Antibiotics: Mechanism of Action Flashcards
Define infection
Invasion and multiplication of pathogenic microbes
Define antibiotic
Antibacterial medication (not including disinfectants) that kill or inhibit growth of bacteria
Define broad spectrum antibiotics
Active against many bacteria (may also kill normal flora)
Define narrow spectrum antibiotics
Effective against specific pathogens (may not kill all pathogens)
Define bactericidal
Kills bacteria by affecting its cell wall
Define bacteriostatic
Inhibits growth of bacteria by affecting its RNA or DNA
Define minimum bactericidal concentration
The lowest concentration that kills 99.9% of a bacteria population
Define minimum inhibitory concentration
The lowest concentration that inhibits visible growth of bacteria
Which antibiotic groups are bacterial cell wall targetting?
Beta-lactams:
- Penicillins
- Cephalosporins
- Carbapenems
Glycopeptides
(usually bacteriocidal)
Which antibiotic types target bacterial RNA and protein synthesis?
Macrolides
Tetracyclines
Aminoglycosides
(usually bacteriostatic)
Which antibiotic types target bacterial DNA structure and function?
Quinolones
Nitroimidazoles
Nitrofurantoin
(bacteriocidal if high dose)
Which types of antibiotics target folic acid synthesis?
Trimethoprim
Which drugs should be avoided in those with penicillin allergies?
Penicillins
Cephalosporins
Which antibiotics are useful in bacterial meningitis, orthopaedic infections, UTIs, LRTIs and abdo sepsis?
Cephalosporins: Ceftriaxone
Which antibiotics are most commonly used for LRTIs?
Beta-lactam: Amoxicillin
Which antibiotics are most commonly used for skin and soft tissue infections?
Beta-lactam: Flucloxicillin
Which antibiotics are most commonly used for mixed infections such as dental abscesses?
Beta-lactams: Co-amoxiclav
Which antibiotics are often used in multi-resistant UTIs and complex infections?
Carbapenems: Meropenem
Which antibiotics are most effective against atypical bacteria, e.g chlamydia?
Tetracyclines: doxycycline and tetracycline
Which antiobiotics are used for anaerobic infections?
Nitroimidazoles: Metronidazole
Which antibiotics are effective in gram negative infections (excluding anaerobes) such as MRSA?
Quinolones: Ciprofloxacin
What factors should be considered when choosing an antibiotic?
- Known/suspected organism +/- sensitivities and resistances
- Allergies/intolerances
- Renal and liver function
- Severity of infection/immunocompromised
- Risk of Abx associated infection
- Route of administration
- Interactions with other medications
- Age/ethnic grup
- Pregnancy/breast feeding
