Antibiotic Review Flashcards
How to select an antibiotic?
- What bacteria are you trying to target?
- What is the antibiotic spectrum of coverage?
- Are there any contraindications or side effects to consider?
Characteristics of gram positive bacteria?
Thick cell wall
2-layer envelope
NO porin channel
NO endotoxin
Vulnerable to lysozyme and PCN
*Lyzozyme: small enzyme that attacks cell walls of bacteria, part of natural immune system
**Gram positive bacteria stain purple on gram stain
Characteristics of gram negative bacteria?
Thin cell wall
3-layer cell envelope
Porin channel
Resistant to lysozyme and PCN
**stains pink/red on gram stain
Gram + vs. gram - cell wall picture (flip for reference)
Types of aerobic gram positive organisms
Streptococcus
Staphylococcus
Enterococcus
Corynebacterium
Listeria
Aerobbic gram positive organisms have enzymes to break down O2 (unlike anaerobes), therefore, blood cultures are taken in 2 tubes (1 w/ oxygen and 1 w/o)
Types of anaerobic gram positive organisms
Peptococcus
Peptostreptococcus
Clostridia (C. diff)
Propionibacterium acnes
Anaerobic gram positive organisms are associated with acne, above diaphragm, tooth abscess
Types of aerobic gram negative organisms
Enterobacteriaceae (E coli, Klebsiella, Proteus, Enterobacter, Serratia, Providencia, Salmonella, Shigella, Morganella, Citrobacter)
Moraxella
Haemophilus
Neisseria
Pseudomonas
Helicobacter
Legionella
Types of anaerobic gram negative organisms
Bacteroides
Fusobacterium
Of note: anaerobics generally below diaphragm (diabetic foot ulcers, etc)
Types of atypical organisms (neither gram + or gram -)
Chlamydia
Chlamydophila
Rickettsia
Mycoplasma (no cell wall)
Spirochetes (Syphilis, Lyme Disease)
Mycobacterium (TB, mycobacterium avium intracellulare)
What are the 3 main MOAs for most antibiotics?
Inhibit cell wall production, inhibit protein synthesis (30s or 50s ribosome), inhibit DNA synthesis
Examples of antibiotics that inhibit cell wall synthesis
Beta-Lactams
(Penicillins, Cephalosporins, Carbapenems)
Vancomycin
Glycopeptides
Fosfomycin
Bacitracin
Examples of antibiotics that inhibit protein synthesis
Macrolides (50s)
Ketolides (50s)
Oxazolidinones (50s)
Clindamycin (50s)
Aminoglycosides (30s)
Tetracyclines (30s)
Examples of antibiotics that inhibit DNA synthesis
Fluoroquinolones (topoisomerase)
Sulfamethoxazole/Trimethoprim (folic acid antagonist)
Rifampin (RNA polymerase)
Metronidazole “alters” DNA
What are some bactericidal antibiotics (“kills the bacteria”)?
Beta Lactams
Fluoroquinolones
Glycopeptides
Aminoglycosides
Metronidazole
What are some bacteriostatic antibiotics (“prevents the growth of bacteria”)?
Tetracyclines
Macrolides
Lincosamides
Sulfonamides
Spectrum of penicillins?
Gram-positive (S. pneumo and Staph resistance), gram-negative, anaerobes
AEs of penicillin?
Hypersensitivity, GI, hematological, seizures
Mostly renal elimination (adjust if CKD) EXCEPT nafcillin (hepatic)
Describe examples, spectrum, and use of natural penicillins
Pen G, Pen VK, Procaine, Benzathine
Spectrum: T. pallidum, streptococcus,
enterococcus,
Neisseria meningitidis,
Borrelia burgdorferi (all gram +)
Use: Syphilis, Strep pyogenes, Lymes
Describe examples, spectrum, and use of anti stapholococcal penicillins
Dicloxacillin, Nafcillin, Oxacillin, Methicillin
Spectrum: Staphylococcal and streptococcal infections (all gram +)
Use: MSSA, skin infections (mastitis)
Describe examples, spectrum, and use of amino penicillins
(IV Ampicillin, PO Amoxicillin)
Spectrum: GAS, GBS, enterococci, listeria, Borrelia burgdorferi, H. pylori (all gram +)
Use: Respiratory tract infections, Lymes, GI ulcers, UTI, endocarditis prophylaxis*
Amox + Mono = maculopapular rash*
Describe examples, spectrum, and use of extended spectrum penicillins
Piperacillin, Ticarcillin
Spectrum: Gram positives and negatives including pseudomonas
Use: IV only, serious infections
Examples agents of beta-lactamase inhibitors
Oral = amoxicillin/clavulanate (Augmentin)
IV = ampicillin/sulbactam (Unasyn), piperacillin/tazobactam (Zosyn), ticarcillin/clavulanate (Timentin)
Spectrum, use, and AEs of beta-lactamase inhibitors?
Spectrum: extends spectrum to beta-lactamase producing organisms (Staph aureus, Moraxella Haemophilus, Neisseria, Bacteroides, Enterobacteriaceae)
Use: Amox-clav = respiratory tract infections, dental infections, animal bites, skin infections
AE: diarrhea (clavulanate)
Example agents of first generation cephalosporins?
Oral: cephalexin (Keflex)
Parenteral: cefazolin (Ancef)
All have ph except Cefazolin, but don’t let that faze you
Spectrum and use of first generation cephalosporins?
Spectrum: Gram positives (staph/strep), MSSA, limited gram negatives (E. coli, Klebsiella), oral anaerobes
Use: Skin infections, streptococcal infections, pre-op prophylaxis
Example agents of second generation cephalosporins?
Oral: cefuroxime (Ceftin)
Parenteral: cefuroxime, cefoxitin, cefotetan
The family is gathered, some wearing fur coats, and your foxy cousin is drinking tea
Spectrum and use of second generation cephalosporins?
Spectrum: Less gram positive, more gram negative than first generation. H influenzae, Moraxella, Neisseria, Enterobacter, Borrelia burgdorferi.
Use: Respiratory tract infections, UTI, Lyme, skin infections
Example agents of third generation cephalosporins?
PO: cefpodoxime, cefixime, cefdinir (Omnicef), ceftibuten
IV: ceftriaxone (Rocephin)
Most end in the suffix -me. Dine Alone (Cedinir and Ceftriaxone)
Spectrum and use of third generation cephalosporins?
Spectrum: Less gram +, more gram - **(including pseudomonas) **
Use: Respiratory, skin (not great), UTI, gonorrhea, meningitis
Example agents of fourth generation cephalosporins?
IV: cefepime (Maxipime)
Spectrum and use of fourth generation cephalosporins?
Spectrum: **Gram + and - coverage (including Pseudomonas) **
Use: Unknown cause of infection pending blood cultures
Example agents of fifth generation cephalosporins?
IV: ceftaroline
Spectrum and use of fifth generation cephalosporins?
Spectrum: Gram + and - coverage (NOT including Pseudomonas) **
Use: MRSA and resistant S. pneumoniae
“Think Ceftriaxone + MRSA coverage”
MOA of carbapenems?
Inhibits cell synthesis
Carbapenem agents?
Imipenem, meropenem, ertapenem (ALL IV)
Spectrum and AEs of carbapenems?
Spectrum: VERY BROAD (includes ESBL organisms)
“Heavy hitters”
**Ertapenem is the only carbapenem with NO pseudomonas coverage (narrower spectrum)
ESBL: extended-spectrum beta-lactamases
AEs of carbapenems?
Hypersensitivity (penicillins), GI, seizures, hypotension
MOA of monobactams?
Inhibit cell wall synthesis
Monobactam agents?
IV only aztreonam
Spectrum of monobactams?
Spectrum: aerobic gram negative only (including Pseudomonas)
“Heavy hitters”
AEs of monobactams?
GI
Aztreonam pearls
Similar to aminoglycosides
Little cross reactivity with PCN allergies
Note renal dosing
Is not often used unless allergic to something else
Fluoroquinolone MOA?
Inhibits DNA synthesis (topoisomerase - inhibit twisting of DNA)
FQ agents?
Ciprofloxacin, ofloxacin, levofloxacin, moxifloxacin