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USMLE Antibiotics

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xizodoju's version from 2016-09-17 18:43

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
ChloramphenicolOrganismsMeningitis (H influenzae/N meningitidis/S pneumoniae)3N/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
SulfonamidesOrganismsGram+/- (Nocardia/Chlamydia)/UTI3N/A
TrimethoprimOrganismsUTIs/Shigella/Salmonella/PCP4N/A
FluoroquinolonesOrganismsGram- rods in UTI/GI/Pseudomonas/Neisseria/some gram+5N/A
MetronidazoleOrganismsGiardia/Entamoeba/Trichomonas/Gardnerella vaginalis/Anaerobes (Bacteroides/C difficile)/H pylori6GET GAP on the metro
IsoniazidOrganismsM tuberculosis1N/A
RifampinOrganismsM tuberculosis/H influenzae/Meningococcal prophyaxis3N/A
PyrazinamideOrganismsM tuberculosis1N/A
EthambutolOrganismsM tuberculosis1N/A
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Identification

DrugQuestionAnswerNumberMnemonic
PenicillinsIDPen G (IV/IM)/Pen V (oral)3N/A
Penicillinase resistant penicillinsIDOxacillin/nafcillin/dicloxacillin3N/A
AminopenicillinsIDAmpicillin/amoxicillin2N/A
AntipseudomonalsIDTicarcillin/piperacillin2N/A
1st gen CephalosporinsIDCefazolin/cephalexin2N/A
2nd gen CephalosporinsIDCefoxitin/cefaclor/cefuroxime3N/A
3rd gen CephalosporinsIDCeftriaxone/cefotaxim/ceftazidime3N/A
4th gen CephalosporinsIDCefepime1N/A
30S inhibitorsIDAminoglycosides/Tetracyclines2buy AT 30/CCEL at 50
50S inhibitorsIDChloramphenicol/Clindamycin/Erythromycin (macrolides)/Linezolid4buy AT 30/CCEL at 50
Beta Lactamase inhibitorsIDClavulanic Acid/Sulbactam/Tazobactam4CAST
MonobactamIDAztreonam1N/A
CarbapenemIDImipenem/meropenem2N/A
AminoglycosidesIDGentamycin/Neomycin/Amikacin/Tobramycin/Streptomycin5Mean aMINoglyocosides GNATS caNNOT kill anaerobes
TetracyclinesIDTetracycline/doxycycline/democycline/minocycline4N/A
SulfonamidesIDSulfamethoxazole (SMX)/sulfisoxazole/sulfadiazine3N/A
FluoroquinolonesIDCipro/nor/levo/o/spar/moxi/gatifloxacins/enoxacin/nalidixic acid9N/A
MacrolidesIDArithromycin/clarithromycin/erythromycin3N/A
LincosamideIDClarithromycin1N/A
Azoles (not antibiotics)IDFlu/keto/mi/itra/voriconazoles/clotrimazole6N/A
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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
ChloramphenicolMechanism50S Blocks peptidyl transferase1buy 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
SulfonamidesMechanismPABA antimetabolites (at dihydropteroate synthase PABA to DHPA)1N/A
TrimethoprimMechanismPABA antimetabolites (at dihydrofolate reductase DHF to THF)1N/A
PyrimethamineMechanismPABA antimetabolites (at dihydrofolate reductase DHF to THF)1N/A
FluoroquinolonesMechanismInhibit DNA topoisomerase II/IV (II is gyrase)2N/A
MetronidazoleMechanismForms free radical toxic metabolites that damage DNA1N/A
IsoniazidMechanismDecrease synthesis of mycolic acids1N/A
RifampinMechanismInhibits DNA dependent RNA polymerase1Rifampin's 4 Rs (RNA polymerase/Revs up P450/Red-orange body fluids/Rapid resistance if used alone)
PyrazinamideMechanismUncertain/thought to acidify intracellular compartments where TB is engulfed1N/A
EthambutolMechanismBlock arabinosyltrasnferase/stops carbohydrate polymerization in myobacteria1N/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
TicarcillinToxicityHypersensitivity1N/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
ChloramphenicolToxicityAnemia/aplastic anemia/gray baby syndrome (lack UDP glucuronyl transferase)3N/A
ClindamycinToxicityPseudomembranous colitis/fever/diarrhea3N/A
SulfonamidesToxicityHypersensitivity/hemolysis in G6PD deficient/nephrotoxic/photosensitive/kernicterus in infants5N/A
TrimethoprimToxicityMegaoloblastic anemia/leukopenia/granulocytopenia3TMP (Treats Marrow Poorly)
FluoroquinolonesToxicityGI upset/superinfection/skin rash/headache/dizziness/bones (tendonitis/rupture/cramps/myalgias)/long QT7lones hurt attachment to bones
MetronidazoleToxicityDisulfiram rxn w/alcohol/headache/metallic taste3N/A
IsoniazidToxicityNeurotoxicity/hepatotoxicity/lupus3INH Injures Neurons/Hepatocytes
RifampinToxicityHepatotoxic/P450 drug interactions/Orange body fluids (nonhazardous)3Rifampin's 4 Rs (RNA polymerase/Revs up P450/Red-orange body fluids/Rapid resistance if used alone)
PyrazinamideToxicityHepatotoxic/hyperuricemia2N/A
EthambutolToxicityOptic neuropathy (red green colorblindness)1N/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
ChloramphenicolResistancePlasmid encoted acetyltransferase inactivates1N/A
SulfonamidesResistanceAltered target enzyme1N/A
FluoroquinolonesResistanceChromosome encoded mutation of DNA gyrase/plasmid mediated proteins bind DNA gyrase and protect/efflux pumps3N/A
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Keys to Use

DrugQuestionAnswerNumberMnemonic
AminopenicillinsKey to useAmoxicillin>Ampicillin2Oral availability of amOxacillin
Ticarcillin/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
DemeclocyclineKey to useADH antagonist/Diuretic in SIADH/rarely used as antibiotic1N/A
TrimethoprimKey to useCombination with sulfonamides1N/A
FluoroquinolonesKey to useDon't take with antacid1N/A
MetronidazoleKey to useTriple therapy w/PPI/clarithromycin against H pylori1N/A
IsoniazidKey to useBacterial catalase peroxidase (KatG) must convert INH to active metabolite1N/A
RifampinKey to useRapid resistance if used alone1Rifampin'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

DrugQuestionAnswerNumberMnemonic
M tuberculosisProphylaxisIsoniazid1N/A
M tuberculosisTreatmentRifampin/Isoniazid/Pyrazinamide/Ethambutol4RIPE for treatment
M avium intracellulareProphylaxisAzithromycin1N/A
M avium intracellulareTreatmentAzithromycin/Rifampin/Ethambutol/Streptomycin4N/A
M leprae tuberculoidTreatmentDapsone/rifampin2N/A
M leprae lepromatousTreatmentDapsone/rifampin/clofazimine3N/A
Meningococcal infectionProphylaxisCiprofloxacin/rifampin in children2N/A
GonorrheaProphylaxisCeftriaxone1N/A
SyphilisProphylaxisBenzathine penicillin G1N/A
Recurrent UTIsProphylaxisTMP/SMX2N/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
SulfonamidesWhy to avoid in pregnantKernicterus (bilirubin induced brain dysfunction)1N/A
AminoglycosidesWhy to avoid in pregnantOtotoxic1N/A
FluoroquinolonesWhy to avoid in pregnantCartilage damage1N/A
ClarithromycinWhy to avoid in pregnantEmbryotoxic1N/A
TetracyclinesWhy to avoid in pregnantDiscolored teeth/inhibition of bone growth2N/A
RibavirinWhy to avoid in pregnantTeratogenic1N/A
GriseofulvinWhy to avoid in pregnantTeratogenic1N/A
ChloramphenicolWhy to avoid in pregnantGray Baby1N/A
MnemonicWhy to avoid in pregnantSulfonamides/Aminoglycosides/Fluoroquinolones/Clarithromycin/Tetracyclines/Ribavirin/Griseofulvin/Chloramphenicol8SAFeChildren 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