L02 - Introduction, Overview & Mechanisms of Action of Classes of Antimicrobial Agents Flashcards
What two types of antibiotic inhibit cell wall synthesis? - Give an example
Beta Lactams (Penicillins) Glycopeptides (Vancomycin)
What four types of antibiotics interfere with DNA synthesis and replication? - Give an example
Sulphonamides (Sulphamethoxazole)
Diaminopyrimidines (Trimethoprim)
Quinolones (Ciprofloxacin)
Nitroimidazoles (Metronidazole)
What five types of antibiotics inhibit protein synthesis? - Give an example
Macrolides (Erythromycin) Aminoglycosides (Gentamicin) Tetracyclines (Doxycycline) Lincosamides (Clindamycin) Rifamycins (Rifampicin)
What types of antibiotics disrupt the cell membrane? - Give an example
Polymixins (Colistin)
Lipopeptides (Daptomycin)
Give three examples of Beta Lactam antibiotics
Penicillins
Cephalosporins
Carbapenems
Give two examples of Glycopeptide antibiotics
Vancomycin
Teicoplanin
What are the three main types of Beta Lactam structure? - Give an example
Thiazolidine Ring - Penicillins
Dihydrothiazine Ring - Cephalosporins
Carpaneme Core - Carbapenems
Describe the features of a Thiazolidine Ring Beta Lactam antibiotic
Ring is 3 carbons, 1 nitrogen, 1 sulphur
Modifiable residue to increase stability/spectrum
Describe the features of a Dihydrothiazine Ring Beta Lactam antibiotic
Ring is 4 carbons, 1 nitrogen, 1 sulphur
2 modifiable residues to increase stability/spectrum
Describe the features of a Carbapenem Core Beta Lactam antibiotic
Ring is 4 carbons, 1 nitrogen
3 modifiable residues to increase stability/spectrum
Describe how Gram staining distinguishes between bacteria
Gram +ve bacteria (blue) have a thick cell wall
Gram -ve bacteria (red) have a thin cell wall with 2 membranes (outer and inner)
Name and describe the two types of Gram +ve cocci
Staphylococci (Clumps)
Streptococci (Strips)
Name and distinguish the two types of Staphylococci
S. aureus (coagulase +ve)
Coagulase Neg Staph (coagulase -ve)
Name and distinguish the three types of Streptococci
Beta Haemolytic (Complete breakdown of blood) Alpha Haemolytic (Partial breakdown of blood) Non Haemolytic (No breakdown of blood)
Name the three common types of Gram +ve Bacilli
Listeria
Cornyebacterium
Clostridium
Give two examples of Gram -ve Cocci
N. meningitidis
N. gonorrhoea
Give four examples of Gram -ve Bacilli
Bacteroides
Pseudomonas
Haemophilus
Enterobacteriae
Give four examples of Enterobacteriae
E. Coli
Klebsiella
Enterobacter
Proteus
Define the atypical bacteria and give two examples
Atypical bacteria do not have a cell wall
Examples are Mycoplasma & Chlamydia
(Cannot treat with a/b that target the cell wall)
Describe the MoA of Beta Lactam antibiotics
Bacteria produce cell walls in layers, joined together by amino acid side chains
The chains are linked by Penicillin Binding Protein
Beta Lactams block PBP and expose the cell to osmotic stress
What are Beta Lactamases?
Beta Lactamases are bacterially produced compounds that confer antibiotic resistance
How do Beta Lactamases confer antibiotic resistance? - And how can we avoid this?
Beta Lactamases hydrolyse the Beta Lactam ring, causing inactivation
We can co-administer Beta Lactamase inhibitors to avoid resistance (Clavulanic Acid)
Describe the MoA of Glycopeptide antibiotics
Glycopeptide antibiotics bind to the amino acid side chains on cell wall layers, preventing the binding of PBP
Give two examples of Macrolide antibiotics
Erythromycin
Clarithromycin
Give two examples of Tetracycline antibiotics
Doxycycline
Tigecycline
Give three examples of Aminoglycoside antibiotics
Gentamicin
Amikacin
Tobramycin
Describe the structure of Macrolide antibiotics and their target
Large ‘macro’ ring structure forms the core
Target the 50s Ribosome subunit
Many chemical derivatives
Describe the structure of Tetracycline antibiotics and their target
Four ‘tetra’ ring structure
Target the 30s Ribosome subunit
Avoid in pregnancy/children (teeth discolouration)
Describe the structure of Aminoglycoside antibiotics
Three rings linked via oxygen residues
Target the 30s Ribosome subunit
Narrow therapeutic window (toxicity)
What two types of antibiotics target Nucleotide Synthesis? - Give an example
Sulphonamides (Sulphamethoxazole)
Diaminopyrimidines (Trimethoprim)
What type of antibiotics inhbits DNA Gyrase? - Give an example
Quinolones (Ciprofloxacin)
What is the MoA of Sulphonamides and Diaminopyrimidines?
Sulphonamides/Diaminopyrimidines act as Folate Synthesis inhibitors
Avoid Diaminopyrimidines in 1st trimester
What is the MoA of Quinolones (and Fluoroquinolones)?
Quinolones/Fluoroquinolones stop DNA unwinding before replication
Define Fungi and describe their grouping
Fungi are eukaryotic cells, grouped as:
Yeasts
Moulds
Dimorphic
What are the main types of Antifungals? - Give an example
Azoles (Fluconazole)
Polyenes (Amphotericin B)
Echinocandins (Caspofungin)
What are the two types of Azoles?
Triazoles
Imidazoles
Give two examples of Triazoles
Fluconazole
Voriconazole
Give two examples of Imidazoles
Clotrimazole
Miconazole
Give two examples of Polyenes
Amphotericin B
Nystatin
Give two examples of Echinocandins
Caspofungin
Micafungin
Describe the structure & MoA of Triazoles
Triazole rings have 2 carbons, 3 nitrogens
They inhibit ergosterol synthesis via Lanosterol (essential for fungal cell membranes)
Describe the structure & MoA of Polyenes
Polyenes are macrocyclic and form C=C
They bind ergosterol (essential for fungal cell membranes)
Describe the structure & MoA of Echinocandins
Echinocandins are macrocyclic with a carbon tail
They inhibit glucan synthesis in the cell wall
Give four examples of human mycoses
Tinea Candidiasis Mucormycosis Aspergillosis (Moving superficial to deep)