Antimicrobials - B-lactams Flashcards
Cell wall synthesis can be targeted in bacteria using B-lactams. However, vancomycin cannot be used. True or false?
False - B-lactams and vancomycin can be used
It is more difficult to prevent bonds being formed than break them in a bacterial cell wall. True or false?
False - more difficult to break bonds than prevent them from being formed
Gram stain on gram positive bacteria cannot be washed out by acetone. True or false?
True
Gram stain on gram negative cannot be washed out by acetone. True or false?
False - can be
Are norcardiform bacteria gram positive or negative?
Positive
Give two examples of norcardiform bacteria.
M.tuberculosis and mycobacteria
The cross-link of polysaccharide chains on peptidoglycans is species dependent. True or false?
True
What sort of reaction forms crosslinks on peptidoglycans?
Transpeptidation
Give three examples of B-lactam antibiotics
Penicillins
Cephalosporins
Carbapenems
Who discovered penicillins?
Fleming
What was the main barrier Fleming faced when producing penicillin?
Cultivating the fungus
What was the antibacterial broth prepared from in Flemings discovery of penicillin?
penicillium notatum fungus
What are the three amino acids that make up penicillin G?
Cysteine
Valine
Phenylalanine
How do B-lactams work?
form covalent interactions with transpeptidase/carboxypeptidase
6-aminopenicillinic acid is a ____________ penicillin
semi-synthetic
6-aminopenicillinic acid has independent antibacterial activity. True or false?
False - can be built up in lab to produce amoxicillin
Penicillin G is resistant to B-lactamases. True or false?
False- sensitive to them
Which penicillin can be taste-masked?
Amoxicillin
Which class of B-lactamase enzymes is amoxicillin resistant to?
Class 1
Which two penicillins are resistant to all B-lactamases?
Flucloxicillin
Methicillin
1st generation cephalosporins are widely used today. True or false?
False - rarely used
2nd generation cephalosporins are administered orally. Are they gram positive or negative?
Negative
Are 3rd generation cephalosporins gram negative or positive?
negative
Cefaclor is a 2nd generation cephalosporin. Which bacteria is it mainly used against?
Haemophilus
Which generation of cephalosporins is ceftriaxone?
3rd generation
Carbapenems have narrow-spectrum activity. True or false?
False - broad-spectrum
Carbapenems are resistant to most B-lactamases. True or false?
True
Imipenem is rapidly deactivated by the kidneys unless administered with _______
cilastatin
Astreonam is the only monobactam. True or false?
True
Vancomycin is a ribosomal peptide. True or false?
False - non-ribosomal
Vancomycin is used to treat gram-negative infections only. True or false?
False - gram positive infections only
Vancomycin is usually injected. Why?
Because the digestive system hydrolyses peptides
Vancomycin can be used to treat MRSA. However, there is a preferred treatment. What is it?
rifampicin-vancomycin combination
What is oral vancomycin used for?
clostridium difficile (infections of the gut)
What is an alternative drug to vancomycin that has a very similar mode of action?
Teicoplanin
Vancomycin side effects may have been exaggerated early on. Why?
Due to impure preparations
