Antibiotic Classes Flashcards
Natural Penicillins - G (IV) and V (oral)
beta-lactam targets transpeptidase (PPG synth),gram+, use for strep, meningococcus, syphillis
Penicillnase-resistant penicillins. Eg. methicillin, oxacillin, cloxacillin, dicloxicillin
beta-lactam, resistant to some beta-lactamses, use for Staph
Extended spectrum penicillins. Eg. ampicillin, amoxicillin, carbenicillin, pipericillin
beta-lactam with improved activity against gram-, less effective against gram+, often used with beta-lactamase inhibitor, used for uncomplicated UTI, otitis media, community pneumonia, H. flu, listeria meningitis
Beta-lactamase inhibitors (give examples)
clavulanate (w/ amoxicillin = Augmentin), sulbactam, tazolbactam… are examples of what?
Pencillin side effects
hypersensitivity - rash/hives; or anaphylaxis… are side effects of what? Nausea and vomiting are not side effects. C. diff colonization is not common because these drugs tend not to have broad gram- coverage
Cephalosporins
inhibit peptidoglycan synth, have 6 member ring adjacent to beta-lactam, wider spectrum than penicillins, beta-lactamase resistant, have 4 generations
1st Gen. Cephalosporins
beta-lactam with adjacent 6 membered ring. active against gram+ including Staph (but not MRSA), moderate against gram-‘s such as E. coli and Klebsiella; used for community UTI and resp infections; one used for surgical prophylaxis
2nd Gen. Cephalosporins
beta-lactam with adjacent 6-membered ring. increased gram- coverage, used for otitis media in children, H. flu, resp infection, UTIs
3rd Gen. Cephalosporins
beta-lactam with adjacent 6 membered ring with less gram+ coverage, more gram-. Used for hospital gram- septicemia, inPt pneumonia and UTIs, can penetrate CNS; used for gonoccocal infections
4th Gen. Cephalosporins - Cefipine
beta-lactam with adjacent 6 membered ring with enhanced activity to enterobacte.
Side effects of Cephalosporins
hypersensitivity (like penicillins, 5% of people have cross-reactivity), coverage of gram- causes increased risk of C. diff colonization. These are side effects of what ABx class?
Macrolides, eg. Azithromycin, erythromycin
binds reversibly to 50s ribosome, preventing translation -> Bacteriostatic. broad activity against gram+, some gram-. Used for community pneumonia, skin infections (not MRSA), upper resp tract inf, atypical pathogens such as Legionella, Chlamydia, Mycoplasma; often used when Pts allergic to penicillins
Aminoglycosides, eg. streptomycin, gentamycin, tobramycins, amikacin, neomycin
binds irreversibly to 30s ribosome ->Bacteriocidal. Transport into bacteria requires ATP, so won’t touch anaerobes. Synergistic with beta-lactams that damage cell wall. Good gram- coverage, particularly against Pseudomonas. Must be given IV or IM. Toxicity limits the use (ototoxicty, nephrotoxicity). Used for Pseudomonas, serious pneumonia, complicated UTIs. Can be used with beta lactams for endocarditis.
What does the pneumonic CLEan TAg stand for?
Pneumonic that tells you that Chloramphenicol/Clindamycin, Linezolid, and Azythromycin (and other macrolides) bind to the 50s subunit of the ribosome; and that Tetracycline and Aminoglycosides bind the 30s subunit. (50s is top of home plate, 30s is bottom)
Quinalones/Fluoroquinalones; levofloxacin, norfloxacin, ciprofloxacin
binds DNA gyrase. Targets gram-. Used for MDR Pseudomonas, eneterics (E. coli, salmonella, shigella, campylobacter), complicated UTIs, enterococci. Can be taken orally. Because kills gram- broadly, can lead to C. diff colonization
Which classes of drugs target nucleic acid synthesis?
quinalones/fluoroquinalones, metronidazole, rifamycins (What to these classes of drugs target?)
Sulfonamides, eg. sulfamexazole
inhibits folic acid pathway. Bacteriostatic for both gram+ and gram-. Often used synergistically with trimethoprim for Strep and H. flu, gram- enterics, pneumocystis (seen w/ AIDS).
Trimethoprim
inhibits folic acid pathway (downstream of sulfonamides). Used synergistically with sulfonamides to target both gram- and gram+.
Sides effects of trimethoprim/sulfamexazole (Bactrim)
hypersensitivity; inhibits warfarin metabolism -> high warfarin levels / bleeding (What ABx causes these side effects?)
Ciprofloxacin
a fluoroquinalone. Best gram- coverage among FQs, almost no gram+ activity. Used for UTIs, pseudomonas, GI/intraabdominal infections (often with Flagyl - metronidazole)
Levofloxacin
“Respiratory Fluoroqinalone.” great for gram+, esp Strep pneumo. less good for Pseudomonas. Not good for Staph aureus. “good for atypicals”
Moxifloxacin
a respiratory FQ with 0 urine activity and 0 Pseudomonas activity.
Carbapenems (Imipenemem, meropenem, ertapenem, doripenem)
Super powerful beta-lactams. Inhibit PBPs. Resistance to beta-lactamases. Bacteriocidal. Usu given IV. Highly active against gram+, gram-, aerobic, and anaerobic. Empiric therapy for critically ill Pts; “last resort for E. coli and Klebsiella.” Metabolised by dehydropeptidase - often coadministered with cilastatin to inhibit dehydropeptidase.
How does resistance to Carbapenems happen?
These are mechanisms of resistance to what class of drug? NDM-1 beta-lactamase. Lack of the OprD porins of gram- rods (esp. Pseudomonas) through which this drug enters them.
Monobactams - i.e. Aztreonam
beta-lactam w/ side chains (no adjacent ring). Narrow spectrum. Only active against Gram- aerobes. Used for Pts allergic to penicillin.
Vancomycin
This glycopeptide targets D-Ala-D-Ala terminus to prevent peptidoglycan crossbridge formation (upstream of beta-lactams). Given IV (unless GI infection) as poorly absorbed from gut. Excellent gram+ coverage (such as MRSA, Strep - though inferior to oaxacillin for MRSA). Oral used for C. diff.
Notable vancomycin side effect
Red Man Syndrome
Bacitracin
This drug is a mixture of peptides used topically. Not effective against Staph.
Tetracyclines - the T in CLEAN TAg. Ex doxycline.
Block 30s subunit. Broad spectrum and bacteriostatic. Used for acne, chronic bronchitis, Lyme disease, mycoplasma pneumo, Rickettsia, Chlamydia, travelers diarrhea, inPt UTI (w/ a cephalosporin)
Notable tetracycline side effects
Discolored teeth. GI upset and phototoxic dermatitis are notable side effects of which class of drugs?
Chloramphenicol - the C in CLEAN TAg
binds to the 50s subunit. Very wide spectrum. Used for meningitis if bug unknown and Pt allergic to penicillin. Rocky Mountain Spotted Fever if tetracycline contraindicated. Only used to last resort due to rare but deadly side effect
Notable chloramphenicol side effect
Aplastic anemia (wipes out the bone marrow) is a rare (1 in 20 - 40 thousand) but usually-fatal side effect of which drug?
Oxaolidone (Linezolid) - the L in Clean Tag
Binds to the 50s subunit. Bacteriostatic. Active against staph, strep, enterococci. IV or PO. Often used w/ beta-lactam for hospital pneumonia and Staph (including MRSA). Side effect: myelosupression. High cost!
Notable Linezolid side effect
Myelosuppression, indicating weekly CBC, is a side effect of which drug?
Lincosamides (Clindamycin) - the C in Clean Tag
50s subunit binder. Bacteriocidal. No gram- activity. Excellent gram+ activity including Staph aureus and Strep. Good anaerobic coverage. Doesn’t penetrate CNS. Often used w/ beta lactam for serious strep or Staph infection (inhibits toxin production). Major side effect: diarrhea w/ pseudomembranous colitis.
Metronidazole (aka Flagyl)
good anti-parasitic. Must be activated by target bug. induces dsDNA breaks. Used for protozoans such as Trichomonas, Giardia, various Amebic infectiosn. Also good for anaerobes and C. diff (when Vanco doesn’t work)
Rifamycins
Anti-TB drugs. inhibits RNA polymerase. Bactericidal -> orange urine. Active against gram+ and mycobaceteria