimethoprim Adverse Effects
- Increased incidence of adverse effects in AIDS patients w/TMP/SMX: fever, rash, decreased blood cells; **folate deficiency may cause macrocytic anemia; supplement w/folinic acid**
45
Sulfonamides Precaution for UTIs
- **No FQ, no sulonamides near term**
46
Prostatitis Treatment
- **Give a Fluoroquinolone** - Male \<35 w/infection often due to C. trachomatis- **Ofloxacin** BID 7 days, 6 weeks if chronic infection; Cipro not used anymore

CMBM Exam 4 (14 decks)

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