Antibiotic Therapy Flashcards
Mechanism of action of glycopeptides
Inhibition of bacterial cell wall synthesis. Work at an earlier stage than do beta-lactams.
Vancomycin is a “BLANK”
Glycopeptide
Daptomycin is a “BLANK”
Lipopeptide
Mechanism of action of Lipopeptides
Disruption of cell wall.
- Calcium dependent
- Depolarizes cell membrane
- Disrupts RNA, DNA, protein synthesis –> cell death
In general, Glycopeptides/Lipopeptides are active against:
Gram +ve organisms, including beta-lactam resistant organisms (i.e. MRSA)
Are Glycopeptides/Lipopeptides bacteriostatic or bactericidal?
Bactericidal
This Glycopeptide is slowly cidal, and when given PO is not systemically absorbed
Vancomycin
Lung surfactant inactivates “BLANK”; therefore, this agent should not be used to treat pneumonia!
Daptomycin
Spectrum and indications for Vancomycin IV
Spectrum: Gram +ve (Enterococci, penicillin resistant Streptococci, MRSA, CNS
Indications: Bacteremia, pneumonia, endocarditis, bone/joint, SSTI, surgical prophylaxis
Spectrum and indications for Vancomycin PO
Spectrum: C. difficile
Indications: C. difficile infection
Spectrum and indications for Daptomycin IV
Spectrum: Gram +ve (Enterococci, penicillin-resistant Streptococci, MRSA, CNS, and VRE)
Indications: Bacteremia, endocarditis, bone/joint, SSTI
Gentamycin and Tobramycin are both “BLANKS”
Aminoglycosides
Mechanism of action for Aminoglycosides
Inhibit protein synthesis by binding the 30S ribosomal subunit
Are Aminoglycosides bacteriostatic or bactericidal?
Bactericidal
Aminoglycosides are renally excretable and may cause the following toxicities (2)
- Nephrotoxicity
2. Ototoxicity
Gentamicin and beta-lactams act synergistically against what?
Enterococci
Spectrum and indications for Gentamicin IV
Spectrum: Gram -ve, Pseudomonas, synergy vs Streptococci and Enterococci with beta-lactam or vancomycin
Indications: Drug resistant UTI, combination therapy for Gram -ve sepsis, synergy for Gram +ve bacteremia and endocarditis
Spectrum and indications for Tobramycin IV
Spectrum: Gram -ve, Pseudomonas (better than gentamicin)
Indications: Drug resistant UTI, combo therapy for serious Pseudomonas infections
Azithromycin is a “BLANK”
Macrolide
Mechanism of action for Macrolides
Inhibit protein synthesis by binding the 23S rRNA in the 50S ribosomal subunit
Macrolides are active against intracellular organisms, true or false?
TRUE
Are Macrolides bacteriostatic or bactericidal?
Bacteriostatic
Does Azithromycin have a long or short half life?
LONG
Spectrum and indications for Azithromycin IV/PO
Spectrum: Mycoplasma, Chlamydophila, Legionella, M. catarrhalis, Chlamydia trachomatis, N. gonorrheae, MAC
Indications: Combo therapy for MAC Tx, MAC prophylaxis in HIV pt’s, 2nd line for STI’s, combo with beta-lactam for CAP
Why is Azithromycin the preferred macrolide over erythromycin and clarithromycin? (5)
- Broader spectrum
- Fewer drug interactions
- Once daily dosing
- Tolerability
- IV option
Clindamycin is a “BLANK”
Lincosamide
What is the mechanism of action of Clindamycin?
Inhibits proteins synthesis by binding to the 50S ribosomal subunit
What is the bioavailability of Clindamycin?
Excellent
Is Clindamycin bacteriostatic or bactericidal?
Bacteriostatic
Clindamycin inhibits toxin production from what?
Group A Streptococcus
Clindamycin is used in combination with what other antibiotic to treat necrotizing faciitis?
Penicillin
Clindamycin is high risk for what?
C. difficile
Spectrum and indications for Clindamycin PO/IV
Spectrum: Streptococci, S. aureus, MRSA (if susceptible), anaerobes
Indications: SSTI, bone/joint, abscesses, alternative for dental infections, polymicrobial infections in combo with Gram -ve agent, combo vs necrotizing faciitis
Doxycycline and Tigecycline fall under what family of antibiotics?
Tetracyclines/Glycylcyclines
What is the mechanism of action of Tetracyclines/Glycylcyclines?
Inhibits protein synthesis by binding the 30S and 50S ribosomal subunits
Tetracyclines/Glycylcyclines are bacteriostatic, true or false?
TRUE
Tetracyclines and Glycylcyclines are active against intracellular pathogens, true or false?
TRUE
Spectrum and indications for Doxycycline PO
Spectrum: Mycoplasma, Chlamydophila, Legionella, Chlamydia trachomatis, S. pneumoniae, Haemophilus, Moraxella, S. aureus (including MRSA)
Indications: COPD, CAP, Chlamydial STIs, purulent cellulitis (suspected MRSA)
Spectrum and indications for Tigecycline IV
Spectrum: Broad spectrum, Gram +ve (E. faecalis, MRSA), Gram -ve, anaerobes
Indications: Last line option of polymicrobial, multidrug resistant organisms if susceptibility confirmed
3 problems with Tetracycline PO
- Requires QID dosing on an empty stomach
- Poorly tolerated
- Narrower spectrum than Doxycycline
Ciprofloxacin and Levofloxacin are both “BLANKS”
Fluoroquinolones
What is the mechanism of action of Fluoroquinolones?
Inhibition of DNA gyrase and topoisomerase
Bioavailability of Fluoroquinolones
EXCELLENT
Are Fluoroquinolones bacteriostatic or bactericidal?
Bactericidal
What 2 Fluoroquinolones are active against intracellular pathogens?
- Levofloxacin
2. Moxifloxacin
Fluoroquinolones are high risk for C. difficile, true or false?
TRUE
Widespread use of Fluoroquinolones is leading to the development of resistance by which type of bacteria?
Gram -ve
Spectrum and indications for Ciprofloxacin IV/PO
Spectrum: Gram -ve, Pseudomonas
Indications: Not usually 1st line due to increasing Gram -ve resistance, UTI, in combo with metronidazole or clindamycin for polymicrobial infections
Spectrum and indications for Levofloxacin IV/PO
Spectrum: Streptococci, Mycoplasma, Chlamydophila, Legionella, Gram -ve
Indications: Not 1st line, reserve for suspected drug-resistant respiratory infections or allergy to 1st line agents.
Moxifloxacin is a respiratory fluoroquinolone, what is the risk of C. difficile with this drug?
High
Which Fluoroquinolone is active against multidrug resistant TB?
Moxifloxacin
Which Fluoroquinolone has no Pseudomonas activity and does not get to therapeutic concentration in the urinary tract?
Moxifloxacin
TMP-SMX and Nitrofurantoin are considered to be part of what family of antibiotics?
Anti-folates
Mechanism of action of Trimethoprim-sulfamethoxazole
Together they inhibit purine synthesis, preventing DNA synthesis
What is the mechanism of action of nitrofurantoin?
It is reduced inside the cell to produce reactive intermediates that cause cellular damage. There is minimal resistance due to complex mechanism.
TMP/SMX acts as a “BLANK” agent
Bacteriostatic
The bioavailability of TMP/SMX is…
EXCELLENT (PO)
Nitrofurantoin is (bacteriostatic/bactericidal), and only achieves therapeutic concentrations in (urine/blood)
Bactericidal, Urine
Nitrofurantoin is effective for cystitis, but not “BLANK”
Pyelonephritis
Spectrum and indications for Trimethoprim/Sulfamethoxazole IV/PO
Spectrum: Gram -ve, S. aureus (MRSA), S. pneumoniae, Nocardia, Pneumocystis jiroveci
Indications: UTI (not first line), purulent cellulitis (MRSA), Nocardia infections, PCP Tx and prophylaxis
Spectrum and indications for Nitrofurantoin PO
Spectrum: E. coli, Klebsiella, E. faecalis
Indications: 1st line for cystitis
Metronidazole is in which family of antibiotics?
Nitroimidazoles
What is the mechanism of action for Metronidazole?
It inhibits DNA synthesis
What is the bioavailability of Metronidazole?
EXCELLENT - also has excellent penetration of the CNS
What should you avoid when taking Metronidazole?
Alcohol (disulfiram reaction)
Spectrum and indications for Metronidazole PO/IV
Spectrum: Anaerobes (including C. difficile), Protozoa (i.e. Giardia)
Indications: C. difficile, used in combo for polymicrobial infections/abscesses, trichomoniasis
Linezolid belong to this class of antibiotics…
Oxazolidinones
Mechanism of action for Linezolid
Inhibits protein synthesis by binding to 23S rRNA in 50S ribosomal subunit - prevents the formation of 70S ribosome.
Bioavailability of Linezolid…
EXCELLENT
Linezolid is bacteriostatic/bactericidal…
Bacteriostatic
What is there a risk of with prolonged use (> 2 weeks) of Linezolid?
Cytopenias
Linezolid has activity against beta-lactam and vancomycin resistant organisms, true or false?
TRUE
Spectrum and indications for Linezolid PO/IV
Spectrum: Streptococci, Enterococci, Staphylococci, anaerobes
Indications: Resistance, allergy or failure with vancomycin therapy
Which 4 drugs were presented as anti-tuberculosis drugs?
- Rifampin
- Isoniazid
- Pyrazinamide
- Ethambutol
The 4 drug combo used for TB is bacteriostatic/bactericidal?
Bactericidal
Anti-tuberculosis drugs are poorly absorbed, true or false?
FALSE
Rifampin is a potent inhibitor/inducer of CYP 3A4?
Inducer
What type of toxicity should you monitor for when giving someone the empirical 4 drug combo for TB?
Hepatotoxicity
Indications for Rifampin
Penetrates Staph biofilms, TB, MAC, latent TB Tx
Indications for Isoniazid
TB and latent TB Tx
Indications for Pyrazinamide
TB
Indications for Ethambutol
TB, MAC
How much can you save by switching to Geico?
15% or more
Which antibiotics are effective against MRSA?
- Vancomycin IV (PO is not systemically absorbed)
- Daptomycin IV
- Clindamycin PO/IV (if susceptible..) - High risk of C. difficile!
- Doxycycline PO
- Tigecycline IV (last line option)
- TMP/SMX IV/PO
- Linezolid PO/IV (expensive, cytopenias with prolonged Tx)