Infectious Disease (ID) Flashcards
Cmax: MIC (concentration-dependent)
aminoglycosides, quinolones, daptomycin
AUC: MIC
vancomycin, macrolides, tetracyclines, polymyxins
Time> MIC (time-dependent)
beta-lactams (penicillins, cephalosporins, carbapenems)
Natural penicillins (Penicillin G)
Cover gram-positive cocci (Streptococci and Enterococci), gram-positive anaerobes (mouth flora)
Aminopencillins (PO: amoxicillin (Moxatag), IV:ampicillin)
Adds gram-negative coverage (HNPE)
Aminopenicillin + beta-lactamase inhibitor (clavulanate, sulbactam, tazobactam)
Adds MSSA, more resistant strains of Gram-negative bacteria (HNPEK), and Gram-negative anaerobes (B. fagilis)
Extended-spectrum penicillin + beta-lactamase inhibitor (piperacillin/tazobactam)
Adds expanded coverage of other gram-negative bacteria (CAPES), Pseudomonas.
Antistaphylococcal penicillins (IV: nafcillin, oxacillin; PO: dicloxacillin)
- Only covers Streptococci and MSSA
* No renal dose adjustment
HNPEK
H. influenzae (gram-negative bacilli or coccobacilli) Neisseria sp. (gram-negative cocci) Proteus mirabilis (gram-negative rods) E. coli (gram-negative rods) Klebsiella spp. (gram-negative rods)
CAPES (all gram-negative)
Citrobacter Acinetobacter Providencia Enterobacter Serratia Pseudomonas
Atypicals (have no cell wall)
Chlamydia spp.
Legionella spp.
Mycoplasma pneumoniae
Mycobacterium tuberculosis
Penicillin class trends
- All cover Enterococcus (except antistaph PNCs)
- Do not cover atypicals or MRSA
Natural penicillins
PO: Penicillin V Potassium
IV: Penicillin G aqueous
IM: Penicillin G Benzathine (Bicillin L-A)
1st gen cephalosporins (IV: cefazolin; PO: cephalexin)
Cover Staph, Strep, PEK, mouth anaerobes
PO Keflex: good for outpatient tx of strep throat, MSSA skin infections
IV Cefazolin: commonly used for surgical ppx
2nd gen: IV/IM/PO cefuroxime (Ceftin)
Better gram-negative coverage (HNPEK)
Cefotetan and cefoxitin have anaerobic activity (B. fragilis)
3rd gen: PO cefdinir; IV/IM ceftriaxone; IV/IM cefotaxime; PO cefpodoxime, IV/IM ceftazidime, IV ceftazidime/avibactam
Group 1: IV ceftriaxone, PO cefdinir (less Staph coverage, but better Strep coverage)
Group 2: ceftazidime, ceftazidime/avibactam (cover Pseudomonas)
4th gen: IV/IM cefepime
Broad-spectrum: Gram-positives, HNPEK, CAPES, Pseudomonas
5th gen: IV ceftaroline (Teflaro)
Similar to ceftriaxone, but with MRSA coverage
siderophore cephalosporin (IV)
cefiderocol (Fetroja): 2g IV Q8 hrs
cephalosporin class trends
- No Enterococcus or atypical coverage
Carbapenems: class effects. (commonly used for polymicrobial infections, empiric therapy when resistance is suspected, and resistant Pseudomonas or Acinetobacter infections)
- Drug of choice for ESBL-producing organisms
- All cover Pseudomonas (except ertapenem)
- Avoid in beta-lactam allergy & or seizure risk
- All IV; ertapenem is stable in NS only
- Do not cover atypicals, VRE, MRSA
ertapenem (Invanz)
- IV/IM: 1 gram daily
- CrCl ≤ 30 mL/min: dose adjustment required
- Stable in NS only
- No coverage of Pseudomonas, Acinetobacter or Enterococcus
Common Resistant Pathogens
Klebsiella pneumoniae (ESBL, CRE) E.coli (ESBL, CRE) Acinetobacter baumannii Enterococcus faecalis, Enterococcus facecium (VRE) Staph aureus (MRSA) Pseudomonas aeruginosa
monobactam (aztreonam)
Drug of choice for patients with beta-lactam allergy
Covers many Gram-negatives, including Pseudomonas. Has no Gram-positive or anaerobic activity.
Aminoglycosides (inhibit protein synthesis by binding to 30S ribosome)
Pros: Cover gram-negatives, synergistic with beta-lactams for Gram-positive infections, low resistance and low cost
Cons: renal and ototoxicity
Aminoglycoside: traditional dosing
- Draw trough 30 min before 4th dose
- Draw peak 30 min after the end of the 4th dose infusion
Peak: 5-10 mcg/mL
Trough: < 2 mcg/mL
Extended Interval Dosing Nomogram
- Draw random level sometime between 6-14 hours after the start of the infusion
- Plot on nomogram to determine dosing interval
- If the level plots on a line, round up to the next dosing interval to avoid potential toxicity
Quinolones (inhibit bacterial DNA topoisomerase IV and DNA gyrase)
- Have concentration-dependent activity
- Broad-spectrum of activity against Gram-negative, Gram-positive and atypicals
Respiratory quinolones (gemifloxacin, levofloxacin, moxifloxacin)
“My Good Lungs”
Enhanced coverage of S. pneumoniae and atypicals.
Antipseudomonal quinolones (ciprofloxacin and levofloxacin)
- Have enhanced Gram-negative activity, including Pseudomonas coverage.
- Commonly used for Pseudomonal infections, UTIs, intra-abdominal infections, traveler’s diarrhea
Moxifloxacin
- Has enhanced gram-positive and anaerobic activity. —- Can be used alone for mixed infections (intra-abdominal infections).
- The only quinolone that cannot be used to treat UTIs. - Has the highest risk of QT prolongation.
- IV:PO= 1:1
Quinolones: class effects
Boxed warnings: tendon rupture, peripheral neuropathy, CNS effects (including seizures), use last-line only
Warnings: QT prolongation, hypo and hyperglycemia, psychiatric disturbances, photosensitivity, avoid use in children
Interactions: chelation with divalent cations
delafloxacin
-Newer quinolone approved for skin infections, active MRSA coverage. Other quinolones are noted to have activity against MRSA, but avoid due to resistance.
Quinolone drug interactions
- Antacids and other polyvalent cations, multivitamins, sucralfate, and bile acid resins can chelate and inhibit quinolone absorption
- Lanthanum carbonate and sevelamer can decrease the [ ] of oral quinolones; separate by at least 2 hours before, and at least 2 hours after (with lanthanum) and 6 hours after (with sevelamer)
- can increase effects of warfarin
- can increase effects of sulfonylureas, insulin, and other hypoglycemic drugs
- caution with CVD, low K and Mg, and use with other QT-prolonging drugs (e.g. azole antifungals, antipsychotics, methadone, macrolides)
- Probenecid and NSAIDs can increase quinolone levels
- Ciprofloxacin can increase levels of caffeine, theophylline, and tizanidine
Macrolides (inhibit protein synthesis by binding to 50S ribosomal subunit)
- Commonly used for CAP and strep throat
excellent atypical coverage and H. influenzae - azithromycin, clarithromycin, erythromycin
Macrolide: drug interactions
- Erythromycin and clarithromycin are major substrates for CYP3A4 and CYP3A4 inhibitors. Avoid medications that are metabolized by CYP3A4 (C/I with simvastatin, lovastatin) or monitor.
- Use caution with CVD, decreased K and Mg, and when using with other QT-prolonging drugs
Erythromycin
Increases gastric motility, may be used for gastroparesis
Tetracyclines (inhibit bacterial protein synthesis by binding to the 30S subunit)
- Cover many Gram-positives (MRSA), Gram-negative bacteria (Haemophilus, Moraxella, atypicals) and other unique pathogens (spirochetes, Rickesttsiae, Bacillus anthracis, Treponema pallidum)
- Common uses: CA-MRSA skin infections, acne
Tetracycline safety
- Avoid use in children age <8 years, pregnancy, breastfeeding
- Photosensitivity
- Interaction with divalent cations
- IV: PO =1:1 (doxycycline, minocycline)
- Minocycline: drug-induced lupus erythematosus (DILE)
doxycycline
First-line for Lyme disease, Rocky Mountain Spotted Fever (tick-borne illnesses), CAP, COPD exacerbations, VRE UTI, monotherapy for chlamydia, combo therapy for gonorrhea
