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USMLE Antibiotics

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woyupaya's version from 2015-12-27 11:42

Antibiotic Uses

DrugAnswerMnemonic
PenicillinS pneumoniae/pyogenes/Actinomyces/N meningitidis/Treponema pallidumGram+ cocci/gram+ rods/gram- cocci/spirochetes bactericidal
NafcillinS aureusUse naf for Staph
AminopenicillinsH influenzae/E coli/Listeria monocytogenes/Proteus mirabilis/Salmonella/Shigella (enterococci)Ampicillin/aomoxicillin HELPSS kill enterococci
Ticarcillin/piperacillinPseudomonas/gram- rodsN/A
CephalosporinsNOT cover Listeria/Atypicals (Chlamydia/Mycoplasma)/MRSA/EnterococciLAME
1st gen CephalosporinsProteus mirabilis/E coli/Klebsiella pneumoniaePEcK
1st gen CephalosporinsCefazolin prevents S aureus/ceftaroline covers MRSAN/A
2nd gen CephalosporinsH influenzae/Enterobacter aerogenes/Neisseria/Proteus mirabilis/E coli/Klebsiella pneumoniae/Serratia marcescensHEN PEcKS
CeftriaxoneMeningitis/gonorrheaN/A
CeftazidimePseudomonasN/A
4th gen Cephalosporins (cefepime)Pseudomonas/gram+N/A
AztreonamGram- rods onlyN/A
VancomycinMRSA/enterococci/C difficile (for pseudomembranous colitis)N/A
AminoglycosidesSevere gram- rodN/A
ChloramphenicolMeningitis (H influenzae/N meningitidis/S pneumoniae)N/A
ClindamycinAnaerobic aspiration pneumonia/lung abscesses/oral infections (Bacteroides fragilis/Clostridium perfringns)Clindamycin treats anaerobe above diaphrahm/metronidazole below
TetracyclinesBorrelia burgorferi/M pneumoniae/Rickettsia/ChlamydiaAccumulates intracellulary
MacrolidesAtypical pneumonias (Mycoplasma/Chlamydia/Legionella)/STD (Chlamydia)/gram+ cocci (strep in pen allergic)N/A
SulfonamidesGram+/- (Nocardia/Chlamydia)/UTIN/A
TrimethoprimUTIs/Shigella/Salmonella/PCPN/A
FluoroquinolonesGram- rods in UTI/GI/Pseudomonas/Neisseria/some gram+N/A
MetronidazoleGiardia/Entamoeba/Trichomonas/Gardnerella vaginalis/Anaerobes (Bacteroides/C difficile)/H pyloriGET GAP on the metro
IsoniazidM tuberculosisN/A
RifampinM tuberculosis/H influenzae/Meningococcal prophyaxisN/A
PyrazinamideM tuberculosisN/A
EthambutolM tuberculosisN/A
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Identification

DrugNumberMnemonic
PenicillinsPen G (IV/IM)/Pen V (oral)N/A
Penicillinase resistant penicillinsOxacillin/nafcillin/dicloxacillinN/A
AminopenicillinsAmpicillin/amoxicillinN/A
AntipseudomonalsTicarcillin/piperacillinN/A
1st gen CephalosporinsCefazolin/cephalexinN/A
2nd gen CephalosporinsCefoxitin/cefaclor/cefuroximeN/A
3rd gen CephalosporinsCeftriaxone/cefotaxim/ceftazidimeN/A
4th gen CephalosporinsCefepimeN/A
30S inhibitorsAminoglycosides/Tetracyclinesbuy AT 30/CCEL at 50
50S inhibitorsChloramphenicol/Clindamycin/Erythromycin (macrolides)/Linezolidbuy AT 30/CCEL at 50
Beta Lactamase inhibitorsClavulanic Acid/Sulbactam/TazobactamCAST
MonobactamAztreonamN/A
CarbapenemImipenem/meropenemN/A
AminoglycosidesGentamycin/Neomycin/Amikacin/Tobramycin/StreptomycinMean aMINoglyocosides GNATS caNNOT kill anaerobes
TetracyclinesTetracycline/doxycycline/democycline/minocyclineN/A
SulfonamidesSulfamethoxazole (SMX)/sulfisoxazole/sulfadiazineN/A
FluoroquinolonesCipro/nor/levo/o/spar/moxi/gatifloxacins/enoxacin/nalidixic acidN/A
MacrolidesArithromycin/clarithromycin/erythromycinN/A
LincosamideClarithromycinN/A
Azoles (not antibiotics)Flu/keto/mi/itra/voriconazoles/clotrimazoleN/A
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Mechanisms

DrugAnswerMnemonic
VancomycinInhibits cell wall peptidoglycan formation/binds D-ala D-alaPay back 2 D-alas for vandalizing/vancomycin
Macrolides50S Translocation inhibitionmaCROlide/eryTHROmycin/tranSLOcation
Lincosamide/Clindamycin50S Translocation inhibitionbuy AT 30/CCEL at 50
Chloramphenicol50S Blocks peptidyl transferasebuy AT 30/CCEL at 50
Tetracyclines30S A site blockingbuy AT 30/CCEL at 50
Linezolid50S Blocks initiator tRNA binding/ribosome formationbuy AT 30/CCEL at 50
Aminoglycosides30S initiation complex formationA initiates the alphabet
SulfonamidesPABA antimetabolites (at dihydropteroate synthase PABA to DHPA)N/A
TrimethoprimPABA antimetabolites (at dihydrofolate reductase DHF to THF)N/A
PyrimethaminePABA antimetabolites (at dihydrofolate reductase DHF to THF)N/A
FluoroquinolonesInhibit DNA topoisomerase II/IV (II is gyrase)N/A
MetronidazoleForms free radical toxic metabolites that damage DNAN/A
IsoniazidDecrease synthesis of mycolic acidsN/A
RifampinInhibits DNA dependent RNA polymeraseRifampin's 4 Rs (RNA polymerase/Revs up P450/Red-orange body fluids/Rapid resistance if used alone)
PyrazinamideUncertain/thought to acidify intracellular compartments where TB is engulfedN/A
EthambutolBlock arabinosyltrasnferase/stops carbohydrate polymerization in myobacteriaN/A
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Toxicity

DrugAnswerMnemonic
PenicillinHypersensitivity/hemolytic anemiaN/A
OxacillinHypersensitivity/interstitial nephritisN/A
NafcillinHypersensitivity/interstitial nephritisN/A
DicloxacillinHypersensitivity/interstitial nephritisN/A
AmpicillinHypersensitivity/rash/pseudomembranous colitisN/A
AmoxicillinHypersensitivity/pseudomembranous colitisN/A
TicarcillinHypersensitivityN/A
PiperacillinHypersensitivityN/A
CephalosporinsHypersensitivity/Vit K deficiency/increases nephrotoxicity of aminoglycosidesN/A
AztreonamUsually nontoxic/occasional GI upsetN/A
ImipenemGI distress/skin rash/CNS toxicity (seizures)N/A
MeropenemGI distress/skin rash/CNS toxicity (seizures)N/A
VancomycinNephrotoxicity/Ototoxicity/Thrombophlebitis/diffuse flushing/red man sydromewell tolerated in general/NOT many problems
AminoglycosidesNephrotoxicity/Neuromuscular blockade/Ototoxicity/TeratogenMean aMINoglyocosides GNATS caNNOT kill anaerobes
TetracyclinesGI distress/discoloration of teeth/inihibition of bone growth in children/photosensitivity/contraindicated in pregnancyN/A
MacrolidesMotility issues/Arrhythmia (long QT)/Cholestatic hepatitis acute/Rash/eOsinophiliaMACRO
ChloramphenicolAnemia/aplastic anemia/gray baby syndrome (lack UDP glucuronyl transferase)N/A
ClindamycinPseudomembranous colitis/fever/diarrheaN/A
SulfonamidesHypersensitivity/hemolysis in G6PD deficient/nephrotoxic/photosensitive/kernicterus in infantsN/A
TrimethoprimMegaoloblastic anemia/leukopenia/granulocytopeniaTMP (Treats Marrow Poorly)
FluoroquinolonesGI upset/superinfection/skin rash/headache/dizziness/bones (tendonitis/rupture/cramps/myalgias)/long QTlones hurt attachment to bones
MetronidazoleDisulfiram rxn w/alcohol/headache/metallic tasteN/A
IsoniazidNeurotoxicity/hepatotoxicity/lupusINH Injures Neurons/Hepatocytes
RifampinHepatotoxic/P450 drug interactions/Orange body fluids (nonhazardous)Rifampin's 4 Rs (RNA polymerase/Revs up P450/Red-orange body fluids/Rapid resistance if used alone)
PyrazinamideHepatotoxic/hyperuricemiaN/A
EthambutolOptic neuropathy (red green colorblindness)N/A
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Resistance

Drug AnswerMnemonic
AminoglycosidesTransferases inactivate via acetylation/phosphorylation/adenylationN/A
TetracyclinesDecreased uptake/increased efflux by plasmid encoded pumpsN/A
MacrolidesMethylation of 23S rRNA (of 50S subunit) binding siteMacrolides methylation inactivated
ChloramphenicolPlasmid encoted acetyltransferase inactivatesN/A
SulfonamidesAltered target enzymeN/A
FluoroquinolonesChromosome encoded mutation of DNA gyrase/plasmid mediated proteins bind DNA gyrase and protect/efflux pumpsN/A
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Keys to Use

DrugAnswerMnemonic
AminopenicillinsAmoxicillin>AmpicillinOral availability of amOxacillin
Ticarcillin/piperacillinUse with clavulanic acidN/A
3rd gen CephalosporinsWhen other Beta Lactams are resistedN/A
ImipenemCilastatinKills is Lastin with cilastatin
AminoglycosidesRequire O2 for uptake/ineffective against anaerobesMean aMINoglyocosides GNATS caNNOT kill anaerobes
MacrolidesIncreases serum concentration of theophyllines (oral anticoagulants)N/A
TetracyclinesDon't take w/milk/antacids/iron/pregnancyDivalent cations inhibit absorption
DemeclocyclineADH antagonist/Diuretic in SIADH/rarely used as antibioticN/A
TrimethoprimCombination with sulfonamidesN/A
FluoroquinolonesDon't take with antacidN/A
MetronidazoleTriple therapy w/PPI/clarithromycin against H pyloriN/A
IsoniazidBacterial catalase peroxidase (KatG) must convert INH to active metaboliteN/A
RifampinRapid resistance if used aloneRifampin's 4 Rs (RNA polymerase/Revs up P450/Red-orange body fluids/Rapid resistance if used alone)
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Guidelines for Treatment and Prophylaxis

DrugAnswerMnemonic
M tuberculosisIsoniazidN/A
M tuberculosisRifampin/Isoniazid/Pyrazinamide/EthambutolRIPE for treatment
M avium intracellulareAzithromycinN/A
M avium intracellularetAzithromycin/Rifampin/Ethambutol/Streptomycin (T): N/A
M leprae tuberculoidDapsone/rifampin (T): N/A
M leprae lepromatousDapsone/rifampin/clofazimine (T): N/A
Meningococcal infectionCiprofloxacin/rifampin in childrenN/A
GonorrheaCeftriaxoneN/A
SyphilisBenzathine penicillin GN/A
Recurrent UTIsTMP/SMXN/A
Endocarditis w/surgical/dental proceduresPenicllinsN/A
Pregant women w/GBSAmpicillinN/A
Streptococcal pharyngitis in child w/prior rheumatic feverOral penicillinN/A
Post surgical S aureusCefazolinN/A
Gonococcal/chlamydial conjunctivitis in newbornErythromycin ointmentN/A
MRSAVancomycin (T): N/A
VRELinezolid/streptogramins (quinupristin/dalfopristin) (T): N/A
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To Be Avoided in Pregnancy

DrugAnswerMnemonic
SulfonamidesKernicterus (bilirubin induced brain dysfunction)N/A
AminoglycosidestOtotoxicN/A
FluoroquinolonesCartilage damageN/A
ClarithromycinEmbryotoxicN/A
TetracyclinesDiscolored teeth/inhibition of bone growthN/A
RibavirinTeratogenicN/A
GriseofulvinTeratogenicN/A
ChloramphenicolGray BabyN/A
MnemonicSulfonamides/Aminoglycosides/Fluoroquinolones/Clarithromycin/Tetracyclines/Ribavirin/Griseofulvin/ChloramphenicolSAFeChildren Take Really Good Care
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Distinctive Side Effects

Question Answer
Optic neuropathy (red green colorblindness)Ethambutol
Vitamin K deficiencyCephalosporins
Red man syndromeVancomycin
Long QTMacrolides/fluoroquinolones
Gray babyChloramphenicol
Kernicterus in infantsSulfonamides
Orange body fluidsRifampin
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USMLE Antifungals and Antivirals