Antibiotics Flashcards
Beta-lactams
Penicillins (natural, antistaphylococcal, extended-spec, and antipseudomonal)
Cephalosporins (1-5)
Carbapenems
Monobactams
Cell-wall synthesis inhibitors
beta-lactams (PBPs = no synthesis of stable cell wall), vanco (transglycosylase = prevent binding of peptidoglycans, bacitracin (interferes with transport across cell)
Bactericidal, time-dependent
Cell membrane disruption
polymyxin, daptomycin
Classes that inhibit protein synthesis
Tetracyclines (30S), macrolides (50S), and aminoglycosides (30S - bactericidal)
Classes that inhibit nucleic acid synthesis
RNA polymerase inhibitor - rifampin
DNA replication inhibitor - Fluoroquniolones (cirpfloxacin)
Classes that inhibit folic acid synthesis
Trimethoprim and sulfonamides (sulfamethoxazole)
Streptococcus treatments
Penicillin V
Amoxicillin
Cephalexin
Amoxicillin+clavulanic acid
Allergy to beta-lactam: azithromycin, clarithromycin, clindamycin
MSSA treatments
Nafcillin Oxacillin Dicloxacillin Cephalexin Amoxicillin+clauvulanic acid 3rd gen cephalosporins for severe infections
Allergy to beta-lactams: azithromycin, clarithromycin, clindamycin
MRSA treatments
Ceftaroline (moderate) Vanco (severe) Dapto (severe) SMX/TMP (mild-moderate) Doxy (moderate) Minocycline (moderate) Clindamycin (moderate) Linezolid (severe)
Extended spectrum penicillins treat these gram-
Haemophilus influenzae Heliobacter pylori Escherichia coli Listeria monocytogenes Proteus mirabilis Salmonells Shigells Enterococci (HHELPSSE)
Superinfection
- Broad-spectrum antibiotics (frequent: extended-spec penicillins, cephalosporins, clindamycin, fluoroquinolones; occasionally: TMP/SMX, macrolides)
- organisms: Clostridium difficile (pseudomembranous colitis), Staphylococcus aureus (entercolitis), candida albicans (vagina and mouth infections)
Activity of cephalosporins moving from 1st to 4th gen
Increasing activity against g-, beta-lactamase, pseudomonas, anaerboes; increasing ability to cross BBB
1st gen cephalosporins
- Cephalexin, cefazolin
- g+ (staph and strep, PEcK - proteus mirabilis, E.coli, and Klebsiella pneumoniae
- UTI
- SSTI caused by staph and strep like cellulitis or abscess
Vancomycin use
MRSA, Enterocolitis, C. diff, enterococci
Vanco adverse effects
Nephrotoxicity
Ototoxicity
Thrombophlebitis
Red man syndrome - histamine release (pre-treat with anti-histamine and slow infusion rate)
Vanco resistance
D-ala-D-ala to D-ala-D-lactate
Dapto clinical use
Staph aureus (including MRSA), enterococcus faecalis and faecium, strep pyogenes (GAS)
Dapto major side effects
Myopathy (elevated CK)
Spectrum of polymyxins
g- (mostly aerobes - pseudomonas)
Clinical use of polymyxins
Significant toxicity with systemic use so topical; systemic use limited to serious infections
Side effects of polymyxin
Nephrotoxicity and neurotoxicity
SMX and TMP MOA
p-Aminobenzoic acid converted to dihydropteroic acid via dihydropteroate synthase (inhibited by sulfonamides); dihydropteroic acid converted to dihydrofolate via dihydrofolate reductase (inhibited by trimethoprim)
SMX/TMP clinical use
- MSSA and mild-moderate MRSA
- UTI
- respiratory tract infections (H. influenzeae, strep pneumoniae - increased resistance)
- enterocolitis (shigella)
- traveler’s diarrhea (E. coli and shigella)
- otitis media
SMX side effects
Allergies (fever, nausea, vomiting, diarrhea, rash, dermatitis, Steven Johnson syndrome); hematological disorders (megaloblastic anemia, leukopenia, granulocytopenia, thrombocytopenia, hemolytic anemia in pt with G6PD deficiency)
Side effect unique to SMX
kernicterus in newborns (drug displaces bilirubin from albumin»free bilirubin deposist in basal ganglia and subthalamic nuclei»encephalopathy
Tetracyclines MOA
Bind to 30S of bacterial ribosome, blocking access of aminoacyl-tRNA to mRNA-ribosome complex
Clinical use of tetracyclines
MRSA, anthrax, mycoplasma pneumonia, chlamydia, rickettsiae, Lyme, GI
Tetracyclines side effects
GI distress, photosensitivity, discoloration of teeth in children, inhibition of bone growth in children (tetracycline binds to Ca)
Macrolides MOA
Binds to 50S to inhibit peptide transfer
Macrolides clinical use
Substitute for penicillins, strep and staph (not MRSA), more on g-
Major side effects of macrolides
MACRO gi Motility Arrythmia acute Cholestatis hepatitis Rash eosinOphilia
Clindamycin MOA
50S subunit
Clindamycin clinical use
strep and staph; anaerobic infections
Side effects of clindamycin
Fever, diarrhea, superinfection: pseudomembranous colitis
Linezolid MOA
50S
Clinical use of linezolid
broad g+
MRSA
VRE
Side effects of linezolid
bone marrow suppression (thrombocytopenia, anemia, neutropenia), optic and peripheral neuropathy, serotonin syndrome when administered with SSRIs
