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Antibacterials: inhibitors of bacterial cell wall synthesis
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- 1Which group of antibiotics do cephalosporins have the same mechanism of action as?Penicillins, as they are a large group of natural and semi-synthetic β-lactam drugs too.
- 2How do cephalosporins inhibit bacterial cell wall synthesis?By inhibiting transpeptidases, preventing N-acetylmuramic acid cross-linking, resulting in cell lysis due to osmotic pressure. Peptidoglycan is composed of alternating N-acetylglucosamine and N-acetylmuramic acid residues, and the N-acetylmuramic acid residues cross-link with short peptide side chains. Cephalosporins form covalent bonds with transpeptidases which catalyse the cross-link formation, so the cell wall cannot resist the high osmotic pressure and the bacterial cell lyses.
- 3Cephalosporins are broad-spectrum. What does this mean?They can be used against a wide range of both Gram-positive and Gram-negative bacteria.
- 4List some of the conditions that cephalosporins can be used to treat.Septicaemia, meningitis, urinary and biliary tract infections, peritonitis, and some STIs such as gonorrhea (caused by Neisseria gonorrheae), as well as nosocomial infections such as Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae.
- 5Is there wide-spread resistance to cephalosporins?No. Although resistance to cephalosporins does occur, such as its low affinity for methicillin-resistant Staphylococcus aureus which has a modified transpeptidase enzyme, many cephalosporins are stable to β-lactamases which render penicillins ineffective, so their use is maintained.
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- From the 29-01-14 Drugs and Disease lecture.
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- sophietevans
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