clostridium perfringens
metronidazole, chloramphenicol, penicillin G
what kind of killers are beta lactams? what does this imply?
time-dependent; since they have short half-lives you need shorter dosing intervals
penicillin G and V: spectrum
- gram positive anaerobes (notably, C. perfringens)
- gram positive (notably, 1st line for strep throat)
- narrow gram negative: neisseria meningiditis
- Syphilis
what is oxacillin?
a beta lactam penicillin antibiotic used against beta-lactamase-positive staph
amoxicillin: class, uses
- beta lactam
- otitis media in children caused by strep pneumoniae
- alternate choice for Lyme disease
2 important uses that ampicillin has that amoxicillin doesn’t
meningitis, GI infections
otitis media by strep pneumoniae (2)
amoxicillin, TMP/SMX
ticarcillin: class, uses
- beta lactam
- broad gram negative spectrum (notably, Pseudomonas aeruginosa)
piperacillin: class, uses
- beta lactam
- broad gram negative spectrum like ticarcillin, but also more Pseudomonas and Klebsiella
pseudomonas aeruginosa
CC TT PNG
ciprofloxacin, ceftazidime, ticarcillin, tobramycin, piperacillin, norfloxacin, gentamicin
mechanism of clavulanic acid and tazobactam
beta-lactam “analogs” that bind irreversibly to beta-lactamase
mechanism of beta-lactams
competitively and irreversibly inhibit PBPs which catalyze cell wall cross-links
mechanism of cephalosporins
they are beta-lactams = competitively and irreversibly inhibit PBPs
1st generation cephalosporins: uses, two drugs
- gram positive
- surgical prophylaxis for skin flora
- drugs: cefazolin, cephalexin
surgical prophylaxis for skin flora
cefazolin
3rd generation cephalosporins: uses, two drugs
- gram negative
- ceftriaxone, ceftazidime
ceftriaxone: uses
- common types of meningitis
- gonorrhea
ceftazidime: use
Pseudomonas aeruginosa
only beta-lactam with no cross-reaction with other beta-lactams
aztreonam
imipenem: what it is, uses
- broad spectrum beta lactam resistant to many beta-lactamases
- mixed, ill-defined, resistant infections (notably, C. perfringens)
aztreonam: what it is, use, unique aspect
- beta lactam
- gram negative aerobes
- no allergic cross-reactions with beta lactams
- beta lactam
- gram negative aerobes
- no allergic cross-reactions with beta lactams
aztreonam
vancomycin: what it is, -cidal or -static, mechanism, uses
- glycopeptide antibiotic
- bactericidal
- binds to free end (D-Ala-D-Ala) of pentapeptide, which interferes with crosslinking and elongation of peptidoglycan chains
- gram positives ONLY (notably, MRSA and C. difficile)
fosfomycin: mechanism, uses
- inhibits synthesis of peptidoglycan building blocks
- use: uncomplicated UTIs caused by E. coli, Enterococcus (2 F’s for 2 E’s)
bacitracin: what it is, mechanism, use
- polypeptide
- interferes with lipid carrier that moves cell wall components through cell membrane
- topical use only, gram positive spectrum
polymyxin B: mechanism, uses
- cationic detergent that binds LPS in the outer membrane of gram negatives
- topical use only, gram negative spectrum
daptomycin: mechanism, uses
- binds to bacterial cytoplasmic membrane, causing rapid membrane depolarization
- gram positive (notably, MRSA)
cell membrane agents
polymyxin B and daptomycin
quinolones: mechanism, -static or -cidal, killing type, drugs, side effects
- inhibits DNA gyrase –> interferes with supercoiling
- bactericidal; killing dependent on area under the curve
- norfloxacin, ciprofloxacin, moxifloxacin
- side effects: EKG irregularities, tendon rupture, seizures
quinolones used for UTIs
norfloxacin, ciprofloxacin
ciprofloxacin: what it is, uses
- quinolone
- useful for infections at many sites: UTIs, chlamydia
moxifloxacin: what it is, uses
- quinolone
- best gram positive activity out of quinolones
- respiratory infections: community-acquired pneumonia and bacterial bronchitis
community-acquired pneumonia (2)
moxifloxacin, tigecycline
nitrofurantoin: mechanism, uses, side effects
- converted to reactive compounds which can damage DNA
- UTIs
- side effects: acute and chronic liver damage, leukopenia, acute hemolytic anemia
rifampin: mechanism, -static or -cidal, uses, side effects
- inhibits bacterial RNA synthesis by binding RNA polymerase
- bactericidal
- uses: tuberculosis, meningitis prophylaxis (neisseria meningitidis, haemophilus influenza type b)
- side effects: serious hepatotoxicity, strongly induces hepatic CYPs, orange colors to bodily fluids
fidaxomicin: use
C. difficile
metronidazole: mechanism, -static or -cidal, uses
- anaerobes reduce the nitro group of metronidazole –> resulting product damages DNA
- bactericidal
- uses: anaerobes (C. difficile, C. perfringens), H. pylori, gardnerella vaginalis, giardia
C. difficile enterocolitis: causes, treatment
- can be caused by all antibacterials, consider in all patients with antibacterial drugs in last 2 months
- metronidazole (first choice), vancomycin, fidaxomicin
aminoglycosides: mechanism, -static or -cidal, uses, drugs, what kind of killing
- bind to 30S/50S interface; inhibits protein synthesis
- bactericidal
- gram negative aerobes
- tobramycin, amikacin, gentamicin
- concentration-dependent killers
why are aminoglycosides bad at killing anaerobic microbes?
they need to be transported into bacteria by an energy-requiring aerobic process
what is a drug you could give to someone with strep throat who has a penicillin allergy?
clarithromycin
tetracyclines: mechanism, -static or -cidal, uses, drugs, side effects
- bind to 30S ribosomal subunit
- bacteriostatic
- preferred agents for “unusual bugs”=rickettsia, lyme disease, chlamydia; also syphilis and gonorrheae
- doxycycline, minocycline
- side effects: teeth discoloration (contraindicated in children and pregnancy)
what class of drugs show post-antibiotic effect? name the drugs.
aminoglycosides: tobramycin, gentamicin, amikacin
what drug class are doxycycline and minocycline in?
tetracyclines
what drug class are tobramycin, gentamicin, amikacin in?
aminoglycosides
tigecycline: mechanism, -static or -cidal, use
- mechanism like tetracyclines (binds to 30S subunit) but also binds to other sites
- bacteriostatic
- broad spectrum (notably, MRSA, C. perfringens), but last line due to risk of death
chloramphenicol: mechanism, -static or -cidal, use, side effects
- binds 50S subunit
- bacteriostatic
- broad spectrum (notably, C. perfringens) but last line due to serious side effects
- side effects: bone marrow depression, blindness
macrolides: mechanism, -static or -cidal, drugs
- binds 50S subunit, blocks translocation along ribosomes
- bacteriostatic
- erythromycin, clarithromycin, azithromycin
erythromycin: what it is, -static or -cidal, mechanism, uses, side effects
- macrolide
- bacteriostatic
- binds 50S subunit and blocks translocation along ribosomes
- gram positive (notably, Strep. A pharyngitis)
- side effects: enhanced GI motility, inhibits CYP3A metabolism, CV effects
clarithromycin: what it is, -static or -cidal, mechanism, why it’s better than erythromycin, uses
- macrolide
- bacteriostatic
- binds 50S subunit and blocks translocation along ribosomes
- better kinetics/less frequent dosing than erythromycin, less GI motility effects, wider spectrum
- spectrum similar to erythromycin + others (notably, used with amoxicillin plus an acid blocker to treat H. pylori)
azithromycin: what it is, -static or -cidal, mechanism, uses
- macrolide
- bacteriostatic
- binds 50S subunit and blocks translocation along ribosomes
- outpatient respiratory tract infections (notably, Strep. pneumoniae)
- genital infections: chlamydia, gonorrheae
clindamycin: what it is, -static or -cidal, mechanism, uses
- NOT a macrolide but same mechanism
- bacteriostatic
- binds 50S subunit and blocks translocation along ribosomes
- gram positive, anaerobes (notably, C. perfringens)
linezolid: mechanism, -static or -cidal, uses, side effects
- binds to 50S subunit, preventing formation of 70S complex
- gram positive (notably, MRSA)
- VRE
- side effects: non-selective inhbitor of MAO, bone marrow suppression
first choice therapy for uncomplicated UTIs
TMP/SMX
1st line for strep throat
penicillin V
syphilis
penicillin G&V, tetracyclines (doxy- and mino-cycline)
best treatment for bacterial meningitis
ceftriaxone+vancomycin
quinolone for respiratory infections: community-acquired pneumonia and bacterial bronchitis
moxifloxacin
quinolone with best gram positive activity
moxifloxacin
meningitis prophylaxis (neisseria meningitidis, haemophilus influenza type b)
rifampin