Antibiotics 1 Flashcards
Describe the characteristic structures of gram-positive bacterium [2]
- thin cell membrane
- thick peptidoglycan cell wall
Describe the characteristics structures of gram-negative bacterium [4]
- thin cell membrane
- thin peptidoglycan cell wall
- thick periplasm
- outer membrane
What is a periplasm? [1]
concentrated gel-like matrix in the space between the inner cytoplasmic membrane and the outer membrane of the bacteria
What do antibiotics tend to target on a bacterium? [4]
- cell wall peptidoglycan
- metabolism
- DNA
- ribosome
What are the 2 types of antibiotics (classifed in terms of action)? [2]
- bactericidial antibiotics
- bacteriostatic antibiotics
How do bactericidal antibiotics work? [2]
- Achieve sterilisation of the infected site by directly killing bacteria
- Lysis of bacteria can lead to release of toxins and inflammatory material
How do bacteriostatic antibiotics work? [2]
- Suppresses growth but does not directly sterilise infected site
- Requires additional factors to clear bacteria → immune mediated killing
Define the term: antibiotic spectrum [1]
The range of bacterial species effectively treated by the antibiotic
What are the features of broad spectrum antibiotics? [2]
- hints:
- definition?
- function?
- Antibiotics that are active against a wide range of bacteria
- Treat most causes of infection but also have a substantial effect on colonising bacteria
What are the features of narrow spectrum antibiotics? [3]
- hint:
- definition?
- when is it useful?
- limitations?
- Antibiotics that are active against a limited range of bacteria
- Useful only where the cause of the infection is well defined
- Have a much more limited effect on colonising bacteria
Give examples of gram negative bacteria [5]
- pseudomonas
- haemophilus
- neisseria
- other coliforms
- E. coli
Give examples of gram positive bacteria [3]
- staphylococcus
- enterococcus
- streptococcus
Give examples of anaerobes [2]
- clostridium
- bacteroides
What are the 3 types of antibiotic therapies? [3]
- guided therapy
- empirical therapy
- prophylactic therapy
What is guided therapy? [1]
- hint: what is it dependent on?
Depends on identifying cause of infection and selecting agent based on sensitivity testing
What is empirical therapy? [2]
- hint:
- definition?
- when is it used?
- Best (educated) guess therapy based on clinical/epidemiological acumen
- Used when therapy cannot wait for culture
What is prophylactic therapy? [1]
preventing infection before it begins
What are the types of antibiotic associated harm? [2]
- disruption of bacterial flora
- development of C. difficile colitis
Overgrowth of bacterial flora with yeasts can lead to…? [1]
thrush
Overgrowth of bacterial flora of the bowel can lead to…? [1]
diarrhoea
What type of antibiotic is used for guided therapy? Narrow spectrum or broad spectrum? [1]
narrow spectrum antibiotic
What type of antibiotic is used for empirical therapy? Narrow spectrum or broad spectrum antibiotics? [1]
broad spectrum antibiotic
What are the 5 types of β-lactam antibiotics? [5]
- Penicillin
- Cephalosporins
- Carbapenems
- Monobactams
- β-lactam/β-lactamase inhibitor combinations
Give 3 examples of penicillin (β-lactam antibiotics) [3]
- Benzylpenicillin
- Flucloxacillin
- Amoxicillin
Give an example of cephalosporins (β-lactam antibiotics) [1]
Ceftriaxone
Give an example of carbapenems (β-lactam antibiotics) [1]
meropenem
Give an example of monobactams (β-lactam antibiotics) [1]
aztreonam
Give 2 examples β-lactam/β-lactamase inhibitor combinations [2]
- co-amoxiclav
- piperacillin/tazobactam
Describe the mechanism of action of ß-lactam antibiotics [4]
all ß-lactams share the same branching structure of peptidoglycan which acts to inhibit crosslinking of cell wall peptidoglycan leading to lysis of bacteria
- it is bacteriostatic
Define beta-lactamases [1]
enzymes that lyse and inactivate beta-lactam drugs
Which organisms commonly secrete beta-lactamases? [2]
- gram -ve bacteria
- S. aureus
What is the complication beta-lactamase secretion? [1]
high level resistance to antibiotic (usually total antibiotic failure)
How are ß-lactam antibiotics typically administered? [2]
- most are given intravenously (IV)
- some can be given orally
- amoxicillin
- flucloxacillin
- however vomiting limits dose
How are ß-lactam antibiotics usually excreted? [2]
- Usually excreted unchanged in urine
- Some also via bile
What is the half-life of the β-lactam: benzylpenicillin? [1]
1 hour
What is the half-life of the β-lactam: ceftriaxone? [1]
8 hours
What are the potential GI toxicity adverse effects of β-lactam antibiotics? [3]
- nausea/vomiting
- diarrhoea
- cholestasis
What are the potential hypersensitivity adverse effects of β-lactam antibiotics? [3]
- type 1 hypersensitivity
- urticaria
- anaphaylaxis
- type 4 hypersensitivity
- mild to severe dermatology
- interstitial nephritis
What are the potential infection adverse effects of β-lactam antibiotics? [2]
- candidiasis (oral/vulvovaginal)
- clostridium difficle infection
What are the miscellaneous rare adverse effects of β-lactam antibiotics? [3]
- seizure
- haemolysis
- leukopaenia
What is a urticarial rash? [1]
raised, itchy rash that appears on the skin in type 1 hypersensitivity
How is benzylpenicillin typically administered? [1]
via IV
What type of agent is benzylpenicillin?
Narrow spectrum or broad spectrum? [1]
narrow spectrum antibiotic
Which bacteria are benzylpenicillin effective at targeting (incl. which class each bacteria is in)? [3]
- Streptococcus = gram +ve
- Neisseria = gram - ve
- Clostridium = anaerobe
How is amoxicillin administered? [1]
orally
Which bacteria are amoxicillin effective at targeting (incl. which class each bacteria is in)? [5]
- Streptococcus = gram +ve
- Enterococcus = gram +ve
- Neisseria = gram -ve
- Haemophilus = gram -ve
- Clostridium = anaerobe
What is unique about flucloxacillin? [1]
it is a synthetic penicillin developed to be resistant to beta-lactamase produced by staphylococci
Which bacteria are flucloxacillin effective at targeting (incl. which class each bacteria is in)? [2]
- Staphylococcus aureus (except MRSA) = gram +ve
- Streptococci = gram +ve
Beta-lactamase inhibitors are combination drugs that are often co-admininstered with penicillin
Name 2 beta-lactamase inhibitors and state which drugs each are made of [4]
- Clavulanic acid & amoxicillin = co-amoxiclav
- Tazobactam & piperacillin = tazocin
Which bacteria are co-amoxiclav effective at targeting (incl. which class each bacteria is in)? [9]
- Streptococcus = gram +ve
- Enterococcus = gram +ve
- Staphylococcus = gram +ve
- Neisseria = gram -ve
- Haemophilus = gram -ve
- E. coli = gram -ve
- Other coliforms = gram -ve
- Clostridium = anaerobe
- Bacteroides = anaerobe
Ceftriaxone is 3rd gen. cephalosporin antibiotic.
Which bacteria are ceftriaxone effective at targeting (incl. which class each bacteria is in)? [8]
- Streptococcus = gram +ve
- Staphylococcus (except MRSA) = gram +ve
- E. coli = gram -ve
- Neisseria = gram -ve
- Haemophilus = gram -ve
- Other coliforms = gram -ve
- Clostridium = anaerobes
- Bacteroides = anaerobes
Aztreonam is the only monobactam antibiotic out there.
Which bacteria are aztreoname effective at targeting (incl. which class each bacteria is in)? [5]
- E. coli = gram -ve
- Neisseria = gram -ve
- Haemophilus = gram -ve
- Pseudomonas = gram -ve
- Other coliforms = gram -ve
Describe the mechanism of action of vancomycin [1]
Inhibits cell wall formation in Gram +ves only
How is vancomycin typically administered? [1]
administered intravenously (IV)
Which bacteria are vancomycin effective at targeting (incl. which class each bacteria is in)? [4]
- Streptococcus = gram +ve
- Staphylococcus = gram +ve
- Enterococcus = gram +ve
- Clostridium = anaerobe
What are the potential complications of vancomycin toxicity? [3]
- Nephrotoxicity → more likely with higher doses
- Red-man syndrome
- Occurs if injected too rapidly
- Anaphylactoid reaction
- Very rare now infusion rates slow
- Occurs if injected too rapidly
- Ototoxicity (rare)
