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ID48 Infectious Diseases
Antimicrobials Toronto Notes 2019
7. Others
• doxycycline/tetracycline/minocycline(GP,syphilis,Chlamydophila,Rickettsia,Mycoplasma)
• tigecycline(forresistantGPinfections,GN,anaerobes,Chlamydophila,Rickettsia,Mycoplasma) • vancomycin(allGPandC.difficile–theoralformfor)
• linezolid(forresistantGPinfections)
• daptomycin(forresistantGPinfections)
• clindamycin(mostGP,GNanaerobes)
• TMP/SMX(mostS.aureusincluding:MRSA,GNaerobes,Pneumocystis)
• nitrofurantoin(GNbacilli,S.saprophyticus,Enterococcus)
• metronidazole(anaerobesincluding:Bacterioidessp.,C.difficile;Trichomonas,Entamoeba)
Antimicrobials
Antibiotics
• empiricantibiotictherapy
■ choose antibiotic(s) to cover for most likely and lethal organisms for the type of infection prior to
obtaining laboratory results (usually reserved for serious infections) ■ adjust antibiotic(s) based on C&S and clinical response
• ifcausativeorganismidentified,useantibiotictowhichorganismissusceptible
• ifcausativeorganismnotidentified,re-evaluateneedforongoingantimicrobialtherapy(andcontinue
with empiric antibiotic(s) if indicated)
Reasons for Combination Therapy
TOXIC METABOLITES • Metronidazole
CELL WALL
• Penicillins
• Cephalosporins • Carbapenems • Glycopeptides
RNA POLYMERASE • Rifampin
DNA GYRASE
• Fluoroquinolones
PROTEIN SYNTHESIS • Nitrofurantoin
50S RIBOSOME • Macrolides
• Lincosamides
30S RIBOSOME
• Aminoglycosides • Tetracyclines
FOLIC ACID PATHWAY • TMP/SMX
• Dapsone
• Sulfoxone
MYCOLIC ACID PATHWAY • Isoniazid
• Ethambutol
• Polymicrobial infection
• Empiric therapy pending culture results
• Synergy for difficult to treat pathogens (e.g.
Enterococcus spp. causing endocarditis) • To prevent emergence of resistance
Bactericidal Antibiotics
“Very Finely Proficient At CCell Murder”
Vancomycin Fluoroquinolones
Penicillin Aminoglycosides Cephalosporins Carbapenems Metronidazole Daptomycin
Bacteriostatic Antibiotics
“ECSTaTiC” Erythromycin (and
other macrolides) Clindamycin Sulfamethoxazole Trimethoprim Tetracyclines Chloramphenicol
PABA FAS I
DHFA THFA
FAS II
Mycolic acid
Figure 20. Mechanism of action of antibiotics
©Stuart Jantzen 2012