Antimicrobial Agents Flashcards
Define antimicrobials
Drugs with activity against microorganisms including antibacterial, antivirals, antifungals and antiparasitic agents
Define antibiotic
Chemical compound made by a microorganism that inhibits or kills other microorganisms at low concentrations. Does not include synthetic agents.
What do bactericidal agent do?
Bactericidal agents kill bacteria
What do bacteriostatic agent do?
Bacteriostatic agents inhibit growth of bacteria
What is the bacteria that penicillin is derived from?
Penicillium notatum
What are the conditions for the ideal antimicrobial agent? (8)
- Selective toxicity against microbial target
- Minimal toxicity to the host
- Cidal activity (kill micro-organisms)
- Long plasma half-life
- Good tissue distribution
- Low binding to plasma proteins
- Oral and parental preparations
- No adverse interactions with other drugs
What are some mechanisms of action for antimicrobials? (5)
- Inhibition of cell wall synthesis
- Inhibition of protein synthesis
- Inhibition of nucleic acid synthesis
- Inhibition of folate synthesis
- Disruption of the cytoplasmic membrane
What are some mechanisms of resistance for antimicrobials? (5)
- Production of enzymes
- Alteration in the outer- membrane permeability
- Alteration of target sites
- Efflux pumps
- Alteration of metabolic pathways
What problems arise from human use of antibacterials? (5)
- Adverse effects
- Drugs interactions
- Few organisms become virtually untreatable
- Rising rates of resistance
- Superinfection
What is antimicrobial stewardship? (4)
A coordinated program that aims to:
- Promotes the appropriate use of antimicrobials
- Improves patient outcomes
- Reduces microbial resistance
- Decreases the spread of infections caused by multidrug-resistant organisms.
What is the mode of action for drugs in the penicillin family?
Inhibit cell wall synthesis by binding to penicillin binding proteins and inhibiting transpeptidation of peptidoglycan
What is the mode of resistance for drugs in the penicillin family? (3)
- Resistance by Β-lactamases
- Efflux
- Low affinity binding of antibacterial to target penicillin binding proteins
Name some potential side effects of drugs from the penicillin family (6)
- Allergic reaction (anaphylactic reaction)
- Delayed hypersensitivity
- GI complications (diarrhoea)
- Renal complications
- CNS complications (seizure)
- Haemolytic anaemia
What can be given alongside penicillin to ensure effectiveness?
Beta- Lactamase inhibitors
Give some examples of macrolides (3)
- Erythromycin
- Clarithromycin
- Azithromycin
What is the mode of action for macrolides?
Inhibit RNA-dependant protein synthesis
What is the mode of resistance for macrolides?
- Decreased outer membrane permeability
- Efflux
- Alteration in rRNA
- Enzymatic inactivation by phosphotransferases
Are drugs from the penicillin family bacteriostatic or bactericidal?
Bactericidal
Are macrolides bacteriostatic or bactericidal?
Bacteriostatic
What are some side effects of macrolides? (6)
- GIT symptoms
- Skin rash
- Fever
- Eosinophilia
- Jaundice
- Transient hearing loss
What interactions do macrolides have with warfarin?
Potential for increase effect of warfarin because macrolides inhibit metabolism and clearance
What is the mode of action for Clindamycin?
Inhibit RNA-dependant protein synthesis
What is the mode of resistance for Clindamycin? (a lincosamide) (4)
- Resistance by decrease outer membrane permeability
- Alteration in rRNA
- Alteration in 50S ribosomal proteins of the receptor sites
- Enzymatic inactivation by transferase
What are some side effects of Clindamycin? (5)
- C. difficile colitis
- Allergic reaction
- Transient hepatitis
- Neutopenia
- Thrombocytopenia
What is the mode of action for Tetracyclines?
Inhibit bacterial protein synthesis (30S)
Are Tetracyclines bacteriostatic or bactericidal?
Bacteriostatic
What is the mode of resistance for Tetracyclines? (3)
- Resistance by efflux
- Ribosomal protection protein
- Enzymatic inactivation
What are some side effects of Tetracyclines? (6)
- GIT symptoms
- Photosensitivity
- Pigmentation
- Deposition in growing bone and teeth
- Superinfection
- Allergy
Name 2 examples of polyenes
- Amphotericin (IV)
- Nystatin (PO)
What is the mode of action for Nitroimidazoles?
Interact with nucleic acids and proteins causing breakage, destabilization and cell death
What is the mode of action for Nitroimidazoles?
Interacts with ergosterol and forms a transmembrane ion channel in the fungal membrane which increases membrane permeability causing leakage of cell contents and cell death
What are some side effects of Polyenes? (6)
- Anaphylaxis
- Nephrotoxicity
- GIT upset,
- Muscle and joint pain
- Anaemia
- Cardiovascular toxicity
What is the mode of action for Azoles?
Inhibit the synthesis of ergosterol
What are the 2 subtypes of Azoles?
- Imidazoles
- Tiazoles
Miconazole is an example of?
Imidazoles
Fluconazole is an example of?
Tiazoles
How do antivirals work? (5)
- Attachment
- Viral entry
- Viral uncoating
- Nucleic acid synthesis
- Assemble and release of viral particle
