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USMLE Antibiotics

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mgiwerc's version from 2015-09-23 04:55

Antibiotic Uses

DrugQuestionAnswerNumberMnemonic
PenicillinOrganismsS pneumoniae/pyogenes/Actinomyces/N meningitidis/Treponema pallidum5Gram+ cocci/gram+ rods/gram- cocci/spirochetes bactericidal
NafcillinOrganismsS aureus1Use naf for Staph
AminopenicillinsOrganismsH influenzae/E coli/Listeria monocytogenes/Proteus mirabilis/Salmonella/Shigella (enterococci)6Ampicillin/aomoxicillin HELPSS kill enterococci
Ticarcillin/piperacillinOrganismsPseudomonas/gram- rods2N/A
CephalosporinsOrganisms NOT coveredListeria/Atypicals (Chlamydia/Mycoplasma)/MRSA/Enterococci4LAME
1st gen CephalosporinsOrganismsProteus mirabilis/E coli/Klebsiella pneumoniae3PEcK
1st gen CephalosporinsExceptions to normal coverageCefazolin prevents S aureus/ceftaroline covers MRSA2N/A
2nd gen CephalosporinsOrganismsH influenzae/Enterobacter aerogenes/Neisseria/Proteus mirabilis/E coli/Klebsiella pneumoniae/Serratia marcescens7HEN PEcKS
CeftriaxoneOrganismsMeningitis/gonorrhea2N/A
CeftazidimeOrganismsPseudomonas1N/A
4th gen Cephalosporins (cefepime)OrganismsPseudomonas/gram+2N/A
AztreonamOrganismsGram- rods only1N/A
VancomycinOrganismsMRSA/enterococci/C difficile (for pseudomembranous colitis)3N/A
AminoglycosidesOrganismsSevere gram- rod1N/A
ClindamycinOrganismsAnaerobic aspiration pneumonia/lung abscesses/oral infections (Bacteroides fragilis/Clostridium perfringns)2Clindamycin treats anaerobe above diaphrahm/metronidazole below
TetracyclinesOrganismsBorrelia burgorferi/M pneumoniae/Rickettsia/Chlamydia4Accumulates intracellulary
MacrolidesOrganismsAtypical pneumonias (Mycoplasma/Chlamydia/Legionella)/STD (Chlamydia)/gram+ cocci (strep in pen allergic)4N/A
MetronidazoleOrganismsGiardia/Entamoeba/Trichomonas/Gardnerella vaginalis/Anaerobes (Bacteroides/C difficile)/H pylori6GET GAP on the metro
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Identification

DrugQuestionAnswer
PenicillinsIDPen G (IV/IM)/Pen V (oral)
Penicillinase resistant penicillinsIDOxacillin/nafcillin/dicloxacillin
AminopenicillinsIDAmpicillin/amoxicillin
AntipseudomonalsIDTicarcillin/piperacillin
1st gen CephalosporinsIDCefazolin/cephalexin
2nd gen CephalosporinsIDCefoxitin/Cefotetan/cefuroxime
3rd gen CephalosporinsIDCeftriaxone/cefotaxim/ceftazidime
4th gen CephalosporinsIDCefepime
30S inhibitorsIDAminoglycosides/Tetracyclines
50S inhibitorsIDChloramphenicol/Clindamycin/Erythromycin (macrolides)/Linezolid
Beta Lactamase inhibitorsIDClavulanic Acid/Sulbactam/Tazobactam
MonobactamIDAztreonam
CarbapenemIDImipenem/meropenem
AminoglycosidesIDGentamycin/Neomycin/Amikacin/Tobramycin/Streptomycin
TetracyclinesIDTetracycline/doxycycline/democycline/minocycline
MacrolidesIDArithromycin/clarithromycin/erythromycin
LincosamideIDClarithromycin
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Mechanisms

DrugQuestionAnswerNumberMnemonic
VancomycinMechanismInhibits cell wall peptidoglycan formation/binds D-ala D-ala1Pay back 2 D-alas for vandalizing/vancomycin
MacrolidesMechanism50S Translocation inhibition1maCROlide/eryTHROmycin/tranSLOcation
Lincosamide/ClindamycinMechanism50S Translocation inhibition1buy AT 30/CCEL at 50
TetracyclinesMechanism30S A site blocking1buy AT 30/CCEL at 50
LinezolidMechanism50S Blocks initiator tRNA binding/ribosome formation1buy AT 30/CCEL at 50
AminoglycosidesMechanism30S initiation complex formation1A initiates the alphabet
MetronidazoleMechanismForms free radical toxic metabolites that damage DNA1N/A
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Toxicity

DrugQuestionAnswerNumberMnemonic
PenicillinToxicityHypersensitivity/hemolytic anemia2N/A
OxacillinToxicityHypersensitivity/interstitial nephritis2N/A
NafcillinToxicityHypersensitivity/interstitial nephritis2N/A
DicloxacillinToxicityHypersensitivity/interstitial nephritis2N/A
AmpicillinToxicityHypersensitivity/rash/pseudomembranous colitis3N/A
AmoxicillinToxicityHypersensitivity/pseudomembranous colitis2N/A
PiperacillinToxicityHypersensitivity1N/A
CephalosporinsToxicityHypersensitivity/Vit K deficiency/increases nephrotoxicity of aminoglycosides3N/A
AztreonamToxicityUsually nontoxic/occasional GI upset2N/A
ImipenemToxicityGI distress/skin rash/CNS toxicity (seizures)3N/A
MeropenemToxicityGI distress/skin rash/CNS toxicity (seizures)3N/A
VancomycinToxicityNephrotoxicity/Ototoxicity/Thrombophlebitis/diffuse flushing/red man sydrome5well tolerated in general/NOT many problems
AminoglycosidesToxicityNephrotoxicity/Neuromuscular blockade/Ototoxicity/Teratogen4Mean aMINoglyocosides GNATS caNNOT kill anaerobes
TetracyclinesToxicityGI distress/discoloration of teeth/inihibition of bone growth in children/photosensitivity/contraindicated in pregnancy5N/A
MacrolidesToxicityMotility issues/Arrhythmia (long QT)/Cholestatic hepatitis acute/Rash/eOsinophilia5MACRO
ClindamycinToxicityPseudomembranous colitis/fever/diarrhea3N/A
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Resistance

DrugQuestionAnswerNumberMnemonic
AminoglycosidesResistanceTransferases inactivate via acetylation/phosphorylation/adenylation3N/A
TetracyclinesResistanceDecreased uptake/increased efflux by plasmid encoded pumps1N/A
MacrolidesResistanceMethylation of 23S rRNA (of 50S subunit) binding site1Macrolides methylation inactivated
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Keys to Use

DrugQuestionAnswerNumberMnemonic
AminopenicillinsKey to useAmoxicillin>Ampicillin2Oral availability of amOxacillin
PiperacillinKey to useUse with clavulanic acid1N/A
3rd gen CephalosporinsKey to useWhen other Beta Lactams are resisted1N/A
ImipenemKey to useCilastatin1Kills is Lastin with cilastatin
AminoglycosidesKey to useRequire O2 for uptake/ineffective against anaerobes1Mean aMINoglyocosides GNATS caNNOT kill anaerobes
MacrolidesKey to useIncreases serum concentration of theophyllines (oral anticoagulants)1N/A
TetracyclinesKey to useDon't take w/milk/antacids/iron/pregnancy4Divalent cations inhibit absorption
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Guidelines for Treatment and Prophylaxis

DrugQuestionAnswerNumberMnemonic
GonorrheaProphylaxisCeftriaxone1N/A
SyphilisProphylaxisBenzathine penicillin G1N/A
Endocarditis w/surgical/dental proceduresProphylaxisPenicllins1N/A
Pregant women w/GBSProphylaxisAmpicillin1N/A
Streptococcal pharyngitis in child w/prior rheumatic feverProphylaxisOral penicillin1N/A
Post surgical S aureusProphylaxisCefazolin1N/A
Gonococcal/chlamydial conjunctivitis in newbornProphylaxisErythromycin ointment1N/A
MRSATreatmentVancomycin1N/A
VRETreatmentLinezolid/streptogramins (quinupristin/dalfopristin)3N/A
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To Be Avoided in Pregnancy

DrugQuestionAnswerNumberMnemonic
AminoglycosidesWhy to avoid in pregnantOtotoxic1N/A
ClarithromycinWhy to avoid in pregnantEmbryotoxic1N/A
TetracyclinesWhy to avoid in pregnantDiscolored teeth/inhibition of bone growth2N/A
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Distinctive Side Effects

Question Answer
Vitamin K deficiencyCephalosporins
Red man syndromeVancomycin
Long QTMacrolides
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USMLE Antifungals and Antivirals