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00:00 Let's talk about cephalosporins. 00:03 Now we divide the cephalosporins into first, second, third and fourth generations. 00:08 And in general the first generation are more gram positive active. 00:11 And the fourth generation tend to be more gram negative. 00:14 And there is a spectrum in between. 00:16 Now cefazolin and cephalexin are first generation agents. 00:20 They are gram positive active. 00:22 And they are very useful in surgical infections because a lot of surgical infections come from Staphylococcus aureus and other skin surface agents. 00:31 There's minimal effectiveness of these drugs against gram negative bacteria. 00:38 The second generation, the probably typical agent is cefotetan. 00:42 They are much more active against gram negative. 00:45 And what's interesting is they'll often work again, also work against haemophillus influenzae which is one of the major causes of pneumonia in many of our patients. 00:53 Other agents are in this group include, cefuroxine. 00:58 Now if you notice very carefully, I've underlined two of the agents. 01:01 I've underlined cefotetan and I underlined cefuroxine. 01:05 These are the drugs you need to know. 01:07 Cefuroxine is commonly used in pneumonia treatment. 01:13 The third generation agents are more gram negative active. 01:17 Once again I've underlined two of them. 01:19 Cefotaxine and ceftriaxone. 01:21 Cefotaxine is kind of our go to drug. 01:24 It's a very, very good gram negative agent. 01:27 It will often work against organisms that are resistant to penicillin. 01:31 We only use these drugs in serious infections. 01:34 And in general they're only available in intravenous form. 01:39 Let's move on to the fourth generation cephalosporins. 01:44 So cefepime is your prototypical agent. 01:46 And notice that I've underlined it because it's a drug that I want you to know. 01:50 These are more resistant to the beta lactamases. 01:53 And they're also active against Entrobacter, Haemophillus and Neisseria. 01:58 Ceftaroline has activity in infections caused by methicillin resistant staphylococci. 02:04 So we sometimes use it in that case. 02:06 Now remember that the cephalosporins are less likely to cause rashes and allergic reactions when compared to the penicillins. 02:14 Penicillins seems to be associated quite heavily with rash and other allergic activity. 02:21 Other beta lactamases drug include aztreonam. 02:24 Now this is not commonly used in clinical practice. 02:27 And you don't hear much about it. 02:29 It is a drug that you need to know. 02:31 Why? Because it's resistant to beta lactamases which is huge. 02:34 There is no activity against gram positive drugs with this particular agent. 02:39 It binds to penicillin binding protein type 3 or PBP3. 02:45 The half life is prolonged in renal failure. 02:48 So you can adjust your medication accordingly. 02:51 Adverse events include GI upset, vertigo, headache. 02:56 But the nice thing is once again, it's resistant to beta lactamases and there's no cross out allergy with the penicillins.
The lecture Cephalosporins – Cell Wall Synthesis Inhibitors (Antibiotics) by Pravin Shukle, MD is from the course Antimicrobial Pharmacology. It contains the following chapters:
Different generations of cephalosporins are active against different organisms. What are 4th generation cephalosporins active against that 1st generation cephalosporins are not?
Which of the following cephalosporins is active against methicillin resistant staphylococci?
Which of the following statements about Aztreonam is INCORRECT?
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I loved the lecture so much! But sir, isn't there something called as fifth generation cephalosporins? And please please pleaaaase add more questions to each chapter. Only 3 questions per chapter is not enough. Please consider this sir.
