Antimicrobial Chemotherapy Flashcards
MIC
Minimal inhibitory concentration
The minimum concentration of antimicrobial needed to inhibit visible growth of a given organism
MBC
Minimal bactericidal concentration
The minimum concentration of the antimicrobial needed to kill a given organism
Routes of administration
Topical
Systemic (internally, either orally or parenterally)
Parenteral (IV or IM)
Antibiotic modes of action
Inhibition of cell wall synthesis
Inhibition of protein synthesis
Inhibitors of nucleic acid synthesis
Beta lactams
Penicillins and cephalosporins
Glycopeptides
Vancomycin and teicoplanin
Inhibition of cell wall synthesis
Beta lactams
Glycopeptides
What type of bacteria do glycopeptides work on? (gram positive or negative)
Gram positive
Toxic antibiotics
Vancomycin
Gentamicin
Inhibition of protein synthesis
Aminoglycosides
Macrolides and Tetracyclines
Oxazolidinones
Cyclic Lipopeptide
Example of an aminoglycoside and what type of bacteria do they work against
Gentamicin
Gram negative bacilli
TOXIC
Macrolides
Erythromycin
Clarithromycin
Inhibitors of nucleic acid synthesis
Trimethoprim and sulphamethoxazole (combined form => cotrimoxazole)
Fluoroquinolones
Fluoroquinolones
Ciprofloxacin (gram negative, not in children)
What are MRSA resistant to?
All penicillins and cephalosporins
What infection is a side effect of antibiotic therapy?
Clostridium difficile (CDI)
How is CDI treated?
Oral metronidazole or oral vancomycin
Antifungal drug classes
Polyenes
Azoles
Allylamines
Echinocandins
Polyenes
Amphotericin B
Nystatin
Amphotericin B
Polyene
IV
Toxic
Fluconazole
Used to treat yeast, not all yeasts are sensitive
What is used to treat aspergillosis?
Voriconazole and itraconazole
Terbinafine
Allylamine
Treatment of fungal infections of skin and nails
What are echinocandins used to treat?
Serious candida and aspergillus infections
What does aciclovir treat?
Herpes simplex and varicella zoster
Penicillins
Penicillin V
Amoxicillin
Flucloxacillin
Co-amoxiclav
In what way is trimethoprim toxic?
Folate inhibitor
What is linezolid used for?
2nd line agent for MSSA, MRSA, VRE
VRE
Vancomycin-resistant enterococci
What is empiric therapy?
Without microbiology results
What is directed therapy?
Based on microbiology results
Principles of prescribing
Indications for antimicrobials
Diagnosis
Patient characteristics
Antimicrobial selection
Types of antibacterial sensitivity testing
Disk defusion (to test for resistance) Etest (for MIC)
What are the four main mechanisms of resistance?
Enzymatic inactivation of drug
Modified targets for drugs
Reduced permeability to drug
Efflux of drug
Genetics of resistance
Chromosomally mediated
Plasmid mediated
How are plasmids passed between bacteria?
Conjugation
Medically important resistant organisms
MRSA VRE ESBL CPE C diff
ESBL
Extended spectrum beta lactamase
CPE
Carbapenemase producing enterobacteriaceae
Reasons for failure of therapy
Inadequate dose of antibiotic
Inappropriate route
Non-compliance with antibiotic
Bacteria walled off in abscess cavity
Foreign bodies eg surgical implants/prosthesis
Poor penetration of drug to site of infection
Antibiotics with good biofilm activity
Rifampicin
Daptomycin
Ceftobiprole
How can healthcare workers help to tackle AMR?
Practicing effective infection prevention & control
Prescribing and dispensing antibiotics only when truly needed
Prescribing & dispensing the right antibiotic(s) for the right duration to treat the illness
