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Flashcards in Antibiotics Deck (25):
1

Centor Score

Indicator of bacterial infection
- Absence of cough
- Age (3-14)
- Anterior Cervical Lymphadenopathy
- Fever
- Tonsillar erythema or exudate

2

Rapid Antigen Strep Test

Specific but not sensitive
- detects the C-carbohydrate protein on cell wall
If negative --> take a culture (gold standard)

3

Beta-lactams

Penicillins, cephalosporins, carbapenems, aztreonam
- bind to PBP and inhibit transpeptidases --> build up of cell wall precursors --> cell lysis

4

Anaphylaxis from penicillin

Give Epi
- Vasoconstricts alpha receptors (increase BP)
- Bronchodilates beta-2 receptors

5

Aztreonam

beta-lactam antibiotic that can be used for patient with penicillin allergy
only effective against gram - organisms

6

Macrolides

Erythromycin, Azithromycin, Clarithromycin
- binds 23s rRNA of 50S subunit inhibiting translocation
- Broad spectrum coverage of respiratory pathogens
- methylation of 23s resistance and efflux
- GI discomfort, hepatic failure, QT syndrome, clarithromycin --> miscarriages

7

Treatment failure of antibiotics

1. Resistance
2. Compliance
3. Viral cause
4. Neighboring flora express beta-lactamases
5. Strep pyogenes enter epithelial cells

8

Influenza antivirals

Adamantane --> resistance is extremely high b/c of change in viral M2 proton ion channel
Neuraminidase inhibitors --> active against dividing virus (prevent release)
- Oseltamivir - > 1yr, oral prodrug activated by hepatic esterases, renal excretion, GI, headache, fatigue
- Zanamivir - > 7yr, poor orally, inhaled but don't give with asthma or pulmonary disease b/c of bronchospasm

9

Superinfection

secondary infection occurring after previous infection
- induced by broad spectrum antibiotic killing of normal flora
- influenza infection --> apoptosis of airway epithelial cells --> enhances bacterial growth

10

Community Acquired Pneumonia

spread of organisms normally in URI into LRI
- pneumonia + influenza are most common cause of infection-related mortality in US
Tx = otherwise healthy --> doxycycline or macrolide
comorbidities --> fluoroquinolone or beta-lactam

11

Mechanisms of Drug Resistance

1. Increased elimination --> efflux
2. Drug-inactivating enzymes
3. Alteration in target molecule
4. Decreased Uptake --> porins

12

Strep pneumo

penicillin resistance due to mutations in PBP and macrolide resistance due to changes in ribosomal binding site or efflux

13

Fluoroquinolones

Gemifloxacin, Levofloxacin, Moxifloxacin
bactericidal - direct inhibitor of DNA replication by binding bacterial topoisomerase (II (-)) and (IV +)
Broad spectrum
Resistance developed from overprescribing --> active efflux and mutations in topo
S.E. - GI, tendinopathies, avoid pregnancy

14

Mycoplasma pneumonia

Doxycycline and azithromycin
Beta-lactams aren't effective b/c of lack of cell wall in mycoplasma

15

Tetracyclines

Doxycycline --> [ ] dependent
bacteriostatic - binds 30S subunit preventing attachment of tRNA
Limited spectrum b/c of resistance
Resistance --> increased efflux
S.E. - photosensitivity, discoloration of teeth, inhibits bone growth

16

[ ] dependent killing and time dependent

[ ] dependent --> concentrations >10 times above MIC
Time dependent --> effect depends on time above MIC

17

Vancomycin

glycopeptide that inhibits cell wall synthesis by binding to D-ala-D-ala and inhibiting transglycosylation reactions
- mainly against Gram + organisms
MRSA

18

Linezolid

oxazolidone that targets 50S subunit and inhibits protein synthesis
- mainly against gram + organisms

19

Porins of gram negative organisms

Gram - organisms have an extra layer on their cell with porins that medications have to enter through --> makes treatment more difficult of gram - organisms

20

Polymyxin E/Colistin

binds phosphatidylehanolamine creating holes in the membrane
covers multidrug resistant Gram -
nephrotoxic --> use as last resort
no resistance

21

Histoplasma capsulatum

reticuloendothelial cells
Mississippi/Ohio river valleys
- treat with amphotericin or itraconazole

22

Blastomyces dermatitidis

Rotting wood, Eastern US
broad based yeast
- treat with amphotericin or itraconazole

23

Coccidioides immitis

"valley fever"
Endospores in spherule
SW US, dry climates
- treat with amphotericin or itraconazole

24

Amphotericin B

binds ergosterol, creating holes in membrane
used for invasive systemic fungi in immunocompromised patients
Toxic because it can binds cholesterol too --> 80% of patients have nephrotoxicity
Rare resistance

25

Azoles

Voriconazole, Itraconazole
binds fungal P-450 --> blocking production of ergosterol and causing accumulation of precursor
wide spectrum, orally available
Hepatotoxicity, neurotoxicity, alters hormones
Resistance --> altered P-450, efflux