Abx Flashcards
Penicillin
G - IV, IM (“given at hosp”)
V - oral
MAO: D-ala-D-ala analog that binds PBPs (transpeptidases) to block transpeptidase crosslinking of peptidoglycan in cell wall
Resistance: Penicllinase (beta lactamase) cleaves beta-lactam ring
Amoxicillin, Ampicillin, Aminopenicillin
“amped up penicillins”
Same MAO and resistance by penicillinases
Wider spectrum than penicillin (HHEELPSS - H flu, H pylori, E coli, enterococci, Listeria, Proteus, Shigella, Salmonella)
amOx - Oral
Nafcillin, Dicloxacillin, Oxacillin
Same MAO as PCN but NOT resistant to penicillinases b/c bulky R group blocks access to beta lactam ring
Use naf for staph aureus (not MRSA)
Piperacillin, ticarcillin
Same MAO and resistance as PCN but extended spectrum to cover Pseudomonas and gram neg rods
Combine w/ beta-lactamase inhibitor
Beta Lactamase Inhibitors
CAST
Clavulanic acid
Avibactum
Sulbactam
Tazobactam
Cephalosporins (generations 1-4)
Same MAO as PCN but less susceptible to penicillinases
Organisms not covered by generations 1-4: LAME
Listeria
Atypicals
MRSA
Enterococci
1: cefazolin, cephalexin (skin and soft tissue)
2: cefaclor, cefoxitin, cefuroxime (cover HENS - H flu, E coli, Neisseria, Serratia)
3: Ceftriaxone (good CNS), Ceftazidime (Pseudo)
4: Cefepime (Pseudo)
Resistance: structural change in PBPs
5th Generation Cephalosporins
Ceftaroline
Broad gram pos and neg
Now covers Listeria, MRSA, enterococcus BUT no Pseudo or atypicals
Carbapenems
Same MAO as PCN
Cover anaerobes but sig side effects (skin rash, GI, sz)
Imipenem (give w/ colistin), meropenem, ertapenem, doripenem
Monobactams
Aztreonam
Same MAO as PCN but less susceptible to beta-lactamases
Specifically binds PBP 3
synergistic w/ aminoglycosides
Gram neg only; good for allergy
Vancomycin
MAO: binds D-ala-D-ala portion of wall precursors to prevent synthesis of peptidoglycan
Resistance: not sensitive to beta lactamases but AA modification of D-ala-D-ala to D-ala-D-lac
Nephrotoxic, Ototoxic, Thrombophlebitis (NOT)
Red Man’s Syndrome
MRSA, C diff, some enterococcus
Aminoglycosides
Gentamicin, tobramycin, neomycin, amikacin, streptomycin
Bacteriacidal
MAO: bind 30S subunit to irrev inhibit formatino of initiation complex - misread mRNA and blocks translocation
Need oxygen for uptake so does not work on anaerobes
Nephro and ototoxic
Resistance: acetylation, phosphorylation, adenylation by bacterial transferase enzymes
Tetracyclines
Tetracycline, Doxycycline
MAO: bind 30S subunit to prevent aminoacyl-tRNA attachment (bacteriostatic)
Do not take w/ divalent cations
Resistance: dec uptake or efflux pumps
Good for borrelia, m pneumonia, rickettsia, chlamydia
Tigecycline
Tetracycline derivative; also binds 30S; bacteriostatic
MRSA, VRE (aggressive like tiger)
Chloramphenicol
MAO: blocks peptidyltransferase at 50S subunit (bacteriostatic)
Meningitis and Rocky Mt Spotted Fever
Resistance: plasmid encoded acetyltransferase blocks drug
Clindamycin
MAO: blocks peptide translocation at 50S subunit (bacteriostatic)
Anaerobic infections above diaphragm (aspiration or oral)
Bad for C diff
Linezolid
MAO: inhibit protein synthesis by binding 50S subunit and prevent formation of initiation complex
Gram POS only - MRSA and VRE
Resistance: pt mutation of rRNA
Macrolides
Azithromycin, clarithromycin, erythromycin
MAO: inhibit protein synthesis by preventing translocation (macro-SLIDE) bind 23S rRNA of 50S subunit
Side effects = MACRO (motility, arrhythmia, cholestatic hepatitis, rash, eOsinophilia)
Atypicals
Resistance: methylation of 23S rRNA binding site
Sulfonamides
SMX, sulfisoxazole, sulfadiazine
MAO: inhibit dihydropteroate synthesis thus no folate synthesis; bacteriostatic
UTI, Nocardia
Resistance: altered dihydrop synthase enzyme, dec uptake, inc PABA precursor synthesis to overcome
Dapsone
MAO similar to SMX but diff structure
Uses: PJP prophylaxis and leprosy
Trimethoprim
MAO: inhibits bacterial dihydrofolate reductase (bacteriostatic)
PJP, toxo prophylaxis, in combo w/ SMX for UTI
Bad for marrow
Fluoroquinolones
Ciprofloxacin, levo, oflo, moxi, gemifloxacin, enoxacin
MAO: inhibit prok topoisomerase II (DNA gyrase) and topo IV (bacteriacidal)
NO ANTACIDS
Tendon rupture
Resistance: chromosome encoded mutation in DNA gyrase, plasmid-mediated resistance, efflux pumps
Daptomycin
MAO: lipopeptide that disrupts cell mem of gram pos cocci by creating transmembrane channels
Uses: MRSA skin infections, bacteremia, endocarditis, VRE
Do not use for pneumonia b/c inact by surfactant
Metronidazole
MAO: form toxic free radical metabolites in bac cell that damade DNA (bacteriacidal)
Metal taste
Rifamycins
Rifampin and rifabutin
MAO: Inhibit DNA-dep RNA polymerase
Inc CYT P450 for rifampin
Orange body fluids (non-hazardous)
Resistance: mutations dec binding to RNA polymerase; RAPID if used alone
Tb
Isoniazid
MAO: dec synthesis of mycolic acids (requires catalase-peroxidase encoded by KatG to convert to active metabolites)
CYP450 inhibition, B6 def
Resistance: mutations leadint to KatG underexpression
Tb prophylaxis
Pyrazinamide
Unknown MAO
Converted to active pyrazinoic acid
Works best at acidic pH (in phagolysosomes)
Tb
Ethambutol
MAO: dec carb polymerization of mycobacterium wall by blocking arabinosyltransferase
Red-green color blindness
Tb
Streptomycin
MAO: interferes w/ 30S ribosome
2nd line for Tb
