00:00 / 00:00
Antimetabolites: Sulfonamides and trimethoprim
Cell wall synthesis inhibitors: Cephalosporins
Cell wall synthesis inhibitors: Penicillins
DNA synthesis inhibitors: Fluoroquinolones
DNA synthesis inhibitors: Metronidazole
Mechanisms of antibiotic resistance
Miscellaneous cell wall synthesis inhibitors
Miscellaneous protein synthesis inhibitors
Protein synthesis inhibitors: Aminoglycosides
Protein synthesis inhibitors: Tetracyclines
Miscellaneous antifungal medications
Anti-mite and louse medications
Integrase and entry inhibitors
Non-nucleoside reverse transcriptase inhibitors (NNRTIs)
Nucleoside reverse transcriptase inhibitors (NRTIs)
0 / 37 complete
1st Generation Cephalosporin
2nd Generation Cephalosporin
3rd Generation Cephalosporin
4th Generation Cephalosporin
5th Generation Cephalosporin
Chlamydia spp. p. 146
Chlamydia trachomatis p. , 731
for gonococci p. 140
for Haemophilus influenzae p. , 140
mechanism and use p. 186
mechanism (diagram) p. 184
meningitis p. 177
meningococci p. 140
prophylaxis p. 194
typhoid fever p. 142
ceftriaxone p. 186
Cephalosporins are antibiotics which got their name from a mold known as cephalosporium, from which they were originally extracted.
They belong to the pharmacological group of beta-lactam antibiotics.
What all beta-lactams have in common is a beta-lactam ring in their structure, which gives them their name, and also the mechanism of action - which is the inhibition of cell wall synthesis in bacteria.
So, our body is made out of eukaryotic cells.
Bacterias belong to a different type of cells, called the prokaryotes.
From the outside to inside, they have a slimy capsule made out of polysaccharides.
Then, there’s a cell wall in most prokaryotes.
A cell wall is a structural layer, which encapsulates bacteria, and offers structural support and protection, like a suit of armor. It also offers some filtering capabilities, as not everything can pass freely through it.
Finally, on the inside, there’s a pretty standard cell membrane.
Should something happen to this wall, say, if its synthesis mysteriously stopped, its owner’s life expectancy will turn to that of a snowflake in Sahara. And that’s exactly what we’re hoping to do.
Bacterial cell walls are made of a substance called peptidoglycan, or murein.
Peptidoglycan is a very strong, crystal lattice resembling three-dimensional structure, composed out of long using “strands” of amino polysaccharides, running in parallel.
These are made of made out segments of N-acetylglucosamine, or NAG, and N-acetylmuramic acid, or NAM, in an alternating pattern - so, NAG, NAM, NAG, NAM, and so on, like a pearl necklace.
These strands are also cross linked by short, four to five amino acids long, or tetrapeptide chains, protruding from NAM subunits.
Those pentapeptides reach out and link to pentapeptide chains from the neighboring strands, for structural stability, a sub-process known as transpeptidation.
All of this is made possible by enzymes called DD-transpeptidases, that are also better known as penicillin binding proteins, or PBPs.
These enzymes are highly specialized to grab and hold two pentapeptide ends and fuse them together, creating a stable link between the two polysaccharide strands, essentially creating peptidoglycan.
If you imagine the enzyme as a “lock”, then the pentapeptide chain would be a key, so it fits perfectly in, and allows the enzyme to do its work.
In essence, all beta lactam antibiotics, like the cephalosporins, somewhat resemble the tetrapeptide chains.
Inside the bacteria, PBP enzymes will mistakenly bind to the beta lactams antibiotic molecule instead of a tetrapeptide and stick inside the PBP forever, like chewing gum in a keyhole, permanently disabling it.
As more and more of PBPs get disabled, the crosslinking fails to occur, and the wall becomes weak and unstable.
Latest on COVID-19
Nurse Practitioner (NP)
Physician Assistant (PA)
Create custom content
Raise the Line Podcast
Copyright © 2024 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Cookies are used by this site.
Terms and Conditions
USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.