00:00 Let's move on to the macrolides antibiotics. 00:03 These macrolides antibiotics are very important group of medications because we use them all the time. 00:08 Specially in respiratory infections. 00:11 Now these agents are blocking the 50S unit from translation. 00:15 Important agents include erythromycin and clarithromycin. 00:19 They're rapidly eliminated from the body. 00:22 They're considered broad spectrum antibiotics. 00:25 And as I said before they're most commonly used in respiratory infections. 00:29 Azithromycin concentrates into macrophages and other tissues and it is actually eliminated quite slowly. 00:37 This particular medicine also effective in gonarrhea. 00:41 The nice thing about azithromycin is that you can actually give it as a three day set of medications but it will last for ten days. 00:48 So the killing activity actually lasts much longer than the drug is actually in the body. 00:55 Other medications are more narrow spectrum within this drug group. 00:59 The selectivity targets are generally gram positive anaerobes and aerobes. 01:04 And these are used often in clostridium difficile infections. 01:10 Let's talk about the resistance to macrolides antibiotics. 01:14 It's actually quite an interesting topic because of the mechanism and the resistance patterns. 01:20 Now you actually will develop ejector pump mechanisms in some bacteria that literally pump out the drug, the active drug out of the cell. 01:28 It's quite an interesting phenomenon. 01:30 The other thing that may happen in resistance patterns is changing the binding site of the macrolide by perhaps adding a methyl group. 01:38 Now the problem here is that there is a 100% cross resistance pattern between one macrolide and another. 01:45 So if for example you give a patient clarithromycin for a respiratory infection on week 1, they come back with resistance and you decide to try a different medication, there's going to be cross resistance between those two, say between clarithromycin and azithromycin. 02:01 There's partial cross resistance with drugs like clindamycin and the streptogramins as well. 02:08 And the resistance in the enterobactriaceae species and that is due to the production of drug destroying esterases. 02:16 Not because of the ejector pump. 02:19 So it's a slightly different mechanism but still 100% cross resistant pattern. 02:25 Let's move on to the ketolides. 02:26 Now the ketolides are structurally similar to the macrolides. 02:30 And I haven't put a separate triangle here. 02:32 Let's just say that that triangle is both for K and M. 02:35 It has the same mechanism of action and the same antibiotic spectrum as the macrolides as well. 02:41 Now a lot of times macrolides resistance strains are susceptible to the ketolides. 02:46 And there is an increase affinity to the ribosomes with the ketolides than with the macrolides. 02:51 They are also poorly ejected through ejector pores which is why we think these maybe really good choice for some people.
The lecture Macrolides and Ketolides – Bacterial Protein Synthesis Inhibitors (Antibiotics) by Pravin Shukle, MD is from the course Antimicrobial Pharmacology. It contains the following chapters:
What are bacterial resistance mechanisms to macrolides? Select all that apply.
What resistance mechanism have Enterobacteriaceae developed against macrolides?
What statement about azithromycin is INCORRECT?
5 Stars |
|
5 |
4 Stars |
|
0 |
3 Stars |
|
0 |
2 Stars |
|
0 |
1 Star |
|
0 |